Here's an even harsher assessment of plant-derived ethanols from Dr. Tad Patzek, chairman of the Department of Petroleum & Geosystems Engineering at The University of Texas at Austin:
Basically, [corn] ethanol is obtained from burning methane, coal, diesel fuel, gasoline, corn kernels, soil and environment. We destroy perhaps as many as 7 units of free energy in the environment and human economy to produce 1 unit of free energy as corn ethanol, and make a few clueless environmentalists happier and a few super rich corporations richer. The story is even worse for switchgrass ethanol.
Almost everything on TheOildrum.com is not a mainstream view, some of the minority views are right many are not.
An ethanol plant has more outputs than ethanol. Distillers Grain is a major output stream, which is a useful lifestock feed.
The paper, which I have read, counts as energy inputs all the energy required to make ALL of the inputs and takes every step possible to make the largest energy input amount possible.
Ethanol isn't the most efficent process, but the tech is being pushed ahead and the end output is a liquid high energy density fuel which is more useful that some of the energy input into the system.
As an energy economist would you mind commenting on Elon Musk's assertion that the best case with a perfect plant for making biofuel, the efficiency per unit of land used is still 2 orders of magnitude less than capturing energy with solar cells?
He also claimed that for most nuclear power plants, if you covered them and their exclusion zones with solar cells, you'd generate more energy than the plant itself generates.
(Both assertions seem pretty strong. Both were made during the interview at Oxford that was put online yesterday.)
Regarding Elon Musk, I think it is irrelevant if you get more energy out of solar panels vs. biofuels as that is simply the wrong question because you’re getting two very different types of energy out of each. Solar produces electric power which needs to be moved across a large capital intensive grid and also has to have supply and demand balance in realtime, solar has problems producing power when it is needed. Biofuels are high density portable energy sources that work with a trillion dollar base of invested infrastructure.
The portability/infrastructure view can be seen by a market based approach.
One MMBTU of natural gas delivered at Henry Hub, sells for $3.50
A Barrel of Brent oil sells for $110 a barrel
6 mmbtu’s of Natural gas has the same energy content of a barrel of Brent, or you could buy the energy content of a barrel of oil for $21 with natural gas. The FORM that a unit of energy comes in matters a lot.
Regarding Elon Musk’s claim on nuclear power plants I think there must be an assumption he’s made that I’m not aware of. On it’s face I don’t believe this is true, there likely is an important assumption missing like perhaps every single inch of the site is covered. Also even if the absolute outputs of energy are the same because solar isn’t going to always deliver a steady planed amount of power output, peaker power plants are going to be needed when days are shady etc. changing the economics.
The FORM of energy matters, Nuclear power plants run for months at full capacity and when they need to be out of service that is planned ahead of time to occur during times of the year when demand is lower. My job at Enron was to know everything about every Nuclear power plant in the country because there was a lot of money to be made in predicting if one wouldn’t be able to produce.
The compressed air storage investment that PG recently made is all about the timing and form of energy, being able to shift those has a LOT of economics value.
PG
Musk's assertion regarding biofuels was correct, but I think it was made within the context of using them as fuel. He didn't discuss many side-products that are generated during the production of biofuels.
The problem with counting "side effect" products is nobody ever takes into account the supply/demand for that product. Sure making enough biofuel for the entire US produces 100 tons of X. But if the worldwide demand for X is 5 tons, then you've now generated 95 tons of waste that needs to be disposed of.
However, the major side product of corn based biofules is distillers grain which is animal feed for Cows/pigs. There is enough demand there to actually consume all of the distillers grain produced.
He also claimed that for most nuclear power plants, if you covered them and their exclusion zones with solar cells, you'd generate more energy than the plant itself generates.
He's talking about corn. Generalizing this to "plant-derived ethanols" is a stretch
But yes, Corn ethanol is not good for a series of reasons. Other plant based ethanols may not suffer from the same problems.
Ok, I read the article, typical "only oil is good" atitude.
And by the way: efficiency with respect to sunlight doesn't matter because sunlight is free. (enough) free * anything -> free (It matters in respect to other processes)
Sunlight is not free. In order to collect it you must use some land, and that incurs the opportunity cost of not doing something else with that land, such as growing plants for food.
That's not what he means. A solar energy harvester with 0.1% efficiency might still be worth it if the costs are low, it doesn't matter that you "wasted" the other 99.9% since it's unlimited.
It does matter when it comes to CO2 fixation though... if you only get 0.1% efficiency in fixing CO2 with biofuel production, but would get 1% with normal forestation, then there is a quantifiable difference.
I assure you that it would be madness to try to grow food in the places where solar cells are most effective.
Try looking for the "Desertec" project.
The main cost of solar cells are the resources you need to built them and the chemical waste that gets produced
In the process.
Sunlight is free. But efficiency with respect to sunlight translates to efficiency with respect to land use. And land use is emphatically not free.
According to Elon Musk, even if you assume perfectly ideal biofuel production through photosynthesis (which no existing plant is), the amount of land that you'd need to devote to biofuel production to meet current energy needs is similar to what is currently devoted to human agriculture.
I'm not sure I understand this. Solar power could power the US with a 100 mile square area, and it seems like 'perfectly ideal' biofuel production would be just as efficient. Of course, solar panels are around 30% efficient right now (perhaps more for solar-thermal, etc) while biofuels are at negative efficiency - but that's what science is for.
Why would a perfectly ideal biofuel production be just as efficient? Commercial electric cells are close to 20% efficient. From that form to useful work is typically over 90% efficient.
By contrast from what I'm reading on Wikipedia the reaction that drives photosynthesis has a theoretical max of 25%. But you only get that efficiency at 1/4 of normal sunlight levels during the day (the rest of the light has to be wasted). We're already well below solar. And then you've got to give some of the energy to the plant for growing. Then you lose energy in the chemical reactions that make a biofuel. And the biofuel goes into an engine. Every one of these steps has a maximum theoretical efficiency that is fairly low. (For instance a gasoline car engine's maximum efficiency is in the 25-30% range.)
If I remember correctly, Elon claimed that biofuel production had a theoretical max of about 0.5% of incident sunlight energy being converted in the end to useful work. (We're a long ways away from this maximum in practice today.)
There are still problems with any plant-based biofuels, but they're problems with scaling, crop rotation, pesticides, and the current state of the art of ag in countries where sugarcane is grown.
But the energy return of sugarcane ethanol is high enough to make it non-silly.
Compared to solar, they're all silly. You live the glow a giant nuclear reactor, so large it is contained only by its own gravity. A .01% yield on the energy incident on earth would power everything we ever need.
A .01% yield on the energy incident on earth would power everything we ever need.
I can never understand why people trot out this sentiment. Humans are a biological species subject to normal ecological principles. One of those principles is that, in the absence of a limiting factor in our environment, we will grow. If energy availability is removed as a limiting factor, we will grow ("gettin' larger in waist and taste") until it is again. Anyone who pretends otherwise has not stepped outside to notice all the millions/billions of people clamouring for food, clean water, jobs, holidays, new computers, clothes, homes, education, etc etc. Imagining that, unlike every time in the past where human societies have chafed against resource limits and hoped that just a little more would fix everything, this time human needs will finally be satisfied, is the oldest fallacy in the book. It's just not how life works.
You live in a valley full of aurochs, horses, and boars, more than any man could eat. Taking just a fraction of these bountiful riches would give us all the food we could ever need.
I'm not sure it's broad ecological principal - humans are not simple animals - however I do think if we had "limitless" energy, we would all start flying around in personal aircraft, terraforming deserts, creating subsea buildings, and doing all sorts of wasteful things - until energy somehow became a problem again. In doing so, we would likely find other ways to disrupt our environment - just because energy is cheap and clean, doesn't mean using it has no effect.
Every time I buy a new laptop, I can't imagine how I'll fill up the drive, but I know I will.
Humans don't eat electricity or oil. Sure, they may be used to increase yields of harvests, but the limitation is still how fast plants grow and how much area they need.
Effectively we do eat oil. We replenish soil fertility with fertilisers made with oil energy, we farm large areas with machines powered by oil, etc. etc. We grow more plants faster, with shorter turn-over times, and use less human effort to do so, thanks to oil. There might be a few intermediaries but the end result is that energy from oil ends up converted into human biomass. I can guarantee you if we had never discovered oil there would be far fewer people, with far slimmer waistlines.
"is that energy from oil ends up converted into human biomass"
No, that's the whole point!
Humans surely cater to farming using oil, and we would be a lot worse without it.
But in the end food came from two sources: energy from the sunlight and CO2 (matter) from the atmosphere. (Well, then we could say we're eating car emissions).
Unless you're converting oil directly into food (let's say carbohydrates), no, all energy from plants comes from solar energy. You could of course have a giant oil powered lamp that produces light and shine that over the crop.
Water? With unlimited ultra cheap energy, there is plenty of sweet water in the oceans.
On the other hand: what is stopping us now from combining salt evaporation ponds with sweet water production in e.g. the coastal regions of the Sahara?
Except for nuclear, geothermal and tidal wave generation (and other lesser used energy sources) all energy in planet Earth is solar, accumulated during different time frames.
Sure, solar is great, except current technology is really bad at using it.
Solar has one really great aspect, it can be installed easily at the point of use. Tranporting power on the grid results in a lot of loss, by being at the point of demand solar gets an instant bump in terms of value.
>A .01% yield on the energy incident on earth would power everything we ever need.
This sounds like the Chinese soda analogy [1] in a different form. The fact that we only need 0.01% doesn't indicate the ease of capturing 0.01% in the form of usable energy.
Guy Kawasaki: "If a company can get just 1% of the people in China to drink its soda, it'll be selling a ton of soda. This is true. At the same time, it glosses over the difficulty of getting 1% of any market to use a particular product".
We destroy perhaps as many as 7 units of free energy in the environment and human economy to produce 1 unit of free energy as corn ethanol
And yet they still make a profit, and it is still highly rational to do so. Because it turns out 1 Joule of liquid hydrocarbons is more valuable than 7 Joules of methane or coal or sunshine.
This is why a tax on carbon is better than subsidies. Then that 7 fossile fuel Joules to 1 biofuel Joule would be a huge loss. Incentivize what you actually want to optimize.
A comment below mentions subsidies - that's certainly part of the answer. In addition, for mobile applications, not all energy sources are equal. Transportability (stability, energy density, etc.) also contribute to liquid hydrocarbon Joules being more valuable than methane, coal or sunshine.
Tangent- we have LPG, and from what I understand it's actually very successful in niche applications. Have we tried liquefied methane gas? We have many more sources of methane than propane.
Generally, it hasn't been very economical to do so, although I wonder what the numbers are now that we've got so much natural gas production in the US.
He really, really misses the point: what matters most is economics, not technical metrics in vacuo.
“… these values even do not take into account that more than 50% of the energy stored in the biofuel had to be invested in order to obtain the biomass (for producing fertilizers and pesticides, for ploughing the fields, for transport) and the chemical conversion into the respective biofuel.” [...] “The production and use of biofuels therefore is not CO2-neutral. In particular, the energy input is very large for the production of bioethanol from wheat or maize, and some scientists doubt that there is a net gain of energy. Certainly the reduction of CO2 release is marginal.”
In real world economics, biofuels are not energy; they are high-density liquid transport fuels. The economics make it clear: e.g., gasoline costs ten times as much as coal, per unit energy. You're paying for the chemistry, not the joules.
It matters very litte in real life, that much of the energy (cheap) is wasted; that much of the energy comes from (cheap, external) sources. If biofuels are viable, they can be seen as a conversion of energy to hydrocarbons: of (comparatively) cheap electricity and methane/hydrogen to expensive liquid fuel. Not as a primary energy source. It's the carbon that's valuable.
Farming machinery can be electric powered. Nitrogen fertilizer can be created from nuclear- or solar- powered hydrogen. And voilà, it is carbon-neutral. Nuclear electricity, solar electricity, hydrogen -- these are only marginally viable fuels (c.f. the world market for EV's; opinions may differ). Converting them to liquid hydrocarbons is a very useful thing.
> In real world economics, biofuels are not energy; they are high-density liquid transport fuels. The economics make it clear: e.g., gasoline costs ten times as much as coal, per unit energy. You're paying for the chemistry, not the joules.
Somehow, this is hard to get through people's skulls. Liquid hydrocarbons are a really potent energy storage medium with fantastic economics. (Compare a metal tank to Li-ion battery.) So long as we have need of bulldozers and heavy equipment at sites outside of fully established infrastructure, like construction sites, we will have a good use for such fuels. It's not overall efficiency that's important here. It's efficiency in a mobile context.
> Farming machinery can be electric powered. Nitrogen fertilizer can be created from nuclear- or solar- powered hydrogen. And voilà, it is carbon-neutral.
This really bothers me, and it happens all the time. Of course everything in our current infrastructure has a carbon footprint!
A large amount of the "bulldozers and heavy equipment at sites outside of fully established infrastructure" are the giant machines used to pull oil and natural gas from remote locations (tar sands, arctic and offshore oil rigs) and transport them the large distances to places inside fully established infrastructure. The need for hydrocarbons is compounding.
Similarly with biofuels, even if we are to genetically engineer more efficient plants to grow fuel, it still must be grown in a remote location, processed, and transported to places with existing established infrastructure.
In comparison, most places where people need energy already have the electric infrastructure to support it. We should be using liquid fuels in cases where it is truly necessary, not just for the short distances and minor wants of most.
We are not disagreeing. My position is that liquid hydrocarbon fuel is always going to have a specialist niche. I also think the bulk of transportation should be electric, ultimately deriving power from the sun. There's no reason to be dogmatically absolutist about energy storage technology. I say we use what works in whatever context it works. This way, we're never stuck by the disadvantages of a particular technology.
It matters very litte in real life, that much of the energy (cheap) is wasted; that much of the energy comes from (cheap, external) sources.
you are just arguing that the production of bio fuels is cheap and that hence they are economically viable. obviously you'll make a profit with selling bio fuels, but that's because the market incentives are botched and a lot of the external costs have not been internalized in agriculture. ultimately the production of bio fuels is not ecologically viable - it competes against the food production and requires significant energy for the conversion (as you say) into hydrocarbons.
If biofuels are viable, they can be seen as a conversion of energy to hydrocarbons: of (comparatively) cheap electricity and methane/hydrogen to expensive liquid fuel. Not as a primary energy source. It's the carbon that's valuable.
that doesn't make any sense, because hydrocarbons have a very small intrinsic value - the (most common) usage you derive from hydrocarbons is motion energy. and the most efficient source for motion energy is again the electric motor (which could be powered more efficiently by electricity from solar panels).
* He says the energy input is very large. I say it's reasonable for it to be so, because it's converting a cheap form of energy into a valuable one
* He says it is CO2-intensive because of the large energy inputs. I say this is just a reflection of the whole energy economy being CO2-intensive; that in principle the inputs can be CO2-free, and so biofuels can be CO2-neutral. (And they unique in this aspect; there is no other way to make CO2-neutral hydrocarbons, short of chemically scrubbing CO2 from the atmosphere.)
This sounds quite reasonable. If left to their own devices, plants don't optimize for energy content, they optimize for spreading.
However, we humans already managed to genetically modify them (using simple selection of seeds over the millenia) to optimize plants for nutritional content instead.
It would be interesting to know to what extent human selection and other forms of genetic manipulation could improve the efficiency of photosynthesis in plants to make them viable for biofuels.
After all, large scale agriculture is still much simpler to pull off than the kind of industrial process needed to build solar cells on a large scale.
The article doesn't quote much on algae; it just dismisses them. In fact, there is no comparison of the actual economies involved; its just a sunlight-efficiency argument which is interesting but far from conclusive.
Solar cells cost something to build - ignored in the article. Using all sorts of minerals and industrial processes, very hard to trace thru our entire economy to get an 'energy budget' and thus a payback. So its easy to call them more efficient, if you don't actually calculate their cost.
Plants 'build' themselves - essentially nanotechnology for free. They can be built over and over again, or the land can be repurposed for food or grazing or parks or whatever. Solar cell farms are heavy infrastructure investments that have to be manufactured, hauled into place, installed, maintained, replaced.
The kind of large-scale agriculture most often used today relies on a huge amount of hydrocarbons. As I mentioned above, the need for hydrocarbons would still be compounding -- the more biofuels grown, the more biofuels required to grow them -- unlike capturing and transporting electricity on the already-existing infrastructure.
I would love to see large-scale sustainable agriculture that doesn't require such a staggering amount of resources. There are many smart people working on this problem. Unfortunately I don't see those advances outpacing the advances being made in electricity storage and transport.
Theoretically, it seems to me that if the plants were efficient enough, one should be able to obtain the hydrocarbons from them there are needed during the process of agriculture.
I guess the really important point is your second paragraph: As long as there are advances in both the plants and the technology, the plants may simply be unable to catch up.
That's the real key, black paint is really cheap and really good at converting most of the spectrum to heat, combined with the fact that mirrors are orders of magnitude cheaper than solar panels and you've got a winning combination.
It's also really cheap to store energy as heat and we've got two centuries of knowledge around turning heat into mechanical energy.
It's also really easy to apply heat and pressure to most organic material and directly convert long chain hydrocarbons to short chain hydrocarbons.
Also if you can generate steam you can just inject it into the ground and recover the oil in bitumen, your friendly neighbours to the north have like a trillion barrels of it.
He is absolutely correct that biofuels are not efficient use of land. But the market would quickly sort that out if it were not for biofuel subsidies. That is what needs to be stopped.
I'm not sure that the market would sort this out. People in the first world already pay more to fill up their car than people in the third world spend on food. And biodiversity often isn't given a monetary value at all (although there are people working on valuing ecosystem services). Subsidies aren't helping, but the underlying problem is that we want and are able to use more than our 'share' of resources.
That isn't what the article is about. He is talking about the energy efficiency of capturing solar power via photosynthesis. From the perspective of this article, growing crops for food is just as inefficient.
If acquiring solar energy through biofuels is less efficient than through photoelectric cells or other means then the market will definitely sort this out (though would not directly account for externalities such as carbon pollution).
That makes more sense. But we still pay a premium for energy in a high-density, liquid form that we can pump into vehicles. Of course, that's changing as battery technology improves.
market can't solve the current CO2 problem - it assumes the price of emissions is zero, when it clearly isn't. belief that it'll fix biofuels is naive at best. carbon and other products of burning fuel need to be taxed to have a price; musk also talks about it.
Seams to me that the market it the only way we can slow global warning down. Its companys like Tesla that make a diffrence not some goverment that tries to regulate existing stuff.
The have neither the insentive nor the knowlage to do so.
Electric cars, solar cells are the things that will change the world, not goverment regulation.
engine type doesn't matter much, what matters is energy storage for use in that engine. batteries aren't even in the same order of magnitude of both energy density (energy per liter) and specific energy (energy per kg) compared to liquid hydrocarbon fuel and that's the problem that needs solving. tesla currently gets away with it by placing batteries in clever ways, but it's still inferior to plain old gas in multiple areas (recharge speed, maximum range, mass, etc.)
what's that got to do with the market? without pricing gas correctly, electric will always be inferior. technology can only help so much - it's a question of fundamental physics of chemical bonds.
Electirc cars are better in some respects. Nonreusable energy will get more expensive while reusable energy will get better.
The market will figure out if electirc cars are a workable, maybe it want work. Maybe we should have hydrogen cars or maybe something else. Maybe we just have to live with it, use all the oil and only then we will stop. Sure you can add a carbon tax or something but that will at most drag things out (or maybe make the adoption of diffrent cars faster).
Fundamentally the way we will live and how we will produce energy will be guided by markets.
"nonsense" feels like an understatement. It competes with our food sources and even more so with ecological diversity. It should be one of those factors that assure that food prices rise to the sky with fuel prices and as they both go up, nature will fold.
Feel free to criticise my ignorance of economics. I'm probably mostly wrong.
His point was that putting energy into biofuels is an inefficient way to use the suns energy, and then getting it out is also inefficient. He compared the efficiency to solar.
Not just "an inefficient way". In the best case, biofuels are 2 orders of magnitude less efficient than solar. That said we could theoretically produce around our current energy needs with a perfect biofuel. (Existing biofuels are much, much worse than this theoretical fuel.) We'd just need to convert all land we currently use for agriculture to that purpose. (And then what would we eat?)
If his numbers are correct - and I see no reason to doubt it - biofuels have to be a dead end.
I don't know a single thing about biochemistry or biofuels, but in reading this I can't help but be reminded of Arthur C. Clarke's first law of prediction:
> When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
Hear Hear. Haven't heard that one before but it probably has quite some truth to it. Sort of like the old: "Science advances one funeral at a time" - Max Planck.
Anyways. His criticisms are all good ones, and yet I can't help but feel like he's missing the big picture- that or he thinks we are just doomed.
In the short to medium term future (5-25years) biofuels are probably not the answer they've been hyped to be. Yet there are still some places where they will still work well, such as any thing that isn't in contact with the grid. These biofuels will be competing with oil that must be drilled through kilometers of ocean and earth, or from injecting massive amounts of steam into the ground... talk about inefficient.
Further, biofuels do not necessarily need to use arable land or potable water.
In particular I'd like to know specifics about reports of "higher efficiency" than should be possible. I wonder if these reports aren't based on efficiency as calculated from creating biomass. One thing that immediately comes to mind, is that perhaps simple circulation and dispersal of light in water can account for increased "surface area" that makes up for the "max efficiency at 20% sunlight" statement.
In the end, aren't coal and oil biofuel? Just fuels that take millions of years to make. That seems to be proof by counterexample that not <i>all</i> biofuels are useless. But at doublerebel says, the headline should really be "we should not grow plants for biofuel production". Which is not the same thing at all.
I like how everyone comes into this debate with a different concept of what bio-fuels "do."
If you think about supplying the worlds energy needs using bio-fuel it is a non-starter, and that is basically what the editorial says. Converting incident sunlight into useful energy through existing photo synthesis processes is inefficient and does a great harm in terms of food production.
If you think of it as a way of converting sunlight into something that pre-existing infrastructure can use (fuels) that can be justified on the expense of swapping out the existing infrastructure.
Big picture -> move everything to electricity and gas, since those two forms of energy are pretty readily convertible into the other forms we need.
Intermediate points -> you need a petroleum fuel cycle while you're converting everything else.
There are different types of biofuel research. He seems to ignore the whole sector that is bioengineering the plants to solve these problems. One example that comes to mind (and I can't find a link to on my phone) involves changing the color of the leaf to absorb more light.
It's been obvious for some time that using food crops as fuel (first generation biofuels) is a terrible idea. Well, obvious to everyone except the governments subsidising them.
What people are still interested in is 2nd gen - converting inedible biomass (mainly cellulose) into liquid fuel - and 3rd gen - growing algae, which have all sorts of cool properties. In theory, you can engineer the algae to produce a usable fuel directly. In practice, it's still proving tricky.
"Competing with food crops" is a curious notion. When did we run out of space for food crops? Not on this planet.
Corn grown in Iowa could feed 2 United States. So we make all sorts of other things out of it, or the govt pays folks (me for instance) to NOT grow corn and keep the price up.
At this point in history, with our current distribution system, biofuels can make money. In the future they will become more efficient, perhaps orders of magnitude more in ways we haven't thought of yet (oil-drop lenses on the leaves; kelp that fills its pods directly with waxy carbohydrate films; seeds that can be eaten OR converted to fuel etc).
The dumb thing would be to stop innovating now, because of FUD about imaginary issues.
It competes with food crops for fertile land. That means: it pushes food production to places with worse water, farther from consumption centers, increasing waste and costs related to transport.
Maybe in the US the situation is not clear because you have vast plains so it doesn't matter if you cover the entire surface with corn, but here in Brazil, my state vanished with an entire forest just for sugar cane and soy crops. Google "Atlantic Forest".
Oh that's easy to solve: simply insert a gene that makes biofuel corn toxic to humans, rendering them non-edible and solving the fictitious moral dilemma.
I think you were joking, but the sad part is, yes, that is what they do (minus the genetics) in order to avoid import restrictions (that apply to food but not "denatured", inedible corn/biofuel).
And it's long been practice to make alcoholic substances toxic if they're not intended for human consumption so that they avoid regulations and taxes that apply to alcoholic beverages.
Depends on the biofuel. I remember watching something a few years ago where Brazil (I think it was Brazil) was processing sugar cane waste into bio-fuel. Granted, sugar cane waste is a much better bio-fuel than corn ethanol is (I think on the order 8 times better).
Edit: Should have read @hcarvalhoalves's comment. ^^;;
How is its edibility relevant? Being edible means it's in a certain configuration that the human "engine" can process. I don't think it's obvious that this configuration is inherently inefficient for non-biological engines, even if it is the case.
Well, there is the definition of modern argiculture, which goes something like:
"Modern agriculture is the process of converting hydrocarbons to carbohydrates."
In other words, the way we feed the large human population, is by leveraging a diminishing supply of fossil fuels to grow food. Replacing fossil fuels with food in that equation doesn't really work; we need to think of something else.
Not because making biofuel is impossible, but because one of the main uses for fuel would be to make food -- and making food and making biofuel is in direct competition for resources.
Biofuels are of course nonsense from energy efficiency standpoint. Biogas is produced for a different purpose: it results in storable energy, which is theoretically supposed to balance energy produced by intermittent sources. Overally, biofuels are not supposed to be energy-efficient or net energy positive. If we can one day produce oil from nothing spending 2x the energy the resulting oil will contain it will be a great achievement, even a holy grail of all renewable energy work: storable, high density renewable energy good for peak loads and for transport (worst case: airplanes).
My pet theory is the reason they are so popular is "biofuels" has the word "bio" in it, which excites the sorts of greenies that don't examine things too closely.
Supporting evidence: aggressive marketing of "probiotic" supplements
Plant based biofuels are only problematic if you imagine replacing all transportation energy needs with them. Cut that out! Develop all technologies and let the market decide. I predict that there will be specialist niche applications for biofuels, and that most of transportation will be electric. For a cheap, robust means of storing lots of energy, it's really hard to compete with a metal tank of hydrocarbon fuel, but this doesn't doom us to run everything this way.
Headline: oil industry experts slam alternative energy.
Alternatives have only just begun being explored. Innovation in this area are very likely to surprise that chemist. E.g. steam from room-temperature water posted on HN today: http://news.ycombinator.com/item?id=4824205
Bioengineered plants may work any way we can imagine, not just the way an oil-industry chemist imagines.
Irrelevant. If if a renewable source is 10x less efficient than non-renewable sources, the key here is NON-RENEWABLE. We've got to take the pressure off of petroleum based fuels until such time as we come up with some alternative system - hydrogen, high-capacity battery storage, etc.
PS. Adding Nobel Prize to someone's argument doesn't have the gravitas as perhaps it once had. I think Linus Pauling and vitamin C diminished that.
Damn you math! PV works just fine. Too bad we don't have a high density mobile energy storage method to compare to liquid oil. When that happens, sub power will rule all.
Basically, [corn] ethanol is obtained from burning methane, coal, diesel fuel, gasoline, corn kernels, soil and environment. We destroy perhaps as many as 7 units of free energy in the environment and human economy to produce 1 unit of free energy as corn ethanol, and make a few clueless environmentalists happier and a few super rich corporations richer. The story is even worse for switchgrass ethanol.
(As quoted from http://www.theoildrum.com/node/9619 )