Next Generation Energy is managed and written entirely by Seed editors and expert guest bloggers. Read more about them There are claims coming from around the world that by tagging ethanol as green, and increasing our demand for "green energy," we've been doing damage to the environment rather than saving it. I'll leave evaluation of these claims to someone else for now.
However, I'm interested in whether discovering a thermodynamically efficient process for generating cellulosic ethanol might cause more environmental harm than it prevents. Some reflection on the issue suggests that the potential for damages (in the form of habitat, biodiversity and ecological stability losses) are far greater than anything we have observed yet with standard ethanol. In fact, since it seems unlikely that we will be able to tightly control the use of whatever cellulose-to-fuel technology we invent, perhaps we actually have a responsibility to stop research in this field, protecting ourselves from an uncontrollable economic process that we might have a reasonable belief will follow such a discovery (if this suggestion strikes you as ridiculous, just hear me out). I alluded to the following issue in a previous post where I argued that relying heavily on ethanol is foolish on security grounds alone.
In a famous paper, Vitusek et al (BioScience, 1986) tried to estimate how much of the Earth's photosynthetic products were "appropriated" by humans. Their "middle of the road" estimate suggested that we prevent natural systems from utilizing 19% of their primary photosynthetic production in the ways that they would if we humans weren't around. They also estimate that 30% of all terrestrial photosynthesis is appropriated from "nature" by us humans. This is a large number; and it suggests that we have dramatically altered the movement of energy through the global ecosystem. And that was twenty years ago.
This study got me wondering. How much of the planet's photosynthesis would it take for us to power the global economy with ethanol? For all of you who have made arguments against chasing a "silver bullet" in favor of "buckshot," this sounds silly. But perhaps it's not. Imagine a world where we discover an incredible catalyst that turns cellulose into ethanol, providing energy at lower cost than any alternative by a large margin. Would the world spend the extra money just to diversify our energy supply to other sources? Whatever your thoughts on this last question, it seemed interesting to think about the global potential of ethanol, especially since it might suggest something about the long-run potential for cellulosic ethanol. Consider the following thought experiment.
(Note: Before we get started, and in case it wasn't clear from earlier posts, cellulosic ethanol is a fuel whose production, in theory, captures the energy stored in cellulose. Cellulose is the tough material surrounding plant cells that they construct out of light, water and carbon dioxide. It is the material that makes up most of a plant.)
Could we run the world on cellulosic ethanol?
For this thought experiment, let's make two heroic assumption: (1) we discover a way to make cellulosic ethanol without energy loss and (2) we choose to supply all our energy needs with only this ethanol.
To get a handle on this question, I do a simple back-of-the-envelope estimate. According to the IEA (2005), global energy consumption in 2005 was approximately 11,000 Mtoe (Mega-Tons of Oil Equivalent) or 14,630 GW (since 1 Mtoe/yr = 1.33 GW) or 14.6 TW (TerraWatts). What fraction of the world's plants would we have liquefy to meet this demand?
The global supply of light from the sun is about 340 Watts per square meter (this is an "average square meter" for the whole earth). The surface of the earth is about 5.1 x 10^8 square kilometers. Before any plants can absorb this energy, about 30% is reflected back to space. This leaves us with 121 x 10^15 Watts or 121 PW (PetaWatts) of light available to plants for conversion to cellulose. However, not all of this light can actually be turned into cellulose.
First, only about 43% of this light is in the correct portion of the electromagnetic spectrum for plants to use. Then, the photosynthetic reaction only exhibits a maximum efficiency of about 28.6%. Further, plants actually need to use some of this energy to keep themselves alive, leaving about 2/3 left to be stored in their tissue. Combining these numbers (0.43 x 0.286 x 0.67) leaves us with 0.082, implying that at maximal efficiency, 8.2% of the light that reaches plants could be conceivably stored as cellulose. Combining this with our 121 PW of total available energy, this suggests that about 10 PW of energy could be converted to plant tissue if the entire earth was covered with plants running at full-photosynthetic-tilt.
However, most of the earth is not covered by plants. About 70% of it is covered by water (and it may not be unreasonable to assume, for such a rough estimate, that land is well distributed across latitudes). If we restrict out attention to potential terrestrial photosynthesis, then we have only 300 TW left (I discard the conversion of algae to biofuel because oceanic productivity is so diffuse, difficult to harvest and might not even utilize atmospheric carbon the same way that terrestrial systems do).
This is starting to look promising. We're consuming about 14.6 TW globally, and land-plants could be storing up to 300 TW in their tissue. But what fraction of this energy can we access practically? A good internal-combustion turbine might capture 1/3 of the energy in its fuel; so perhaps if we burned all of the biomass on the planet, at the rate that it's produced, we could acquire 100TW.
But if we go through an intermediary fuel type, i.e. expend energy trying to convert this biomass into a convenient liquid form, say, ethanol, than we'll loose another large fraction. Right now, that fraction is greater than 100%, since we put more energy into the conversion process than we get out. But, for the sake of our thought experiment, let's call on assumption (1) above and imagine that we discover a miraculous enzyme that lets keep 1/3 of the energy in cellulose in the fuel we derive from it. This miracle product would give us a max of 33 TW of ethanol, assuming that we're harvesting 100% of the biomass from all terrestrial surfaces all the time. Not bad, huh? We can even leave half of the planet pristine (or farmland that produces food, which we also need...) and still meet our demand for 14.6 TW. When I sat down to write this, I didn't know what to expect. But this is certainly an interesting result.
Could we run the future world on cellulosic ethanol?
The above result seems promising, we might have our ethanol cake and get to eat it too. But if we're at all serious about sustainability, we need to think about the future. We need to think about sustainable development. An interesting comment on a previous post of mine suggested that perhaps we should create a global economic depression in order to reduce energy consumption. The ethical considerations surrounding this argument are interesting (and not obvious to me). But that aside, such a strategy simply doesn't seem feasible. People like to be happy. They like to eat. To feed their families. To go to the movies and to own cars. Whatever depression someone tries to execute, people will still produce and consume and trade the things they and others want. Countries will generally tend to get wealthier as their economies are driven by people's basic instincts, despite political or environmental setbacks. And who are we to say that this is wrong? It doesn't always seem heartwarming or socially-optimal, but it does seem to be the observable pattern. And if we ignore it when we plan for the Next Generation, we'll be in trouble.
The plot below is one I made using data from the International Energy Agency. It's the logarithm of total primary energy supply on the Y-axis against the logarithm of GDP (in Purchasing Power Parity) on the X-axis (basically, it's energy consumption on the Y and wealth on the X). There are points on the graph representing most countries over the last thirty years. The red line is the least-squares best fit. The trend is obvious. As countries get wealthier, they also consume more energy. The trend also seems to be reasonably consistent, the fit is pretty tight. So my second question is: if everyone shifted along that red line until they were as wealthy as the US, in per capita terms, could we still run the world on ethanol?
If the highest point on that graph were exactly on the red line (its actually slightly above) that would represent 1.74 x 10^6 kToe or 2.3 TW being consumed, on average, by Americans in 2004 (recall that global consumption is about 14.6 TW). In 2004, there were about 297 million people in the US. If everyone around the world eventually becomes as wealthy as Americans were in 2004 (something that economists suggest people would like to do), and they slide along that red line accordingly, then the world demand for energy could be 48 TW! (6.2 billion people x 2.3 TW per 297 million people). And this assumes no population growth.
Its almost unthinkable that we will every get to the point where we could convert 100 TW of available cellulosic-biomass-energy into 48 TW of ethanol (no matter what the catalyst is) and still feed ourselves. Fine. So cellulosic ethanol won't be the only fuel of the future. We'll have to diversify with our silver buckshot and use a portfolio of alternative energies (and hopefully strategies to improve our efficiency too). Perhaps it was our assumption (2) that doomed this question. So why did I waste your time with it?
Incentives to harvest everything
The exercise above demonstrates one important point: demand for energy cannot be met by ethanol alone. But there is a corollary to this point that is significantly more important: no matter how much cellulosic ethanol we make, there will [probably] eventually be an excess demand for energy, regardless of how much cellulosic ethanol we have already produced. For a producer facing the energy market, it's likely that she will continue to turn a profit by cutting down whatever biomass she can access and selling it to the ethanol distillery. Could this set up a situation where there is always an incentive to "appropriate" the products of photosynthesis until there is nothing left for the natural system? We would expect food prices to rise until the value of land under food-cultivation was equal to the value of that land under biofuel-cultivation, but that still means that eventually all land will be under some type of cultivation. For a large number of reasons, this is an unacceptable outcome.
Of course, the story above depends on cellulosic ethanol being competitive with other energy sources. But if it doesn't end up being competitive with other sources, why are we pursuing it? This seems like a lose-lose situation.
In an economist's terms, discovering a process to create cellulosic ethanol opens up Pandora's Box because it will suddenly create value for all the biomass-garbage out there that, until now, had no market value. This biomass-garbage is made up of all the little plants and useless trees that weren't valuable on the market but kept the world ecosystems functioning. In fact, a big complaint among ecologists is that these systems haven't had the market value they deserve, but the ecologists are referring to the value that cellulose holds in its still-living-and-breathing-solid-plant state, not in its liquid-that-I-pour-into-my-truck state.
So the farmers ask, "What about the corn stalks and the switchgrass that nobody uses and grows everywhere? If we don't turn it into fuel, it just goes to waste!" Well, that may be true. Perhaps we will be unable to monetize every gram of photosynthetic product that we have appropriated from Nature. Because if we try to, and and we can't guarantee that only corn stalks and switchgrass go into the distilleries, in all likelihood, we'll be opening the gates of an ecological disaster. Moreover, our experience with blood diamonds, narcotics, and ivory suggests that when there is demand for something, and the technology exists to produce the good desired, it will be produced, no matter how much we try to regulate it.
The dominos look like this. Farmers have waste products that are not valuable to them, cellulose. Someone can imagine a technology that will turn this waste into a valuable resource, cellulosic ethanol. The farmers pursue this technology (or pay chemical engineers to) until they discover a way that works. Once this process is discovered, the secret eventually escapes to the rest of the world; and we observe self-interested production-behavior leading to the liquefaction of plant tissue around the planet and the ecosystems it supports (since we have established the virtually inevitable existence of future excess demand for energy).
Now, tell me which one of these events is something that we, standing here today, can foresee and control with reasonable effort. Perhaps it is worth it to reconsider my title.
References
International Energy Agency, "Key World Energy Statistics," 2005
International Energy Agency, "Energy Balances of OECD Countries," 2005
International Energy Agency, "Energy Balances of Non-OECD Countries," 2005
Vitousek, P. M., Ehrlich, P. R., Ehrlich, A. H., and Matson, P. A., "Human Appropriation of the Products of Photosynthesis", BioScience,1986, 36, 6, pg 368-373
Comments
Your thought experiment was proceeding admirably in time-tested back-of-the-envelope fashion, until you skidded into the word "eventually" and ran catastrophically off the rails.
Your thought experiment til that point has been applied before in an analogous way to covering the land masses with photovoltaic cells. But what number would you assume for their efficiency? The correct answer is a moving target, since their efficiency is still improving significantly. They'll take time to construct, after all.
And that's where your "eventually" steered you right into a ditch. Cellulosic ethanol technology doesn't need to work until "eventually" gets here. (That's a very long time.) Or even until the entire planet's population has reached today's US per capita energy consumption level. (Also a very long time.)
It simply needs to work until something better is devised, in combination with other green technologies, in a way that's less painful to current and future generations than fossil fuels.
Space-based solar collection, possibly. Eventually.
Posted by: melior | July 18, 2008 3:24 AM
Sorry to be a grammar pedant, but this one is like nails on chalkboard:
"This seems like a loose-loose situation."
That's 'lose-lose'.
Otherwise an interesting calculation, caveats and all.
Posted by: Dlux | July 18, 2008 5:41 AM
Why are you assuming that government regulations are not strong enough to ensure that ethanol would only be produced from a subset of our land. There are big interests out there that would love to log and strip mine huge tracks of the American West right now for reasons other than ethanol production. However, the development of state and National Parks as well as regulatory agencies has helped to keep that in check and ensure that logging is done with limited ecological harm. Biofuels clearly are not the only solution to our energy needs, but they may help.
Posted by: tuatara | July 18, 2008 7:54 AM
In this thought experiment it is assumed that biological waste materials from farms are not valuable to the farmers, this is incorrect. Although there are by products that cannot be sold like cornstalks and other biological waste, these materials when left on the field provide important fertilizer to the soil and improve soil health over time. This maintains yields, and does turn into a monetary pay off for the farmer. If we were to take all of this biological waste out of the field and use it to satisfy our need energy needs, we would eventually run into food shortages or the need for synthetic (petroleum derived) fertilizers and pesticides would rise.
http://www.npr.org/templates/story/story.php?storyId=92455289
Posted by: Jillian | July 18, 2008 8:07 AM
One more time with feeling:
Fuel is different from power generating source
We don't need to power the world with any 'fuel', and trying to do so profoundly dumb for many many reasons. We should power the world with electricity generated from a host of options. (Yeah, you mentioned buckshot... so you got 1/2 my point.)
We do need high energy density fuels for certain things, most notably transportation. This is a much tougher nut to crack than providing power. Much better to think of fuel as something we use energy to make, an energy storage medium.
Oil, syngas, biofules, and such conflate energy production with fuel production in an extremely unhelpful way.
Here is a concrete suggestion. Why don't we all agree to talk about fuels in terms of how hard they are to produce materials and energy efficiency wise. Fuels which also produce energy can be accounted for by having great over unity energy efficiencies compared with options like batteries of H2... however material resources wise they pose problems.
Anyway, long to short: Celulostic ethanol is a fuel. It only needs to replace petrochem liquid fuels, not power the world. (I don't think it can, at least not without coupling it with conservation and increased use-efficiency leading to very significantly reduced demand.)
Posted by: travc | July 18, 2008 8:18 AM
In your calculation you are mixing power and energy. toe is a unit of energy. Watt is a unit of power. So 1 Mtoe = 1.33 GW should actually read 1 Mtoe/yr = 1.33 GW. And the other references to Mtoe should also be replaced with Mtoe/yr.
Posted by: Michael | July 18, 2008 11:00 AM
Back to my anti cellulosic ethanol rant, which is becoming more and more an anti ethanol rant....
Fuel quality cellulosic ethanol is akin to rayon in its cost and complexity of manufacture. Would you burn rayon to heat the house? You get more heat value by burning the wood and skipping all the complexity.
Every ethanol scheme ends at a distillery. Unlike petroleum which arrives as a fuel which is 100% useable, ethanol arrives at 3-15% concentration in water - somewhere between beer and wine, depending on the starting sugar content of the juice. All that water has to be evaporated, wasting the energy potential of the derived fuel. The cellulosic plants themselves contains much less water at the start than fermentation ethanols. So rather than make any alcohol at all from any plant, you are better off from a sustainability standpoint just to burn the entire plant. Cut the sugar cane, or the wood, or the corn, or the soybeans, or the switchgrass, dry them, and burn them. Skip the fancy separation processes altogether.
Posted by: tom quick | July 18, 2008 11:28 AM
I have a slightly different take, kinda-sorta.
I view ethanol production from corn to be a prototype for future development. It's the beta-test version of ethanol production.
It didn't work. The best minds got together, built a large system, tried it for a couple years, and now they've found out it would have been cheaper and less polluting to simply use the land, the diesel, the electricity and the fertilizer that went into producing the ethanol, and use all that stuff to make food, and burn the diesel to power vehicles. Once added up, they figured out that David Pimentel was right after all.
Now, if this was a car company, and they were faced with the outcome of, "Our best engineers proposed a system, and wow, it was a spectacular failure!", they'd quit the project.
But it was not to be.
Instead, we get federal subsidies and massive PR campaigns that help wash away the inherent inefficiencies of the prototype, and induce us forge ahead anyway.
In other engineering fields, we'd say, "Oops!" and walk away. Begin working on V2, and write a "Lessons Learned" report, so subsequent versions benefit from our errors.
But this is corn ethanol, and it helps make us energy self-sufficient (even though it doesn't), so it's worth it. Yay us.
Things must change. I hope people are able to, without emotion, learn from our failures and our successes, and can move on to the next version.
I'm not saying ethanol as a large-scale fuel source will never work. I am saying that the current model is a dismal flop, and we must abandon this version and look for the next one (which will benefit from what we've learned, so what we're doing isn't a complete waste of time).
For the record, I believe that Pimentel's calculations are spot-on. Without federal subsidies, we would not be attempting this experiment.
Posted by: MikeM | July 18, 2008 12:48 PM
These are all valuable comments. It's good that people are pointing them out. Thanks also for the notes on spelling and units, those have been corrected.
But the comments here demonstrate the issue that I'm raising (apparently not very well), so I will try to clarify.
In the energy discussions, the conversation often proceeds like this:
(1) Is the technology reasonable, from a technical perspective? (eg. can we actually turn cellulose into fuel? does it actually reduce GHG emissions?)
(2) Can it compete, in terms of cost, with existing technology?
(3) Is it scalable? If so, how much energy is out there for capture?
(4) Let's start a company and save the planet.
This is, considering the standpoint of the engineering community charged with saving all of us from ourselves, a perfectly reasonable conversation to have. My point in the post is that there are some important considerations that have been left out of this discussion.
Reflection on historical precedent suggests that we systematically under-estimate the creativity (and fail to consider the incentives faced) by those individuals who will "misuse" the technology that we invent. It is not usually in the training of engineers and scientists to think about the strategic interactions, politics, crime, etc. Completely understandable considering the time they dedicate to thinking about solving technical problems. But history has demonstrated that once their technologies are released into the public domain, many technologists are upset at how their innovations are applied. A prime example is Alfred Nobel (the many behind the Nobel Prizes). His invention of dynamite was for peaceful purposes, such as quarrying rocks. Upset at its application in weapons technology, he used his tremendous profits to institute the Prizes, some say to assuage his guilt.
In the Manhattan Project, the men and women who worked so hard to usher in the nuclear age were so engrossed by the technical details of their work that numbers of them never paused to consider the ramifications of their actions. Many reported shock when they learned that the weapon they built had actually been used. It seems to me that this is a systematic problem in our pattern of innovation, and most of the comments above are consistent with this: we are so preoccupied with technical details that we miss the whole main argument of this post.
My point is that there is a context, a world of individuals who interact strategically with one another, into which cellulosic ethanol might be introduced, should we discover a way to efficiently generate it. The "back of the envelope" discussion began by assuming away the technological questions. These assumptions allow us to get away from the points 1-3 in the "standard technology discussion" and think hard about what should be point (4): "What would happen to the world if we actually did create what it is we are planning?" If the answer to this fourth question is unpleasant, we might rethink whether it is worth spending time on the technical issues. So perhaps, this should actually be question (1).
The "back of the envelope" estimate really was not supposed to be a technical issue, it was just to understand whether cellulosic ethanol production could or could not rule out the existence of future demand for energy. This is relatively weak criteria, but it does matter.
If the production of cellulosic ethanol cannot rule out the existence of excess demand for energy, then we cannot rule out the possibility that it would be profitable for all biomass to be converted to fuel, someday. It may not be likely, but we do not have the power to rule it out.
The primary point is that creating a technology that values the extraction of an easily accessible resource could be potentially disastrous. Especially in a situation where we can expect demand to be so large that it might be profitable to extract all of it. In economics, this situation is known as "the tragedy of the commons." In a world where cellulosic ethanol production is profitable and there are two agents looking at the enormous cellulose deposits that are the Amazon rainforest, we expect a large fraction of the publicly valued forest to disappear because each agent predicts that if she doesn't steal the cellulose, the other will, so she might as well get some benefit out of the forest's destruction.
The interesting part of this "tragedy of the commons" is that it is one we will actively create if we choose to pursue this technology, because this technology is the key that creates the profits from extraction. It think two examples make my suggestion of outlawing this innovation clearer.
In the US, we have outlawed the sale of human organs. We did not stop the technology for organ transplantation from being developed (a good thing) but we struggle to prevent the emergence of a "price" or "value" for human body parts. We've done this because the existence of a market in these goods is a slippery slope. We might fear that lives could be ended early so that their organs could be harvested and profits could be made. So we have tried to regulate the system. However, the market has still emerged and it is well known that individuals wishing to buy or sell organs can do so in other nations, either where it is not illegal or regulations are not as well enforced. Why then, do we not all fear being abducted in the night, transported to one of these organ-market hubs, and being killed for our parts? Probably because there is not an enormous amount of excess demand (from an economic standpoint, but it is clearly true that many people who need organs cannot receive them in time). In many of the nations where organs are sold, the demand is met by local individuals in relative poverty who are willing to sell a kidney for less than it would cost to abduct and transport an American. If, however, some epidemic swept the nation and millions and millions more Americans needed organs, it is unlikely we would all continue to feel so safe. This is why I spent time on the "back of the envelope" demonstrating the potential existence of excess demand. We, luckily, did not chose to make transplantation technology illegal just because we feared the emergence of these organ markets. However, we have done this with other technology.
Cloning humans is illegal. There are a large number of reasons why the world we envision post-human-cloning is undesirable, so we have actively regulated against the innovation of the technology itself. Such regulation is exactly analogous to what I was proposing with respect to cellulosic ethanol. I imagine that nobody has discussed this issue for cellulosic ethanol because imaging the outcomes of such technology is significantly more nuanced and portrayed by Hollywood with lower frequency than a world with human cloning.
So I continue to contend that the development of cellulosic ethanol is a slippery slope that we may not see coming if we do not step back and look very carefully at the bigger picture. If I turn out to be right, then it would make all these technical arguments moot points.
Posted by: Solomon Hsiang | July 18, 2008 1:07 PM
Solomon, you miss (not just assume away) a few very important points.
First and foremost, no one with half a brain should be considering ethanol as a major energy source. It is a fuel, one which has some real benefits in the short term, the biggest being its relatively easy substitution for petrochem fuels. For the final time, fuel is a much harder problem than energy, and it is very unhelpful to conflate the two.
Secondly, you can't just assume that the costs of harvesting and processing biomass into ethanol are negligible. Even if we had a magical way of processing biomass into ethanol, collecting the biomass is not free. There is a calculation possible here, but the inputs are tricky to find. However, my instinct is that there are already many energy sources which are cheaper than just the harvesting side of biomass in most cases. Farms growing biomass (especially ones collecting biomass along with crops for other purposes) are a special case where harvesting is much more cost effective.
All that said, you do have a point. We should not depend on ethanol (or any other single fuel) for our fuel demands. That is a very bad idea for a huge variety of reasons, but one which actually has a chance of happening none the less.
We need to have enough foresight to actually invest in infrastructure (and vehicles) which are flexible with respect to fuel. Flex-fuel isn't really nearly as flexible as we should be shooting for, but is a start. Diesel and turbine engines are generally better but not great on the flexibility side as well.
By far, the biggest (short/mid term at least) flexible fuel is just not using as much fuel. Conservation and efficiency gains are equivalent to perfectly substitutable fuels.
Plug in hybrids are also a very very good thing, since they use very flexibly and much more efficiently generated electricity to displace demand for fuel a lot of the time, and rely on fuels only when those hard to satisfy constraints (safety, high energy density, simplicity of utilization, easily distributable, ect) are really critical.
In summary, you have an interesting idea and possibly a valid point... but your argument kindof sucks (sorry). I suggest attacking it from a standpoint of how we might substitute our demand for petrochem fuels (not energy). Using ethanol to simply replace petrochem fuels, even in the best case production wise, probably won't work and trying to do so could cause real environmental problems. So we have to look at other fuels (including conservation and efficiency gains as a substitute 'fuel').
Posted by: travc | July 18, 2008 6:25 PM
Solomon:
I find it hard to accept an argument that ethanol production could be so successful that it needs to be completely outlawed to prevent irresponsible harvesting. If you don't think governments will respect laws restricting production to certain feed stocks, why would those same governments respect an outright ban?
Tom Quick:
While it's clear you can get more energy by directly burning raw plant material than you can by processing the plants and burning the result, the problem is you can't pump dry plants into the fuel tank of a truck. Ethanol's only real advantage is that it is a liquid fuel largely compatible with the existing internal combustion engines on the road today.
If you only want to generate electricity then burning hog fuel is much better than ethanol; but I would use burning anything as a lower-priority powerplant. Surely low-to-zero emission power is preferable to carbon-neutral power wherever possible...
The previous blog post suggests we have to plateau our emissions in the next 7 years, and we've only got 25 years to phase in replacement technology. There are 600 million vehicles on the roads, and I just can't see us removing them all in the next 40 years, let alone 10!
I don't even like ethanol. It's a solution that feels like running flat-out just to stand still. But I think we might have to do just that -- come up with some alternative liquid fuel to keep transportation running just long enough for it to be replaced by something better (ie. electric vehicles).
The only other option is pretty much to stop driving altogether. And I don't think our civilisation can function without a transport network.
Posted by: Kagato | July 18, 2008 9:51 PM
On my list of worries, the idea that cellulosic ethanol will get so good that everyone will rush off and do it ... is not high.
1) Electricity is far higher-quality energy for everything that it can do, and the EROI's seem better than the sun->fuel pathways.
Between:
efficiency
BEV & PHEV cars and light trucks and even tractors
hybrid locomotives
more electrification of railroads
after petroleum is mostly gone, that leaves
biofuels for ships, airplanes, some farm machinery, off-road vehicles, and whatever Class 8 trucks there are.
I hope for algae biodiesel and some other interesting bioengineering, and maybe switchgrass/miscanthus or derivatives thereof.
2) There are natural limits, in particular:
Google: corn stover carbon replenishment
3) In addition, the *pollution* problems make this impossible. Replacing (some of) petroleum with biofuel is at least better from the CO2 viewpoint, but it doesn't help air pollution, like in Los Angeles or Beijing.
3) But in any case, Solomon: how's your live experience with life on a working farm? Especially in the mid-West? You might take a look at my July 17 post over at Climate Progress and especially look at the Iowa Office of Energy Independence referenced there.
I raise this issue because:
About 2% of Americans now live on farms, which means that a much larger percentage of people no longer understand farm economics quite so well.
I think there is a period coming, in which the only way that anything like current American farming will persist will be because farmers produce at least enough biofuels for farmings' own needs. It is unsurprising that places like Iowa (which don't have oil or much other fossil fuels) would rather avoid going out of business when petroleum costs too much, especially if they can grow something to power their machinery and something to sell whose prices track fuel.
For a lot of reasons, we'd better hope that corn ethanol disappears in favor of appropriate cellulosic, especially across the period before we can electrify everything around.
Posted by: John Mashey | July 18, 2008 10:09 PM
John Mashey makes good points... but one minor quibble.
Most locomotives are hybrids. There are plenty of places where we should be putting in electrified rail IMO (as well as building new rail lines and upgrading old ones). The safety concerns are pretty damn irrational, diesel exhaust is far more of a public health and safety concern.
You point about farm economics being pretty misunderstood, or at least under the radar, is quite true. More and more ag facilities are installing various alternative energy production facilities because it makes economic sense for them... this is much more like a factory using co-generation than what most people imagine.
Posted by: travc | July 19, 2008 2:56 AM
travc: I don't think we disagree.
But a clarification, because the term the term "hybrid" covers a lot of different things, as seen in Hybrid Locomotives. Sorry, I should have been more specific, but that was already long enough.
a) Most locomotives are diesel-electrics, i.e., diesel burns fuel; to drive motors. In that sense, they are hybrids, but not quite in the sense that forthcoming PHEVs are hybrids. [In car parlance, serial hybrids, but without the batteries.]
b) The GE locomotive mentioned above, and others, are now including batteries, ultracapacitors, and regenerative braking to recapture the (substantial) energy lost to braking.
Given that one has:
1) Completely electric drivetrains.
2) Batteries/ultracapacitors for recovering energy.
3) Ability to plug in (car) or use electrification (train)
THEN
4) One only burns fuel when needed.
For instance, one can imagine locomotives that normally run electrified, but burn fuel for visits to spurs that aren't worth electrifying.
One can certainly imagine vehicle families that share most components, but in increasing order of non-electric range:
- BEV car or pure electric train
- PHEV car with small tank or diesel-electric with small tank
- PHEV with larger tank, diesel-electric with larger tank
Farm economics: yes, for sure. After all, farms have had (little) windmills for a long time. Here in CA, there's a noticable uptick in recapture of methane from cow manure.
Posted by: John Mashey | July 19, 2008 8:43 PM
My impression regarding locomotives was that at the point where a non-electrified track begins you have a depot and just switch the locomotives to diesel or electric depending on the direction of the train. Why would you need a hybrid?
Posted by: Michael | July 20, 2008 1:38 PM
Kagato,
We'll all have to buy new cars and trucks to get any substantial use of ethanol. I come back once again to the foolhardiness of trying to break down lignocellulosics to get alcohol...get your liquid fuels from soy biodiesel, or sugar-based alcohols, or even Fischer Tropsch biodiesel from recombining of gasified lignocellulosics. But don't tout cellulosic ethanol, please.
Posted by: tom quick | July 21, 2008 4:02 PM
Tom,
I really should have said 'biofuel' rather than 'ethanol' -- I don't want to promote any one specific fuel production method, and more knowledgeable people than me will pick the best ones.
A quick search turned up flex-fuel conversion kits from ~$500, which adds up to an awful lot of money; but it's a tiny fraction of replacing the entire vehicle fleet. If we were to replace every car & truck, then they'd really better all be electric or hybrid. (And the ICE should be as fuel-agnostic as humanly possible.) Anything else and we'll just be doing it all again in 20-30 years.
So what do we do until the fleet does finally get replaced? Just keep burning petroleum as we do now? People apparently tend to keep cars for 7-10 years on average, so even if manufacture of petroleum-based cars were banned tomorrow, we might not see a significant effect for a decade.
Posted by: Kagato | July 21, 2008 8:25 PM
Michael:
I've looked at railroad maps, and there are lot of spurs (which sometimes get abandoned if trucks take away enough usage.)
So for example, suppose a train should go along a mainline for a while, stopping off to visit a set of low-usage spurs. The question is:
A = cost of electrifying the spurs
B = cost of building locomotives able to run either electrified or via diesel.
C = cost of leaving a diesel locomotive at each (or many) spur9s), and (small) time cost for switching, and whatever infrastructure needed to get diesel fuel there, and maintain them there.
A is obviously most desirable
B people do build different-flavored locomotives for different uses, and actually "dual-mode" diesel-electric/third-rail locomotives are are already in use by L.I.R.R..
C may work if leftover diesels become really low-cost
Posted by: John Mashey | July 21, 2008 11:04 PM
Here's an interesting link to a description of conventional technology ethanol from wood using sulfuric acid hydrolysis to make sugars, followed by fermentation to ethanol.
http://www.distill.com/woodhydrolysis/woodprocess.html
I don't know whether this plant in Siberia is still operating. Yield of alcohol on incoming wood appears to be about 20% (on a daily basis 36,000 liters of alcohol from 180T dry wood). The lignin byproduct, about 60,000 tons per year, is landfilled.
It's a pretty elaborate system, using a lot of high pressure batch reactors, operating at low pH. The result is a little over 3 million gallons of ethanol per year, enough to fuel about 5000 cars.
Posted by: tom quick | July 21, 2008 11:33 PM