Biofuels vs. Biodiversity and the Need to Think Beyond Carbon Neutral

Seminar given at the University of Michigan, Thursday, February 8, 2018, as part of the 2016-2018 "Beyond Carbon Neutral" seminar series.

Download the presentation slides [PDF]

ABSTRACT

Just over a decade ago, policymakers gave a big boost to biofuels through the Renewable Fuel Standard (RFS) and similar policies. These policies included sustainability provisions for protecting sensitive lands; the intent was to spur the production of advanced biofuels that would be sustainable in many ways including low CO2 emissions. Now, new studies appear each year revealing the destruction of diverse habitats as biofuel production amplifies the global demand for land. There have also been multiple bankruptcies of highly-subsidized advanced biofuel operations. What went wrong and how can we find a better path forward?

Carbon balance effects of biofuel expansion

The 4th biennial America's Grasslands Conference organized by the National Wildlife Federation was held in Fort Worth, Texas, on 14-16 November 2017. What follows is the narrative with key slides from my presentation in the session on "The Ethanol Mandate as a Driver of Land Conversion and Carbon Emissions." 

I imagine that you have often heard that ethanol and other biofuels are "clean and green" compared to ordinary gasoline. Even if not perfect, aren't biofuels better than petroleum because they recycle carbon from the atmosphere instead of getting it from under the ground? That makes them inherently carbon neutral, many people believe.

Unfortunately, that belief is quite misleading. Take, for instance, the claim that corn ethanol reduces greenhouse gas emissions by 43% compared to gasoline, as given by a recent USDA study (which is critiqued here). That value is based on computer modeling and the assumption that biofuels fully recycle carbon is hard-coded into the model. However, when using field data to evaluate how much CO2 is actually recycled, it turns out that such modeling is off base, and not by just a small amount. In fact, biofuels fall so far short of being truly carbon neutral that they cause higher rather than lower CO2 emissions than petroleum fuels.

A new and deeper wrinkle in the biofuel debate

Two short articles just published by the journal Climatic Change highlight the divide in scientific thinking about the effect of biofuels on CO2 emissions. A commentary by Robb De Kleine and colleagues at Ford Motor Company criticizes a paper on the topic published last year by myself and colleagues at the University of Michigan. My response to their commentary explains why I believe that our approach is correct, in contrast to the established lifecycle analysis method that our critics say is the best way to address the question.

Cropland adjoining patches of forest. All arable land
removes carbon from the atmosphere at varying rates. 

This quarrel reflects a new stage in the long-running debate because it does not involve disputes about net energy use or even the food-versus-fuel and land-use change issues raised over the past decade. It is instead a disagreement about the core assumptions to use when examining the question, particularly whether or not biofuels should be treated as inherently carbon neutral. That's the assumption that the CO2 emitted when biofuels are burned does not count because it is biogenic, i.e., newly removed from the atmosphere when feedstocks are grown. My work challenges this assumption, showing that it only holds under certain conditions. De Kleine and colleagues defend the assumption, arguing that it is true unconditionally.

The disagreement is not merely academic. Because new oil production technologies have expanded the supply of economically attractive fossil-based liquid fuels, the business case for biofuels rests increasingly on their value for mitigating CO2 emissions. The stakes are high for both the biofuels industry and for policies to address global warming.

A to-the-point radio interview on biofuels and climate

As a guest yesterday on the WEMU (89.1 FM from Eastern Michigan University) "Issues of the Environment" segment, I answered host David Fair's questions about how our recent work differed from the established lifecycle analysis methods used to analyze the greenhouse gas emissions impacts of biofuels.

The resulting interview has great questions from David and clear explanations from myself about why the results of government modeling of the issue are misleading and why, as far as climate is concerned, it's better to repeal biofuel policies and focus on reforestation and other ways to remove carbon from the air and sequester it on land.

Morning Edition: Issues of the Environment 

U-M Researcher Calls For End To Current Biofuel Policy In The U.S.

http://wemu.org/post/issues-environment-u-m-researcher-calls-end-current-biofuel-policy-us

By DAVID FAIR • WEDS 01 FEB 2017

In August of 2016,  University of Michigan Energy Institute scientists, led by John DeCicco, released an 8-year study.  It estimated powering an American vehicle with ethanol made from corn increased carbon pollution more than using gasoline.  In this week's "Issues of the Environment,” David Fair talks with Professor DeCicco about the findings and what it means to future policy. 

IMAGE CREDIT: DREW FROM ZHRODAGUE / FLICKR.COM

Listen Here [10:09 mp3 link] 

Separating fact from fiction in the newest U.S. federal ethanol study

Debates about the merits of biofuels have been going on for at least a generation. My favorite clip from the early, oil-crisis era ethanol push was Nicholas Wade’s article, "Oil pinch stirs dreams of moonshine travel," published by Science in June 1979. Save for one topic, the terms of the debate — the costs of producing biofuels, whether ethanol took more energy to make than it delivered, the extent to which it really helps energy security, the hope for cellulosic biofuels and the food-versus-fuel dilemma — were the same nearly forty years ago as they are today.

Global warming is the topic not on the table then that is so important now. The effect of biofuels on greenhouse gas (GHG) emissions is the focus of many recent studies. To compare fuels according to their GHG impact, policymakers have adopted a form of computer modeling known as lifecycle analysis (LCA). A new report from the U.S. Department of Agriculture (USDA) is the latest LCA study to claim significant GHG reductions from the use of corn-based ethanol, concluding that it has net GHG emissions 43 percent lower than those of petroleum gasoline. Those results are similar to the findings of lifecycle modeling from Argonne National Laboratory (ANL), on which this latest USDA study heavily relies.

My own work has long come to an opposite conclusion. It shows that the use of biofuels (both ethanol and biodiesel) makes GHG emissions worse that they would otherwise be. This finding is not based on computer modeling, but relies instead on field data to assess the real-world CO2 flows involved when substituting biofuel for fossil fuel.

A simple comparison of ABC to LCA results for corn ethanol

Our recent paper [1] provides an example that compares annual basis carbon (ABC) accounting results to typical lifecycle analysis (LCA) results for corn ethanol. As noted in the paper's discussion section, we used the same process GHG emissions as used in a standard LCA but then adjusted for the fact that biofuel combustion is not fully carbon neutral, as LCA assumes. The implication is then that corn ethanol is 27% more carbon intensive than gasoline instead of 44% less carbon intensive as was claimed by the LCA previously published by Wang et al [2]. This post describes how we made that comparison.

Carbon balance effects of real-world biofuel use

Most of the debate about the environmental merits of biofuel use has been based on lifecycle analysis (LCA). Also known as life-cycle assessment, carbon footprint analysis, "cradle-to-grave" analysis, or (in the case of motor fuels) "well-to-wheels" analysis, LCA is a method for adding up all of the impacts of interest associated with a product. It includes the effects of producing a product and its component materials, associated shipping and packaging effects (as relevant), the use of the product and any related disposal effects. For assessing climatic impacts, LCA tallies the greenhouse gas (GHG) emissions associated with the production, use and disposal of the product. When the product is a motor fuel, the numerical result of such LCA modeling is called the fuel's "carbon intensity," as calculated for California's Low-Carbon Fuel Standard (LCFS), for example.

A cornfield does not absorb CO2 from the atmosphere
any more quickly when it is used to make ethanol than
when it is grown for food or feed. This basic fact of 
carbon mass balance is ignored by the lifecycle studies
that claim climate benefits for biofuels. 

The question, "how does the overall emissions impact of using a biofuel such as ethanol compare to that of a fossil fuel such as gasoline?" seems straightforward, and sounds like something that LCA can answer. However, that question is actually ill-posed scientifically speaking. In other words, when one looks carefully at what actually happens when a given biofuel substitutes for a fossil fuel, it turns out that LCA cannot give a straightforward, unambiguous answer. Properly qualified, the answer will always be, "it depends." And it doesn't just depend on the particular fuel and how it is produced; it also depends on the design of the LCA model and the assumptions it invokes.

Questions and responses on RFS testimony

House Science Committee Hearing on the RFS, November 3, 2015
(photo credit: Michael A. Waring) 

Following the recent hearing on the Renewable Fuel Standard (RFS) held by the House Science Committee, the subcommittee chairs asked me to respond to some questions for the record, following up on my testimony at the hearing. Here are the questions and an abbreviated version of the answers, summarizing my full written response. 

In his testimony, Mr. Coleman referenced cellulosic ethanol that is "129 times better than gasoline on carbon emissions." Based on your research, is this a reasonable claim?

No, that is not a reasonable claim. Such assertions are based on paper studies of hypothetical ethanol production methods. There is indeed a literature on the subject that applies lifecycle analysis (LCA) to proposed cellulosic ethanol production methods and projects that the resulting systems would not only fully offset tailpipe CO₂ emissions but also offset other CO₂ emissions such as those from fossil-based electricity generation.

However, as pointed out in my testimony (and in papers explained elsewhere on this blog), the LCA methods used to justify such claims are scientifically incorrect. Moreover, the cellulosic processing methods involved remain speculative as far as any meaningful commercial-scale operation is concerned. In short, claims of biofuels that achieve a more than 100% reduction in carbon emissions are rooted in flawed analysis of fantasy fuels. 

Testimony on the RFS

Here's my statement at today's House hearing on the RFS; see links at the end to access the written testimony and related videos. 

My research shows that the Renewable Fuel Standard, or RFS, has been harmful to the environment from its inception. Now, ten years after the 2005 Energy Policy Act, the program has resulted in higher CO2 emissions than would have occurred otherwise. It also harms the environment in other ways. Sadly, the adverse impacts of the RFS have grown worse since it was expanded by Energy Independence and Security Act (EISA) of 2007.

The notion that renewable fuels readily reduce CO2 is based on a scientifically incorrect understanding of carbon neutrality. Only under certain conditions does substituting a biofuel for a fossil fuel neutralize the CO2 leaving the tailpipe. For that to occur, harvesting the feedstock must significantly increase how rapidly cropland absorbs CO2 from the atmosphere on a net basis. That condition is not met for the corn ethanol mandated by the RFS. It might be satisfied for cellulosic feedstocks, but once properly evaluated, the gains may not be as great as advocates assume.

Thinking Beyond Carbon Neutral

Global climate change is a defining challenge of the 21st century and efforts to address it have many dimensions. Reducing greenhouse gas (GHG) emissions through higher energy efficiency, using solar, wind and nuclear energy, deploying carbon capture and storage (CCS), reducing deforestation, reducing methane emissions and minimizing other causes of excessive radiative forcing are all important. No one option will suffice and it is crucial to integrate technology solutions with policy drivers.

Because the carbon dioxide (CO2) emitted by fossil fuel use is the largest source of anthropogenic GHG emissions, the climate challenge is often characterized as the need to "decarbonize" the economy by eliminating fossil fuels. However, carbon is literally the fuel of life; the natural carbon cycle annually circulates twenty times as much carbon as released from fossil fuels and the majority is biogenic carbon fixed through photosynthesis. Although rapid release of fossil carbon is the primary cause of rising atmospheric CO2 concentrations, the real problem is an imbalance in the carbon cycle rather than fossil fuel use per se. Thus, the real need is to bring the carbon cycle into balance and eventually restore a global net carbon sink.

The mistaken modeling behind biofuel boosters' emissions claims

Arguments about the pros and cons of biofuels such as ethanol have gone on for many years. The latest debates pertain to whether proposals to limit the ramp-up of the Renewable Fuel Standard (RFS) would result in higher or lower emissions of carbon dioxide (CO2) and other climate-disrupting greenhouse gases.

This week Environmental Protective Agency (EPA ) Administrator Gina McCarthy tweeted the benefits of biofuels: 

and signaled the agency's intent to further raise the RFS volumetric mandate: 

At the crux of the issue is the ability to determine the “carbon footprint” of biofuels using computer models. These models, such as the GREET model developed by Argonne National Laboratory in Illinois, use what are known as lifecycle assessment techniques that claim to account for all of the emissions associated with producing and using a fuel. GREET modeling is the basis for assertions by BIO (the Biotechnology Industry Organization) that the RFS has reduced carbon emissions since it was passed in 2005. It is also the basis for the recent University of Illinois statement that the proposed RFS limits would increase CO2 emissions as much as putting nearly one million more cars on the road. 

Scrutinizing the logic on biofuels

This post picks up a thread based on comments that Prof. Robert Brown and Prof. Bruce Dale made on my "Don't pitch low-carbon fuel ..." post. Both Robert and Bruce take strong exception to my analysis. They invoke the commonly made assumption that substituting a biofuel for a fossil fuel reduces net CO₂ emissions because biofuel use recycles carbon while fossil fuel use does not.

This widely used view of the biofuel lifecycle does not tell
the whole story.  [Image credit: www.EthanolRFA.org] 

Their argument is based on the following logic:

(1) Fossil fuels send old carbon on a one-way trip to the atmosphere, thereby increasing the amount of CO₂ in the atmosphere.

(2) Biofuels use carbon recently taken from the air that is then released back to the air, resulting in no net change in the amount of CO₂ in the atmosphere.

(3) Therefore, substituting a biofuel for a fossil fuel reduces the rate of CO₂ buildup in the atmosphere.

Although this basic analysis neglects processing emissions, we can leave those aside for the purpose of this discussion. They are not what's at the heart of the disagreement, and in any case processing emissions do get tracked by lifecycle models, e.g., as used in the RFS and LCFS. 

LCFS: some early history of the concept

The idea of regulating transportation fuels through lifecycle analysis (LCA) has now become widely accepted; it is the basis for California's low-carbon fuel standard (LCFS) as well as provisions of the renewable fuel standard (RFS) and other policies. Although my recent work criticizes the use of LCA to define policy, this disapproval reflects a major change of perspective from 15-20 years ago. Back then I was among the first to propose that LCA -- or "full fuel cycle" (FFC) analysis as we termed it -- would be a great way to regulate motor fuels in terms of GHG emissions. 

The LCA script

Lifecycle analysis (LCA) is a very popular form of environmental assessment. A good number of academics and others assert that it is the ideal way to examine greenhouse gas emissions impacts and so advocate LCA as a way to compute "carbon footprints."

This view has come to dominate energy policy discussions of ways to reduce GHG emissions from transportation fuels. In particular, nearly everyone involved in the issue says that biofuels should be evaluated according to their full lifecycle impacts. As the major UNEP report on Assessing Biofuels puts it, "Environmental and social impacts need to be assessed throughout the entire life-cycle."

However, biofuel LCA has become ever more complex and has resulted in models that are no longer even close to being scientifically verifiable. Therefore, no amount of new data that one puts into a lifecycle study can put an end to the disputes over LCA-based estimates of the net GHG impact of biofuels. This argument is made in the paper "Biofuels and Carbon Management" Climatic Change (2012), which then proposes a different approach to analysis.