How Green Is Your Ride?

This is a guest post by Jeff Radtke. Jeff is an independent researcher holding BS degrees in Nuclear Engineering and Physics, and an MS in Nuclear Engineering and Engineering Physics. He is a member of the American Physical Society and The Institute of Electrical and Electronic Engineers. In addition to recent work with electric bicycles, for the past 27 years he has been designing and building nuclear instruments for materials studies, medical, physics and educational applications. He is a longtime lurker, and recent poster on TOD as CyclemotorEngineer.

This post is based on an article published in 2008 in the peer-reviewed "Open Fuels and Energy Science Journal" as The Energetic Performance of Vehicles. The article showed that the accepted vehicle performance metric known as the Gabrielli-von Karman Limit is the same as twice the maximum vehicle kinetic energy divided by maximum motor output power. This result was not found in an extensive literature search.

This type of analysis is useful because it is easy to factor in conversion efficiencies and payload versus tare weight. Rather than use motor output power, one can use the thermal power theoretically available in the flowing fuel. EROI may be factored in, as well as GHG emissions. Analysis may be completed at the level of individual trips, vehicles, or an entire system with resource extraction, infrastructure development, manufacturing and direct fuel use.

Kinetic energy divided by required power is considered a residence time for the input energy in the utilized form. This model may provide an intuitive understanding of energy use. Residence time for anything in a container is the quantity residing divided by the flow rate. This is as true for a vehicle containing kinetic energy as it is for a mountain lake holding melted glacier, or the CO2 present in our atmosphere.

Common Vehicle Performance Criteria

Payload Mass.  In the US, the automobile is most commonly used to carry one person, even though it is capable of far greater payloads.  In this analysis, automobiles are considered personal vehicles hauling a 70 kilogram payload mass.  By including payload mass in a performance metric, it is possible to obtain an economically relevant comparison means.  In this article, Mp denotes payload mass.    

Speed.  Vehicle speed may be the most obvious performance metric.  The most fuel conservative choice may not be the best, since time is also a finite resource.  For most automobile trips, speed is governed by safety considerations, especially in the presence of other vehicles.  Congested urban roadways result in an average speed in US cities of only about 20 miles per hour [8.9 meters per second].  In this article, <v> denotes average speed.

Fuel Economy.  Fuel economy is a complex performance metric.  It depends on payload mass, speed, and host of vehicle characteristics.  Payload density can effect fuel economy indirectly by changing vehicle displacement requirements, as reflected in shipping carrier dimensional weight charges.  Variations in speed will decrease fuel economy, but the utility is dependent on average speed.   For example, a trip via expressway is no more or less useful than a trip at same average speed through a series of stoplights.  The most familiar unit used to express fuel economy is miles per gallon of gasoline.  Since a gallon of gasoline typically contains 133 million Joules of thermal energy, fuel economy may be expressed in meters per Joule.  Fuel economy is length traveled divided by thermal energy used, and is denoted below as l/Eth.  

Vehicle Energetic Performance

Definition.  The above performance criteria are combined via multiplication.  The result is a ratio of the benefits of vehicle use (payload mass, average speed and distance moved) to the cost, expressed in universal currency as thermal energy.  Vehicle energetic performance (Q) is:

(1)           Q = Mp  <v> l /Eth

G-K Limit.  Q is an economically meaningful refinement of a vehicle performance “limit” known as the G-K limit.1  This limit was first described in 1950 by the former president of Fiat Motors, Guiseppi Gabrielli and the great aerodynamicist Theodore von Karman.2

Click to see PDF version

Table 1.  Table 1 lists the energetic performance of various vehicles.  Some vehicles are listed more than once to indicate different speed or payload.  Since greenhouse gas emissions are tied to thermal energy use and fuel choice, it is possible to compare emissions for various transport means provided that primary fuel choice is known.  Electric vehicles are thus compared by estimating thermal energy utilized in a matrix of powerplants fueled by various means to produce the electricity that charges vehicle batteries.

Click for larger image

Figure 1.  Figure 1 graphically compares these vehicles.  Logarithmic scales were chosen for both axes not to distort, but to fit the vastly differing numbers on a single screen.  A factor of ten, for example, is the same length everywhere on this graph.  Diagonal lines on this logarithmic graph represent the product of values from each axis, which is Q.  Payload mass is indicated by another logarithmic scale using color.  Notice that supertankers, bicycles and urban automobiles all travel at about 20 miles per hour, but fuel economy differs by a factor of 3000.

Energy Primer

Energy Forms.  Energy may take many forms, but the most familiar are thermal and mechanical.  Energy can be released in thermal form by burning a fuel to raise the temperature of something.  An increase in temperature is another way of saying that the average speed of atoms increase in a random fashion.  This thermal energy can be converted to mechanical or kinetic form, moving all of the atoms comprising something in a uniform manner by, for example, spinning it or sending it down a road.  Thermal energy is less organized than mechanical energy, and is said to have a lower quality.  Conversion of thermal energy to mechanical energy in modern large-scale powerplants is typically 30-40% efficient.  Automobile engines exhibit considerably less efficiency.  Mechanical energy can be converted to electrical energy very efficiency, often about 90%, since these two forms are both highly organized.  

Rejection.  When discussing energy use, it is important to be clear about which form of energy is being described. Powerplant engineers typically do this by adding a subscript or parenthetic (th), (m), or (e) to powerplant specifications. For example, a 1000 Megawatt(e) powerplant may also be described as a 3000 Megawatt(th) powerplant. The apparently lost 2000 Megawatts is said to be “rejected” power. 

Waste.  It is a theoretical impossibility to convert thermal energy to mechanical form without rejection loss, which increases as the temperature of a thermal energy source decreases.    Energy rejected in conversion between forms is very different from energy wasted because of forgetfulness or oversight.  Energy is rejected at the powerplant because of natural laws, but energy may be wasted at the point of use because a light is left on when nobody is there to see by it.  Similar end-use waste occurs in driving a two ton car when a 60 pound electric bicycle would do the same job faster, and with much less energy.

Energy Measurement.  Just as distance can be measured with various units, such as centimeters, feet or fathoms, energy may be measured in a number of ways.  If a thing is heated or moved, a transfer of energy is involved.  This energy may be inferred from measurements of the things mass and temperature or distance moved over a period of time time using instruments calibrated in whatever measurement system is convenient. Various academic disciplines or trades are accustomed to seeing energy measured in different units, resulting in some confusion.  A physicist might use the Joule, or the electron-volt.  A chemist may use the calorie.  A nutritionist may use the Calorie, which is the same as 1000 chemist-style calories, or one kcal.  A heating contractor may use the BTU.  An electric utility may use the kiloWatt-hour.  A motor manufacturer might use the horsepower-hour.  A mechanical engineer might use the foot-pound.  A nuclear engineer might use atomic mass units.  An electrical engineer might use watt-seconds.  An energy macro-economist might use the Quad, shorthand for a Quadrillion BTU.  All of these units describe the same physical parameter, energy.  The most standard international unit of energy is the Joule, which is the energy transferred when a single kilogram mass is dropped one 102 centimeters to the earth’s surface. 

Power.  Another source of confusion results from the terms power and energy.  Power is the rate of energy use, or energy flow rate, in a system.  Given the preceding plethora of energy units, and the variety of ways time is described, power units may appear confusing indeed.  The most standard international unit of power is the Watt, which is one Joule flowing per second. 

Power Measurement.  Power may be measured over a long period of time, such as a year, in which case it is an average.  Peak or instantaneous power is measured over a period which is comparable to the response time of the energy system.  Peak power is often much higher than average power.  A healthy adult, for example, is capable of producing 800 Watts of mechanical power for ten seconds, but a yearly average power of only about 33 Watts. 

Physical Meaning of Energetic Performance

Kinetic Energy.  The energetic performance, Q, may be calculated for steady state (cruising) conditions by multiplying numerator and denominator in equation 1 by the elapsed time.  Since distance covered divided by elapsed time is speed, and energy transferred divided by elapsed time is power Pth, equation 1 becomes:

(2)           Q = Mp v2 / Pth

Because conditions are steady state, the use of average values is redundant.  The numerator may be recognized by any student of general physics as twice the kinetic energy of the payload.

Why Seconds?  Q is expressed in seconds, and it is natural to ask what this might mean.  It turns out that the average residence time of a physical substance flowing into a full container is routinely calculated as the container size divided by the flow rate.  This concept of residence time can also be applied to the abstraction we call energy, since a moving mass is a container of energy.  Steady-state Q is twice the time during which fuel thermal energy resides as payload kinetic energy.     

Figure 2.  The complex flow of energy in an automobile traveling at highway speed is represented in figure 2. The kinetic energy of a vehicle and its payload is converted back to thermal energy through friction, either with the surrounding environment or between moving parts on the vehicle.  As a passenger in a conventional automobile, your body contains kinetic energy that was derived from burning gasoline.  The length of time this energy stays in your body decreases if you choose to upgrade to a sporty model, which requires a higher fuel flow to maintain a given speed.

Click for larger image. Image available with better resolution in this link.

Figure 3.  Equation 2 suggests another way to depict data presented in table 1, organizing according to vehicle power and payload kinetic energy.  Effective values for the residence time of energy were calculated from average speeds and plotted in figure 3.  In this log-log plot, diagonals are drawn to represent the ratio of kinetic energy to thermal power. Economies of scale are evident as the high power and energy vehicles which lie in the upper right corner tend to have significantly longer residence times than the much smaller personal vehicles in the lower left. 

Reversibility.  The Voyager 1 spacecraft has been traveling in the essentially frictionless environment of deep space for decades.  The average power used to move to its present distance from earth is the booster fuel energy content divided by this elapsed time.  Residence time for this energy in this vehicle will only increase with time as the vehicle is in a state of perpetual motion.  All of the other vehicles described lose their kinetic energy through friction with the surrounding environment.  Kinetic energy returns to thermal form in these utilization processes, as quantified by the residence time.  The most reversible processes change their state with the least transfer of energy, and energetic residence time is a measure of this reversibility.


Performance Incorporates Efficiency and More.  Performance describes the utilization of energy, and efficiency describes the conversion of energy.  Whether directly or indirectly, performance measurement includes efficiency measurements, but efficiency measurements do not include performance.  Voyager 1 demonstrates that there is no limit to energetic performance.  While efficiency is often used colloquially to describe performance, any true efficiency metric must lie between zero and one. 

Figure 4.  Energetic residence time measures the utilization effectiveness of an energy resource, and is the ratio of a sustained energy benefit to the corresponding rate of resource consumption.  

Analysis bounds may be defined along various time scales, and with respect to many levels of resource use, so as include EROI, emissions, or other external cost considerations. Average values can be calculated for a vehicle, single trip, or an entire transportation system.   Comprehensively applied, it would be useful in a long-term comparison of our existing transportation paradigm to a hypothetical, dominated by ultra-light personal vehicles and robotic couriers. In the most optimistic scenario, energetic performance may measure of how much more is accomplished with how much less.

Vehicle Characteristics.  This analysis shows that light personal vehicles perform far better than heavy ones.  Vehicle and infrastructure embodied energy were not considered, and such an inclusion would make light vehicles appear even more attractive.  Since people tend to travel individually when possible, and energy resources are becoming increasingly scarce with respect to demand, it would appear that personal vehicles of the future will be very light by today’s standards.  High performance vehicles also tend to be compact and streamlined.  Commercial airliners perform well because people are willing to crowd themselves in an aerodynamically optimized fuselage for fast, long distance travel.  The greatest gains in performance may be obtained by redefining vehicle use mode, tare weight, shape and dimensions, rather than changes to vehicle motor or fuel system.

[1]  Radtke, J.L.  The Energetic Performance of Vehicles.  Open Fuels and Energy Science Journal 1, 11-18 (2008).

[2]  Gabrielli, G., von Karman, T. What Price Speed? Mechanical Engineering 72, 775-781 (1950).

Any chance we could get links to high resolution images of figures 1 and 3?

Edit: I see they are in the PDF so never mind...

This is a fantastic post BTW!

He probably should have given this link:

He also has this PDF with hi-res:


Below are links to high resolution graphs which are old versions of Figs 1 and 3, respectively.

I am looking into inclusion of the more current versions as direct links to high resolution graphic files. Thank you for the compliment!

I inserted higher resolution graphics, if you click on the Figures 1 and 3. The larger versions have "lg" in the names. This seems to produce a reasonably viewable graphic for Figure 1, but Figure 3 is still hard to read. The link I put up for Figure 3 ( mentioned above) seems to be pretty readable, if you enlarge it. It may be an old version, though.

Thanks Gail. Below is link to high resolution version of current Fig 3. Click twice for maximum magnification.

Vehicle Characteristics. This analysis shows that light personal vehicles perform far better than heavy ones. Vehicle and infrastructure embodied energy were not considered, and such an inclusion would make light vehicles appear even more attractive. Since people tend to travel individually when possible, and energy resources are becoming increasingly scarce with respect to demand, it would appear that personal vehicles of the future will be very light by today’s standards. High performance vehicles also tend to be compact and streamlined. Commercial airliners perform well because people are willing to crowd themselves in an aerodynamically optimized fuselage for fast, long distance travel. The greatest gains in performance may be obtained by redefining vehicle use mode, tare weight, shape and dimensions, rather than changes to vehicle motor or fuel system.

One can see how far vehicle manufacturers have to go in this respect when one takes a quick look at GM 2010 models.
Consumer demand still dictates a certain degree of comfort and safety that keeps vehicle weight high.

Changes to use mode, tare weight, shape and dimensions are exemplified by these:

Personal Vertical Takeoff and Landing (VTOL)

Two seats, too light to be a car:

I calculated NASA Puffin performance based on battery chemistry and weight, along with cruise speed and range. Aptera did not share such specs.

Fantastic post. Thank you. Do you have any references relative to comparisons of oil to gas pipelines?
It seems logical that gas would travel as a volume of energy much faster.

Improvements in natural gas combustion engines and fuel delivery systems should allow us to continue to enjoy the safety of our vehicles, and not have to drag around large battery cells.

None of these vehicles will ever be suitable for mass personal transportation, because of the issue of safety.

The Ford F-Series was the highest selling vehicle last year and probably will be this year (F-150 gross vehicle weight rating (lbs) 6,450) exemplifies the type of vehicle that these others will have to compete with for road space in the future. This makes for a dangerous situation because of the weight disparity in collision, regardless of the frame construction or crumple zone affordances of the light weight vehicle.

I do worry about how my Prius will hold up in a collision with one of these monsters.

None of these vehicles will ever be suitable for mass personal transportation, because of the issue of safety.

Actually, these vehicles are eminently suited to mass transportation, it is the F-series trucks that are NOT suited.
Small light cars can be built very safe - look at F1 and Indy cars, they weigh about 1100lbs, and drivers regularly walk away from 100+mph crashes.

There will always be bigger vehicles on the road (semi trailers etc) so we shouldn't let that stops us from building and driving small efficient ones.

Aside from the possibility of a collision with an F-150 truck, I'll bet the Aptera is safer in almost any type of single vehicle accident, is less likely to roll over, handles better, stops faster etc etc. And, of course, universal driver education, and licence re-testing every ten years, would do wonders for reducing accident rates.

To say we can't drive small, efficient vehicles just because some people are driving large, inefficient ones is giving up, we can do much better than that.

Simple physics: if you increase the linear dimensions of a car or an animal, it weight increases 8 times, but the strength of any structural element (like bones, muscles, or car’s body or suspension) and heat rejection increases only 4 times.

In the animal kingdom it means that birds are small, an elephant can not jump, and whales are crushed under their own weight if washed ashore.

For vehicles, bigger vehicles unavoidable have unproportionally high wear and stresses on brakes, tires, suspension, higher body twist, unproportionally higher aerodynamic drag due to an oversized radiator, higher stresses in drivetrain, and so on. Bigger vehicles have longer braking distances, and perform poorly on a skidpad. Basic physics, nothing can beat it.

Some car companies have recognized this - for example BMW's motto for a long time was “Lighter vehicle is better than powerful engine”.

Simple physics: if you increase the linear dimensions of a car or an animal, it weight increases 8 times, but the strength of any structural element (like bones, muscles, or car’s body or suspension) and heat rejection increases only 4 times.

Not so, the structural stiffness of a member increases as the thickness squared. A larger volume vehicle can have a lower average density then a smaller one, and still maintain similar structural worthiness. Of course that doesn't mean bigger is the way to go. But, the scaling exponent is under three.

the structural stiffness of a member increases as the thickness squared.

That's what I said: double the dimensions, and the strength goes up by 4...but the weight goes up by 8.

To say we can't drive small, efficient vehicles just because some people are driving large, inefficient ones is giving up, we can do much better than that.

If it was just some (a few percent) that would be sensible. Afterall even if you drive a Hummer you are a flyweight competitor against the average semi-truck. But, the numbers of large industrial vehicles are relatively small. Not so the case with multithousand pound consumer vehicles.

So the real challenge is to reduce the number of heavy commuter vehicles - not that difficult, if we really want to. WE can simply adopt the European way of taxing vehicles at sale, and annual registration, on the basis of weight. Make the tax high enough, like it is in Europe, and people will only drive heavy vehicles if they need to (tradesmen, etc) or have some much money they don't care (an increasingly smaller minority).

Higher fuel price will eventually force this change, but lots of money and oil will have been wasted by then.

Consumer demand still dictates a certain degree of comfort and safety that keeps vehicle weight high.

It's interesting to compare today's vehicles with those of the past in this respect. For example, the 2010 Ford Taurus weighs over 4000 pounds and has a load capacity of about 1200 pounds, or 30% of its weight. The 1910 Ford Model T had a weight of 1200 pounds and a load capacity of 750 pounds or 62% of its weight. How's that for a century of improvement? Like "green"? The 2010 Toyota Prius weighs 3042 pounds, with a load capacity of 825 pounds or 27%.

Years ago I owned a 1956 VW pickup, which weighed about 2000 pounds and had a load capacity of about 2000 pounds (100%).

A few years later, I owned a 1961 Citroen ID19 Safari, which weighed 2900 pounds and had a load capacity (according to a plate in the engine compartment) of 1100 kg or 2420 pounds (83%).

Then later I owned a 1972 Citroen Dyane, weight 1400 pounds, load 750 pounds (54%).

Today's cars are safer (largely due to seat belts, airbags and better brakes, none of which add much extra weight) and generally more comfortable, thanks to air conditioning, softer springs, and higher unloaded weight.

The air conditioning does add quite a bit of weight, and the soft springs limit load capacity because few manufacturers are prepared to equip their passenger vehicles with the self-levelling suspension Citroen had fifty years ago (though many, or even most, heavy duty trucks are equipped with self-levelling suspension today).

Modern cars also have much better acceleration, which really does not add much to weight because modern engines are more efficient. An American V6 engine today (such as the Ford Ecoboost V6, 415hp and 449 pounds) produces more than twice the power of an American V8 (Ford 260 V8, 460 pounds and 164 hp) from fifty years ago, and weighs much less.

People are not "consumers."

Meanwhile, small cars mean small profits, and U.S. infrastructure was built for big cars. And there's also the tyranny of small decisions.

Capitalists are opposed to both serious democratic scrutiny of transportation policies and truly small cars.

I live in Wisconsin and you can tear my car AC from my COLD dead hands... :)

I've owned a lot of vehicles over the years... My ZX2 i owned ('99) would get low 40's mpg (5sp) if i kept the speed around 60mph and in 5th gear... Plus it could pull my small trailer and a small boat no problem. Still had a lot of power for a little 4 cylinder. It had AC, but no power windows/locks/cruise...

Audi and Jaguar are using aluminum to reduce weight while maintaining high degrees of comfort and safety.

More people would ride bikes if more bike paths were available, making bicycling a safer mode of transportation than competing with cars for road space.

Jaguar XJ 2010, curb weight Diesel: 1,813 kg (4,000 lb)

Audi B8 S4 quattro 2010, curb weight: 1,650–1,735 kg (3,638–3,825 lb)

I don't see how these vehicles can be considered lightweights by any definition, please explain.
Bicycles cannot form the basis of modern economic life the way automobiles can, so they are not a viable substitute, as the would require a cultural change in attitudes regarding energy use to accompany them.

The cars are lightweights relative to other high performance luxury cars from BMW and Mercedes which have a gas guzzler tax attached to their high performance brands. An aluminum bodied TDI Golf would use less fuel than a steel bodied equivalent, so on an so forth through different car makes.

The Rocky Mountain Institute has been ahead of the curve on using light weight materials to increase fuel efficiency:

While bicycles can't form the basis of a modern economic life as we know it, they certainly can be used where the car isn't needed. More people would ride bikes if they weren't competing with fast, heavy cars, for road space. Portland Oregon seems to be making progress in this regard.

Bicycles cannot form the basis of modern economic life the way automobiles can, so they are not a viable substitute, as the would require a cultural change in attitudes regarding energy use to accompany them.

...stating that a cultural change in attitudes is impossible is a bit absurd here, given that the bulk of the site is devoted to explaining how our global energy situation requires a cultural change in attitude, among other things.

Cultural change in attitudes here in America will greatly be influenced by gasoline prices. Most Americans see bicycles as a recreation tool and not a method of transportation. I've been riding an electric bike to supplement car transportation for about three years now, yet I have only seen one or two other electric bikes on the road. I suspect I will see more electric bikes on the road as gas prices go up and others begin seeing bicycles as a method of transportation, and not merely recreation.

Here's a comparison of attitudes in China vs America concerning cycling as transportation:

Yes, something like 25 million new electric bicycles on the road last year, much more than car sales. I've also read that there are about 2,000 small-scale manufacturers of the E-bikes; sounds like the kind of robust entrepreneurial economy we used to brag about in the US, in past ages.

Bicycles cannot form the basis of modern economic life the way automobiles can, so they are not a viable substitute, as the would require a cultural change in attitudes regarding energy use to accompany them.

"Modern economic life" is on the skids. Attitudes can and do change very fast when people face very different circumstances which they can't really avoid.

I would say that bicycles could form the basis for a very healthy economic life. But it would not be the fast, long-distance life we are used to.

Hey there, My name is Isaac, I'm not from these parts. I have some questions and see that this is the place to ask them.I see that there is almost a dangerous amount of brain-power on this site. I love it. I am not an engineer or physicist,tho' I work as a freelance consultant for different fields, so I do have some understanding of things...anyways..

If water based mud is provides the strength when it stops moving and starts to settle or " gel " , and it is a slurry mixture, and realistically not much different than cornstarch and water, in terms of particle equidistant positioning in the fluid, could it be considered to be a Non-Newtonian fluid..?

If the only way to rapidly overtake opposing pressure, is by producing stronger opposing pressure in a 3 dimensional space, that is really about density VS density...? It is what allows the rapid transit of waves, the rate of travel is determined by opposition of the intensity of the wave to the density of the fluid., ...the law of inverse proportion....?...I apologize if I do not make sense here, lol.

If H2S stress cracking is a common problem with sour oil, and the flow from this deposit has a high sand/particulate content from the surrounding shale/sand that's possibly been acting like a cnc water-jet on the surface of the inner diameter of the casing, does this make it prone to failure.

I saw by reading one of yesterday's posts, that there is space left as a void in-between the casing and the concrete used to line the bore. Does that mean that stratigraphic pressure that normally helps provide structural integrity to the contents of the wellbore, ie : the casing, not there..?

If a stressed pipe is structurally reinforced by pressure applied from the outside, and it keeps stress-cracks in the plastic zone from creeping, but there is a void outside the casing, then it would make it more prone to fail from the inside when greater pressure is applied...?

A 3 mile column of mud with 2 concrete plugs, set no more than 200' from the mudline is the norm for plugging and abandoning a well..?

What happens if a 3 mile column of mud pops the casing at these depths...? If an established fluid column is given space to move at the bottom, and releasing the bottom pressure ( by a new void created by casing failure )breaks the " gelled " structure of the mud at the bottom of the column..and this 3 mile column of mud suddenly applies gravity waves to the that what will produce a massive " kick " ?

Just for the sake of knowing..There are other types of minerals that they have not mentioned that are actually heavier than Barium Sulfate

Possible substitutes for barite, especially in the oil drilling industry, include other similar minerals, such as celestite (strontium sulfate, and iron ore. A German company is producing synthetic iron ore (hematite) which is proving a good substitute for barite.

Also, I understand that this type of alloy can flex 6 degrees for every 10' that true..?

And,lol...sorry, Has anybody taken into consideration the Ursa-Princess waterflood project, or the East Independence Hub projects...?...they are joint BP collaborations in the same area that the Horizon blowout....WIKO Flowserve pumps is all I will say about that matter., ...I have some more on my blog..

Ok, that's all, thanks for taking the time to answer.


Maybe best to repost over in todays open thread spill discussion over here:

Lighter and smaller vehicles makes sense to me. How much more efficient can IC engines get? I imagine we have reached the limits of improving such technology. Would converting to light duty diesel engines/fuel help us in terms of refining? If heavier inputs become the norm for our nations refineries, would it make sense to switch to produce diesel instead of gasoline? Or do we lack such refining capacity? And, or would it be too expensive to replace the gas motor passenger fleet with diesel engines?

I suppose the ultimate goal is to get away from all ffs for transport.

We lack the political will power to plan for decline, adopt depletion protocols as Heinberg would say. We desperately need to change course with respect to our energy consumption here. I fear many the changes we make will be forced upon us rather than planned for, in the near future.

why replace an entire fleet with more ice,even diesel , why not plugins? hybrids and the like?

Simply because a modern diesel vehicle can be even more efficient than a hybrid because it doesn't have to carry the dead weight of a battery. The 2010 VW Golf TDI returns fuel economy similar to the 2010 Toyota Prius under many conditions, not as good in the city, much better on the highway, and has a payload 25% larger. It can also tow a small trailer, which the Prius cannot.

This is in spite of the wasteful extra weight the Golf has, like many new cars, to increase comfort, and in spite of the unnecessarily large engine it has (in the U.S.). The same vehicle equipped with a smaller diesel engine (as is available in Europe) would probably exceed the overall fuel economy of the Prius under all conditions.

The diesel engine is also much simpler than the hybrid system.

Yes. In Europe (this is true for Portugal, I'm assuming true for other countries) hybrids are not particularly popular, because so many cars can run more efficiently than them in terms of gas-mileage. My mom bought a Toyota Yaris, the basic no frills model (except air conditioning) and it's not only a great car to drive, excellent for mostly urban driving, with extremely well designed interios (a lot roomier than it looks from the outside) ... it gets 100km for about 5,5 l of gas!

Since it's also advertised as a ultra-low emissions vehicle (but I have no idea if it's true, althoguh I'm inclined to believe it) and comes in at almost half the price of a hybrid.... I'm envious of her car!

This sort of sub-compact urban cars (Fiat, Renault, etc... have numerous models that are comparable) makes cars such as the Prius unattractive here.

Just another thought. A Diesel hybrid should be part of the mix. It's better than both as we commonly refer to them today.

Alas all the more efficient technologies still seem to suffer from the vehicle obesity problem. The 2000 lb. Echo which was the platform for Gen. 1 Pruis is now a bloated 3600 lbs. in Gen 3. A 100 mpg 2000 lb. hybrid or diesel is well within manufactures' grasp now but weight still has a high correlation to safety and comfort for many.

The diesel vs. hybrid debate is less important IMHO in the face of the 'elephants' which include total miles driven, complete alternative transport, speed, and

Pic is of both of our rides.

Is a modern turbodiesel really that much simpler than, say, a Prius? It has a turbo for a start, and a high pressure injection system. The Prius has a chunky electric motor, but this does the job of starter motor and alternator, I think. They both have pretty sophisticated engine management systems.

Simply because a modern diesel vehicle can be even more efficient than a hybrid because it doesn't have to carry the dead weight of a battery.

This may be true for an individual vehicle, but not for a systems level system. The problem is the percentage of diesel versus gasoline from refining is hard to change. So if we convert any substantial fraction of gasoline powered vehicles to diesel we end up with either a diesel shortage, or a gasoline surplus -or both.

Diesel engines are also more pricy than a gasoline engine, so I'm not sure how the cost advantage of avoiding the hybrid components works out. The hybrids provide a stepping stone towards plug-ins and ultimately electric vehicles, wheras diesel would seem to be a technological dead end.

Given the way few drivers turn off their engines when stopped -like waiting for Johny to get out of school, the hybrid is the only current class of mass market vehicles suited to the urban/suburban environment most vehicles are used in today.

An Israeli start up is experimenting using a micro jet engine as the power plant for a hybrid, which can run on multiple fuels including petrol & diesel.

Batteries are like dead weight when normal batteries are used. I imagine speculatively the difference between standard roof solar cells and the nanoskin type solar cells outside a building. Could battery type storage of energy be like a skin, meaning the whole car material (chassis material) could double to save and discharge the energy? I envision a sort of dual use material out of which the car is made but at the same time it is the battery material. Maybe a sort of impregnated metallic nanoskin. This would save all the weight of batteries and this material would be flexible, and strong with a much higher storage cpacity than current batteries. I googled nanobatteries and there are some start ups for smaller apps, but nothing like for cars.

Diesel engines gain most of their efficiency advantage over gasoline engines by their higher operating temperature (think Carnot). However these engines still could be made more efficient if they could run hotter. Some 40 years ago my father was involved with a DARPA program to build a ceramic diesel engine that could theoretically be run without external cooling, however the difficulty of finding lubricants that would operate at these temperatures along with the brittle nature of the ceramics kept this concept a research project.

However if these issues could be solved there is quite a bit to be gained. Even the best low speed marine diesels only get about a 54% thermal efficiency.

Actually diesel engines get their higher operating efficiency from their greater compression ratio, not higher temperatures. You can run a diesel on pure ethanol or methanol (port fuel injected), both of which burn cooler than diesel, and actually get better efficiency than on diesel!
The Otto cycle is actually more efficient than the diesel cycle, at the same compression ratios, it's just that the properties of diesel fuel allow it operate at double the compression ratio, and so it is more efficient than a gasoline engine. The combustion temperatures are similar.

As for those marine diesels, "only" 54% efficiency is pretty damn good, more than double that of car engines, and only just below the state of the art in combined cycle turbines, where they are at 60%. If all our engines could get 54% we would not have an oil crisis.

Sorry, but you are not correct. The maximum efficiency that any IC engine can achieve is determined by Carnot's Law which is a function of temperature.

For a given fuel/air mixture (and injection temperature) the maximum temperature is related to the compression ratio. They are pretty much the same thing.

Indeed, the adiabatic flame temperature for almost all hydrocarbons is 2150C at atmospheric pressure, and increases with compression.
The compression ratio does lead to higher temperatures, butt he real advantage is the compression ratio also gives an equally high expansion ratio, allowing the engine to capture the work.

The Carnot Cycle is indeed governed by the temperature difference, but in real engines, there are many other factors at play the limit the engine to a fraction of Carnot efficiency. With flame temperatures of 2150C, the Carnot efficiency is 89%, but gasoline engines max out at 30%, and diesels in the low 50's, so clearly there are plenty of other limitations than temperature

Keep in mind, a modern supercritical steam turbine can get 40+% efficiency, with a maximum steam temperature of 600C. The maximum Carnot efficiency for this temp is 69% so we are well under that.

It is the different nature of the engines, primarily compression and expansion ratio, that allows them to wring more work out of the fuel. The hottest engine in the world (e.g. burning acetylene and oxygen)is not going to be very efficient if the compression ratio is only 3:1

The temperature sets the theoretical upper limit, and is about the same for all combustion engines, from there on it is the configuration of the engine itself, and the other properties of the fuels that determine how much efficiency is actually achieved.

Indeed,the use of water injection, which lowers the peak flame temperatures, actually improves power and fuel efficiency of both diesel and gasoline engines, under peak load conditions, partly by reducing the compression effort required.

That is also why, in the same engine, methanol can give better efficiency than diesel, less work is used on the compression so there is a higher net output for the same fuel energy.

Directly related to cylinder pressure which is a function of compression ratio AND how the cylinder is filled ( porting/camming).
Change the cam or porting and you change the cylinder pressure for a given compression ratio.....holding everything thing else constant of course.


Did your Dad work with Smokey Yunick?

A problem with high temperature combustion is nitrogen oxides, which are one of the pollutant classes that it is important to minimize. We could water down the fuel -or use ethanol, and sustain somewhat higher compression ration before things get too hot. But, if there were not such difficulties with increasing compression ratios I think it would have been done already.

Diesel engines gain most of their efficiency advantage over gasoline engines by their higher operating temperature

Actually, the bulk of the gain comes from reduced pumping losses (no throttle).  Most diesels operate above the ideal compression ratio, which is set by reliable ignition of the fuel and not the actual thermodynamics (which I understand are optimal at about 15.8).

Some 40 years ago my father was involved with a DARPA program to build a ceramic diesel engine that could theoretically be run without external cooling

I've held the piston and cylinder from such an engine in my hand.  The silicon nitride required no lubrication.  However, I understand that heat losses to the intake air created enough irreversibilities to make the basic adiabatic diesel about as efficient as water-cooled metal walls.  The gains came from rejecting all the waste heat in the exhaust, which can run a compounding turbine.

If there were a large scale move to diesel engines in passenger cars in the US we would probably be faced with higher and higher diesel fuel prices and, conversely, gasoline would likely get cheaper. While it is possible to take heavier fractions of crude and crack them into lighter ones, such as diesel to gasoline, it isn't practically possible to go the other way, hence there is more or less a ceiling on the proportion of diesel that can be refined from a barrel of crude.

My own understanding of the efficiency difference between diesel and gasoline is that, given roughly equal engines, diesel is roughly 30% more efficient than gasoline, roughly half of which is due to the higher energy content of the fuel, and the other half is due to the engineering differences between the typical gasoline and diesel engines (throttle issues that I don't fully understand).

If you were trying to make an engine which can run on anything which can be made from cracking heavy crudes, a direct-injection unit with a sealed and pressurized fuel system might be a good candidate.  It would allow all the butane to be used year-round, and the propane too; "too light" fractions wouldn't be an issue until you got to ethane.  Eliminating evaporative emissions would be another benefit.

Here is a list I compiled on the energy efficiency of various modes of transport, measured in pmpg (person-miles per gallon of gasoline). Fairly similar to the one above, except that I measure the pmpg of freight vehicles differently (I equate 4000 lbs of cargo to one person, since that's the avg. weight of a consumer vehicle today when all the big SUVs etc are factored in).

Looking at the chart, I noticed that faired bikes have over 3 times the speed of a racing bike for the same energy expended. So for the same sweat and given that I don't have any traffic stops, that means I could get to work in 1/3 the time as I do now. Sign me up if this is true. (Even though I will eventually get flattened.)

BTW, new road bikes above a certain price-point have much more efficiency and durability than the old clunkers of a few years ago. Don't get an old used Schwinn bike unless that is the only thing you can afford. GD&R

The faired bike builder (and rider!) who provided the best numbers for energy use was Matt Weaver. Here are photos of his work:

Road bikes have not changed dramatically in 50 years.

The speed figure quoted for a faired bike of 75mph is not realistic. The speed record over 100M for a fully faired recumbent at altitude is a little over 80mph, but that is a supreme effort for a supreme athlete.

A realistic speed for a realistically fit adult is 25mph sustained in a faired recumbent tricycle, called a velomobile. A range of designs are available in Europe, at a price.


Mechanical power requirement at speed is based on Matt's actual measurements using his vehicle.

The human body was assumed to be 25% efficient in converting the caloric content of food into mechanical work, as per reference 11 of my 2008 paper. EROI for food was not considered.

Supreme athlete, special conditions, yes. It is realistic, but not practical for getting to work.

EROI for food may be relevant - we are using LCA (Life Cycle Analysis) to analyse mobility. One indicator to measure impacts is CED, the Cumulative Energy Demand (discussed e.g. here). Some of our preliminary calculations show that the global warming potential of pedaling your bicycle can be greater then using an e-bike and sit still!

EROI is relevant for food powered transport, but was not immediately considered in this post about the simple physics of energy use.

I did consider it elsewhere. There is a minimum in the food intake vs exercise plot. Don't know about your neck of the woods, but most Americans are on the low exercise end, meaning that most could bike more AND eat less. It so happens that an active person is better able to gauge satiation, and will actually want to eat less. So we need more exercise, and spend too much time in our cars. Solution: bikes with motors and pedals.

I've bookmarked your paper, and will read in detail.

I don't think 25 MPH will work unless it is flat ground.

One rate example that I personally relate to contrasts riding a bike in flat versus hilly country. If I set a goal of traveling between points A and B in the shortest amount of time, I know from experience how the rates affect my progress. For one, I know that the hilly country would always result in the longest travel time. For the figure below, I set up an example of a x=4 mile course consisting of four 1-mile segments. On flat ground (a) I can cover the entire course in T=24 minutes if I maintain a constant speed of r=10 mph (T = x/r = 4/10*60).

For the hilly course (b), one segment becomes steep enough that the constant rate drops to 5 mph. Work out the example, and you will find that the time it takes to cover the course will exceed 24 minutes for any finite value of speed going down the backside of the hill. For a 15 mph downhill, the extra time amounts to 4 minutes. Only an infinite downhill speed will match the flat course in completion time. And that jives with the agonizing learned behavior that comes with the physical experience.
Yet if we quickly glanced at the problem as stated we may incorrectly assume that the two hill rates average out to 10 = (5 +15)/2 and if not careful we may then incorrectly conclude that we could certainly go faster than 15 mph on the backside and actually complete the hilly course faster!

So curious thing about averaging speeds as you go up and down hills is that it biases towards slower speeds. You spend more time going slower uphill so it weights more in the average.

How many people intuit this behavior?

Yes, average refers to the time-averaged speed you describe. However, an electric motor will flatten the human effort required to negotiate challenging topology. A 1 Hp electric motor will carry me up most Wisconsin hills at 25 MPH.

Living in the Seattle area, I found that a nominal 500 watt motor is insufficient (without pedaling) for the 10% grades we have. Fortunately, I was able to add a second motor which together with the first will push me up a 10% grade with no pedaling but extracting 50 amps out of the 36 volt pack or about 2.4 hp (1800 watts). The total weight of the rig is 33 pounds for the bike and 105 for the trailer. Those lead/acid batteries are heavy!

Don't bad mouth the pink cruiser, it's my granddaughter's who's in college. The little one is another. I used the bike as a test vehicle for the trailer. The trailer is ubiquitous, available in stores like Sears, WalMart, Target, etc and is German made. I just added a couple of cheap Chinese hub motors. The battery is below the deck. I'm using a 100 amp Kelly controller with both brushed motors in parallel, one running reversed. The system works surprisingly well.

The battery is below the deck.

Although the cost would be high, it might be a fun "Part 2" project to use a large solar panel (or two) as combined (shade-for-trailer + engergy source) that might mean you can use a lighter battery, or just for extended range and in-situ charging, since I presume the unit would mostly be used for daylight riding?

A standard approx 4ft x 3ft solar panel is about 200w (

In aviation we have a heuristic saying "Headwinds hurt more than tailwinds help". In fact any wind from any direction is detrimental. You might extend your research to include wind in the bicycle solution.
Cheers all.

You might be interested in this as well.

Rainshadow Solar proprietor John Mottl’s bright yellow velomobile should make anyone smile: it can roll over hill and dale, at a cost of five pennies for every 60 miles. But Mottl rides for free, as he’s been off the grid for over 25 years and powers his velomobile, called the Quest, with the excess energy from his solar panels.

“It’s just incredibly fun to ride these things,” Mottl said. “It’s truly amazing what it can do. It defies your imagination. It makes hills so easy, it’s unbelievable. This thing finds downhills you didn’t know existed.”

The Quest is a Dutch-designed velomobile, enclosed in fiberglass and pedal-powered like a bicycle. Mottl has formulated an electric assist option for the Quest and will be offering them for sale on Orcas Island through Rainshadow Solar, the only company in North America currently electrifying a velomobile.

Don't get an old used Schwinn bike unless that is the only thing you can afford. GD&R

Or you must leave it in a theftprone area, such as a college campus. In those situations unsightliness, which translates into unsalability is as asset (so is a good lock).

WHT: I think a fully fared bike is pretty dangerous in all but the most controlled circumstances. Imagine getting hit with turbulent crosswinds. Also cooling of the rider would be an issue. I think partial faring would be the way to go. Stuff such as bubble style handlebar covers I think might be worth 20-30% reduction in drag. The problem has been that racing rules have prevented these sorts of changes, in an attempt to stave off a technological arms race. But, if the bicyle is going to advance we want such an arms race. What fraction of riders and bicycles are actually raced?

Also experiment with roids and hgh. If we want to get efficiently, why not?
I was hitting about 22 mph on flats tooling around today. I did not have a cyclometer for the longest time so it waas interesting getting recalibrated .


I suggest us regular bikers be conservative in talking about average speeds on bicycles lest we create unrealistic expectations.

For starters, world class professional racers doing something like the Tour de France, average 25 mph or a bit more (much nit picking about this number - some say up to 30 mph).

For us mere mortals, a sustained 15 mph is admirable. For something like a 50 mile per day vacation tour, a good rule of thumb is 10 mph overall - this includes rest/food stops but not extended stops at tourist attractions and the like. So, plan for 5 hours for riding and incidental stops but additional time for visiting various attractions on your route.

I see lots of happy folks on the bike trails that are not doing much more that 10 to 12 mph.

That's the current record holder (PacCar II 5'385km/l)

about Energy Measurement:
1J = 1Nm
1N = 0,102kg * 9,81m/s^2 (i.e. the weight of approx 100g on earths surface)

thus 1J equals dropping 100g (a small apple) for 1m on our planet

Thanks for the correction!

Cycle, I noticed you had the same passenger mpg for the 4passenger Prius as the single. Probably an error caused by copying and editing.

Yes. Error propagated to multiple passenger cars in the person-MPG column. kg-m/Jth values seem correct. Thank you for pointing this out.

That's the current record holder (PacCar II 5'385km/l)

5,385 km/l is only part of the story. It looks faster than a snail. If we know average speed, we can calculate Q.

here the European rules:
min payload: 50kg (drivers weight in full driving gear)
min speed: average speed 30 km/h (...must complete the eight laps (total distance to cover is 25.485 km) in a maximum time of 51 minutes with an average speed of approximately 30 km/h...)

Speed: 30 kph = 8.33 m/s
Energetic Economy: 5385 km/(liter of 133MJ/gal gasoline)* 50 kg = 0.154 m/Jth * 50 kg = 7.68 kg-m/Jth
Qe = 64 seconds

Pretty darn good! I suspect that the improvement over Matt's velo is caused by the 25% efficient human powerplant, and not the aerodynamics.

I now routinely walk to work and back, or public transit to work + walk home.

My carrying capacity is maybe 5%, as I have my work laptop in a soft briefcase :)

Walked 20miles this week: One round-trip walking on Monday and Wednesday, and on Thursday I only walked home after public transportation to work.

My ride is not green at all. It is red.

Sorry, that thing would be way on the left of the speed/economy chart.


You've analyzed the MPG of electric vehicles using the average utility mix of generating sources. I think a better choice would be the average mix at night, when most vehicles would charge. This will increase the share of wind and nuclear significantly.

More importantly, EVs are uniquely suited for a synergistic pairing with intermittent wind production, as EV charging can be scheduled dynamically for periods of maximum wind generation. Thus, EV's actually support wind power buildout.

I think it would be fair to assume that EVs are charged using wind and nuclear almost exclusively. That will make them fare much better in your analysis.


You point about people needing exercise is a good one. Still, I think the 9:1 ratio of FF inputs to food kilocalorie outputs needs a bit more emphasis, as it's a real, and very large, factor.


When it comes right down to it, any kind of electric transportation is far, far better than any other kind of transportation with regard to either CO2 emissions or oil consumption. Electric bikes are better than electric cars, but the difference between the two is much smaller than the gulf between them and everything else.


Electric cars are not YET able to do dynamic wind based charging. There are also some places that have little or no nuclear, so night charging is actually wind + coal, and the continent wide mix, for night would still be more coal than nuclear. I would think it is more appropriate to have two points - one for the average (off peak) electricity mix, across the continent, and the other for wind only, from dynamic charging. This will give a good indication of the difference between charging an electric car today, and what an ideal system would deliver.

As for electric transportation, cars and bikes are good, but well designed trains/trams are better still - even though you are transporting more vehicle mass per person than bikes, (or even a full car), they deliver many other benefits than just reduced transport energy.

Electric cars are not YET able to do dynamic wind based charging.

The Volt (and, I believe, the Leaf) will be able to do dynamic wind based charging.

There are also some places that have little or no nuclear

True, but most import at least some of their night time power from areas that do.

night charging is actually wind + coal

I know you don't feel that CO2 reduction is a highest priority. For those who do, the support for wind provided by the availability of dynamically charged EVs would be very important.

I would think it is more appropriate to have two points - one for the average (off peak) electricity mix, across the continent, and the other for wind only, from dynamic charging.

That's not a bad idea, though I think the first wouldn't be that useful.

cars and bikes are good, but well designed trains/trams are better still

I agree, except: 1) rail is better for only roughly half of VMT: commuting and medium distance inter-urban travel - the rest is far better served by personal transportation, 2) that's a long-term solution, and 3) it's much more expensive than personal EVs when you include the cost of transit-oriented housing.

PNM (public Utilities of New Mexico) gets about 20% of its power from Palo Verde, which is 50 miles West of Phoenix, AZ...about 360 miles away. There are no commercial nuclear reactors in the state of NM.

PNM (public Utilities of New Mexico) gets about 20% of its power from Palo Verde

And most of the rest comes from coal. Richardson (the governor) has been trying to make the state a center for renewables, but the current generation mix is pretty carbon heavy.

20% of its power from Palo Verde

Which is comparable to the US average. The night time % will be much higher, perhaps 50%.

My ride is not very green. It is an older large pickup truck. It would be nice to have a smaller hybrid or high mileage vehicle to do most of my driving when the pickup truck is not needed.

However, my miles driven footprint is fairly small, maybe 100 miles per week. In my previous career my average was closer to 100 miles per day on workdays, maybe 500 miles per week.

Obviously driving higher mpg vehicles is better, but so is driving less miles.

500 miles @ 30 mpg = 16.67 gallons of gas

100 miles @ 15 mpg = 6.67 gallons of gas

What about the energy required to build new high mpg vehicles to replace older low mpg vehicles when they are only driven a few miles per week? How long does it take to recoup the energy expenditure to build the new vehicle?

Not trying to rationalize my situation driving a low mpg vehicle, less driving with better mileage would be better for sure. Building websites is my second job and I'm working to make that my main job which would mean driving even less miles.

My own track record when it comes to fuel efficient transportation is far from stellar but, like you, I try to minimize my usage whenever possible. I now average about 3,000 km a year, more or less evenly split between urban and highway. My current vehicle is equipped with 3.5 litre HO V6 and 4-speed automatic and it typically consumes 8.2 litres per 100 km highway and closer to 12.0 or 13.0 litres city -- that ultimately translates to be a little over 300 litres or 80 U.S. gallons a year. So the left side of my brain screams Prius!, but the right side says screw that, hence the 300. And the HEMI, we don't talk about.


So the left side of my brain screams Prius!, but the right side says screw that

If your usage is that low, a Prius would be wasted on you. Given a limited number of hybrids available, it is better if they are owned by people with high miles driven. I suspect for your line of work a full sized pickup to haul lightfixtures and tools and ladders makes the most sense. PUs are wonderful things. The problem is that they are not well matched to the typical yuppie user.

I cheat. The bulk of my workday is spent in my home office as opposed to out in the field -- the installation end of things is handled by our crews and those are the guys driving around in the Rams. And, for the most part, whenever I do audits/site visits, my business partner picks me up in his car since this work generally involves the two of us. I'm also fortunate in that our home is located within a five minute walk of the local library and a ten minute walk of pretty much everything else we require in terms of commercial services. When it comes down to it, I could eliminate my car and simply borrow my partner's wagon as needed, but I appreciate the added convenience of having a second vehicle at my disposal.


To suit my needs for speed, reliability and style I built an e-bike from scrap bikes and electrical conduit with a drive system from China. It is about 10 feet long, recumbent, springer suspension, low-slung and looks like a black chopper from a Mad Max movie. Sorry, no pics at the moment. It is called The Blackbird. People see it fly past like a low-flying SR-71 and simply cannot believe their eyes. I get stopped all the time for pictures and videos.

36 volts, paired LiFePO batteries for a total 30Ah. Range is about 40 miles without pedaling, perhaps 80 miles with. Including a nice sized trailer it replaces a car for 95% of the things I do, and I ride it about 1,200 miles a month to/from work and for pleasure and to do errands around town.

It charges in about 5 hours. The amount of power being consumed seems trivial. It is easy to believe that after the fixed cost of building the bike it is virtually free to ride it, apart from the amortized cost of battery replacement, which I calculate to $50/month for 1,000 miles a month. But I am probably really hard on the batteries.

More to the point: This machine that contains 5% of the materials and 1% of the labor and infrastructure that goes into building a Prius hybrid (which is held as the benchmark these days) provides 90% of the functionality if a Prius is being used mostly to move one person under 30 miles one-way to/from work on surface streets. I see this scenario play out constantly on my ride, you know who you people are. Plus I get exercise, and meet people, and enjoy the sights, and it only adds an extra hour to a 30 mile commute, an hour I would spend in the gym anyway to get the same exercise.

There is no reason for more people not to ride these things for commutes or errands at or under 30 miles one-way, 60 miles round-trip. I had to make this bike in my garage, but that could easily change if there was demand or incentives. GM should make these by the millions. They should be forced to do so.

The savings to society by this change in scale are nearly impossible to overestimate. Blackbird doesn't harm roads. Doesn't pollute the communities I ride through. Doesn't make any noise. Wouldn't kill anyone if I hit them. Doesn't take up a parking space. Doesn't require massive freeways or ubiquitous service stations or vast networks of charging stations. It charges like a laptop computer, in nearly the same amount of time. It is human-scale, humane, and a game changer in black and chrome. It is the distillation -- in metal -- of pure sex.

We need to get people out of personal cars. Period. The rest then takes care of itself.

Great solution! Would love to see some pics.

Your post makes me very curious to see a picture of your ebike.

Would like to get details on the "drive system from China". Is it a modification of something you got off something made in China ... or what is it?

I do agree with you that ebikes have a great potential as an alternative to the single-occupancy vehicle ... especially in the US where there are so many suburbs. Bikes without an electric-assist are fine for cities, but once you get into suburban distances, the slower speed of bikes on hills becomes a practical issue ... esp. if you're pulling a trailer, or otherwise hauling a load.

I think the increasing price/limited availability of gasoline is what eventually is going to change the bike/ebike adoption/usage picture.

My advice is: if you don't have a bike now, get a good one before prices for them skyrocket.

Regarding electric bikes, interest in them is growing, I think. A new magazine

devoted to electric bikes is now being launched by the editor/publisher of my favorite bike magazine, Velo Vision.

Happy and safe pedaling everyone!

I'll third the motion for some pics, cougar. (-:

I am also interested in learning more about your build process and materials; specifically, the batteries, controller and throttle. Were they all part of a kit with the drive system or did you piece them together yourself? My understanding is that lithium batteries are a lot trickier for this type of application (multiple batteries, high load, etc.) than SLA batteries.

Materials: From the local hardware store (Orchard Supply in these parts, but HomeDepot or Lowes would work just as well). Frame and forks from thin-wall EMT (electrical conduit). Other bits are flat iron stock. Springs off-the-shelf heavy duty. Cranks from 2 scrap bikes, one in the middle as an idler for the 7 foot long drive chain loop. Forks are paired tubes running all the way to the wheel, probably 6 feet long, to a used heavy-duty Worksman industrial bike wheel with integrated hub brake.

Design: You sit between the wheels, not above. The rear wheel is right behind the seat (which has a backrest) along with the batteries. The front wheel is in the next county. The handle bars are fixed to the forks. There are 2 cranks, one in front for your feet another in the middle to act as an idler and split the chain, because you cannot run a single chain 7 feet to a moving wheel on springs.

Build: It's all iron and very tough. Everything welded together by a Lincoln hobbyist-grade wire welder, available most places that sell welding supplies. Because the tubing is so light the frame is very light and strong; like a bird, it is mostly air. However the engineering of a 10' long frame and fork assembly is epic, you would need to see the pictures (maybe I'll put something up when I get home.) There are 50 ways to screw this up, and one way I know of to get it exactly right. And I ride it every day.

Drive system: Rear wheel is the drive. Started with a 750W 36V hub motor from (China) rated at 20A. They also have the controller and special brake handles to manage regen braking. Batteries from GMotor also, and have been okay and were cheap enough, but you can get batteries anywhere. I bought a pre-built wheel (included a rim and heavy spokes) but immediately broke it; the spokes simply pull through the rim, due to the rotation power in the hub. I built my own wheel after that, using a Worksman 36" iron rim and quarter inch bolts. It's heavy, but it rocks really hard and looks sick, like something from Frankenstein's lab.

Do not use lead/acid batteries. I mean that.

This really only works with LiFePO due to weight. LiFePO formulations are not tricky at all. Very light, safe, easy to manage. Energy density for weight is simply insane. I use a matched pair in parallel to get massive amperage out. The bike moves fast even at 36V, it would probably be dangerous with more than that.

(EDIT: It is worth mentioning that I have nearly $1000 invested in 2 LiFe batteries, and another $300 in the wheel and supporting electronics, then the frame build. This is not a cheap ride, and this is not a toy. At the same time this is not a $40K Prius or a $85K Tesla roadster. A serious eBike that combines distance+speed is in reach of most riders, while a Tesla is not, and you get nearly all the bragging rights at a fraction of the carbon footprint.)

Took me a couple months to fab, working on the weekends, referencing a rough drawing on a scrap of drywall. Rolled right the first time, never looked back. A minor miracle; you hear horror stories about frame design and stability.

It CAN be done. People STILL invent things. Things that change the way we approach problems and solutions. The Blackbird is just a machine. But it changed everything.

Thanks for the detailed reply, cougar.

I don't mind saying I'm envious of what you have built! A couple of years ago I added an e-bike kit from Electric Rider to my late 80's Schwinn steel-frame mountain bike, along with some ape-hanger handlebars so I could pedal without my gut getting in the way of my legs. Other than the scary ICE vehicle traffic, it's suited me well so far. I've enjoyed the hell out of it but I would like to replace the SLA batteries--which, due to my own neglect and stupidity no longer hold their former charge after a Montana winter out in the garage--with something with higher energy density. Do you think a charger designed for SLA will work with lithium batteries? Again, my impression only, they require different hardware for different battery chemistry.

I'm a big American fat-ass so most recent off the shelf bicycles won't handle my weight, at least according to specs. I have an uncle and at least one cousin nearby who know how to weld and I've been thinking about asking them to help me build a recumbent style bicycle that will support me. Other than the frame and drive train itself, I have all the parts (except, currently, the batteries) to make it an electric assist bicycle.

Still looking forward to pics of The Blackbird. (-:

One must be cautious about the widespread claim that it takes nine calories of fossil energy to provide one calorie of food energy to human beings. That may be true as an AVERAGE. But there vast differences in the inputs themselves, along with big differences in diet. A lot of rice-and-bean eating vegans tend to be self-locomoted, while grain-fed-marbled-steak lovers tend to rely on nineteen-foot-long, three-ton motorized codspieces branded with names like "F250" and "Avalanche" and "RAM Tough".

There is no way it takes nine calories of FF to put one calorie of wheat flour on the grocery shelf. And for people who use muscle-power to grow some food at home, the FF input for those foods is closer to zilch. Let's remember that throughout history we humans have often managed to produce more than enough food calories for ourselves without ANY FF inputs. Our main problem today is all the hungry machinery.

Let's remember that throughout history we humans have often managed to produce more than enough food calories for ourselves without ANY FF inputs. Our main problem today is all the hungry machinery

... by having anywhere from 50% to 90% of the population work full-time at backbreaking labour doing nothing but growing food. The hungry machinery makes modern life possible.

Your claim is incorrect. What makes our current diet so inefficient, is that it contains a great deal of beef and pork. Lose the beef and pork, use modern methods to grow the plants, eat moderate amounts of poultry and small fish, and the diet becomes very efficient. It would not require a massive reallocation of labor.

It would when the tractors and the nitrogen fertilizers and the phosphates shipped from halfway around the world are no longer available.

Better to use electric tractors.

Farm tractors can be electric, or hybrid . Here's a light electric tractor . Batteries can be trucked to the field in swappable packs. Farm tractors are a fleet application, so they're not subject to the same limitations as cars and other light road vehicles(i.e., the need for small, light batteries and a charging network). Providing swap-in batteries is much easier and more practical. Zinc-air fuel cells can just be refuelled. Many sources of power are within the weight parameters to power modern farm tractors, including lithium-ion, Zebra batteries, ZAFC's and the latest lead-acid from Firefly Energy, and others.

Nitrogen fertilizers: better to use low fertilizer crops, and get the remaining hydrogen needed by electrolyzing water using electricity from wind, nuclear, etc.

phosphates: we have several hundred years of supply ( ). When that runs out, we'll recycle.

Given the problems caused by phosphate pollution, we'd be better off recycling now.

Absolutely. But, of course, that's a pollution problem, not a limit to resources problem .

This could be re-framed as a "limit to environmental sinks" problem, but I think that is misleading, as the two things behave differently.

Pollution is a destructive and undesired side effect. It's magnitude isn't necessarily related to the size of the polluting activity (pollutants can be extremely destructive or only mildly destructive); and pollution can and should be eliminated, while resource consumption generally is intended, and has value.

There is no way it takes nine calories of FF to put one calorie of wheat flour on the grocery shelf. And for people who use muscle-power to grow some food at home, the FF input for those foods is closer to zilch. Let's remember that throughout history we humans have often managed to produce more than enough food calories for ourselves without ANY FF inputs. Our main problem today is all the hungry machinery.

Not sure where that particular measurement came from; but I wonder when I see those types of food/energy ratios. Did the author realize that 1 Calorie = 1000 calories ? And food calories are actually Calories. It does also seem unlikely that 9 calories of FF produce 1000 calories of wheat. Possible tho since its the sun that does most of the work.

Did the author realize that 1 Calorie = 1000 calories ?


The majority of this energy is outside the farm: processing, refrigeration at the plant, refrigeration during the trip to the market, refrigeration at the market, transportation home (larger than all transportation before this point), refrigeration at home, cooking...

The result is a ratio of the benefits of vehicle use (payload mass, average speed and distance moved) to the cost, expressed in universal currency as thermal energy.

It is not intuitive why the product of mass, speed and distance should be the "benefit". Mass times distance seems to be directly related to "benefit", i.e. the benefit of moving a million tonnes of oil from port to port or the benefit of moving a 70 kg person from home to office.

However, speed tends to be more of a constraint and related to non-energetic considerations of the value of time. If the distance from home to office is fixed, then the modes of transportation to be considered are those that cover the distance in some reasonable number of minutes. A shorter time may be prefered, but I doubt that the value relationship is accurately represented by multiplying the kg-km by m/s.

This analysis does not put a dollar value on speed. The point is that speed does have some economic value, and if you simply factor it in using SI units, the result has a physical meaning. It is consistent with the G-K limit determination. It is a residence time. This time is inversely proportional to entropy generation associated with completing a task in a given time. It is proportional to thermodynamic reversibility. Effects on larger systems can be factored in as well, since things like EROI and GHG emissions are directly proportional to the energy use for a given process.

Tri-hybrid Stealth, gets and estimated 200mpg and still travels over 100 miles per hour. The Stealth runs off electric, diesel and human power produced through pedaling.

Three wheel vehicles seem to be leading the mpg race

Solar/Human Vehicle

with electric , the goal is Watt hours/mile
my favorite ..

Many colleges are working on efficiency ...

This paper shows why (we) transit advocates need to be very careful about their (our) claims. From an energy consumption standpoint, existing AMTRAK and urban bus services are not dramatically better than our existing automobile fleet – especially when these mass transit modes operate well below passenger carrying capacity (Table 1, fourth column: Person-MPG). This is not to dismiss the enormous land-use benefits of mass transit over the private auto, but claims that buses and trains are significantly more energy efficient (and less GHG intensive) than autos will undermine (our) credibility. That said, passenger rail in other countries is quite a bit more energy efficient than cars.

It is worth noting that air travel is pretty darn good on a Person-MPG basis. The “problem” with airplanes, so to speak, is that we can travel so far in such short periods of time! Well, that's not really true: being inanimate objects the airplanes aren't the problem; it is our lusts for speed and novelty, our desire to pack our life lists with impressive evidence of our worldly experiences.

One great thing about airplanes is that they require very little on-the-ground infrastructure relative to the number of people moved. Admittedly, airports themselves are massive things, but the planes need no roads or tracks between them. And those "betweens" are long!

Back to passenger rail efficiency in the USA; how much could it be improved if we revisited passenger car safety standards (which are probably 100 years old by now) along with evaluating what could be done with contemporary high-strength materials and modern design tools (CAD). Seems to me that existing passenger cars (which may be based on 50+ year-old designs) are God-awful heavy things relative to their human cargo.

Perhaps (probably) some European companies have already done this, and all we need to do domestically is copy them. Which requires setting nationalistic hubris aside, of course...

Your comments about rail passenger cars are interesting. I think that newer car designs are lighter and more efficient, but the interiors need to be competitive with the comfort of busses, airlines and automobiles.

Efficiency figures for light rail and subway seemed to be missing, and it wasn't clear to me whether the commuter and other passenger rail figures were for third rail, overhead electric or diesel electric. Commuter rail uses all three in the NYC area.

Lastly, there are other costs, such as the costs related to safety, to be considered. One site that had a broader view of costs is Transportation Cost and Benefit Analysis - Techniques, Estimates and Implications [Second Edition] -- Updated January 2009

I mostly drive a '93 Dodge, Cummins powered pickup. It carries around my equipment and tools just fine, and averages 19 mpg. I used to use a minivan for the same job, and when loaded the same, got about 20 mpg, and it was the most fuel efficient minivan ever built.

However, I wore out the minivan at 220,000 miles. The truck, with 280,000 is going strong and will be for another 500,000 to 800,000 miles. Which conserves resources better? The truck, obviously.

Not only that, it's a pre-cat diesel, meaning the soot is large particle, mostly harmless, and biodegrades immediately. In other words, it's cleaner than the minivan.

I would think it is much safer than the minivan. Packing lots of heavy gear in the passenger compartment of a vehicle greatly reduces accident survivability. Imagine all that stuff flying around the passenger cabin at a relative velocity of 30-50 mph different than the passengers. My son does music gigs, and hauls keyboard, amps metal music stands and such. He always wants to borrow the Prius, as it uses far less gas than the PU, and can hold a surprising amount of gear. I don't let him, because of the safety issue.

Generally, nothing large and heavy is inside of the minivan. Some of it is large, but not heavy. The biggest stuff is ladders, which kills the mpg in the minivan. Empty and sans roof rack, it would get 28-30 mpg while freeway blasting at 75-85 mph. With ladders on top, it gets 20 doing 55.

Mostly, the issue is that I go off-road a lot and the minivan gets beat to a pulp dodging stumps and rocks and potholes.

I think you need to go back and check your mileage numbers again. To start with no minivain today can get 28-30 mpg at 75-85 mph, except maybe down hill with a tale wind. And then only get 2/3 of that amount of economy at 1/2 the wind resistance plus maybe an additional 10% frontal surface area resistance from the ladder.

No, i don't need to do anything of the sort. It has actually broken 30 at lower speeds.

Your ignorance of minivans does NOT make me wrong.

Just got back from Rotterdam. I asked a rare cab driver how they managed to plan a city around bikes. He said first the Germans bombed them, then the allies bombed them until only two buildings were left standing. With all the new room they were able to incorporate the bike paths into the new development. So aside from blowing our cities level and starting over maybe we could shut them down and build more efficient cities down the road. Cities in Asia were often abandoned because they suitable for living. Just a thought.

Jeff - One question about the Table. The Column titled "Form" lists either "E" or "C" - at first I thought that this was Electric vs. Combustion, but that doesn't make sense... what do the letters stand for?

E is effective performance. Speed is time-averaged.

C is cruising performance. Speed is constant.

Other methods of determining average speed are discussed in the 2008 paper.

Got it - thanks.
Great work.

Great article.

1) it gave me this thought (background- we are likely to require container ships in the Santa Barbara channel to slow down to reduce pollution):
Ocean-going ships often (typically?) cruise at a speed like 20 knots, when roughly 12 knots provides much better fuel economy. YMMV... anyway in the case of tanker ships, slowing down may not save any energy at all and may in fact be worse. Why? Because the tankers crossing the ocean are part of a system, exactly like an oil pipeline.

So say we slow from 20 knots to 10. Say that saves half the fuel used to move the ship. That means just half as much fuel-cargo is getting through, and we have to double the number of tankers at work. Not only does that lose all efficiency gained, it might add embodied energy costs if new tankers have to be built.

Sorry if thats been discussed to death, but I learned not to always assume that lower fuel use is always more efficient.

2) a quibble: I think the Puffin is total vaporware and in fact cannot fly. According to me no battery on earth contains enough energy to power a VTOL larger than an RC copter. However those RC copters do fly, so maybe I am wrong in the absolute sense.

Regarding your quibble: Lithium nanophosphate batteries will do the job. They feature the highest power density commercially available. 3 kW/kg, so the 45 kg battery will give us 135 kW. Motor power output specified on Puffin is 60 hp, or 46 kW, so you have extra capacity for backup. I would hope for two independent battery channels for safety, since there is no conventional landing gear. While VTOL power analysis is not my area, 60 Hp seems like it would do the job, and NASA people lift things all the time.

That means just half as much fuel-cargo is getting through, and we have to double the number of tankers at work.

Tankers spend part of their time in port, so reducing speed by half doesn't double the number of tankers needed.

Not only does that lose all efficiency gained

No, you don't lose the efficiency. The tankers reduce their fuel consumption per mile by 50% (and reduce their fuel consumption per hour by 75%), so total fuel is actually reduced by 50%.

Actually, the efficiency gain by slowing down is even better than that. Power varies with the cube of speed, (until you reach the "hull speed", which these large ships do not) so if you cut your speed in half, your power decreases by a factor of 8. You take twice as long to make the voyage, but using 1/8 fuel per hour, so you only use 25% of the fuel per mile travelled.

Given the "dead time" of loading and unloading, to cut speed in half probably only increases round trip travel time by 50% or so, for a large fuel saving. You just have to weight it up against the time cost of going slow
The ship operators are well aware of this. When oil was $147/barrel, they were travelling slower than when it was at $40 a barrel a year later.

The same applies to aircraft too, decrease your cruising speed from 550mph to 500 mph and you get about a 20% fuel saving. You can;t slow down too much though, or the plane will fall out of the air. Design the plane for slower speed in the first place, and you can have smaller engines, and carry less fuel and more people/cargo for the same trip. The biggest cause of fuel inefficiency is speed, which is what prompted Gabrielli and von Karman to produce their landmark study in the first place.

Generally fluid resitance scales as velocity squared. Power as the third power. Of course wave drag effects may create sweet and sour spots. But in any case, the cargo miles per gallon of fuel dramatically increase at lower speeds. Also the fraction boost from stuff like traction kites would be greater as well. I think it is mainly the capital cost of the ships, and the cost of the crew that create cost pressure to go fast.

it is mainly the capital cost of the ships, and the cost of the crew that create cost pressure

It's mainly the cost of the cargo - a ship carrying iPhones isn't going to slow down at all.

Some good points made. I had heard a figure of avg speed 20 knots and optimum speed 12 knots for actual container ships. So I'll assume 20/10 just to make it easy to make a rough calculation. Assume 50% of time at sea, though I doubt this one - fast turnaround is clearly a huge savings for the shipper - but no matter lets use that number too.

Say we need to get a steady 1 shipload per day unloaded at our port and the crossing is 5 days. The time in port is then 5 days at each end so the round trip is 20 days. We use 2 crossings ( 2X ) worth of fuel for a round trip. It takes 20 ships to keep up the 1 load/day pace. Each ship burns 1/10 X per day for a total of 2X burned per day for the fleet.

So we slow to 10 knots and the crossing becomes 10 days and we use 50% of the fuel. So each shipload round trip now takes 30 days instead of 20. So now we need 30 ships to keep up the pace. We burn .5X fuel per crossing now, or 1X per round trip, so we burn .034X per day per ship or a total of 1X burned per day for the fleet.

red-face I was totally wrong - The number of crossings is the same, so of course the fuel used is half. duh.

While this is an interesting post indeed, we need to really think about the value of:

Human Happiness and Quality of Life / Eth


Human Happiness and Quality of Life / Mass * Speed * Distance

Unless we look at the problem of the survival of Civilization at the cliff of Peak Oil, Rising Population, Shrinking Topsoil and Water flows in these terms ponderings of the like of this post will do nothing real to reduce our addiction to high flows Eth per capita. The article here may tell us (falsely) that its cool to jet about because we get such a great mileage from it. But that is a moot argument indeed if traveling these huge distances in absolute terms is causing a huge amount of Eth flow (which is a limited resource) for what may be just another trip to Disneyland.... While a family elsewhere took their backpacks and went for a camping trip in the nearest bit of beautiful nature...

Yes, this post will not tell us whether a trip is ill-advised. That is another topic.

Suppose the destination has been chosen. An environmentally-aware person traveling alone can feel better about flying than driving, AND will arrive sooner. If cars were designed like airplanes, this would be less true, but most people will want more elbow room and armor in their personal chariot.

An environmentally aware traveller should choose their plane carefully, and be mindful of the height at which it flies.

Some planes get much better MPG, and some get much worse: people should consider which plane their airline will put them in, when choosing a flight.

Emitting CO2 at 30k miles is 2x as bad as at sea level, as the CO2 molecules are resident at high altitudes (where they do the damage) for longer periods.

Now, sometimes one has to travel alone, but it would be better not to. Four people in a Prius (even better, a Volt or Leaf) is very, very hard to beat.

For once I am in (almost) complete agreement with you here. I do think you meant to say 30k feet instead of miles, though.
When I have to fly from Vancouver to San Francisco, I do it with Horizon Air (Portland based partner of Alaska Airlines) who operate the Q400 turboprops. Those things are almost as quiet as a jet, almost as fast, cruise at a lower altitude, and use about 1/3 less fuel. They are also cheaper to buy and operate, so Horizon's airfares are cheaper.

On the short flight from Vancouver to Victoria (BC) across the Georgia Strait, the turboprops do it faster (about 25minutes) than the jets (about 28 minutes) because the jets cruise at a a higher altitude. On that flight, I would think the turboprops would use about half the fuel.

For flights of less than 600 miles, those things can't be beat!


Emitting CO2 at 30k miles is 2x as bad as at sea level, as the CO2 molecules are resident at high altitudes (where they do the damage) for longer periods

The CO2 lifetime is a hundred years or longer, and CO2 should be considered to be well mixed, in altitude as well of over the planet's surface. There is not an altitude multiplier on CO2 emissions warming potential. It is other stuff, such as condensation nuclei (contrails, cirrus clouds, and black carbon), that increase the warming potential of air travel.

It is other stuff, such as condensation nuclei (contrails, cirrus clouds, and black carbon), that increase the warming potential of air travel.

By how much?

Yes I maintain that the decision of which car to use or which plane to use makes a minor difference. What makes a major difference are lifestyle choices. I work from home = no commute. I build an electric car for the local trips to the village center for shopping. Its 40Km range is three times my average trip distance and thus very ample. It is recharged from New Zealands 65% renewable electricity net. I do have a diesel car for trips out of town. On my annual transport tally though the finesse of which diesel car I would own for that will make a very small difference compared to the guy next door who commutes 50Km daily to his work.
I will carry on using my 1994 diesel for this as the Energy Invested in a brand new vehicle as opposed to the energy invested in fixing the old one up occasionally is huge and would during the remaining lifetime of the old van totally overwhelm any benefit in a lower consumption I might find.
All this brings us back to annual per capita Eth consumption as the deciding factor of them all. Unless we transform society from our current high Eth/Capita life to a low Eth/Capita life we will achieve nothing.

Yes I maintain that the decision of which car to use or which plane to use makes a minor difference. What makes a major difference are lifestyle choices. I work from home = no commute. I build an electric car for the local trips to the village center for shopping.

You can eliminate the commute, or use an EV: both will eliminate oil consumption and dramatically reduce CO2 emissions.

The greater the force on the chain of bicycle the greater the friction. To increase the efficiency of a bicycle, the chain must be removed or designed to either keep the friction constant or reduce it.

Same principle applies but different numbers.

I have a nice Trek road bike. Carbon fiber, Dura Ace, Rolf wheels...the works. The thing about it? It eats tires like crazy on these city streets. People are slobs! I have to swerve around so much broken glass. I've since upgraded to some heavy duty tires, tubes (heavier) and they seem to be holding out better, for now.

If i was starting from scratch i'd go with a basic mtn bike, with semi slicks. I'd skip disc brakes (i have them on a mtn bike, seem overrated). I'd also shoot for steel (vs AL), although with suspension AL works fine. I'd also spend as much as i had to on a GOOD seat. Nothing worse than your pieces going numb.

At the end of the day, 21mm 140psi (960kPa) tires aren't much use on most public roads... there's not just glass, but potholes and broken pavement or poorly patched pavement (utility companies typically ruin the pavement when they cut into it, because their patching jobs are extremely poor.)

Huh? Plenty of riders find this situation acceptable.

Hi Pauls,

I've toured thousands of miles in the West-Central part of Ireland on the most rural roads - some road sections are fairly rough (and some are very nice). But, most of the roads have that rough-tooth finish (better breaking in wet conditions) that is almost never used in the US.

The widest tire my bike will accept is 23 mm and I run them at 110 psi. I've only had one flat tire and no other problems. If I could use a 25 mm I guess that would be ideal - but, I would not care for something wider than that. My engine is very old and really enjoys an efficient tire.

I have a fat tire "grocery store" bike - OK for errands, but I sure would not want to ride it any distance.

It eats tires like crazy on these city streets.

A lot depends upon locaility. A few years back I hated riding in my town, which was a major focus for the housing bubble construction. They problem was mainly nails and construction staples, not glass. Now that new construction has virtually stopped flats are pretty rare again. For mountain bike/cruiser type tires, you can use either/or-both slime and kevlar tire liners to reduce (but not eliminate) flats.

I'd been wearing out bike tires too fast. Turns out my sloppiness about maintaing tire pressure wears tires out much faster. I thought tire wear was just due to the slight slipping of the tire on the pavement scraping away material, but flexing of the rubber is the real culprit, and higher pressure reduces it.

Red bike above 24X3 inch. Last forever. 3500 miles and no real visible wear.

There's some narrowed focus in some parts of the discussion above.

Primarily, "safety" is narrowly defined to be absence of bodily injury. Unless you think a heart attack is "safe", the consequences of not getting enough exercise have to be factored into any safety analysis. So, given this, we must spend some time each week getting exercise in order to reduce the (quite high) risk of heart attack, stroke, diabetes, etc. Some forms of locomotion (notably, walking and cycling) also provide exercise. This complicates the accounting -- arguably, the first few hours of walking or cycling each week, should be regarded as exercise, not transportation, and thus you arrive at your destination in no time at all, if you cycle/walk to someplace you were going anyway. Similarly, the "fuel" charge for walking or cycling, up to the first few hours each week, should also not be charged to transportation, because safety requires that you get the exercise anyway, and exercise burns calories.

Given this slightly broader focus on safety, cycling becomes an incredibly efficient means of transportation.

Note that the number of US deaths from diseases-of-the-unfit is huge -- 616k from heart disease, 135k from stroke, 71k from diabetes. That's not counting cancers, some of which (colon cancer) have their risk reduced by exercise. Car crashes are not even 5% of this.

Obviously, we all die sooner or later, but later is nicer. Exercise reduces your yearly risk of death, and apparently reduces the cardiac disease mortality rate by 28%.

Obviously, this assumes a rational approach to mortality and risks, but I am sure everyone reading this has signed up for that :-).

Note that this does not say much about small cars versus large cars, or that we should junk our cars and ride bikes. What it does say is, if you are not getting enough exercise, and you are not incredibly worried about that, it is irrational to worry about the relative risks of small or large cars. And, further, it suggests that it is poor accounting to "charge" cycling and walking for fuel calories or transit time, up to the weekly quota of time/calories that we should be spending on exercise anyway.

Hey hey Jeff,

How do airships/zeppelins compare in this analysis? They were fuel efficient and carried a heavy payload but not very fast. I'm curious because zeppelins were economically successful until fixed wing aircraft matured. I would assume they will be competitive again when high fuel prices start impacting the aviation industry.

Also, as an aside, the large surface area seems promising for a solar powered PV/electric motor craft.


All this talk about cars!!

Whether gas or electric, the car is a travesty in the 21st century. To do more mobility with less mass requires grade separation. Put the vehicles on a fixed guideway, automate them (as in automobile). Return the surface to the people, not machines.

Now, one more consideration... Energy source. As pointed out here, EVs ... for a long time ... would mean coal. Anyway, since the vehicles are on a fixed guideway, we can put solar panels on the top and conveniently match supply (sunlight) to load (mobility is mostly a daytime activity). A little storage ... Maybe an order of magnitude less than EVs would require.

The point is, ingenuity trumps oil. All this talk about the glorious high energy density of oil goes by the boards, as solar + electricity gets you where you want to go 1,000 X safer, with 50-100X less materials (because vehicles weigh less and are shared 10-20X per day.

Call it the Solar Highway.

Oh, and we can end the already real world war -- the one going on between people and their machines, with one million casualties a year worldwide (not to mention the millions injured).

Beyond oil = beyond cars.

Which motorcycle was used in these calculations?

There is a lot of difference between a roughly 40MPG BMW R1200GS and a roughly 70MPG Kawasaki KLX250. And those are not even the extremes among motorcycles without fairings. Add a fairing and another 5-10 MPG is feasible.

Additionally, what bike was used for the emissions calculations? A contemporary motorcycle with a catalytic converter (present on all road bikes in the USA AFAIK) will be roughly in line with most econocars.

`What keeps my family members and I in heavy vehicles is all of the other people in heavy vehicles, especially pickup trucks. And, there are are a lot of aggressive, bullying people driving them. A common outcome of car versus pickup collisions is that the pickup driver is uninjured and the car driver is killed or hospitalized. I figure our best insurance is to drive heavy vehicles. I imagine there are a lot of people that avoid lightweight energy efficient vehicles for the same reason I do.

This suggests that you would favor taxes and/or regulations that would discourage gratuitous (ab)use of such large vehicles; this would make the roads safer, allow you (and others thinking similarly) to downsize, save energy, etc, etc.

This is a perfect job for government -- to make rules that break destructive social (game-theoretic) traps.

If increased personal transport efficiency is to keep up with growth in demand for personal transport in Asia and total decline of FF supplies (oil for ICE and nuke/coal electric for battery) then a transport revolution has to be set into motion.

Say the number of "cars" or other personal transport units goes to two-three billion and oil/coal/nat gas goes to zero over 30 years. Realistically seen people and markets react to price or govt. incentive (or lack of subsidized fuel). So when the Chindian market for cars grows to a certain point (Current oil supply limit at any given moment) oil prices (preferred transport fuel) will go through the roof several times until people each time stop driving and then switch to dirferent more efficient transport, scrapping previous fleet. There will be a big mess and the technology companies and free markets cannot possibly keep up with all this rapid change on such a large scale if we get real declines in oil (3-5% per year decline) and then such massive growth in private car use in Chindia. Clearly Chinese govt. and similar will force high efficiency technology down companies throats periodically through mpg mandates or zero emissions mandates or forced car pooling or max car weights with taxes. Clearly technology is there but not on a massive scale needed or desired and the price mechanism decides the political/market pressure level to get things done. China is compact and could ban cars and go back to bikes if the govt. had an oil unavailability due to, e.g. US blockade (as USA needs all the oil) but USA has a serious infrastructure problem and could not do without cars so readily. Individual trapsor tis the problem and not the solution. Centralized/mixed living/business and localized supply of goods/services reduces transport needs radically obviating a soltuion to anow nonexistent problem. Tranpsort would then be by water for bulk goods or not at all. This solution is 30 years away if FFs are out of stock in 30 years.

Net energy reduction (3%/annum) x increased energy efficiency(3%/annum) x increased demand (3%/annum) will lose out more than likely as it won't be rationally planned. Hirsch report was right. We needed to change decades ago through a technocratic dictatorship. If we lose three % energy per year but equal that out by efficiency gains which are themselves killed by the jevons effect (increased demand for more efficient products) then there is no way to beat this one without breakdown. In a small closed system like e.g. Holland or Denmark where everyone just switches out their car for on a fixed schedule for a more efficient one as the local oil supply falls very gradually but everyone has a car already it would possibly work under govt. mandated system. However oil is on a price yoyo, deamnd can grow unlimited, nobody is mandating people to reduce usage, a perfect linear increase in efficiency through tech./rational business decisons to replace lost oil supplies cannot be assured, etc.

A car and a house far away with need to always get away and be somewhere else is just an ego trip. Walkable towns and cities are better. Bikes, trams perhaps best solutions until we get back to foot and horse transport and a smaller population globally over time.

My ride is a 2002 Honda Metropolitan scooter. $2000 out the door, no insurance required (in Nevada), no plates, no helmet required. Parking is a snap, and I never have to get into a hot car. The wind is cooling in summer, and in winter I dress warm and slow down in the snow. 100 mpg standard, but since I always punch it, I get about 90 mpg.
Will do almost 35 mph, and I have little problems with cars in town.
I love it, and maintanence costs in the last 8 years have been a total of $600, includes major tune up, and new set of tires, oil changes, new fron fender, etc.
It's a very quiet 4-stroke, electric start, and is saving me probably $500 a month over the cost of a new car, insurance, and all that crap. That's $6K a year saved, or so far since purchase, nearly $48,000 over the cost of an auto....
This vehicle has allowed me to drop to a 30 hour work week, and still put a little bit of money in the bank every month.
Otherwise, I'd still be doing 40 hours and getting nowhere if I still owned a 'car'..

For a look at a unique pneumatic transportation system, please check out to see the potential for 3,000,000 new jobs, building a 200 mph system which will in theory deliver 100 lbs of goods from seatlle to Chicago for $1, and/or passenger travel from Chicago to New York for $5 one way.
A low cost, fast-build out system which, unfortunately is probably even too radical for folks here to consider.
The guy seems to have it together, and it sounds good to me, but then I'm not an engineer.
Would appreciate any input on this system from those in the know....

Unfortunately the link to the pneumatic system didnt work.
I don't know what kind of system is proposed here, but I'm reminded of the Atmospheric Railway as built by the Victorian engineer Isambard Kingdom Brunel on part of the South Devon Railway in England. Pistons traveling in a tube between the rails propelled the carriages. It worked, but was not a success. For one thing the tubes were closed with leather flaps that had to be kept supple with tallow, and were then eaten by rats.
On the other hand, if it refers to trains fitting into round tunnels and being blown or sucked along, the most famous example in the USA was the Beach Railroad in New YOrk
All power to new ideas, but there are many pitfalls. It seems that the Victorians were bolder innovators than we are, in many ways.

Sorry about the link. I supposed it is a good thing to test ones link after posting, eh?
Try to read more about his system.

How does your oil consumption compare to the average oil consumption in your state?

This would be fascinating if it were true. However, the value for Connecticut seems arbitrarily low...does that include heating oil?

The National Priorities data base they reference shows per capita oil use at about 20 barrels per capita from 2000 to 2010...doesn't seem to gibe with their total numbers. (The link was broken, but one can navigate to the NPP data base from the home page.)

I also have to wonder if they are accounting for non-taxed farm diesel in the energy use calculations.

I agree with the Connecticut value seeming low. How true these numbers are, can be debated for sure. What I find relevant, is that per capita consumption per state varies considerably, which is true, so personal transportation options will vary as well. For example, I don't see a bicycle being much of a year round transportation solution in Alaska, whereas in Hawaii, a bicycle might make perfect sense.

Here is a chart showing average petroleum products consumption per person has decreased relatively sharply since 2007. I find the information more relevant than the political opinion.

I live in Central California along the coast in a mild climate, and am able to easily incorporate an electric bike into my transportation needs. I use less than one gallon of petroleum product per day, and live a comfortable lifestyle. I find no need to use more petroleum than this.

So how much petroleum product do you use per day?

Don't forget that about 40% of oil is consumed by industrial/commercial users, so the average individuals consumption is closer to about 1.4 gallons per day.