Apr 21 2014

Not Looking Good for Biofuels

I have yet to be convinced that biofuels will be a significant benefit in our attempts to achieve sustainable energy production. Ideally we would run our civilization on energy that does not burn a limited resource or contribute CO2 or other compounds into the atmosphere. Any limited resource will eventually run out, by definition. Further, no matter what you think about the current effects of climate change, it’s hard to deny that if we continue to pump CO2 into the atmosphere this is likely to be a problem.

Biofuels sound like a good idea at first. Plants get their energy from the sun and fix CO2 from the atmosphere. Because we can grow plants, this is a renewable resource. When we burn fuel made from plants we are releasing the previously captured CO2 back into the atmosphere, and so the process is carbon neutral. Sound pretty good.

However, experts argue that we have to consider in this equation every aspect of the production of biofuels. The equation will change depending on the source of the fuel, and it is possible that if we use the right plant source and have a sufficiently efficient process, then we might have a biofuel with a net benefit. I think we will get there, but even still how much of a benefit is an important question.

In the US, corn stover is a major source of ethanol for biofuel. Corn stover is the parts of the plant left over after the corn itself is harvested – the stalks, leaves, and cobs. A new computer simulation analyses the net carbon effects of either leaving the corn stover in the field vs harvesting the stover, making it into biofuel, and then burning that fuel. Here is a summary of the results:

The researchers, led by assistant professor Adam Liska, used a supercomputer model at UNL’s Holland Computing Center to estimate the effect of residue removal on 128 million acres across 12 Corn Belt states. The team found that removing crop residue from cornfields generates an additional 50 to 70 grams of carbon dioxide per megajoule of biofuel energy produced (a joule is a measure of energy and is roughly equivalent to 1 BTU). Total annual production emissions, averaged over five years, would equal about 100 grams of carbon dioxide per megajoule — which is 7 percent greater than gasoline emissions and 62 grams above the 60 percent reduction in greenhouse gas emissions as required by the 2007 Energy Independence and Security Act.

In other words, making biofuel from the corn stover releases more CO2 into the atmosphere than burning an equivalent (by energy production) amount of gasoline.

The primary negative consequence of making biofuel from corn stover is from removing the stover from the field. If the stover is left in the field then some of the captured carbon will enrich the soil. Messing with the soil tends to release CO2 into the atmosphere. This is also a major problem for tilling soil in the farming process, and why no or low til farming is becoming more popular.

It seems that so far this study has held up to peer review, but of course one study is unlikely to be the final word. Still, it is a serious challenge to the current practice of making ethanol from corn stover.

One potential downside to biofuels (not a factor in the current study) is land use. If we need more farmland to grow crops not for food but for biofuel, then that might also have a net negative effect on CO2 and the environment. That is precisely why corn stover seems like an attractive option – it is using the left-overs of corn growing, and does not require land for itself.

Researchers are looking into other biofuel feedstocks that have optimal features for a net benefit from biofuel production. Any plant that contains cellulose is potentially a feedstock. Wood, for example, could be used (if we had a sufficiently efficient process that could be performed on a large scale and cost effectively). Algae grown in ponds is another option. High energy density perennial crops may also be an option.

Conclusion

Biofuels may ultimately play a role in our sustainable energy future, but I still don’t think it will be a major role. Storing solar energy as cellulose (or any carbohydrate), then making that cellulose into burnable fuel, may simply be too inefficient a process to ever be very useful.

There are other ways to capture solar energy that are likely to be more efficient. Photovoltaic cells capture electricity from sunlight. We can also capture heat from sunshine.

Perhaps the most efficient process may be to use sunlight to cleave hydrogen from water. While hydrogen is not a source of energy, because there is little free hydrogen on the earth, hydrogen is potentially an excellent way to store energy. If we made hydrogen from sunlight and water, then burned the hydrogen for fuel, resulting in water as a waste product, this could be an entirely sustainable and environmentally neutral energy infrastructure.

The hydrogen economy may still be coming (just like Winter in Westeros).

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18 responses so far

18 Responses to “Not Looking Good for Biofuels”

  1. Bronze Dogon 21 Apr 2014 at 12:27 pm

    I still have some hope for biofuels, but I imagine it’ll require a top-down design of the entire process, which might not be so easy if different parts are owned by different companies.

    On hydrogen, I’m still a bit skeptical but hopeful. IIRC, one of the difficult issues with hydrogen is storage and transport. And there’s still that voice in the back of my head saying, “Hindenberg!”

  2. Heptronon 21 Apr 2014 at 1:02 pm

    I also still have hope for biofuels, though it sounds like a new feedstock is needed if corn stover harvesting does more harm than good.

    I always liked the idea that Joule Unlimited (mentioned on the SGU once) put forward where they had a sort of algae solar cell that could be built out in the desert and take in water from waste water treatment plants. (I don’t work for this company, though I did apply there once or twice). It seemed to take care of the land usage issue nicely by using land that would otherwise not be farmed.

    I feel like whatever fuels our vehicles it will have to be made to match the existing infrastructure because to change everything now (gas stations, pipelines, engines, etc…) would be extremely difficult. For that reason I’m not a fan of hydrogen. No offense intended to those out there who support it.

  3. Johnnyon 21 Apr 2014 at 1:50 pm

    Perhaps a stupid question, but could it work to set up huge farms of solar plants in deserts, or desert-like areas? Some of us live in sunlight-challenged places, but it could perhaps still work if a huge farm of solar plants was established in Spain to provide energy for the EU, and perhaps in the US Texas or Arizona could function as a location for that. Maybe in the future the Sahara desert could host a giant solar planet farm to provide for the energy needs of the entire planet.

  4. kaandersonon 21 Apr 2014 at 1:58 pm

    Thanks for sharing this study. I think several important points may have been overlooked in your discussion, so I tracked down the original article and had a look (link below).

    http://www.nature.com/nclimate/journal/vaop/ncurrent/pdf/nclimate2187.pdf

    The first point that should be cleared up is that corn stover isn’t currently being used for biofuels to any great extent. Corn grain is what most ethanol in the Midwest is made out of; many people are excited about using stover and other cellulosic biofuel feedstocks to produce ethonol due to a potential for greater energy returned on energy invested, but the technology isn’t really out there yet.

    Second, I think it’s critical to consider which carbon pool is being used here. In the case of gasoline it’s coming from carbon pools which have been in the ground for millennia and can’t be easily replaced. In the case of corn stover it’s coming from the soil carbon pool, which we’ve been depleting through agriculture and other activities for a long time. We do have the ability to add or replace carbon in this pool. Cover crops(my research area) is one method for doing so which Liska mentions in the article.

    I’ll have to do a bit more reading to make sure I’m getting it right, but I believe that emitting 7% more carbon from a renewable pool would be more responsible than emitting less carbon from a pool that we don’t have the ability to replace. That being said, of course biofuels aren’t a silver bullet and need a lot more development to be sustainable in the long term.

    Thanks for all the work you’re doing,

    Kevin

    PhD student in Applied Plant Sciences at UMN

  5. Heptronon 21 Apr 2014 at 3:02 pm

    @Johnny.

    Not a stupid question. Solar panels in the desert makes sense because of all the sunlight they get, but the catch is that a lot of power consumption happens in the evenings when the sun is fading for the day. Storage of that much electricity would be tough, so it would have to be used at time of production. My hypothetical solution would be to run some sort of transmission lines to another part of the world that is in darkness, like sending power from one side of Europe to the other, or from the US to Europe.
    Because hydrogen is more of a storage medium than a source of energy, others have suggested using solar power at its point of generation to separate water into hydrogen and oxygen. In the evening, the H2 and O2 could be recombined and the heat of reaction could generate electricity at night.

  6. romaimperatoron 21 Apr 2014 at 3:06 pm

    Heptron -

    I think the only way we wouldn’t need to rebuild the entire gasoline-based infrastructure is to continue using gasoline and diesel so I don’t think that says anything about using hydrogen as an energy storage medium specifically. Switching to all electric though means we probably only need new stations.

    Johnny -

    My understanding is the biggest problem with building the power plants far from where it’s used is that a large amount of electricity is wasted in transport as heat. If we had room temperature superconductors though that would be pretty awesome.

  7. zorrobanditoon 21 Apr 2014 at 5:25 pm

    The deserts are not the parking lot wastelands some people imagine. They are valuable and beautiful ecosystems. Covering most or much of them with solar collection panels will destroy many scarce life forms, and most of the ecology, which is very fragile.

    You don’t care so long as you get the energy? How is that different from fracking, which gets petro-chemicals at the cost of the water supply and maybe earthquakes? Or biofuels, which may imperil the food supply? Who cares about clean water, earthquakes or food, so long as we can get our energy “needs” (really, desires) met?

    The desire for energy must be balanced against a lot of other factors.

    We may not be able to have 100% of what we want on all fronts.

  8. petrucioon 22 Apr 2014 at 4:25 am

    Why is sugar cane never mentioned in this post? Why is Brazil the only country that uses it for fuel? The (quick) research I’ve done seemed to indicate that it’s a shitload more efficient than corn to make Ethanol, and so I use it in my own Flex car.

    It seems corn has been shown to be a shitty stock for biofuels, and sugar cane is decent, but sugar cane is tied to Brazil like good board games are tied to Germany… And corn tied to the US.

  9. BBBlueon 22 Apr 2014 at 10:56 am

    It’s one thing to fund or otherwise offer incentives for R&D, but it seems like every time the federal government gets involved in direct payments to encourage a particular behavior or type of business enterprise, unintended consequences prevail and neutralize whatever good intentions there may have been. I don’t think governments should be involved in directly managing economic activity in this way.

    The corn biofuel scheme represented a rare political opportunity; it was a chance to gain support from corn-belt ag interests while enhancing one’s green-tech credentials. Even without Dr. Liska’s work, those political motives alone were reason enough to suspect that the benefits touted originally would never materialize.

  10. BBBlueon 22 Apr 2014 at 11:18 am

    Petrucio-

    I worked on a couple of projects during the 80′s to develop management practices for sweet sorghum (consider it sugar cane for temperate climates) as a potential source of biofuel, but it never caught on because, at best, it was roughly equivalent to corn in terms of biofuel potential, and it isn’t as flexible in terms of multiple uses. I see that Dr. Liska has also been involved in more recent work with that crop. http://bit.ly/RIvzPf

    As for sugar cane, it is essentially a tropical plant. There is some production in Louisiana and Florida, but it is not well adapted to the climate of the corn-belt.

  11. Bruceon 22 Apr 2014 at 11:45 am

    When I was living in Zimbabwe I had a friend who tried to rope me into investing in Jatropha planting for biofuels. I didn’t want to get involved seeing as the use of land was a highly political issue (the plant for food vs fuel debate should really slant towards food when such a high percentage of the population is starving… but the government did not see it that way).

    Just doing a quick search on it now, it seems it is not the great and grand silver bullet it once promised to be either. Fancy that.

    I think chasing biofuels is a waste of time and money and we would be much better off investing in something like the thorium reactors Steve posted a few months ago. Our energy needs are only going to increase and we (currently) have a finite amount of land to use.

  12. colluvialon 22 Apr 2014 at 1:01 pm

    It would be wrong to think of corn stover, or any other crop residue, as a waste product that otherwise has no function. Residues are necessary to maintain soil organic matter. Most agricultural operations have to work hard to maintain organic matter at recommended levels. Soils with low organic matter have reduced infiltration rates, less ability to retain water and nutrients, and they erode more easily.

  13. Bronze Dogon 22 Apr 2014 at 2:21 pm

    I’d also endorse the use of nuclear power, so long as the people who run the power plants are prevented from cutting corners. I don’t know much about the difficulties with developing thorium reactors, but I seem to recall hearing thorium is safer to work with than uranium, because it’s not as eager to go through uncontrolled fission.

  14. tmac57on 22 Apr 2014 at 8:29 pm

    I think some people are missing the point about why biofuels are being pursued so vigorously by researchers. The energy density of the equivalent of gasoline or say,jet fuel,is hard to overcome as an advantage. Therefore,things like jets or or huge cargo ships require high energy density to make them viable. But we must also consider the overall carbon footprint,so this is the ‘nut’ that they are trying to crack.
    We won’t be seeing any thorium jetliners anytime this century as far as I can see.
    But,the failures and problems seen so far with most biofuels, represent the growing pains of discovery and science,and I have no doubt what-so-ever that these early failures can guide us to a viable solution, IF we keep our eye on the goal of a carbon neutral (actually, as low as possible) high energy density,low environmental impact biofuel.
    Believe me,this is being hotly pursued around the world from many angles,not the least of which is from genomic research to genetically engineer plant and bacterial organisms to take advantage of unique properties that can greatly increase the yields of carbohydrates and oils from much smaller land areas,and other lines of research that utilize the ocean and even vertical structures with smaller land area requirements.
    Most of these ideas will fail or be less promising,but that is just how it goes in research,but even failures are platforms for learning,and I see no signs of surrender to pessimism.
    My money is on the researchers and their doggedness to succeed.
    The problem of energy will be solved by many paths for different areas such as electricity for cars,and maybe hydrogen as well.Solar,wind,hydro,geothermal and nuclear for electricity generation. Long haul trucks are trickier,and may require biofuels,and so will air and most sea travel,at least for the seeable future.

  15. Bruceon 23 Apr 2014 at 5:06 am

    tmac,

    I see your point, and while I agree that biofuels might show the best promise for the way we currently fuel our transport (as this seems to be the critical use of these kinds of fuel), I think our efforts would be much better spent trying to find other ways to propel our vehicles.

    As I don’t actually have a solution to that problem, my argument falls apart, so yeah, I guess we are stuck chasing efficient and green biofuels.

  16. tmac57on 23 Apr 2014 at 7:25 pm

    Bruce- In principle I agree that we should find better ways to propel our vehicles. But I don’t see it as an either/or situation. We should,and are,pursuing both pathways,and we should support those efforts that truly show promise,not just wishful thinking greenwashing deadends like corn ethanol for example.
    Chances are that some novel and disruptive technology will shake out from all the diverse research that is now being pursued. That seems to be the nature of discovery.

  17. Bruceon 24 Apr 2014 at 4:20 am

    tmac,

    I can’t argue with that logic. Thanks for you thoughts.

  18. Lukas Xavieron 06 May 2014 at 4:54 pm

    “In other words, making biofuel from the corn stover releases more CO2 into the atmosphere than burning an equivalent (by energy production) amount of gasoline.”

    Does that take into account the emissions of the production of the gasoline as well?

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