Francois, understanding emergy and emergy flows is obviously an important field. Equally important I believe is understanding the ERoEI of the energy source of emergy. As you point out China is a major exporter of emergy using high ERoEI coal as the main source and high "ERoEI" workers in the conversion process (i.e. workers that consume little energy at home).

This introduces the concept of chained ERoEI. I used to be one of those who believed that low ERoEI approaching 1 was unsustainable but I have changed my mind. I now recognise that low ERoEI energy "sources" are not energy sources at all but energy conversions, more like electricity from coal or gas. Bio fuel converts nat gas (fertilizer) to liquid fuel which is a more highly prized energy store. At the end of the day we get all of the energy that was in the nat gas back again but in liquid form. So it is important to consider the ERoEI of the input natgas. If the fertilizer is coming from Qatar, it will be very, very high.

The same applies to tar sands with ERoEI of about 5, most the inputs are nat gas. It becomes interesting then to consider tar sands production using shale gas. I don't know what the answer is, but I'm pretty sure that distortions to the energy system brought about by the finance system may result in some pretty unsustainable activities going on, that have a deleterious effect that may be hidden from view.

The magic ERoEI number of 7 comes for the net energy cliff concept and net energy. If all our energy sources average out below 7 then this means that a huge number of folks are engaged in energy production leaving not enough to man schools, hospitals, factories and retirement homes.

I don't know what all this hoopla is about regarding peak oil being dead. As far as I'm concerned, all of the alleged "nails in the coffin" of peak oil have been repeatedly beaten to death and then urinated on, year after year, right on this site. The reality of the situation is that the end of unconventional oil is going to be rather ugly, regardless of how last it longs, seeing as how atrocious the depletion rates are. This is simply a one-off, just like the opening up of new agricultural lands and fossil fuels easing the pressures of diminishing returns are simply one-offs which are just delaying the IMO inevitable return to Malthusian equilibrium, which has historically reigned throughout all of human history up until the New World and Old World came together and fossil fuels began being exploited and put towards the uses which we know them today for.

As for alternatives, I don't believe that any convincing case has been made for the position that they will replace even a substantial fraction of the energy supplied by fossil fuels (oil in particular).

Yeah, sure, hand-waving about how solar is on the rise as installed capacity explodes and costs are plummeting is rather convincing at face value, however, this must be viewed in the context of the obvious to just about anyone subsidized solar bubble: The whole thing was built on politically & economically unsustainable subsidies from beginning to end. On the demand-side, feed-in tariffs in Germany and other European countries as well as the United States, along with tax breaks or in some cases other subsidies to homeowners who purchased solar PV installations, artificially inflated the demand for solar panels, which resulted in higher utility bills for rate payers and money channeled from taxpayers indirectly to manufacturers — many of them in China. On the supply-side, China, using its tried-and-true mercantilist industrial policies for boosting targeted industries, rapidly ramped up its production of solar panels, driving many German and American manufacturers out of business.

Unfortunately for the solar miracle, Chinese supply-side subsidies outraced disproportionately German demand-side subsidies, leading to global overcapacity and plummeting prices. China is now the victim of its own success in trying to corner the global solar panel market via government-subsidized dumping. These improvements in solar, IMO don't exist, as they're transient.

Wind I guess I can be slightly more sympathetic towards but not by much. Wind energy promoters usually quote the maximum attainable output as the capacity of the wind farm. This is the maximum power that could be produced if ideal winds blew all the time at all turbines. However this needs to be multiplied by the capacity factor to get the actual power likely to be generated. Because of the variable winds and the energy unable to be captured by the generator, the capacity factor lies in the range 25% - 35%. However it can be much lower. UK offshore wind rarely exceeds 20%.

The Danish "success story" with wind doesn't exist. The unreliable Danish wind farms only survive because they call on hydro power from Norway and Sweden to step in at short notice when wind fails. Then they sell excess wind power produced at times of low demand back into the Scandinavian grid. Danish electricity consumers pay higher prices than any other Europeans. And well before they could repay the initial capital, the wind towers are reaching the end of their life and will need to be replaced. Not one coal power plant has been replaced by wind power.

The fact remains, despite all the hand-waving and sensationalism, renewables still only meet a miniscule fraction of the world's energy & electricity demand, and are extensions of edifice that oil & natural gas have built up.

Wind & solar simply are too high entropy (too far down the energy gradient, too dispersed) for me to consider viable alternatives for keeping BAU running anywhere near even 25% capacity.

Nuclear doesn't fare much better. Nuclear's close to the upper limit of how efficient and how allegedly great it can get. The only new developments in nuclear are going to be increasing the size of plants in order to economize on nuclear's strength: relatively low marginal costs. Economies of scale. Thorium's alleged EROEI of 50:1 really makes very little difference in efficiency compared to the EROEI of around 20:1 for your good old thermal light water reactors (it's only 3%). In fact, I know a number of nuclear engineers, and they all invariably say that thorium is a bit of a joke with people who actually do nuclear engineering. Fusion is just a series of laboratory curiosities which will never amount to anything. I know it's frowned upon to say it like this, but IMO that's the way it is.

We are not entering into an age of renewables. We are entering into a age (which will probably only last perhaps 5-10 years) of unconventional oil and the more extensive use of natural gas and coal (even though all it's really doing is temporarily smoothing out the decline, not really replacing it). This will probably make the situation in 5-10 years much worse, as the peaks in oil, natural gas, & coal will be closer together.

Diminishing returns and limits to how much technology can do are now exerting their pressure on us full-force again. Productivity gains simply aren't being made at the extraordinary rate they once were. We're now being forced to search the ends of the earth to find important mineral resource and fossil fuels & being forced to accept increasingly marginal ones. The only reason agriculture is keeping up is because we're exploiting more and more marginal land each and every year. Grain yields is most everything have stagnated or slowed considerably. The amount of arable land per capita has already peaked. In fact, what's even more scary is that per capita grain production may have already peaked as well.

All in all, there's no reason to be optimistic simply because you got bored of reporting on rather mundane things instead of what you were expecting: something closer to a crash and burn scenario.

I'm disappointed with what the TOD staff decided to do.

And *I* don't understand where the hoopla is coming from that there's no more to be said about Peak Oil, or a dearth of quality articles to post on the Oil Drum! Just look at the wealth of knowledgeable, interesting articles on a variety of topics we've been treated to this past month!! If there were even half, or a third as many such articles available, it would make the Oil Drum a terrific continuing site.

You can't fool Mother Nature and you can't change the laws of physics.

It is clear enough that a sufficiently high EROEI must n be achieved for any energy extraction or capture technology to work long term.

it is clear that the embedded energy used in supporting infrastructure must also be taken into account in estimating the sustainability of any energy extraction (mining, etc) or capture process such as biofuel, wind , and pv.

Nature sets the limits.

We apparently don't know with any certainty just where these limits lie, but I presume the figures given by the authors are "close enough" for discussion purposes.

I know only a little about such things, about as much as any dedicated follower of this site may be expected to know.

But I know a couple of things that are dxxed important.

A sound understanding of the limits is necessary to understanding what is and is not going to be technically possible in the future, and such an understanding is critical to controlling the debate as the future, like rust and depletion, never sleeps.

It is very important that we do all we can to control the debate- we don't need another evolution versus creation struggle, or another climate change versus denialist scenario .

But- and this is a big old BUT- we don't want the "puristas" to gain too much influence either.

I love birds and don't have anything against desert tortoises -I'ver never met one but I'm sure I would like him if i did, lol- but reality dictates that we either accept the collateral losses associated with wind and pv, etc, or accept the orders of magnitude greater losses associated with the continued use of depleting fossil fuels. Political reality is such that we simply do not have the will to do a perfect job.

We will be extremely lucky just to survive , over the long haul, as an industrialized society.Even if we had the will, we don't have the resources, since there are so many previous undeniable claims on our limited capital.

So- as I see it, the real question FOR NOW is not the ultimate EROEI question, because we simply aren't doing any thing to solve the EROEI problem. We aren't even seriously thinking about it, except in a few ivory towers, and a few forums such as this one.

What we need to be doing NOW is whatever we can to further the development of renewable energy technologies , and build them out to the maximum possible extent, without worrying about long term EROEI questions.

We must accept that this strategy, combined with an equally heavy emphasis on efficiency and conservation, is our only real hope of pulling thru the coming bottleneck.

It simply DOES NOT MATTER if we put some energy - any amount of energy - into renewables which are ultimately unsustainable , because we have no way of conserving that energy.

It is use it or lose it, given our real life situation.We can put it into wind and solar and other renewables, or we can just stand by as it is all wasted to no good purpose- fetching beer in three ton trucks, heating uninsulated buildings , keeping the skyline lit in cities shut down for the night.

Hopefully- again hopefully- we will figure out ways to improve the EROEI ratios of renewables to the point that they are truly sustainable- if they aren't, already .

Personally I don't think we yet have a good answer to the this question- Pv and wind seem to be efficient enough, if one ignores the emergy aspect.

Including emergy seems to indicate that we are in a heap o' long term trouble.

Francois,

Thank you, this is an important and interesting subject.

Some years ago I was involved in discussions about energy processes with ERoEI < 1, and concluded that the qualities/properties of the energy resources matters. For instance it could be feasible to use hydroelectricity to extract oil with ERoEI < 1 if oil was the desired end product due to its unique properties. (It is [still] hard to make a jet plane fly for some distance on electricity). There is of course a limit to the scalability of such a process.

I consider (net) energy flow (stocks are as well…. if long term considerations are given any attention) to be an important metric. If there was some process with say ERoEI < 1 involving vast resources (stocks) that were scalable (meeting [society’s] need for energy flow of specified qualities) and that resulted in affordable end products, it would happen. Just to make it clear; presently and to my best knowledge I am not aware of such resources and processes.

It could be interesting to integrate energy flows (inclusive ERoEI) into financial models (thus improving the understandings of the dynamics of energy flows (and thus indirectly ERoEI) within the financial framework. This could help illustrate how the financial system (inclusive of subsidies) also may distort energy usage amongst energy sources.

Some of the low ERoEI processes like oil sands are made possible due to financial distortions. Oil sands are primarily about money production (producing financial profits). It could be interesting to see if natural gas prices moved above some threshold, if coal (provided coal became the cheaper substitute) would be introduced to generate steam for the SAGD process also used in oil sand extraction.

I am not fond of Gross Domestic Product (GDP). It is primarily a metric measuring volume of financial transactions. It poorly meters total energy consumption and in recent decades a lot of energy use has been outsourced to countries with lower wages and imported as consumption (embedded energy) in products by countries that previously manufactured the same products.

This has created a distortion that is a favorite amongst economists (thus illustrating how poorly energy flows are understood) pointing out that the developed economies in recent years have become more energy efficient illustrated by the growth in specific GDP expressed as $$$/kJ (or $$$/MTOE or similar).

I am not aware of any studies that have had any in depth looks into this.

ERoEI is a good idea, but seemingly difficult to apply. Two quotations from this short article:

"Charles Hall ... For this reason, he suggested to consider a technology with an ERoEI < 5 to be unsustainable. "

"In the Middle Ages in Britain, soils were only being used for agriculture if the so-called harvest factor (the amount of grain produced divided by the amount of seed grain planted) surpassed a value of 1.6"

The second quotation disproves the first - if an ERoEI of less than 1.6 (not only seed grain is an input to agriculture) was possible in the Middle Ages, then Hall's estimate of ERoEI minimum of 5 is wrong. Also, this means that an economy based on bioethanol may be possible (but it will not be comfortable for 90% of the population).

Isn't emergy just EROI with a wider net to measure the investment?

An excellent, succinct overview of a vital concept. I look forward to the two forthcoming articles. One small quibble. EROEI and emergy are obscure and difficult to understand concepts for the average person - including the typical decision maker. IMO, it's important to maintain the distinction between these ideas of energy 'production' (to use the vernacular) and energy 'consumption', or utilization. The use of the word 'efficiency' blurs this distinction, as most people think of efficiency on the consumption or utilization side - how much use one can get out of a given amount of energy, best expressed as a percent. EROEI, on the other hand is a measure of how much additional energy can one acquire, or make available for use, from a given amount of energy, best expressed as a ratio. This small linguistic point often leads to people mixing up the two concepts, and arguing that EROEI is essentially useless, as clearly the efficiency of energy use is always something less than 1:1, as we consider efficiencies of 80-90% to be excellent, and even 33% to be acceptable, as in thermal electricity generation.

I think perhaps OFM says it most clearly when he uses the words 'energy extraction or capture technolgy' - this is where EROEI applies, whereas efficiency best applies to the end use or consumption of the energy extracted or captured.

I hope I haven't confused things further.

Thank you Francois for a superb article and thanks to some of the follow up comments which are equally superb. It just breaks my heart to see the dispersal of these great minds as TOD closes its doors. It seems that some of the comments confuse renewable solar energy with renewable solar or wind energy electricity production. Solar/Wind energy has an unlimited future and a brilliant past. Electricity production from both sources will never replace cheap one time carbon sources. Those cheap carbon sources have been at the core of wealth production and wealth production will also plummet as their production plummets. What I didn't see mentioned is the role finance plays in energy production and a financial collapse could render these ivory tower discussions moot. All of this production and distribution of energy and emergy is facilitated by credit and debt creation whether were talking about letters of credit or supply chain issues. Crash that system and discussing the EROEI of the various energy sources is just speculation on how many angels can pass through the eye of a needle.

I've written EROEI. The second post is in the making - probably post it after TOD RIP.

http://connectrandomdots.blogspot.com/2012/07/test-post.html
Rgds
WP

If there is anything more overlooked than the tendency for exporters to show an accelerating rate of decline in net exports, as production declines, it's the CNE (Cumulative Net Exports) depletion rate. Here is a link to a discussion of this topic:

http://www.theoildrum.com/node/10213#comment-976162