By all accounts, biofuels deliver startlingly modest reductions in greenhouse gases. In a relatively generous assessment of the environmental benefits of ethanol and biodiesel released last year, University of Minnesota researchers credited corn-based ethanol with 12 percent less net greenhouse-gas emissions than gasoline, while finding that soy-based biodiesel emits 41 percent less.
But here's the catch: It takes so much corn to produce a gallon of ethanol, and so much soy to produce a gallon of biodiesel, that the net GHG advantages are likely to be almost nil. The U of Minn researchers write [emphasis mine]:
[I]f one replaced a total of 5 percent of gasoline energy with ethanol energy, greenhouse gas emissions from driving cars would be a bit more than a half percent lower (5 percent times 12 percent).
Whoa. In 2006, U.S. ethanol producers burned through 18 percent of the corn harvest to offset 3 percent of gasoline use. What the Minnesota study is telling us is that we could increase corn ethanol production by two-thirds (to achieve a 5 percent offset) -- burning through 40 percent of the corn crop -- and still only reduce greenhouse gas emissions by just a bit more than a half percent.
By my calculations -- based on 2006 output of 4.8 billion gallons of corn ethanol -- it would take about 8 billion gallons to achieve that 0.5 percent drop in GHG emissions. Ethanol production is subsidized by a dizzying array of public programs; the most direct one is the $0.51 per gallon blender's tax credit for using the stuff.
To gain that razor-thin GHG advantage, the Treasury would be out some $4 billion ($0.51 times 8 billion) per year, just from that one form of public support. This is sound public policy? In a rapidly warming world, dropping $4 billion on corn ethanol seems clinically insane as a strategic use of the public purse.
And -- finally coming to the point of this post -- a new study [PDF] has emerged declaring that even that comically paltry GHG benefit may be spectral. Biofuel use may actually increase GHG emissions.
The study, published in the journal Atmospheric Chemistry and Physics, was performed by American, German, and British researchers, and included the Nobel laureate Paul Crutzen. I have no information on funding.
It claims that biofuel production emits far more nitrous oxide, a greenhouse gas some 296 times more potent than carbon dioxide, than has normally been assumed.
The source is artificial fertilizer, a potent source of nitrogen. When farmers apply it to soil, a certain amount of it -- between 3 percent and 5 percent, according to the study -- enters the atmosphere as nitrous oxide.
In our email exchange, the University of Edinburgh's Keith Smith, one of the study's authors wrote that, "if you increase the inputs of [fertilizer] through expanding biofuel production, you can expect more N2O [nitrous oxide] pro rata."
As a result, corn-based ethanol releases, at worst, 50 percent more GHGs than conventional gasoline, the study concludes. At best, corn ethanol emits 10 percent less GHGs than gasoline, or less than half of the advantage (22 percent) calculated by the U of Minn researchers.
Biodiesel from rapeseed -- the preferred feedstock in Europe -- is even worse, the study says. It releases as much as 70 percent more GHGs than conventional fuel. Ouch.
I asked Smith precisely how his study's methodology differ from that of the U of Minn researchers. He replied:
Assessments like this one you mention are calculating the net gain when the fossil fuel energy needed to produce a biofuel is subtracted from the energy value of the fuel -- as your figures show, 78% (i.e. 100-22%) or 59% (100-41) of the "gain" is cancelled out by these energy costs. Our assessment of the global warming implications is largely additional to these considerations, becasue most assessments hitherto have ignored the N2O emission issue, or only allowed for PART of it -- we have caclculated a bigger percentage conversion of fertiliser N to N2O than previously accepted.
Smith's study claims that cellulosic ethanol made from agricultural "wastes" -- e.g., Archer Daniels Midland's big plan to use "corn stover" -- would "cause unfavourable or low-gain impacts on climate." Cellulosic ethanol from switchgrass and other perennial grasses would be much better, though, the report states.
Even so, as I reported a couple of weeks ago, the USDA -- cellulosic ethanol's research great sponsor -- is becoming increasingly dubious about the viability of cellulosic technology.
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Comments
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GreyFlcn Posted 6:56 am
25 Sep 2007
I'd look more towards these studies which focus on the N2O aspect (Which the Federal Studies practically ignore)
http://greyfalcon.net/lcarough7.png
http://greyfalcon.net/n2o.png
http://greyfalcon.net/n2ostudy.png
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Then you get in to the indirect emissions caused by palm oil, and soybeans. (And corn)
http://greyfalcon.net/soy
http://greyfalcon.net/palmoil
http://greyfalcon.net/soy2
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GreyFlcn Posted 6:57 am
25 Sep 2007
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Erik Hoffner Posted 7:06 am
25 Sep 2007
The Orion Grassroots Network: 1,100+ grassroots groups working for conservation & more
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GreyFlcn Posted 7:47 am
25 Sep 2007
Considering the DAMAGE causes by all the other biofuels, I'd prefer we swear off it entirely, rather than quible over the merit of a few drops.
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That said, this particular study does let elephant grass (mithcansus) off the hook.
Catch being, as Tom mentioned, Cellulosic stuff is pretty unlikely any time soon.
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That said, another scary thing about Algae.
ONLY if it is grown in an enclosed area, with intensive water recycling, would it not be a problem.
If it was open pond growth, not only would the algae strains get infected with other varieties of algae. But it would require tons of water due to evaporation, and it would result in tons of N2O emissions.
Catch there being that scaling up enclosed algae in a cost competative manner is also highly unlikely.
http://greyfalcon.net/algae
http://greyfalcon.net/algae2
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When it all comes down to it, Photosynthesis is a very inefficient way to harvest sunlight as energy.
http://greyfalcon.net/sugarsolar
http://greyfalcon.net/ethanol.png
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justlou Posted 8:23 am
25 Sep 2007
We are pulling our collective paddle through the water without actually moving the boat forward. The evidence is showing that we are moving backwards and drifting downstream toward the falls. But proponents will tell us the scenery is still looking good.
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Erik Hoffner Posted 9:28 am
25 Sep 2007
The Orion Grassroots Network: 1,100+ grassroots groups working for conservation & more
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Biodiversivist Posted 9:36 am
25 Sep 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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Biodiversivist Posted 10:56 am
25 Sep 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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GreyFlcn Posted 11:19 am
25 Sep 2007
Perhaps, but you have to take in the "aggregate effect" of it.
We would have less greenhouse emissions total if we swore off biofuels entirely.
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That said, thats not entirely going to happen anyways.
But consider this, we could save 3% of our fuel use merely by inflating our tires better.
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GreyFlcn Posted 11:24 am
25 Sep 2007
For instance as lubrication grease.
http://www.soynewuses.org/ProductsGuide/Industrial_Indust ...
Or better yet, having it run an electricity turbine at more than double the energy efficiency.
http://greyfalcon.net/biodiesel.png
http://media.cleantech.com/376/chevron-turning-california ...
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Erik Hoffner Posted 11:38 am
25 Sep 2007
And just in this area, it's common knowledge that restaurants flush their fryer fat down the drain rather than pay to have it collected. It's a huge problem for wastewater treatment plants, as oil is tough to deal with. So I think we could do a much better job of collecting what's out there.
The Orion Grassroots Network: 1,100+ grassroots groups working for conservation & more
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GreyFlcn Posted 11:52 am
25 Sep 2007
It's becoming manditory for new diesel vehicles to have particulate filters. And there's a retrofit program which offers free federal funding for particulate filters on school buses.
That said, that NOx you are talking about, creates Ozone. Which is a primary component of Smog formation. And a greenhouse gas itself.
_
Frankly if we're talking school bus fleet vehicles. The best thing they could do is to convert them to run on natural gas.
It's cheaper, cleaner, and has the lowest greenhouse emissions.
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Erik Hoffner Posted 12:57 pm
25 Sep 2007
But you can't say that diesel has no sulfur in it. Right now Low Sulfur Diesel is on the market, and there are regs coming down mandating Ultra Low Sulfur Diesel for most engines by 2010. But some of the biggest end-users won't even be required to sell it:
Although ULSD fuel will be the dominant highway diesel fuel produced, EPA does not require service stations and truck stops to sell ULSD fuel. Therefore, it is possible that ULSD fuel might not be available initially at every service station or truck stop and that a diesel retailer may choose to sell Low Sulfur Diesel fuel instead of ULSD fuel. The industries involved in the transition are doing all they can to minimize potential inconveniences during the conversion to the new diesel fuel. -Clean Diesel Fuel Alliance website
By contrast, biodiesel contains no sulfur at all. It's cleaner in every category but NOx.
Erik
The Orion Grassroots Network: 1,100+ grassroots groups working for conservation & more
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Rural Populist Posted 2:39 pm
25 Sep 2007
I wonder just how much the U.S. military contributes to global warming with all of their antics designed to make the world safe for oil exploration.
Also, Tom, your headline (Biofuel: Is it a greenhouse gas, gas, gas?) is a bit sweeping. Perhaps "Corn Ethanol: Is it a greenhouse gas, gas, gas?" would be more appropriate.
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GreyFlcn Posted 2:50 pm
25 Sep 2007
It's not that un-sweeping though.
Practically the only biofuels which survive are:
Cellulosic High Growth Grass
Cellulosic High Growth Trees
Theoretically, enclosed Algae production
Waste vegetable oil, etc
Waste paper mill pulp, etc
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So something along the lines of 99% of all biofuels produced today are bad.
So I guess thats not "all biofuels".
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Biodiversivist Posted 2:51 pm
25 Sep 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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GreyFlcn Posted 2:59 pm
25 Sep 2007
The study gives it a slight net positive.
Although thats only in direct emissions.
If you factor in INDIRECT emissions then it's absolutely horrible.
http://greyfalcon.net/palmoil
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As for the ULSD aspect, it's a bit more complex than that.
Over 80% of diesel fuel must be ULSD.
http://www.clean-diesel.org/highway.html
And it's a federal crime to sell the old type of diesel to cars with a model year 2007 or newer.
http://www.clean-diesel.org/images/DPLabelFacts121406.pdf ...
It's a bit more than "completely optional"
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biofuelsimon Posted 11:56 pm
25 Sep 2007
That doesn't apply to all biofuels, but when the volume of corn needed to produce a tank of gas could feed a man for a year, you have to wonder where people's priorities are...
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Biodiversivist Posted 1:22 am
26 Sep 2007
In the end, it all comes down to biodiversity. Poison Darts--Protecting the biodiversity of our world
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bryankwalton Posted 1:33 am
26 Sep 2007
We should be promoting efficiency.
And we should be taxing the hell out of fuel. Until we make fuel more expensive so that we have a disincentive to drive more, we will never fix the problem. We need a steep gas tax.
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wyrick Posted 1:42 am
26 Sep 2007
The hardest part of changing to renewable fuels is not technology, but mindsets of the public at large. Technology and research will keep advancing even in the extremely complex topic of life cycle GHG emission analysis. The use of any alternative to petroleum at this point is as much about changing status quo as it is the new technology.
The elephant in every room regarding energy use is efficiency. It's not the most glamorous solution but it is the cheapest, cleanest, and most immediately available option we have.
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Jon Rynn Posted 2:00 am
26 Sep 2007
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GreyFlcn Posted 2:00 am
26 Sep 2007
No. It's not "marginal gains".
It's "significant losses" in the best case.
It's "HUGE losses" in the worst case.
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And yes, if you take coal-to-liquids, hydrogen, and biofuels out of the equation, then it's ALL about energy efficiency.
_
Switching fuel types at that point is merely for compatibility purposes.
Conventional Engine, 20% energy efficiency
Diesel Engine, 40% energy efficiency
Gasoline-Hybrid Engine, ~50% energy efficiency
HCCI Engine, ~55% energy efficiency
Electric Engine, 80-90% energy efficiency
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Jon Rynn Posted 2:39 am
26 Sep 2007
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GreyFlcn Posted 3:34 am
27 Sep 2007
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Meagan Posted 10:24 pm
01 Oct 2007
You mut be the change you wish to see in the world. -Mahatma Gandhi
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vortex Posted 11:51 pm
01 Oct 2007
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Philip S Wenz Posted 8:51 am
19 Nov 2007
Say you weigh 125 pounds and your two kids combined weigh 75 pounds, so your car's human cargo is 200 pounds. But the car weighs, say, 4,000 pounds. When you're going down the road, 5% of the fuel burned is moving your family, 95% is moving the car!
The ratio can get a little better, but I doubt that any people-to-car weight ratio could get better than 25/75. What we need is public transportation -- more people, less vehicle.
Philip S. Wenz, Editor, Ecotecture.com
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