Environmental benefit of biofuels is overestimated, new study reveals

[OKIsItJustMe]

http://www.eurekalert.org/pub_releases/2012-06/w-ebo060812.php

[font face=Serif]Public release date: 8-Jun-2012

Contact: Rhea Kressman
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[font size=5]Environmental benefit of biofuels is overestimated, new study reveals[/font]

[font size=3]Two scientists are challenging the currently accepted norms of biofuel production. A commentary published today in GCB Bioenergy reveals that calculations of greenhouse gas (GHGs) emissions from bioenergy production are neglecting crucial information that has led to the overestimation of the benefits of biofuels compared to fossil fuels.

The critique extends to the Life Cycle Analysis models of bioenergy production. Life Cycle Analysis (LCA) is a technique used to measure and compile all factors relating to the production, usage, and disposal of a fuel or product. The authors conclude that LCAs are overestimating the positive aspects of biofuel use versus fossil fuel use by omitting the emission of CO2 by vehicles that use ethanol and biodiesel even when there is no valid justification.

Proponents of bioenergy argue that analyses should always ignore this CO2 because plants grown for biofuel absorb and therefore offset the same amount of carbon that is emitted by refining and combusting the fuel. The commentary critiques this method by arguing that doing so double counts the carbon absorbed by plants when the bioenergy crops are grown on land already used for crop production or already growing other plants because the bioenergy does not necessarily result in additional carbon absorption. Biofuels can only reduce greenhouse gases if they result in additional plant growth, or if they in effect generate additional useable biomass by capturing waste material that would otherwise decompose anyway.

The overestimation of bioenergy LCAs becomes increasingly magnified when the omission of CO2 is combined with the underestimation of nitrogen emissions from fertilizer application. According to lead author Dr. Keith Smith, from the University of Edinburgh, "Emissions of N2O from the soil make a large contribution to the global warming associated with crop production because each kilogram of N2O emitted to the atmosphere has about the same effect as 300kg of CO2." He notes that several current LCAs underestimate the percentage of nitrogen fertilizer application that is actually emitted to the atmosphere as a GHG. The authors claim that the observed increase in atmospheric N2O shows that this percentage is in reality nearly double the values used in the LCAs, which greatly changes their outcome.

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http://dx.doi.org/10.1111/j.1757-1707.2012.01182.x

[caraher]

1. I'm not sure I follow the "double counting" argument

Not counting emissions from burning biofuel seems to make a lot of sense because the crop used to make the fuel drew its carbon from the atmosphere, and burning the fuel simply returns it. I don't believe biofuel advocates are claiming, on top of that, to be sequestering carbon in the biomass of the fuel crops, so where's the double counting? This looks like a straw man argument to me. I'm not aware of anybody who claims biofuel use reduces the amount of CO2 in the atmosphere; at best, it doesn't add to atmospheric carbon (or wouldn't in some ideal case).

The impact of other greenhouse gases is, of course, another story.

[OKIsItJustMe]

2. I think I can explain

[font face=Serif]... The commentary critiques this method by arguing that doing so double counts the carbon absorbed by plants when the bioenergy crops are grown on land already used for crop production or already growing other plants because the bioenergy does not necessarily result in additional carbon absorption. ...[/font]

So, let's say there's a forest growing somewhere, absorbing CO[font size=1]₂[/font]. Now, let's cut down that forest, and grow some crop for biofuel instead.

Is the biofuel carbon neutral?

[kristopher]

3. Some context...

The OP is a part of a continuing discussion within that sector; the article isn't a research piece, it is 'insider' commentary on the nature of the research being done. I've quoted an example paper below that specifically address the issue of land use change, which isn't universally part of the discussion. In spite of awareness of problems with the method, many carbon policy decisions are justified (at least in part) by papers that extrapolate primarily from LCA's of a biofuel's net energy balance compared to fossil fuel carbon content. I believe that is the approach that is being criticized in the OP.

Here is an example of what the discussion referred to looks like:

Biofuels, Land Use Change, and Greenhouse Gas Emissions: Some Unexplored Variables
HYUNGTAE KIM,† SEUNGDO KIM,‡ AND BRUCE E. DALE*,‡
Phillips Academy Andover, 180 Main Street, Andover, Massachusetts 01810, and Department of Chemical Engineering & Materials Science, Michigan State University, East Lansing, Michigan 48824-1226
November 20, 2008.

Abstract:
Greenhouse gas release from land use change (the so- called “carbon debt”) has been identified as a potentially significant contributor to the environmental profile of biofuels. The time required for biofuels to overcome this carbon debt due to land use change and begin providing cumulative greenhouse gas benefits is referred to as the “payback period” and has been estimated to be 100-1000 years depending on the specific ecosystem involved in the land use change event. Two mechanisms for land use change exist: “direct” land use change, in which the land use change occurs as part of a specific supply chain for a specific biofuel production facility, and “indirect” land use change, in which market forces act to produce land use change in land that is not part of a specific biofuel supply chain, including, for example, hypothetical land use change on another continent. Existing land use change studies did not consider many of the potentially important variables that might affect the greenhouse gas emissions of biofuels. We examine here several variables that have not yet been addressed in land use change studies. Our analysis shows that cropping management is a key factor in estimating greenhouse gas emissions associated with land use change. Sustainable cropping management practices (no-till and no-till plus cover crops) reduce the payback period to 3 years for the grassland conversion case and to 14 years for the forest conversion case. It is significant that no-till and cover crop practices also yield higher soil organic carbon (SOC) levels in corn fields derived from former grasslands or forests than the SOC levels that result if these grasslands or forests are allowed to continue undisturbed. The United States currently does not hold any of its domestic industries responsible for its greenhouse gas emissions. Thus the greenhouse gas standards established for renewable fuels such as corn ethanol in the Energy Independence and Security Act (EISA) of 2007 set a higher standard for that industry than for any other domestic industry. Holding domestic industries responsible for the environmental performance of their own supply chain, over which they may exert some control, is perhaps desirable (direct land use change in this case). However, holding domestic industries responsible for greenhouse gas emissions by their competitors worldwide through market forces (via indirect land use change in this case) is fraught with a host of ethical and pragmatic difficulties. Greenhouse gas emissions associated with indirect land use change depend strongly on assumptions regarding social and environmental responsibilities for actions taken, cropping management approaches, and time frames involved, among other issues.


Introduction
Critical political, economic, and environmental security concerns are increasingly linked to petroleum dependence. Thus, finding alternatives to petroleum has become a high priority worldwide. One proposed solution is biofuels: liquid fuels such as ethanol derived from plant biomass. Ethanol from biomass has been viewed as a viable alternative to petroleum in part because of its projected greenhouse gas emission benefits compared to the gasoline fuel system. The United States is expected to produce 136 billion L (36 billion gal) of renewable fuels by 2022, including 79 billion L (21 billion gal) of cellulosic ethanol, and this is expected to reduce greenhouse gas (GHG) emissions by at least 20% in comparison to fossil fuels (1). Approximately 57 billion L (15 billion gal) of ethanol will probably be derived from corn...

[caraher]

4. Thanks

I didn't notice mention of land use changes in the original article. Yes, I sure do see how it makes a difference if you turn forests into "energy crops!"

[huntpeter]

5. reply

Bio fuels are environment friendly fuels. They produce low carbon dioxide gas and other harmful elements. Bio fuel can be produce by recycling of waste products like used oil. There are many recycling and ergonomic equipment are available to produce the bio fuel.