Pelamis: A Shot in the Dark?

[editor's note, by Prof. Goose] This is a guest post by lads.

Pelamis is a greek word that means sea serpent. I guess it is the best definition for what I was shown today, a metal serpent riding the waves, harvesting its energy.

A presentation of the pilot project was held here at school, directed to the Hydraulic Engineering students, but open to the general public. The speakers were from Enersis, the company promoting this first full materialization of such technology. I couldn't miss it.

What you see in this picture is a cylindrical metal structure with 150 meters long by 3 meters wide; sitting still onshore it resembles a 5 carriege high-speed train. It weights 400 tons, and uses another 300 tons of ballast on the sea floor to keep it in place. It is supposedly the best present technology for harnessing the waves' energy.



Every state of the EU ratified the Kyoto protocol, but only two are now below the emission levels agreed, moreover the majority of the states is increasing or failing to reduce its emissions. This is posing a huge financial problem, especially for smaller states; from 2012 onwards CO2 credits must be bought, blowing away the budget of these states. This is the main problem that the Enersis folks to compels us to invest heavily on renewable energy. They didn't mention any problems on fossil fuels, but showed some concern with present prices.

A major expansion of renewable energy is therefore needed to minimize the consequences of not complying with Kyoto. But the current forms of renewable energy do not have that expanding potential: the sites for wind energy projects are disappearing (mountain tops are already filled with turbines, and natural reserves also take their toll), geothermal and tidal are also restricted; as for hydroelectric the expansion limits seem already to be reached.

As for the waves they present a vast resource, the restrictions might be way over our needs, this must be the way to go. Moreover larger cities tend to be located in coastal areas, facilitating the connection with the delivery grid. Wave intensity can also be predicted with 4/5 days antecedence, making it easier to accommodate peak output periods to the grid.

At this point they forgot to talk about offshore wind energy; on purpose? I don't know, but the final paragraphs will tell more.

Brief History of Pelamis

It started in 1998 when Ocean Power Delivery Ltd (OPD) was founded in Edimburgh to develop the concept of Pelamis, a Wave Energy Converter (WEC). From then on OPD managed to get funds from venture capital companies, developing at first a 1:7 scale prototype and then moving to a full scale machine that has been under testing in the European Marine Energy Centre in Orkney.

Enersis is a Portuguese renewable energy company, that has been investing in the wind sector since 1998; in 2003 it started considering the hypothesis of wave energy. After some pre-agreements in 2004, in the beginning of 2005 it signed the contract for the first Pelamis production units that will be deployed off Póvoa do Varzim still this year. This project will start with 3 Pelamis units, each with a max production capacity of 750 Kw, totalizing 2250 Kw.

How does it work?

My knowledge of hydraulics and mechanics is very slim, but I'll try to give you an idea.

As usual wave energy is actually solar energy, the sun heats the air masses generating wind, on the oceans the winds cause disturbances on the sea surface originating waves. Waves generated at different parts of the ocean interact with each other adding and creating vast fronts of motion, with immense energy.

Previous ocean WEC projects have failed because of the extreme conditions that can be experienced at high sea. At a site with a mean wave amplitude of 2 meters, waves of 20 meters can be experienced during extreme weather conditions. Pelamis' success comes from the fact of not being designed to maximize energy output, but to survive the high sea fare. The key factor to achieve survival was the concept of the moorings that keep Pelamis in place, rightly oriented to the wave motion; when waves become stronger Pelamis pierces through the wave, avoiding stronger movements.

When a wave passes through Pelamis it "serpents", the 4 sections sway, both horizontally and vertically, this motion actions hydraulic jacks located at the 3 junctions pumping high pressurized oil that put the electric generators at work. This way the pulsating movement of the wave is transformed in a continuous energy flux.

Pelamis sways both horizontally and vertically

Pelamis can be tuned to accommodate the specific conditions of the operating site, maximizing the energy output without compromising the survival of the equipement. This is accomplished by varying the length of each section.

If you want a deeper understanding of this technology please visit the links I furnish below.

Pelamis' Power Convertion Module

The Aguçadoura I Project

Aguçadoura is the name of the nearest village of the deploy site, by so chosen for the name of this pilot project. It is starting with 3 Pelamis units totaling 2250 Kw, and will expand to 5 units sometime in the future. The transportation of these first units to Portugal has begun, as so the final assembling in the shipyards of Peniche, with deployment occurring still this year. These units are tuned to start working at wave heights of 0.6 meters, reaching peak production at 5.5 meters; they are expected to work 2800 hours per year (this is quite close to onshore wind). The life expectancy of Pelamis is somewhat unknown, but 15 years was given as a low estimate (in my view this might be optimistic, we are talking of a semi-submerged steel structure).

This first 3 unit project has a cost of € 8.5 million (to get a better idea a 3000 Kw wind turbine costs here around € 1.2 million - at this point my red light started flashing). The electricity produced by this project will cost the triple of current energy produced in Wind farms (I don't see how this can be so low from the previous numbers).

It seems that other companies are watching closely this project, if it succeeds, you may see Pelamis wave farms in the North Sea (UK and Holland), California or Australia.

Enersis is already planning the Aguçadoura II project, a wave farm with a total of 38 Pelamis. Once Aguçadoura II is operational Pelamis will become fully commercial. From this point on, Enersis expects a period of 7 to 10 years of refinement and development that will lead the monetary costs of the energy produced to the levels of Wind energy.

Future development focus on using materials other than steel, resistant to corrosion (in this chapter seagulls are a headache), and on increasing power capacity. Pelamis with 1000 Kw are being designed, and 2000 Kw can be possible; this is achieved by increasing the length of the Pelamis, but wavelength will put a limit to that.


To start my conclusions I will write here my interaction with the Enersis technician that made the technical presentation, during the Q&A session:

Q: What is the Energy Profit Ratio (EPR) of a project like this?

A: I don't know, I have never done that kind of accounting, but adding the costs of materials, production, paint, etc, I can say it's pretty high, like that of Wind.

Q: Offshore wind energy seems to be bound to EPR figures near those of Uranium. Now imagine I win the Euromillions and I want to invest, what will make me choose Pelamis instead of an Offshore Wind project?

A: Look, I think EPR is a very bad way to evaluate an energy project because of the immense market distortions we have right now...

The guy then started talking about coal, and how the price of electricity from coal at the power plant was half of that at the grid end. He suddenly started talking to someone else, and avoided me thereafter. The room was emptying, I left.

First Conclusion: these guys don't have a clue of what EPR Pelamis has (I also doubt they have a clue of what EPR is).

This project is a Shot In The Dark, like Ozzy says. It has a lot of engineering to it and at first sight it might seem to have a bright future, but EPR must be know in order to evaluate it against similar projects. We must not forget that waves are raised by the wind; wave energy will mostly be redundant to offshore wind energy. This is enforced by comments made by the Enersis people indicating that the southern portuguese coast wasn't useful for wave farms - this is where the wind blows weaker in the western european coast. Since we live in a finite resource world we should use those resources the best way possible.

There are of course different characteristics to wave energy, you can yield waves form winds hundreds of miles way (the highest waves that reach Europe's west coast are formed in the North Atlantic), also wave motion is somewhat smoother than wind, which tens to blow in bursts. But still the intermittent characteristics prevail.

I believe we should wait for the Aguçadoura II to be completed to take final conclusions, by that time Offshore Wind will also be more mature, making comparisons easier. This kind of project should be take forward only if its EPR is above that of Wind Energy. If the EPR of Pelamis is found to be over 1 it can be considered only in situations where Wind energy cannot be directly yielded.

To know more:

Ocean Power Delivery

Slideshow (I strongly recommend this one)

Interactive Model



Thanks once again to the TOD editing team for letting me share my views with the oil drummers.

Comparing this to an offshore wind farm, I wonder which has a greater environmental and societal impact? Pelamis might well have less impact on migrating birds, and perhaps less visual impact, but it would also be a possible hazard to navigation. In places where the water is deep, Pelamis might be easier to implement since offshore wind farms are usually built on concrete pilings. On the other hand, floating wind farms (which still don't exist except on paper) might be a better way to go.
You can always go to the 'egg beater' style wind turbine if you're concerned about the birds. The proponents of that style of wind machine claim it is also more rugged and long-lasting, although I believe it does not collect as much wind energy per pylon.
Eggbeaters. Like this:

Birds avoid 'em and they're prettier, I think, than those propeller-blade things.

I hear a lot of people saying wind power affects migrating birds. Can anyone provide any definitive evidence or research on this? Are we talking about a couple of birds getting chopped up a year or entire flocks?

Also, there's got to be some simple technology that can be used to scare off the birds. Maybe a high-pitched sound alert when birds are detected by the windmill.

The bird problem must be solved!

Seems like windmills are the answer to H5N1.
Horns Rev has proved not to be a problem for migrating birds. They actually avoid the farm, and if they decide to go throw, they also avoid the blades.


Go to google and put in this phrase in the search bar:

Wind turbines and birds

You will have reports to read for days and days!  The problem is, the results are somewhat inconclusive.  From my reading (and I have made my eyes hurt reading the subject, since I am involved in an experimental wind turbine firm)
the main consensus looks like this:

a.  Wind turbines do sometimes kill birds.
b.  Location means everything.  If the turbines are located in a flyway of large predatory birds, the damage can be severe.  If the birds are already endangered species or a population small in number, it becomes a serious issue to confront.
c.  In areas not frequented by larger predatory birds such as hawks, owls, eagles, the damage is less severe, and probably no worse than any other tall structure such as cell phone towers, guy cables to cell and broadcasting towers, taller glass buildings, and fossil fuel towers, etc.  Birds do also strike those.  Let us not forget the killing of birds by aircraft.
d.  It is the spinning motion of the blade that makes wind turbines more dangerous to birds.   They never know what hit them.  However, some studies do indicate behavior change by the birds over time.  The sight/smell of dead birds on the ground make the living ones leery to go there (this is not a joke, birds do "learn".  Experiments have also been done with colered ribbon, noise makers, etc., to dissuade birds from going near wind turbines.  The results are still inconclusive in most cases.
e.  The issue of perception is crucial.  Since wind is percieved by it's supporters as "environmentally friendly" power, any bird kill by wind turbines will be viewed much more seriously than the same kill would be viewed if it were caused by a fossil fuel plant.  Thus, the Audoban Society, Seirra Club, National Wildlife Fund, etc.,  have shown great interest and made intensive studies of the bird kill issue, and the wind industry is always working to address it.  
f.  Regarding the above, almost no such scrutiny concerning bird kill has ever been placed on the fossil fuel industry.  Open waste storage tanks are deadly to birds, and the "catch basin", "retention ponds" and lagoons for oil and coal "tailings" of many oil/coal drilling/processiong operations can contain hundreds, sometimes thousands of dead birds.
g.  Other industries and agriculture can be deadly to birds.  One of the great killers of predatory eagles and hawks is the fence, be it barbed wire or woven wire.  When a predatory bird spots prey, their eyes focus to that prey, and the fence between them and the prey become invisible to them.  I know that in Kentucky and Indiana, several eagles have been rescued from fences with broken wings.

In closing, wind power is expected to act to a higher standard than the fossil fuel industry, and rightfully so.  Any developing technology reducing danger to birds, should and I think will be implemented.

Roger Conner  known to you as ThatsItImout

A local ornithologist here at the west coast of Norway has complained that a new wind farm kills sea eagles in large numbers, particularly in the mating seasons. The park in question can kill over ten eagles per month then, with an average per year of about two eagles per months. Given the low population and slow reproductive rate of these eagles, it's significant. The park's owners have said that they are open to the idea of shutting off the windmills in the mating season.
Very expensive eagles they have down there.
In this thread that discusses the bird kill issue, I offer citations that find each wind turbine is responsible for 2 bird deaths per year on average. That's 0.003% of the total number of human-caused bird deaths -- not even considering biggest factor of all, loss of natural habitat.

In addition to ThatsItImOut's points, it's worth mentioning that the newer, bigger turbines with larger, slower-spinning blades are much easier for birds to avoid and pose less of a danger than the models of 20-30 years ago.

This won't do much to assuage the concerns for Raptors, but Cats and Cars are a couple of our best forms of bird-killing.

Cats are said to take upwards of 10 million birds a year, don't know what the auto estimates are.


Cats kill hundreds of millions of birds annually in the United States, said Jimm Edgar of the Mount Diablo Audubon Society, citing an article in Birders World titled "Cats -- they're soft and cuddly. They're America's favorite pets. They're also natural-born killers."

"Domestic cat attacks ... (have) contributed catastrophically to the decimation of certain avian species, especially some of our most beloved songbirds in North America," the article asserts. The American Bird Conservancy concurs with the hundreds-of-millions figure.

Dairne Ryan of Fix Our Ferals, another cat rescue group, challenges it. "You can find studies that counter that," she said. "We would all like to see better statistics, but feral cats defy statistics."

Many birds are killed not by feral cats but by pet cats whose owners let them outside in the morning and bring them in at night, Ryan said. es_science

Besides cats killing birds, our tall buildings kill them very efficiently.  They try to fly thru the glass windows that reflect the natural outside environment.  Our cars mow them down all the time on our roads.  Cars also kill lots of other animals that we just leave to rot by the side of the road.  We have hunters that think it is great sport to shoot them (including eagles).  We build subdivisions in their breeding areas so we can enjoy nature.  

Compared to all this, windmills are an absolute pleasure.  We worry about a couple of birds and ignore our wholsale destruction of them.

On the other hand, floating wind farms (which still don't exist except on paper) might be a better way to go.

We often talk about how our societal organization is more so the problem than lack of technology. Offshore energy production is a good example. Unlike an on-shore energy platform, when you try to get permission for an offshore facility, you need to please the beureacrats of many governments at the same time: the Fed's who have jurisdiction over the 3-mile/200-mile coastal border and the State guys who take over once you try to string your cable onshore.  

Great Articles! I don't know how well this design will work offshore in the Gulf of Mexico, wave heights are generally less than 2 meters around here. But if it works pretty well this technology could be easily adapted to fit on the legs of offshore production platforms and possibly wind turbine platforms to provide more energy.
  I am a firm believer that it will take many different approaches working together to get us off our reliance on fossil fuels. Solar will work well in the deserts, wind in high wind corridors, methane from waste, wave generators in coastal areas, possibly solar cells in space beaming microwaves to earth. Conservation should be our first approach of course.
  I have nothing but applause for any group of people working towards real renewable sources.
I saw some charts where they showed the average amount of available wave energy for various spots on the planet:


GOMEX appears to be a rather poor choice for these things.  

That would make sense as the GOMEX is quite enclosed in relation to the wave/swell generating ocean and, i believe, doesn't have great tides (due to it's proximity to the equator)...

I'd imagine that what these generators use is "sea swell" rather than waves generated by wind.  You only get good sea swells in regions of open ocean where there is lots of space for the sun/wind to interact and churn the sea.  

Any kind of coastline will quickly knock down sea swell.

The entire Eastern Seaboard of the US/Canada... but especially the North East sections, would be excellent regions as they have strong tides, strong weather (generated by hurricanes in the summer, and winter storms in the winter), and a fairly "open" coastline, where the sea swell washes right up on shore.

The West Coast would be just as good, though the weather isn't as extreme, the Pacific is so vast that waves can be generated on the other side of the Date line and still cause good surf on Long Beach.

I fished in the Queen Charlotte Islands for 4 summers... they are just south of the Alaska panhandle in Canada.  The West Coast of the Queen Charlottes would be absolutely ideal... hardly a day without sea swell there.. and when it comes, it's big.  On the other side, between the Islands and the BC Mainland, is Hecate Strait... it has some of the strongest tides and strongest winds in the world... which makes for a hellish place if your stuck there in a storm (I've seen 50 foot waves towering over our 51 foot boat... a humbling, and frightening experience... good thing I have a strong stomach).

Long story short... even if these generators are expensive... there is no doubt that there are a ton of regions in the world where this would make sense and could contribute.

I'm sure that's what BC Hydro, the public Electric Utility here in BC... helped to fund some of this research (i think).  Hopefully we see some of this stuff of our coast.

The problem is more remoteness.. alot of these "wavey places" are a little "out there" especially in North America... so transmitting that energy into the grid will likely be the biggest stumbling block.

Pelamis was design to use wind generated waves; its maximum performance occurs in the 50 meters deep range.

It can also use the swell of course, I don't see any reason why it shouldn't. Although moorings at high sea would be a problem.

I don't think Pelamis was designed to survive hurricanes. Still your ideas of using it to take advantage of existing stuctures is a good one.

I guess I am not as concerned about the EPR for the things as they build them today.  It sounds like the plant in Portugal is really more of a pilot plant - mainly to get some more experience with the things and learn what the weaknesses might be.

What would be more interesting is what the EPR might be a few years from now, but even this is going to be hard to predict.  We already know they are looking at using different materials for production models - partly to bring the cost down, but also so that they don't have to worry about steel rusting through.  It would seem logical that by selecting different materials, the EPR itself is going to change, but we won't know what that change would be until they select different materials...


I think your exactly right on that point, and I couldn't help but notice the  reply by the Energis technician....
"A: Look, I think EPR is a very bad way to evaluate an energy project because of the immense market distortions we have right now..."

Oh, how true, how true!!

I remember reading a white paper only a couple of years ago by one of the American "think tanks" that absolutely ripped wind energy apart...the paper said that per kilowatt power prices were only going down due to utility plant efficiencies, as they had been for the prior 10 to 15 years (which by the way, was absolutely true, Combined Cycle Gas power plants were amazing in their ability to improve efficiencies), so that wind could NEVER catch up to the return on fossil fuel as a power source.  Conclusion:  Wind would have to be a technical and corporate "welfare" project forever into the future.

The problem was they were basing their projections on a $4 to $5 per MM/btu natural gas price, and $30 oil prices into infinity!  

The other big factor:  Wind was and is still relatively early in it's development as a large scale electricity provider, while the improvements possible with Combined Cylce natural gas and coal plants have gotten pretty far down the road in development, with any further improvement being harder and more expensive.

In other words, most of the EPR stats, EROEI stats,  ROI (Return On Investment) stats for almost all fossil fuel AND alternative energy technology are almost useless if they are more than 4 years or so old, and will be even more out of date and useless in 4 more years.  This is a very fast moving game now.  As the old talkie said, "ya ain't seen nothing yet!"

Roger Conner  known to you as ThatsItImout

You're mixing prices with EPR.

What if EPR is lower than 1?
What if Pelamis' EPR is lower than that of Offshore Wind?
Would you put your money on it?
Would it make sense to spend capital in Pelamis if Offshore Wind is a better option?

Q."What if EPR is lower than 1?"
Answer:  If there seems to be no way to improve it from that, it's dead.
Q What if Pelamis' EPR is lower than that of Offshore Wind?
Answer:  There could be location or other factors making the Pelamis useful in certain situations.  I am biased on this one, though, I prefer wind, just due to the seawater issues, and I actually prefer onshore wind to offshore winds, again, depending on the exact siting situations.
Q. "Would you put your money on it?"  Frankly, not yet, until I actually could see it operate for awhile.  But that doesn't mean no one should.  The United Kingdom could be in a bit of special situation for example, and need the wind and the tide both, and soon, in which case, they may take a bigger chance to see if it can work.
Q. "Would it make sense to spend capital in Pelamis if Offshore Wind is a better option?"
Answer:  No.
(again, my preference is wind, but I am biased due to my own projects)

Roger Conner  known to you as ThatsItImout

As a guess, maintenance is going to make or break it (much like early wind farms) and not original costs (measured in energy or dollars).  I assume these things could last many decades, with periodic maintenance and bottom-cleaning.  The original costs will be amortized across those decades.

We kind of solved wind's maintenance problems by resizing turbines to be bigger and more reliable.

... anyway, I hope their mantinance costs on the pilot projects are being audited.

Wave energy happens to be a little side interest of mine in which I've dabbled a bit. While I recognize that it is even more location-specific than wind energy and will probably never become anything more than a niche in the total energy supply picture, I find it a fascinating subject nonetheless.

There are several categories of wave energy converters, each of which has its own set of pros and cons. In general, the whole trick to making a successful wave energy converter is i) to absorb as much of the wave's energy as possible in the smallest and/or least expensive mechanical embodiment, and ii) to make a wave energy converter capable of surviving the punishment of severe storm conditions.

It is in this last requirement where the Pelamis really excels. All wave energy converters need to have some form fixed 'reference' for the device to work against. In other words, if a float is just bobbing around freely, it is not absorbing any wave energy, but if the same float is tightly moored to the ocean floor, the foreces in the connection between the mooring and the float can be used to absorb energy, either through compressing air in a cylinder, or forcing hydraulic fluid through a turbine etc. However, during a severe storm tremendous stresses are set up  between the mooring an the device. Many test devices have been smashed to pieces after encountering their first big storm.

The Pelamis, on the other hand, is very loosely moored on a very long mooring and does not rely on the connection between the mooring and itself to form that fixed reference. Rather, that reference is provided by the four connected segments of the Pelamis working against each other. When the foremost is at the crest of the wave, the aftmost is at the trough of the wave. This causes a relative movement between the segments, and energy is absorbed by hydraulic cylinders cleverly connected to the joints. In other words, through the hydraulic system, the Pelamis is trying to remain stiff while the wave action is trying to bend its segments relative to each other. Energy is absorbed in the process.

During a severe storm the hydraulic system is deactivated, and the segments then loosely follow the motions of the waves, with very little stress on the segment joints and the loose mooring. In effect, this design feature makes the Pelamis sort of 'invisible' to many of the undesireable effects of severe storms. As best I can tell, the Pelamis is probably the most storm-worthy design out there. The loose mooring also makes it quite suitable for offshore operations where the waves tend to be larger.

By the way, the Gulf of Mexico and tropical waters in general are relatively poor locations for wave power because the average size of the waves is rather small (occassional hurricanes notwithstanding).  The west and north coasts of Ireland and Scotland, most of Norway, and parts of Portugal are also very good. As is the southern tip of South America and parts of Australia. Unfortunately, most of the best wave power locations are also relatively low-population areas.

By the way, near-shore breaking waves may look very dramatic but they don't have the power of the large steady and long-wave length waves that one encounters further offshore. Waves are also much more gradually sloped than they appear when viewed head on. A wave will typically have a wave length to height ratio of approximately 40 to 1. So a 6-ft high wave will have a wave length of typically 240 feet.

I do believe the version of the Pelamis in the photo is rated at 350 KW, but I am not totally sure.

Thanks for adding this piece joule. Is there hope for these kind of systems beyond the 50 meter deep range?

Those pics are probably from the test unit that has been in Orkney. I don't know if its power rate is lower than the production units.

This looks like a promising technology, that being said without any hard numbers to evaluate.  I would be concerned with the maintenance of what appears to be a complex mechanical system with lots of moving parts.  

But the current forms of renewable energy do not have that expanding potential: the sites for wind energy projects are disappearing (mountain tops are already filled with turbines, and natural reserves also take their toll), geothermal and tidal are also restricted; as for hydroelectric the expansion limits seem already to be reached.

Ah, & thermal)??  Expandable, great ERoEI long term, and plenty of space (got 'em on your roof yet?)

"the sites for wind energy projects are disappearing "

That's only true for parts of Europe like Denmark and Germany, where wind has been pursued for a long time.  Other parts of Europe, like Spain, have enormous untapped potential (think Don Quixote).

The US has enormous wind potential - if intermittency problems were solved wind could easily handle three times our current electrical demand

There are two separate issues here.

First, what is the maximum electrical generation possible from wind (I'm assuming in the U.S.), if all the good sites for wind turbines were used.

Second, what is the maximum electrical generation from wind that the national electrical grid can handle without excessive problems due the intermittency of wind?

The AWEA info on wind potential by state is intended to address the first question.  It suggests that wind potential is at least roughly 300% of current electrical production.

The 20% figure is an answer to the second question, and is roughly based on the current state of the art in load balancing, wind prediction, demand management, etc.  If total electrical consumption were to increase, that 20% figure would stay the same.

The key here is that if increased demand came from plug-in hybrids (PHEV), or pure electrical vehicles (EV), the % would increase (and probably faster than the rise in EV demand) because EV's provide storage that helps reduce the mismatch between intermittent wind production and general consumer demand - only very simple demand management would be required to have the EV's preferentially charge when electrical supply was high relative to demand.  Thus, wind could supply all of the additional power needed by EV's.

I guess the key question is "How many of those things will it take to run the steel mill to make more of those things?" ...
I guess the key question is "How many of those things will it take to run the steel mill to make more of those things?" ...

exactly, thats the test none of the so called renewable energy solutions have taken let alone passed yet and it's the only thing that matters. if they can't make replacement units of these or any other renewable(including solar and wind) as cheaply and easily without oil/gas and only the energy input is from in use units then it's not a alternative. otherwise your just digging the hole deeper.

to quote....
"I guess the key question is "How many of those things will it take to run the steel mill to make more of those things?" ..."

I am still having trouble with the deeper philosphical aspects of that line of thinking.

I was looking at pictures of sailing ships the other day.  I don't mean recreational craft, but I mean the old "workboats" of the 17th, 18th, and 19th century.

Having frequented TOD a few times too many, I began to think about the EROEI of the big workboats of more than a century ago.

Now the earliest generation of the big sailing ships were not really "big" in the true sense.  Of the three ships used by Christopher Columbus, in a rather famous voyage in the year 1492 (at least to us Yanks!), the Santa Maria was the longest, with a keel of about 115 feet, while the two smaller ships, the Nina and Pinta, were around 50 feet.

Pause for a moment:  The large sailing ship was still the only intercontinental transport system some 350 years later!  It is still one of the most durable, stunningly successful instruments of transport, commerce and cultural exchange (including war) in world history.  The next time someone tells you "wind won't work"  kind of clue them in, would ya'?

By the time of the "Roaring '40's (1840's that is) the sailing transportation industry of large wooden sailing ships was at it's zenith, and also, relative to it's long history and unbeknownst to the travelers of the time, in it's last dying days.

"It was not considered ominous when, in 1838, the Admiralty had requested proposals for a steam service to America."

And the swan song concluding 3 centuries of trans Atlantic sailing to the new world, which would end in barely over 3 decades:

"The packet ships had held on too long. It had been a stirring episode for the passengers to cheer in mid-ocean when the lofty pyramids of canvas swept grandly by some wallowing steamer and left her far astern, but in the fifties this gallant picture became less frequent, and a sooty banner of smoke on the horizon proclaimed the new era and the obliteration of all the rushing life and beauty of the tall ship under sail. Slow to realize and acknowledge defeat, persisting after the steamers were capturing the cabin passenger and express freight traffic, the American ship-owners could not visualize this profound transformation.

But the finale was grand:
"They were small ships of three hundred to five hundred tons when the famous Black Ball Line was started in 1816. From the first they were the ablest vessels that could be built, full-bodied and stoutly rigged. They were the only regular means of communication between the United States and Europe and were entrusted with the mails, specie, government dispatches, and the lives of eminent personages. Blow high, blow low, one of the Black Ball packets sailed from New York for Liverpool on the first and sixteenth of every month. Other lines were soon competing--the Red Star and the Swallow Tail out of New York, and fine ships from Boston and Philadelphia. With the completion of the Erie Canal in 1825 the commercial greatness of New York was assured, and her Atlantic packets increased in size and numbers, averaging a thousand tons each in the zenith of their glory."

"Meanwhile the era of the matchless clipper had arrived and it was one of these ships which achieved the fastest Atlantic passage ever made by a vessel under sail. The James Baines was built for English owners to be used in the Australian trade. She was a full clipper of 2515 tons, twice the size of the ablest packets, and was praised as "the most perfect sailing ship that ever entered the river Mersey." Bound out from Boston to Liverpool, she anchored after twelve days and six hours at sea.

More, the clippers speed could be stunning, given their size.:
"This clipper, sent across the Atlantic on her maiden trip, left in her foaming wake a twenty-four hour run which no steamer had even approached and which was not equaled by the fastest express steamers until twenty-five years later when the greyhound Arizona ran eighteen knots in one hour on her trial trip. This is a rather startling statement when one reflects that the Arizona of the Guion line seems to a generation still living a modern steamer and record-holder. It is even more impressive when coupled with the fact that, of the innumerable passenger steamers traversing the seas today, only a few are capable of a speed of more than eighteen knots.

Toward the end, the greatest of all sailing ships would be built, as measured by tonnage.  The last would even have steel hulls:

She was built in 1878 by Russell and Company in Port Glasgow, Inverclyde, Scotland, launched as the first of eight iron-hulled four-masted ships built for Wright and Breakenridge's Falls Line.

Here's the irony...."the only surviving sail-driven oil tanker, in the world."

Now let us consider this in ralation to our EROEI discussion of renewable energy.  
The sailing ship created a world trade and world empires.  Tea from India, China dishes and tea sets from of course China, tobacco, cotton, rum, slaves, all were made an international trade by the power of the wind.  The growth in trade, commerce, and cultural exchange meant that the EROEI of a giant sailing ship must have been FANTASTIC.  But, how was that true?  What were the "real" numbers, in man hours, in lumber, in nails and fittings?

In the post I am replying to in writing this, and the post it replies to, we were discussing "wave power" or devices that would harness the power of ocean waves for energy.  The assertion was made that the whole exercise would be "digging a deeper hole" unless the "wave power" device could power the steel mill that built the wave power device.  
Questions multiply:  For how long would it have to power a steel mill?  Would the mill be "dedicated" to only making the wave power device?  What if the Wave power device only "freeded up" enough kilowatts to equal the power used to make the steel, and not run the steel mill per se, would that be good enough?  If the steel was recycled, would that change the equation?  What about recycling the steel when the wave power device was worn out?  Would that change the equation?  What about extreme tempetures needed in handling metal, would the wave power device be expected to match those second by second?

Allow me to return to the giant, beautiful and durable sailing ships.  The commerce they opened up of course caused new industries to develop, new opportunities, so that the last of the last ones could actually act as oil tankers, helping the EROEI of the early oil industry (!)

But in the long history of sailing ships, no one ever suggested that for the sailing ship to be useful, it had to provide the power to build another sailing ship!  

The sailing ship of yesterday, like the windmills, the solar panels, the wave power devices, the hybrid cars of today, were a "component" of a much larger and more involved system.  If the rest of the system had not developed along with the large sailing ship, then the Nina and the Pinta would probably now be regarded as "giant ships" and we would be living in a different world.

The only reason that renewable energy devices would be built to the exacting standard (which applies to no other industry) that oil and fossil fuel could not EVER be used in their construction is if the world were to be truly OUT of fossil fuel.

We don't mean PEAKED, we would mean OUT.  There is no scenario that I am aware of that indicates that would be true for the next 150 years, or for that matter, ever.  PEAKED, yes, but OUT?  That is not even on the table of discussion.

There simply must be some way to regain some touch with reality.  As we write our posts tonight, factories are building airliners and speedboats, shops are building racing cars, all of which require a degree of engineering and a variety of materials that make the "wave power" device look simple and primitive by comparison.  What is the EROEI on an airliner, a speedboat, a racing car?  Yet they are being built.  The oil and gas is there to build them.

When the first steam engine was built, what was the EROEI on it?  It was designed to convert energy from a non renewable resource (unlike the giant sailing ship), not to recapture energy or to use "renewable" energy (excepting the earliest pre coal wood burners!).  The first ones were built by hand labor and wood charcoal fires in blacksmith shops!  How could an industry such as that hope to sustain itself!  Where would the steel come from!  How many million men would have to work in the steam engine factories?  How would they be fed?  How big would the shops have to be to build them?  I have always wondered, in a straight on comparison, what the EROEI comparison between a steel hulled steam ship, or a wood hulled sailing ship, what the comparision would look like.  It woud be fascinating to see, counting the coal burned by the steamer mind you, against the knots per hour covered by the sailing ship!  Would wind power still lose the EROEI race?  How?

I do not have an answer as to exactly what direction the future of alternative energy will take.  I think that there is simply no way people can visualize the "confluence" of ideas and technology, the ways in which one renewable can be used in combination with another renewable, and in combination with the remaining non-renewables  (trillions of barrels of oil and trillions of feet of natural gas EVEN AFTER PEAK)  

Let us not dismiss the way that the factor of time can become a flexible part of the mix:

 I had a friend who in the 1970's home brewed alcohol to drink, (this is Kentucky!)  and fixed up one car to run it....he used a set of three solar panels for distilling, built from leftover lumber and a set of salvaged patio sliding glass doors (double paned, they will hold some heat) corrugated black tin roofing inside the insulated looked like crap, but it would get HOT)...I asked him what he did when the sun didn't shine, and he laughed at my lack of imagination...." I can heat enough on hot sunshine in July and August alone and tank it to run through the year...."  It was the first time I realized that energy does not have to stick to the perfect "9 to 5" shift thinking to be a huge in "batches" can be priceless if it can be stored!)

The key is that we must build the components.  We must test the ideas.  We must engineer a variety of devices.  Ask the question another way:

If I build a solar collector that only returns say a 3 to 1 "energy profit" what good is that, you may say, oil returns 10 to 1!  But if nothing else, three to one slows the curve and buys time compared to the fact that I could have used the equal amount of material/time/engineering/BTU'S to build a speedboat or a racecar....what direction should we be moving?

Roger Conner  known to you as ThatsItImout

you completely miss the point.
your comparing a means of transport to a machine that is supposed to generate energy. this machine though needs energy to be built and maintained. it is cheap to make this NOW because of the fossil fuel economy we enjoy. this is also the question that needs to be answered before this can be considered a alternative. can this device(or any other renewable like solar and wind) be made from it's raw materials under two conditions.

  1. without any input of any kind from the current fossil fuel economy. this includes transport of raw materials, refinement of said raw materials, transport of the finished product, and finally maintenance. the only input that is allowed is the electricity a completed unit would make

  2. and be made cheap enough so the electricity it makes should be affordable to everyone and not just the super rich.

if both of these are not met then your just digging the hole. this is of course not count all the other products oil and natural gas give us other then electricity. oh and no government subsidy's there only use is to hide how bad some solutions are like ethanol.


I agree with your point #2

I do not agree with your point #1, if I understand it correctly:
When the fossil fuel era was born, and to this day, it recieves energy imput from non-fossil fuel sources  (metals, water, and very importantly, human power).  The first fossil fuel projects ran on human and animal power.  

A blacksmith shop using charcoal in a forge, and the pure muscle of a blacksmith was the birthplace of the steam age.  This is true of the early automobile too, by the way...I have seen photos of Carl Benz's origianal shop where the gasoline car was is so quint and primitive, it looks like something out of the days of Issac Newton!

After the original non-fossil fuel imputs, the fossil fuel devices began to feed back in, and sustain themselves.  I do agree that the return must be as great as possible after the birthing phase of the industry, and MUST be over one to one (i.e.  energy out must exceed energy in, or the loses in the transaction will drag you into the hole quicker).  Let's reshape the question though:  Exactly what is the bottom number on EROEI, and how soon must it be achieved to make a project viable?  In other words, if I had a technology, and all the indications was the EROEI was 2 to 1 (lets 10000 BTU's out for every 5000 put in) but it would not reach that point for the first, year?  Two years?  5 Years?

For the first period until break even, I would have to use some other imput, for example, fossil fuel, metals derived from fossil fuel, etc.  But after that, I win on the exchange.  Is that not acceptable?

After all, thats what the fossil fuel technology did in it's birthing days.

One more little thing:   Your sentence "your comparing a means of transport to a machine that is supposed to generate energy."

That's interesting, because the sailing ship was extracting energy directly from the wind to provide transport.

Compare that to steam, in which energy is used to extract energy from the ground, move it to the steamship, load it, then burn it, to.....yep, same job, provide transport! Oh, what about the energy to smelt the metal in the steam engine to provide transport?  What about the energy to haul the steel, and then to haul the finished engine to the steam ship?   Which would have the better EROEI on the transport provided or miles covered?

The goal of both uses of energy (wind powered ship, or coal powered steamer) was exactly the same:  provide transport.

Roger Conner  known to you as ThatsItImout

In the UK, sailing ships built from wood proved to be unsustainable, because we ran short of wood. As you are being rather loose with ERORI, I will interpret this as having an EROEI < 1. Of course, sailing ships don't need to directly replace the wood used to build them, they can be used to get it from other places. Except that then our empire was sustained by colonising other places and taking their resources, and that proved to be unsustainable too.

Of course ships don't need to be built from wood, but the above also equally applies to coal, iron, oil.

IMO the arguement on sailing is best reduced.  Wind for transport in a large open expanse such as the ocean is a no-brainer.  Whether wind or waves makes the most sense for power generation is site specific.  The beaches here in Oregon can be quite windy, but I still asume the waves are more consistant? Machine maintainance?  There has been and will always be maintainance.  Hydro, wind, nuclear, all have maint too.
    The majority of energy related thought patterns on this site are all about machines.  We are so stuck on machines.  We need this (insert name)machine to make fuel to run some other (insert name) machine! We are going to have less energy not matter what and this will be eye opening to say the least.  I applaud that someone has the forsight to mention that we need to look a not using fossil fuel inputs.  This is the world that my greatgrand children will have to live in. Now that we have set ourselves up as a highly mechanized energy dependant society it will be eyeopening how will the deconstruction (if we are lucky) will take place.  Are we going to ride on our iron horses until the last gasp? (I think we will)
Has the EROEI ever been questioned (or even considered) on a horse/ox/or mule?  We are beting society on (switch grass, etc.) ethanol for our machines, and seem concerned with fertilizer inputs? I keep going back to old time farming with horses, and farms as (mostly)energy independant.  What ever was produced by the farm that wasn't consumed by the farm was available for net export off the farm (the small country view).  Was this sustainable?  Can we keep the best of what our machines have given us?  I certainly hope that we can.  
Look at the crap made of plastic that our consumerism society thinks is important to buy and provides enployment to soo many.  Can you forsee anything like we currently have standing up to "power down"?  I just cannot get there, but on the otherhand I cannot see our pampered society willingly changing.
I think you make a good point here, and one that cuts directly across the assumptions some of the extreme pessimists seem to make.  First of all, people need to stop making the assumption that energy is the source of human development (ignoring the fact that the energy from the sun is indeed responsible for all life on Earth).  Humankind was around before we had power plants of any kind, and before we even knew how to use fire (although at this point you get to the question of where you want to draw the line on human and proto-human).  We have harnessed energy and used it to make our current, technological society function, but the energy itself is not the source of our society and us, it's the other way around.  At the very lowest level, energy begins with the food we grow, and our own physical exertion.  There is reason to be optimistic that a self-supporting form of energy is available, as we (and the whole rest of the planet) serve as proof of that concept.  

The whole point about the power from a wave generator building itself is moot, because even the power from an oil well doesn't just build itself.  We are the ones who build it.  In the worst case scenario, we can build things by hand, albeit with much greater difficulty.  Power generation systems are not original sources of power, rather they are a way to leverage current power from ourselves and use it to create more power by harnessing other sources.  In the end, if it takes more power to build something than the power or utility it produces, then yes there's a problem, but that's such an obvious fact that there's no point in even mentioning it.  

Oil also is not going to run out overnight, and neither is coal, and we can continue to exploit them as an energy source for sometime to come.  It seems to me this is the crux of most extremely pessimistic views: that fossil fuels will be used up in such a short span of time, and with absolutely no warning, that we'll have no time to replace them.  

If you assume all of the worst events take place, then you can only come to the worst possible conclusions.  But the flaw in such extreme pessimism is it is just paralyzing and does not accomplish anything.  If the worst comes to pass and tomorrow all of the oil in the world is suddenly gone, then we are screwed anyway, so why even bother worrying about it?  Fixating on the worst possible scenario is just idiotic.  We just have to hope that the worst case scenario does not come to pass and plan for a scenario where we can make a positive impact with alternatives.  

Another feature of extreme pessimism is the tendancy to just throw everything out as being useless or not good enough.  If our only comparison is to the energy production by burning high concentrated fossil fuels, then we're never going to find anything as good.  Once again, what is the point of focusing on that?  But that seems to be a hallmark of the pessimistic view, to see that alternatives are not as good on a one for one basis, as fossil fuels and then just throw up one's hands saying "we're screwed!".  

Almost as bad as pessimism is extreme skepticism, or maybe it's the same thing.  This revolves around the idea that all these alternatives are just a crock, and that the people building them have no intention of actually creating something to produce power, and instead want to pull the wool over everyone's eyes.  There is no point dwelling on the short comings of a technology, especially one that is essentially in the experimental stage.  

Just jumping to the conclusion that its energy production is marginal (after all inputs are considered), as seems to be common around here, is not the least bit helpful.  Neither is saying that if it's not as good as wind then it's useless.  That viewpoint is just dumb on a lot of levels.  While "logical" on some level, it does not take into account reality where we are all aware that people don't always make the most "scientific" or "purely logical" decision.  Maybe that wind farm would produce more power, but the people who live on the coast don't like the thought of looking out their window and seeing a bunch of windmills.  Sure, we can say it's a "stupid" viewpoint, I agree with that wholeheartedly, but it's also a real concern.  This is the huge mistake in settling on an all or nothing approach.  

We need different technologies for different situations.  There is not going to be one single replacement for fossil fuels, and if we go into the future with that narrow viewpoint, we're going to end up coming up extremely short.  There's a thin line pointing out the flaws in an obviously overly optimistic idea (ex: running everything on ethanol when there isn't enough land to grow enough ethanol to fuel everything), and going overboard and declaring every new technology dead on arrival because the designers can't just come out and say it is as good or better than oil in all ways.  

Then we have the people who say stuff like our society won't be willing to change to use less energy.  That is just a bunch of crap.  It doesn't matter if people are "willing" or not, they're going to have to make some changes.  And they will be forced to, whether they like it or not.  Going back to the "source of energy" issue: we model our society around the amount of excess energy available, not the other way around.  If there's not enough power, because alternatives can't produce as much (which I think is not set in stone, it may take a long time to get to where we are now, but it's not impossible), then we'll have to adapt to do with less.  

This idea that if we can't live as we currently are, that we're all just go around bemoaning it as we slowly die off is just ridiculous.  Once again, if you really feel humankind is that pathetic, what is the point of even planning for anything?  

The reality of the situation, and what flies in the face of everyone predicting a massive die-off due to peak oil/food/etc, is that in the developed world we're currently getting by with much more than we need.  Americans are not starving from lack of food, rather they are dying from poor health from having too much food!  People drive inefficient, heavy hunks of metal with the aerodynamics of a brick.  Maybe people who are currently gorging on buffets will have to cut back to a leaner, more vegetarian diet, and people driving SUVs will have to trade in for motorcycles, but our society will still be able to function even with much, much less energy to power it.  

Just to be clear, by "you", I am referring generally to those who happen to harbor that viewpoint, not the person I replied to.  
First no offense taken.
"heavy hunks of metal with the aerodynamics of a brick."  LOL...that new honda box...A lighter hunk of metal with poor aerodynamics...sorry the picture was stuck and they look a brick! :)
I like the optimism!  I agree that we created society based on what (energy) was available and will create the future on what is available at that time.  So much will be recycled into new stuff.  American garages full of stored energy in all those plastics.  Depolymerization will be the future as we learn to power down.  
I especially like the food insight.  Have you watched "supersize me".  Holy cow how much energy do we consume in fried foods that our bodies don't even need or want.  Maybe "powerdown" will give america a giant liposuction, decrease health care costs, and save a lot of energy too...:)  Look at the bright side...  
An alternative technology cannot be a sustainable solution if it significantly increases depletion of another resource, or depends itself on a depleting resource.  Complex technologies by their very nature accelerate increases in entropy.  We need simple solutions that minimize resource depletion and waste while providing a yield, even if only a modest yield.  That also means living within an energy budget delimited by that yield, which can only be a fraction of our current energy splurge.
"An alternative technology cannot be a sustainable solution if it significantly increases depletion of another resource, or depends itself on a depleting resource."

This sounds reasonable in theory, but what do you mean by it?  That it's not ok for wind turbines to use steel?  You could consider iron a depleting resource, but that's not a useful or practical point of view: it's recyclable for  most uses, and we have plenty for long-term capital investments such as wind turbines.  I think this is way too theoretical and pessimistic to be useful as a guideline.

"Complex technologies by their very nature accelerate increases in entropy"

No, I don't think this is true.  A Prius is more complicated than a Chevy Tahoe, but it wastes a lot less energy, and increases entropy a whole lot less than a Tahoe.  A swiss watch is a lot more complex than a bonfire, but it increases entropy a whole lot less.

"We need simple solutions that minimize resource depletion and waste while providing a yield, even if only a modest yield."

No, we need good solutions.  There's no reason to think we're going back to a primitive society that can't maintain complex solutions.

"That also means living within an energy budget delimited by that yield, which can only be a fraction of our current energy splurge."

Well, maybe, but this is misleading.  If we went to an electric society based on wind turbines and solar PV, we'd automatically reduce our BTU use by 2/3, but our effective energy use wouldn't be changed.  If we went to 100mpg cars, we'd reduce automotive energy use by 75%, but we'd be moving around just as much.  We need greater energy efficiency, not "power-down".

Keep in mind that the 2nd law of thermodynamics simply does not apply in any useful way to our overall energy situation.  The 2nd law applies to a closed system: the earth is astonishingly far from a closed system, given that daily solar input is about 10,000 times human energy usage.

Our problems are tactical and temporary: we're using a limited and polluting resource (oil & gas), instead of using the available, plentiful clean resources (wind, solar, etc).  Our heat output has little to do with global warming: GW is an imbalance between the Earth's daily 10,000 BTU's solar input and heat radiation output, not our 1 BTU energy usage.  It's our CO2 output that's the problem, not our heat output.

Our problem is social, not technical: can we find a way to ease the pain of transition for our energy and transportation industries to make planning easier, or will we have to wait for serious oil shortages and have a badly planned, painful transition to better things?

"thats the test none of the so called renewable energy solutions have taken let alone passed yet"

E-ROI (or EPR) has been thoroughly researched for wind. It's about 80 to 1, meaning that the power you put in is recovered in less than half a year.  Furthermore, the power you get out (electricity) is higher quality than much of the power you put in (process heat for steel & concrete, fossil fuel feedstock for carbon/plastic parts, etc), so the return is even better than that.

Labor is the big thing.  For instance, the turbine blades still commonly use primitive, time consuming methods for producing the carbon fibre composites needed.  This will change, and continue to improve wind's cost advantage over fossil fuels (when all costs are included).

I don't discount this, wind, solar or any of a myriad of alternative sources of power. BUT, my concern with all of them is that they promote the illusion that we can postpone the drastic steps needed to CONSERVE and REDUCE our energy consumption. Nothing can save us from that necessity, and nothing can compete in terms of cost effectiveness UNTIL we do that, because here in the US at least, there is SO much that can be done CHEAPLY in that area. CHEAPLY, but thease things WILL interfere with profits of powerful interests, which is why they aren't being done first, or even at all so far.

Once we have squeezed the waste out of our way of life, there will be a need for renewable energy. But there again, the means of extracting it and generating must also be sustainable and renewable. That's the problem with a lot of the alternatives. The energy itself may be renewable, but the infrastructure requirements aren't. Without our current high energy economy, parts of the infrastructure for some of these kinds of things won't be so readily available. That's why nuclear is out of the question. But it's also a problem, though not nearly as big, for some of these kinds of things too.

I don't think alternatives do anything to change the fact that we need to conserve.  But I don't view them as promoting that idea either.  At this point the U.S. government has basically failed to do anything to push conservation.  It's no longer in the realm of government here in the U.S., it's now in the hands of the market.  SUV and truck sales are in the toilet, while compact cars are taking off.  See here.

The changes toward greater efficiency in Europe and Japan, which resulted from their higher taxes on fuel, will no take place here in the U.S. as a result of fuel going up in price.  Expect other moves toward greater energy conservation, and a renewed interest in public transportation.  We're not really so different here in the U.S. than anywhere else, just more shortsighted.  Which is really why we have the whole "live by the market, die by the market" mentality, because we refuse to plan for the future, and instead refuse to make any changes until we absolutely have to.  

Not to pimp my site (Well yeah so sue me)

Here is an overview of OSU's Wave program from a presentation I went to.

There is a company out of New Jersy that is setting up a wave park off the Oregon Coast, but their technology doesn't sound good.  They want about 15 cents per kilowatt-hour subsidy to make the project work.  About the only good thing is they will let OSU try out their bouys in the park as well, which OSU says they can create electricity at 9 cents per KH with the current system they have developed.

30 years ago I was a deckhand on a US Coast Guard bouytender, a ship 180 feet long, fixing, setting and maintaining bouys somewhat similar to this model.

One thing to remember is that any metal object in the brine will both corrode and also collect an amazing assortment of marine organisms, which will hamper and restrict, and ultimately incapacitate these objects.

Also, storms will force them to drag anchor, so there will need to be tenders -- probably the size of the one I was on -- constantly maintaining them.

Maintenance costs will be high and would have to be factored in to any financial analysis.

Do you know how far off shore this pilot project is, and how deep the water is there?
The site is on the 12 miles off shore range, where it doesn't affect the traditional fishermen neither the industrial fishing.

I haven't find the depth, but I think it is to far off to be at the desired 50 meters.

The marine enviorment is so harsh, we have 4 guys on my drillship that are constantly painting scraping priming re painting.  What materials is this serpent made of?  Just a little scratch and it will begin degrading if its not stainless.  As for hydraulics they require huge maintainence.  I know little about wind but my impression was you can stick a windmill in the ground and plug it in.  I really believe this can't be better than offshore wind.  (are windmill mostly corrosion resistant?)  If this thing breaks how do you fix it? at sea or is it retrieved and brought in?  The boats fuel expense for once a year maintainence would cut into energy profit.
Oilrig Medic -

The current version of the Pelamis is made out of plain 'ol carbon steel, primed and painted, just like a ship. The construction is relatively simple, and not much different from normal non-pressurized tank construction. I'm sure it could be made out of fiber glass or other composites,  but then you have a trade-off between low maintenance and high initial capital cost.

Yes, hydraulic motors do require maintenance, but so does every other mechanical device used in the extraction/production of energy. One positive maintenance feature, though, is that it does not have to be maintained or repaired in situ (a very difficult prospect in high wave areas), but rather can be just towed into port for routine maintenance or repairs and then towed back out. I believe the very first version that was installed off one of the islands in the Orkneys (which is one of the best wave energy locations in the world and therefore a rather harsh environment) ran for over 1,000 hour before some minor maintenance had to be performed. Not bad for a demo unit on its first try, I'd say.  

At first glance, the Pelamis strikes me as a very well thought-out design that has pretty much solved the survivability problem. It does this largely by not fighting with the waves.

However, I have no idea what these things cost and what their life-cycle costs look like in relation to the amount of energy it can produce over its lifetime. Time will tell.

Bear in mind that the Pelamis is not the only  good design out there. But it seems to have gotten a good head start on the others.

Most of the wave energy development work is currently in the UK, Norway, and to a much lesser extent, Japan. I don't think there's all that much going on in the US at present,  but it's been a while since I really looked.

Well, in the animal and plant kingdoms, a species need not be all that efficient to survive. It just needs a niche. I'm pretty sure wave power has a small niche, somewhere.

So this is interesting news. It may make a small difference, and small differences add up. Innovation, like evolution, is about small steps, so there's no reason to belittle this project.

This kind of project should be take forward only if its EPR is above that of Wind Energy. If the EPR of Pelamis is found to be over 1 it can be considered only in situations where Wind energy cannot be directly yielded.

This misses one of the essential differences between wind and wave power.  When the wind at the location of the turbine stops blowing - no electricity. A weather system  only a hundred miles away will not help.  With wave power systems located on the edges of the oceans, weather systems many hundreds of miles away can result in productive amounts of swell at the generating site.  Anyone who has spent time on an semi-submersible drilling rig exposed to the atlantic swell knows how seldom the heave is zero. (Heave - the amount the rig rises and falls relative to the seabed).

The mention of drilling rigs also is relevant to the comments made with regard to survivability, construction and maintenance.  Pelamis is being constructed to the same guidelines used by DNV for offshore rigs.  Rigs are far more complex structures, present far greater surface area to both wind and waves, and yet structural and mooring failures (outside of the extreme conditions in hurricanes) are extremely rare.  Normally the hulls are cleaned of the marine loading and inspected at five year intervals, frequently requiring little repair beyond renewal of the sacrificial anodes.

Although both the economic viability and the sustainability of the system are very much open to question, wave power should be looked at not instead of wind power, but together with wind power, biofuels, tidal and solar as part of an overall system, with different components providing power at different times in the weather cycles / seasons.

That is the case, but Pelamis seems to work 2800 hours / year. An onshore wind turbine works during 2600 hours / year; an offshore one will work even more than that.

Pelamis is as much an intermitent source as wind is, so why override both, why not just go for the better?

Because the 2800 hours are going to be a different 2800 hours than the wind power.  The advantages that wind has are only decisive if there is sufficient storage capacity to deal with the non-productive periods.
Although perhaps this isn't technically 'wave' energy, what about efforts to harness the energy of tides?

Someone mentioned vertical axis windmills.  I've been interested in this design for a little while.

Similar to' axis,' the plural of Pelamis would be Pelames, I believe.

Tide energy systems have the potential to achieve EPR values above those of Oil - my personal favorite.

But the places where you can install such system (estuarys) are few.

One can still dream about oceanic currents at high sea though.

By the way Marine Current Turbines is a project nighing on the commercial fase. But the costs are quite ugly.
If the platforms for harnessing the ocean currents are dual purpose with gas and oil production platforms the cost could be substantially lowered. And they could be placed in areas with good current flow but not very good wave potential, like the Gulf Stream in the Gulf of Mexico. But what about the migrating jelly fish and algae mats ?(just kidding)
   Its going to take many different local solutions to actually replace fossil fuels with renewables, just as now gas electric plants make sense some places and coal plants in others, and its going to take lots of experimentation to come up with practical solutions .
Someone mentioned vertical axis windmills. I've been interested in this design for a little while.

This and other small vertical-axis windmills look interesting, but none of the sites seem to provide much information about possible power output. They all seem to have relatively small cross sections, which would suggest that the total power output is also small. The typical household in the US currently consumes about 30 kWh per day. How many of these would it take to provide, say, half of that?

This website seems to some details.


The verticle axis wind turbine is one of those things that look so great, but turn out to be a bit difficult.  The simplicity is obvious in not having to "steer" the turbine into the wind, and in being potentially cheaper to build at lower heights than the giant three blade turbines.

However, the power produced by most vertical axis turbines is limited by the speed the rotor can turn.  

There are two types of vertical axis rotors:  Lift type and drag type.  

The lift type are more complex to construct, and are therefore more expensive and have had reliability problems.  The most well known are the so called Darrieus (the "egg beater" type)  These have been greatly researched, and are covered by the American Wind Energy Association along with the drag type on their website.  It's a great starting place:

Notice that the eggbeater type requires a "wing" profile blade like the tall three bladed horizontal axis rotors, and this must "flex" in some way to be aimed correctly to provide lift.  One other factor not easily dismissed:  If the main bearing at the base of the rotor fails, the whole tower has to be essentially dismantled to repair it, not a cheap operation (several Darrieus type rotors were abandoned when the main bearing failed)

The simpler of the Vertical axis types is the drag type.  The most common are some variation of the Savonius rotor, which is basically an S shape, one "cup" upwind, one down).  Many may remember these as the "homebuilts" constructed back in the 1970's from salvage 55 gallon drums (how's that on the EROEI scale, built out of junk as they were!)

 Some very creative versions of the drag type VAWT have been built, including the one you link,  and a most promising idea being this example, which has been discussed on TOD before (with myself involved in that discussion):
The technical specifications are very informative, giving an idea of the size needed to provide a given amount of energy:

They are simple, cheap and easy to build, and can even be artistic, as the Windside turbines are, so how could they not be the perfect solution?

The drag type turbine has one big limit which the laws of aerodynamicas will not allow it to overcome:  It can never turn faster than the wind.  This means that speeds are low, often not much over 100 rpm in even good wind.  Most electric generator systems are designed to turn 1620 RPM, so the rotor either has to be "geared" up, or it must find some way to change the speed of the rotor to a faster way of providing power.  Gearing by the factor needed makes the windmill hard to self start, and gives up large loss in the gearbox in energy conversion.

There is one path left however, it is on this that a small partnership  (non- incorporated research and design partnership, called Irvington Design)  I am involved with is working:

The drag type vertical axis rotor produces little speed, but a lot of torque.  In other words, the "foot pounds"  or newton metre count is quite high for a given size of rotor.  This is why the vertical axis wind turbine of the drag type has found it's principle application as pumping, in particular, pumping water.

The rotor is able to move a lot of pounds of water.  Not fast, but a lot of pounds none the less.  It is also able, in the same fashion, to compress air.

If a vertical axis wind turbine is used to drive an air compressor, and some storage is provided, the possibilities become obvious:

  1.  The variability problem of wind is greatly reduced.
  2.  The problem of direction change and "unstable" and "gusty" type wind is reduced, and in fact, the turbine can enjoy more utilization time in less than optimal conditions than the high fast wind turbines....which require a very "clean" and stable supply of wind.  The high expensive ones spend over half of the time not operating due to either (a) too high wind, risking damage to the system (b) too low wind, not providing enough speed to kick the turbine in, or (c) unstable wind, making the horizontal axis turbine spend time trying to "steer" into the wind, and lastly, (d) maintainance downtime.
Being aerodynamically incapable of turning faster than the wind, the drag type rotor is self braking, reducing risk of damage in high winds.
  1.  Stored on demand power.  This is a huge leap forward.  If storage can be provided, then wind can be sold when the customer needs it, not just when the wind blows.  
  2.  Starting assist by compressed air.  This is a side advantage, but a not insignificant one.

The question becomes efficiency in compression and storage.  The compressors storing the wind power created by the Vertical axis turbine must be as efficient as possible, and the tanks must be as large as can be afforded.
Technically the system has no real obstacles, using mature and known technology.  But, economically, the price of power provided by fossil fuel, and the price of power provided by horizontal axis three bladed turbines will be the "break points".  

Currently, it is said that a large wind turbine will cost $1 million dollars for each installed Megawatt of power.  However, it is to be remembered that this is one Megawatt of "rated power".  If you count the time the turbine is not operating, (so called "utilization time" or rate) the cost is actually well above the $1 million per Megawatt actually delivered.  That, for the moment, is the number to beat, and a million dollars will pay for a nice set of compressors and tanks!  Only time will tell.

For anyone interested, I do have a website under construction, and it is still not finished....and it still has some typos and errors, but your welcome to look, just give me time and be forgiving of it's flaws, we are very, very early in the game!

Roger Conner  known to you as ThatsItImout  

Here are two links and describing the system and our project here on the Oregon coast.

As for how waves are generated, the primary driver is Earth's rotation followed by solar radiation and tidal forces. The Oregon project is moving along; it's an hour's drive south of my coastal abode; about 1 gallon of gas in my Prius oneway. I prefer the OSU engineering department's design, Here's a ppt of the previous pdf,

IMO, waves are the only real long term energy solution.