Second-generation biofuels can reduce emissions, study says

January 11, 2016
Plant biology professor Evan DeLucia and co-authors found that the renewable fuel standard's greater emphasis on second-generation biofuel can reduce emissions greatly despite economic considerations. Credit: L. Brian Stauffer

Second-generation biofuel crops like the perennial grasses Miscanthus and switchgrass can efficiently meet emission reduction goals without significantly displacing cropland used for food production, according to a new study. Researchers from the University of Illinois and collaborators published their findings in the inaugural edition of the journal Nature Energy. The researchers call it the most comprehensive study on the subject to date.

The U.S. Environmental Protection Agency's Renewable Fuel Standard sets an annual production goal of 16 billion gallons of second-generation biofuel—fuels from plant stems and leaves rather than from fruit or grains—and 15 billion gallons of ethanol by 2022. The study found that even though previous emission reduction estimates were overly optimistic, meeting the federal biofuels goal will reduce annual U.S. transportation emissions by 7 percent.

"Greenhouse gas savings from bioenergy have come under varying levels of attack, and this paper goes a long way to showing that contrary to what some are saying, these savings can be potentially large if cellulosic biofuels from dedicated energy crops meet a large share of the mandate," said study author Evan DeLucia. "This is a viable path forward to energy security, reducing greenhouse gases and providing a diversified crop portfolio for farmers in the U.S."

Under the rules of the renewable fuel standard, corn can theoretically be reduced as other biofuel production increases, until second-generation biofuels account for the 31-billion-gallon total. If that happened, savings in the transportation sector would go from 7 to 12 percent, according to the researchers.

Second-generation biofuels are much cleaner than corn ethanol thanks to a number of biological characteristics, said DeLucia, a professor of plant biology at the U. of I. In a 2011 study, DeLucia used a model to show what would happen if the land being used to grow corn for ethanol production was instead converted to Miscanthus and switchgrass.

"Our results were staggering," DeLucia said. "Since both of those plants are perennial, you don't till every year, so you release less carbon to the atmosphere. The grasses also require less fertilizer, which is a source of nitrous oxide, and they store more carbon in the ground than corn."

Switching from using 40 percent of the corn crop for ethanol production to using the same land to grow biofuel grasses "changed the entire agricultural Midwest from a net source of greenhouse gas emissions to the atmosphere, to a net sink."

He called the new study an improvement of those findings because it applies realistic, economic constraints to the model. The new study assumes farmers won't take their most productive farmland and use it for bioenergy crops, but they may use low-yielding land—for example, low-quality pastures in the West, which already host perennial grasses.

The new approach addresses a frequent complaint about second-generation bioenergy crops. If biofuel crops replace food crops, the critics argue, farmers around the world would be encouraged to indirectly convert new land into production. The carbon emitted from that process would reduce any savings from greenhouse gas reduction. By changing the land that's being used to grow biofuel crops from cropland to marginal land, the researchers say that the indirect land use change effect becomes very small. However, another economic effect arises involving the global oil market, and could offset a part of the greenhouse gas savings achieved by biofuels.

"Adding these billions of gallons of biofuel to the market could lead to a fall in the price of oil, and that could lead people to drive more. That fuel rebound effect could be significant. It all just depends on how OPEC and the price of oil responds to biofuel, and it's very uncertain," said U. of I. agricultural and consumer economics professor Madhu Khanna, a co-author on the study.

"But even after including all these market effects of biofuels, we found that the standard has substantial potential to reduce from the transportation sector in the U.S.," she added.

By giving second-generation biofuel producers a tax credit, the researchers say corn ethanol could eventually be phased out, because it gives second-generation biofuels an edge.

Before that happens, Khanna said two things need to take place: The market for biofuel needs to grow, meaning the amount of cars that can take high ethanol fuel needs to increase, and biofuel producers need to be certain that the policy will stay intact.

"We need a continuity of policies so that this effort doesn't stop," she said. "A lot of people now are saying the standard isn't delivering the amount of benefits that it should have, but that's all based on corn ethanol. The moral of this whole story is that we need to find a way to expand the production of the second-generation biofuel crops and maybe even displace ."

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

More information: Tara W. Hudiburg et al. Impacts of a 32-billion-gallon bioenergy landscape on land and fossil fuel use in the US, Nature Energy (2016). DOI: 10.1038/nenergy.2015.5

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23 comments

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Eikka
5 / 5 (2) Jan 11, 2016
Wasn't switchgrass a first generation biofuel that was abandoned due to difficulties and lower than predicted yields?

It's similiar to https://en.wikipe...ndinacea which produces about 30 MWh per hectare per season, but the handling and transportation costs turned out too high to be economical.
gkam
1.8 / 5 (5) Jan 11, 2016
You are correct, it was one of the original candidates. We used corn because of Agribusiness and the lobby for Ag subsidies. It was never a good idea. But as you note, the switchgrass route was not yet ready.

I'd like to see the biofuels come from algae or other liquid-based sources. Those facilities can go in almost anywhere.
Eikka
5 / 5 (2) Jan 11, 2016
the switchgrass route was not yet ready.


It's hard to see how it would be ready now, since they're suggesting making ethanol out of it which just adds costs and lowers efficiency. It wasn't economical even when they were just compressing it into bricks and burning it as it is.

The main problem was, that the material is so light (poor energy density) that it doesn't pay to transport it for more than 60 miles. Otherwise you end up spending a significant amount of fuel just to transport the fuel.

The same problem applies to the ethanol producing plant. You can't make use of economies of scale, because you only have what feedstock you can produce locally, and so you can't get enough to run an all-year-round huge processing plant.

Eikka
5 / 5 (2) Jan 11, 2016
Nevermind the fact that distillation and fermentation use up so much energy, you spend 3/4 of a barrel of oil to produce one barrel of bioethanol.
TheGhostofOtto1923
3 / 5 (2) Jan 11, 2016
one of the original candidates... first generation
Uh no it wasnt.

"First generation biofuels are produced directly from food crops. The biofuel is ultimately derived from the starch, sugar, animal fats, and vegetable oil that these crops provide... corn, sugar cane, soybeans, vegetable oil... wheat, sugar beets, rapeseed, peanuts..."

"One of the first inventors... use of ethanol was a German named Nikolaus August Otto. Rudolf Diesel... designed his diesel engine to run in peanut oil and later Henry Ford designed the Model T car which was produced from 1903 to 1926... hemp derived biofuel as fuel.

"Although the USDA ARS location in Lincoln, Nebraska, has been conducting switchgrass... regionally specific biomass energy research has occurred since about 1987 at universities such as Auburn, Virginia Tech, and Texas A&M, interest in switchgrass increased exponentially following this [Bush] Presidential address."
Eikka
3 / 5 (2) Jan 11, 2016
"First generation biofuels are produced directly from food crops.


That's not a very good definition, and generally a bad description of what biofuels are about.

Biofuels aren't necessarily liquid fuels. A log of wood for example can be considered a "0-generation" biofuel because trees have been grown for energy long before the word biofuel was coined, and wood gas was invented well before Rudolf Diesel. In fact, before the invention of the Diesel engine, stationary Otto engines were commonly run on town gas which was generated from anything that burns; coal, wood, bales of hay, old rags... Turpentine was sometimes used as a substitute for whale oil - another biofuel - to power oil lamps etc. etc.

The dictionary definition of biofuel is simply: "a fuel (as wood or ethanol) composed of or produced from biological raw materials"
Eikka
3 / 5 (2) Jan 11, 2016
To put things into perspective: if the yield from a switchgrass field is on the order of 30 MWh per year, then a small thermal powerplant with 300 MW input and 100 MW output would need 87,000 hectares of farmland within 60 mile range to get enough fuel.

Thats 335 square miles.

In other words, even a relatively small powerplant would have to sit in the middle of a field some 18 miles across.
TheGhostofOtto1923
3.7 / 5 (3) Jan 11, 2016
That's not a very good definition, and generally a bad description of what biofuels are about
-And yet if you look up the exact phrase "first generation biofuel" you will find on a number of sites that it is repeated as the standard industry definition.

Give it a try.

Switchgrass is not a food crop but it is a feed crop. But it wasnt on the 1st gen list.
gkam
2 / 5 (4) Jan 11, 2016
In 1980 Melvin Calvin revealed a Brazilian tree which produces when tapped a fuel which can be put directly into a diesel engine.
gkam
2 / 5 (4) Jan 11, 2016
Switchgrass was identified by Melvin Calvin for use by us as a biofuel in 1980 or before.

Which generation was that?
Uncle Ira
3 / 5 (4) Jan 11, 2016
In 1980 Melvin Calvin revealed a Brazilian tree which produces when tapped a fuel which can be put directly into a diesel engine.


Must not have worked to good because nobody is using it much. Not even in Brazil.

Switchgrass was identified by Melvin Calvin for use by us as a biofuel in 1980 or before.


Don't look like that has been so good either. otherwise everybody would be using it too.

Which generation was that?


Skippy, I know you like to fling around the buzzy words and the lingo. So you should know that it ain't that kind of generations they are talking about. Not peoples, not even the ideas about it. First generation biofuels come from FOOD CROPS. Cher you really got to start paying attention more. They just spend four postums each talking about the definition of "first generation biofuels".
david_king
5 / 5 (1) Jan 12, 2016
Camelina Sativa is a very promising oil seed crop that's high in omega-3s and the seed cakes left after oil extraction are around 18% protein so useful as animal feed. It's a crop that can tolerate dry land farming and can be rotated in during 3 seasons in many parts of the country. Unfortunately farmers are very risk averse and processing mills are few and far between.
http://portal.nif...eed.html
gkam
2 / 5 (4) Jan 12, 2016
Biofuels are just that. It does not mean they are made from food crops.
Uncle Ira
3 / 5 (4) Jan 12, 2016
Biofuels are just that.


There you messing up the semantical stuffs again.

It does not mean they are made from food crops.


Cher it really does if you put "1st generation" in front of it.
gkam
2 / 5 (4) Jan 12, 2016
Many of us were looking into this around the time you were born, Ira. Perhaps you are just catching up.
Uncle Ira
3 / 5 (4) Jan 12, 2016
Many of us were looking into this around the time you were born, Ira. Perhaps you are just catching up.


Actually Cher, it looks like I am way ahead of you when it comes to facts and details. (But then I don't rely on my imaginations all the time like you seem to do.) Even though you are winning and beating and besting every day all day,,, you still have about a 95% get it wrong rate.

For most peoples guessing ought to get them a 50/50 right/wrong, but for you it seems like 5/95 right/wrong. (Which is why everybody thinks a talking cypress stump is so much fun, even when he is winning.)
gkam
2 / 5 (4) Jan 12, 2016
No, Ira, you are ahead in silly comments and your on-and-off affectation in goober-speak. Looking up stuff on wiki makes you think you understand what was written, but half the time you are unaware of the implications.

You attack me for being real. You thought I was a phony like many here. Do we have to go into all that again?
Uncle Ira
3 / 5 (4) Jan 12, 2016
Looking up stuff on wiki makes you think you understand what was written, but half the time you are unaware of the implications.


Cher, it is the looking up stuffs that means I am smarter than you. The making up stuffs makes you stupider than me. 1) Because when I look up something that you made up out of thin air, that is something I know but you don't know. 2) I understand the implications of making up stuffs because I don't do it and 3) You are really stupid because after getting caught on the daily basis making up facts you still don't realize the implications.

You attack me for being real.


1) I attack you because you attacked first. 2) Because you get mad when you are caught wrong. and 3) Because you are too stupid to realize you are stupid.

You thought I was a phony like many here.


Right, you are. You are a Skippy who done some small normal things and want us to believe they are great wonderful things. Basically you lie.
gkam
2 / 5 (4) Jan 12, 2016
No, Toots, I did things you did not, and you did not believe. When I proved them, you got mad, and wanted to get even, so you get even in every post.

Pathetic.
TheGhostofOtto1923
3 / 5 (2) Jan 12, 2016
Switchgrass was identified by Melvin Calvin for use by us as a biofuel in 1980 or before.

Which generation was that?
Why dont you look it up like you did with this worthless little tidbit of yours?
Biofuels are just that. It does not mean they are made from food crops
According to you. According to experts who actually know what theyre talking about, it does.

You made up that shit about 1st gen switchgrass just to sound knowledgeable.

Thats how full of shit you are.
david_king
5 / 5 (1) Jan 16, 2016
Wow you guys really advanced the debate there. I learn so much from the comments.
Eikka
5 / 5 (1) Jan 16, 2016
-And yet if you look up the exact phrase "first generation biofuel" you will find on a number of sites that it is repeated as the standard industry definition.


But that's just the popularity fallacy. Just because many people use a term incorrectly doesn't mean it's the right way to use it.

http://biofuel.or...els.html

But, I did exactly as you suggested, and in the very first result found out that these guys include syngas into first generation biofuels, which makes wood gas a first generation biofuel. It's neither a liquid fuel, nor is it made from food crops. They also include biogas derived from waste - same effect.

And switchgrass -was- one of the first things they tried to grow to make first generation biofuels, because it's a weed that grows a massive deep root system that makes it hard to get rid of, it grows everywhere, and is a nuisance otherwise.

Eikka
5 / 5 (1) Jan 16, 2016
You made up that shit about 1st gen switchgrass just to sound knowledgeable.

Thats how full of shit you are.


You're in such a zeal to mock gkam that you fail to notice the one time when he's actually agreeing with reality.

The whole division into first, second, third... generation biofuels is rather arbitrary anyways and there actually isn't a clear definition of what belongs to which. The most concise definition is simply to say that first generation biofuels are made with conventional techniques that have been available since history began: pyrolysis, fermentation, or directly burning stuff.

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