Biofuels increase, rather than decrease, heat-trapping carbon dioxide emissions: study

August 25, 2016, University of Michigan
Ball-and-stick model of carbon dioxide. Credit: Wikipedia

A new study from University of Michigan researchers challenges the widely held assumption that biofuels such as ethanol and biodiesel are inherently carbon neutral.

Contrary to popular belief, the heat-trapping gas emitted when biofuels are burned is not fully balanced by the CO2 uptake that occurs as the plants grow, according to a study by research professor John DeCicco and co-authors at the U-M Energy Institute.

The study, based on U.S. Department of Agriculture crop-production data, shows that during the period when U.S. biofuel production rapidly ramped up, the increased dioxide uptake by the crops was only enough to offset 37 percent of the CO2 emissions due to biofuel combustion.

The researchers conclude that rising biofuel use has been associated with a net increase—rather than a net decrease, as many have claimed—in the that cause global warming. The findings are scheduled to be published online Aug. 25 in the journal Climatic Change.

"This is the first study to carefully examine the carbon on farmland when biofuels are grown, instead of just making assumptions about it," DeCicco said. "When you look at what's actually happening on the land, you find that not enough carbon is being removed from the atmosphere to balance what's coming out of the tailpipe."

The use of biofuels to displace petroleum has expanded over the last decade in response to policies, such as the U.S. Renewable Fuel Standard, that promote their use for transportation. Consumption of liquid biofuels—mainly corn ethanol and biodiesel—has grown in the United States from 4.2 billion gallons in 2005 to 14.6 billion gallons in 2013.

The environmental justification rests on the assumption that biofuels, as renewable alternatives to fossil fuels, are inherently carbon neutral because the carbon dioxide released when they are burned was derived from CO2 that the growing corn or soybean plants pulled from the atmosphere through photosynthesis.

That assumption is embedded in the carbon footprint models used to justify and administer policies such as the federal RFS and the California Low-Carbon Fuel Standard. The models, which are based on a technique called lifecycle analysis, have often found that crop-based biofuels offer at least modest net greenhouse gas reductions relative to petroleum fuels.

Instead of modeling the emissions, DeCicco and his colleagues analyzed real-world data on crop production, biofuel production, fossil fuel production and vehicle emissions—without presuming that that biofuels are carbon neutral. Their empirical work reached a striking conclusion.

"When it comes to the emissions that cause , it turns out that biofuels are worse than gasoline," DeCicco said. "So the underpinnings of policies used to promote biofuels for reasons of climate have now been proven to be scientifically incorrect.

"Policymakers should reconsider their support for biofuels. This issue has been debated for many years. What's new here is that hard data, straight from America's croplands, now confirm the worst fears about the harm that biofuels do to the planet."

The Climatic Change paper is titled "Carbon balance effects of U.S. production and use."

Explore further: Time to rethink misguided policies that promote biofuels to protect climate

More information: John M. DeCicco et al, Carbon balance effects of U.S. biofuel production and use, Climatic Change (2016). DOI: 10.1007/s10584-016-1764-4

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14 comments

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Tenstats
2.3 / 5 (3) Aug 25, 2016
Yup. Don't assume away stuff, use the data. If data is lacking, first try to fill in the blanks. If not, state your assumptions, explain why they were made, and point out the pitfalls of using them.
tinitus
Aug 25, 2016
This comment has been removed by a moderator.
tinitus
Aug 25, 2016
This comment has been removed by a moderator.
Eikka
4.2 / 5 (5) Aug 25, 2016
The reason is simple: farming runs on fossil fuels in the first place. Especially corn and soy bean oil rely on fertilizers made from natural gas, and by no means are the tractors and farm equipment, or the rest of the logistics and processing, running on the biofuel because it's far too valuable to "waste" that way.

The biofuels have an EROEI barely above 1 to start with, and if you converted eg. the soy oil into electricity to power the factory, the whole process would become energy negative.

It's been known for a long time that for every barrel of corn ethanol, about 0.73 barrels of oil (equivalent) is consumed but the rationale has always been that the whole process at least emits somewhat less CO2 than burning the oil.

Trick is, you wouldn't have to burn so much oil if you didn't try to produce the ethanol. It's like buying 3 candy bars to get one free. How much did you save? Nothing, because you were only going to buy one in the beginning.

antialias_physorg
3 / 5 (2) Aug 26, 2016
Biofuels really should only be a stop-gap measure for those areas that cannot (yet) be converted - like heavy duty/agricultural/shipping operations. Possibly as a backup reservoir in case energy production from renewables is low on a particular day.

But the focus of research should shift away from them as soon as possible to get better (liquid) battery storage systems going.
antigoracle
2 / 5 (4) Aug 26, 2016
Oh the "genius" of the AGW Cult. Burn fossil fuels to grow and convert FOOD into fuel.
We are saved, hallelujah!
MR166
3.7 / 5 (3) Aug 26, 2016
"Biofuels really should only be a stop-gap measure for those areas that cannot (yet) be converted - like heavy duty/agricultural/shipping operations"

Well first of all they were purported to be the saviour of the world by the same 97% that approve of the AGW theory weren't they.

The truth is that the members of the AGW movement are little more than a sectarian religious cult masquerading as cutting edge science.

dustywells
1 / 5 (1) Aug 28, 2016
Does it really matter if we burn fossil fuel or biofuel? Internal combustion engines produce toxins much worse than CO2 only in smaller quantities. To begin to clean up the atmosphere we must first get rid of ICEs.
leetennant
5 / 5 (2) Aug 28, 2016
"challenges the widely held assumption that biofuels such as ethanol and biodiesel are inherently carbon neutral."

Was such an inherently counterintuitive position really "widely held"? Biofuels were also a terrible idea for multiple reasons, not the least of which is a misallocation of agricultural land and water. And how could that ever be "carbon neutral".
Colbourne
1 / 5 (1) Aug 29, 2016
The figures given are probably accurate for current bio-fuels but they do not need to be the case for future bio-fuels. Choose crops that do not need fertilizer and restrict the use of fossil fuels to power farm machinery and processing and we should see a good result. I accept that not all "Green" ideas are good for the environment e.g. solar cells if they do not produce more power than was consummed in their manufacturer.
antialias_physorg
not rated yet Aug 29, 2016
Does it really matter if we burn fossil fuel or biofuel?

According to the article
, the increased carbon dioxide uptake by the crops was only enough to offset 37 percent of the CO2 emissions due to biofuel combustion.


So yes, it does. Biofuels aren't good by any metric. But fossil fuels are way worse.

To begin to clean up the atmosphere we must first get rid of ICEs.

Easier said than done. For personal transport that seems doable almost immediately. For heavy duty applications/shipping there's still some groundwork to be done.
geokstr
1 / 5 (1) Aug 29, 2016
There isn't enough biomass to replace 30% of our petroleum use.


There is an obvious answer that will appeal to our Marxist/socialist/totalitarian/fascist (but I quadpeat(tm) myself) betters. They can, as they always do when they seize power, commit mass genocide on a grand scale, through their usual methods; starvation and execution, plus the nomenklatura could mandate assisted suicide at a certain age for the lumpenproletariat. That will reduce the population and also lower the demand for energy - a twofer. Then they use the bodies as the new biomass, and call it ...

Soylent Black.

I expect the usual Warmists here to pick up the idea and run with it.
dustywells
not rated yet Aug 29, 2016
, the increased carbon dioxide uptake by the crops was only enough to offset 37 percent of the CO2 emissions due to biofuel combustion.
So yes, it does. Biofuels aren't good by any metric. But fossil fuels are way worse.
So the only real difference is 37% less CO2 that enters the atmosphere at one end while food production suffers and more food must be imported by using FF and emitting much more CO2 resulting in higher food prices at the stores. All while we conveniently avoid mentioning all the other toxic byproducts of internal combustion engines which are produced by biofuel and FF alike.
leetennant
not rated yet Aug 29, 2016
There isn't enough biomass to replace 30% of our petroleum use.


There is an obvious answer that will appeal to our Marxist/socialist/totalitarian/fascist (but I quadpeat(tm) myself) betters. They can, as they always do when they seize power, commit mass genocide on a grand scale, through their usual methods; starvation and execution, plus the nomenklatura could mandate assisted suicide at a certain age for the lumpenproletariat. That will reduce the population and also lower the demand for energy - a twofer. Then they use the bodies as the new biomass, and call it ...

Soylent Black.

I expect the usual Warmists here to pick up the idea and run with it.


Yes, pricing externalities and increasing corporate regulation to prevent pollution is akin to genocide. I hate to think what you believe preventing nuclear power plants from dumping radioactive material into water sources is akin to. Cannibalism?

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