Cellulosic ethanol's highly subsidized failure

Actual U.S. production of cellulosic ethanol and other cellulosic liquids compared to the targets for cellulosic biofuels specified in the Renewable Fuel Standard

Cellulosic ethanol, once a great green hope for cutting petroleum use and CO2 emissions, has been a bust. The chart above compares the volume of cellulose-based liquid biofuels (largely ethanol) actually used in the United States to the targets for such fuels set by Congress when it expanded the Renewable Fuel Standard (RFS) in 2007. Note the logarithmic scale on the vertical axis; the gap between promise and reality is so large that actual production would be barely visible on a linear scale. 

The fuel has been delivered at levels of no more than about 0.1% of (three orders of magnitude less than) the volumes on which the RFS was premised [1]. This chart does not include cellulosic biogas, which EPA re-classified to qualify for RFS compliance purposes and has seen recent production of around 500 million ethanol-equivalent gallons. However, such "renewable natural gas" is not in the spirit of the law, which envisioned liquid biofuels that could be readily used in motor vehicles. The 2019 RFS target for cellulosic biofuels was 8.5 billion gallons, set to reach 16 billion gallons by 2022. But in 2019, before the pandemic-related drop-off in 2020 for nearly all forms of energy, only 9.8 million gallons of cellulosic ethanol were tallied by EPA.  

Breaking down biofuels analysis

Debates about the merits of biofuels have gone on for at least a generation. Over time, one might think that the accumulation of data would resolve key issues, especially those about biofuels and global warming. Nevertheless, the arguments not only persist but have become even more heated.

What has taken things to a new level of contention is that some researchers (myself included) are now rethinking the heart of the matter, namely, the belief that biofuels are inherently carbon neutral. This is the assumption that the CO2 emitted when biofuels are burned does not lead to a net increase in emissions because the carbon in the biofuel is recycled during feedstock growth. My new paper, "Methodological issues regarding biofuels and carbon uptake" published in the journal Sustainability, breaks this aspect of the debate down to its bare essentials.

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.

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.

Tailpipes top smokestacks as nation's largest CO2 emitters

Transportation, which runs almost entirely on petroleum fuels, and electricity generation, which had used mainly coal, have long been the largest sources of CO₂ emissions in the United States. Although power plant smokestacks exceeded motor vehicle tailpipes and other mobile sources such as aircraft in terms of CO₂ emissions for nearly forty years, this year brings a crossover of these two emission trends. The CO₂ emitted by the transportation sector has been greater than that from the power sector for seven of the past eight months, and so 2016 is on track to see mobility overtake electricity as the country's biggest contribution to global warming.

Latest tweak to U.S. biofuel mandate is politically correct and ecologically cruel

EPA's new Renewable Fuel Standard (RFS) proposal modestly increases the amount of biofuel that America's cars and trucks have to consume next year but still keeps the total renewable fuel mandate below the Congressionally scripted target.

In the plan released on May 18, ordinary corn ethanol gets a 300 million gallon boost, biodiesel is bumped up by 100 million gallons and other so-called advanced biofuels see a 200 million gallon increase compared to last year's regulation. Nevertheless, the proposed 18.8 billion gallon total remains significantly lower than the 24 billion gallon goal for renewable fuel in 2017 that Congress wrote into law back in 2007.

EPA's approach reflects a compromise worked out last year after several tortuous years of regulatory delay. This "politically correct" strategy has the agency taking a middle road that balances the money-making interests of the biofuel industry and the corn and soybean lobbies against the engineering and economic realities that render ethanol and biodiesel such inferior motor fuels. Reactions to the proposal were predictable. The renewable fuel lobby and its allies complain "that's not enough" while the oil industry and other critics say "that's too much" biofuel.

House Oversight Testimony on the RFS

This post is a transcript of my oral testimony at the U.S. House of Representatives as delivered on March 16, 2016. 

I wish to thank the Chairs, Ranking Members and other members of the committee and subcommittees for inviting me to today’s hearing.

My name is John DeCicco and I am a research professor at the University of Michigan Energy Institute. My main focus is transportation fuel use and its environmental impact. I hold a doctorate in engineering from Princeton University and have worked on America's energy challenges for nearly 40 years, including 21 years at environmental organizations before returning to academia in 2009.

My recent research has included scientifically rigorous evaluations of the Renewable Fuel Standard (RFS) and other policies that promote biofuels such as ethanol and biodiesel. RFS proponents claim that the policy reduces CO2 emissions. I have found that it does not. In fact, from its inception, the RFS has increased rather than decreased the amount of CO2 entering the atmosphere compared to petroleum fuels such as gasoline.

Fuel Economy Matters

Pump prices are down and given the outlook of a weak global economy, a strong dollar and a lingering oil glut, they could drop even more as the year goes on. The U.S. average retail gasoline price fell below $2.00 per gallon in January and as of last week it averaged $1.93 per gallon. For over a year now, it's been significantly lower than the roughly $3.50 per gallon average of the previous few years, let alone the brief spike to over $4.00 per gallon in summer 2008. 

Consumers respond to gasoline prices and so it's no surprise that new vehicle sales are at a record high while the vehicle mix has shifted away from compact segments and back to trucks, larger SUVs and more luxurious cars. The amount of driving is back up as well. 

The fuel economy of the vehicle fleet doesn't totally backslide even when the price of fuel does. Most efficiency gains are due to improved technology; once such engineering refinements are made they don't get undone. Corporate Average Fuel Economy (CAFE) standards prop fuel economy up even when consumer interest fades, and that policy is now reinforced with greenhouse gas (GHG) emissions standards that limit the amount of carbon dioxide (CO₂) and other GHGs exhausted from tailpipes. 

Average new car and light truck fuel economy (right-hand axis) 

compared to nominal and inflation-adjusted gasoline prices. 

The adjoining graph compares the average fuel economy of new cars and light trucks to the price of gasoline since 1970, shown as both nominal "dollars of the day" and inflated to 2015 ("real") dollars. It's clear how fuel economy ratchets up as fuel prices rise. We can also see the slow backsliding that happened from the late 1980s until a decade ago. Although fuel economy has been climbing since 2005, we may be in for a serious tug-of-war between the need to keep fuel economy heading up and weakened consumer interest due to lower gasoline prices. 

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.

Bringing biofuels back to earth

After all that's been written about the pros and cons of biofuels over the years, it's fair to ask whether there's anything left to say. It turns out that there is, and a new insight comes from evaluating what actually happens on the earth, that is, on the land where the plants used to make biofuels are grown.

When do biofuels really balance carbon?

The belief that biofuels are inherently carbon neutral rests on an assumption that the CO₂ absorbed when their feedstocks are grown balances out the CO₂ emitted when the fuel is burned. That's why it's said that biofuels recycle carbon, in contrast to fossil fuels' one-way flow of carbon into the atmosphere.

However, the extent to which CO₂ emissions actually get balanced needs to be verified, not just assumed, even as obvious as it may seem. A careful analysis shows that biofuel carbon flows balance out only under certain conditions. Moreover, those conditions are at best only partly met for the biofuels now being used. To see why, it is necessary to understand some fundamental concepts about CO₂ flows between the biosphere and atmosphere.

Don't tout low-carbon fuel; track real carbon instead

My recent studies expose the fallacies behind California's Low-Carbon Fuel Standard (LCFS) and similar provisions of the U.S. Renewable Fuel Standard (RFS). Such policies claim to reduce the carbon footprint of motor fuels, but are more likely to actually increase CO2 emissions.

I'm not alone in expressing such concerns. A paper whose authors include the original developer of the lifecycle analysis method that underpins the LCFS points out how such approaches can mislead policy makers. A recent World Resources Institute (WRI) report faults policies that promote biofuels and create an adverse "food vs. fuel" trade-off.

Among the objections to my criticism is that it is merely academic and fails to offer a constructive solution for the transportation fuel-related CO2 emissions that remain after improving vehicle efficiency and limiting travel demand.

Governor Arnold Schwarzenegger signing AB 32 on Sept. 27, 2006
(Source: Getty Images via Zimbio)

In California, however, the answer is right under policy makers' noses. The Global Warming Solutions Act [Assembly Bill (AB) 32] caps carbon emissions statewide, and starting this year also places transportation fuels under the cap. AB 32 is the best climate protection program established anywhere to date, and with a technical correction plus expanded provisions for carbon offsets, it would be an ideal policy for addressing fuel-related CO2 emissions.

Why bad bookkeeping undermines fuel policies

There's a problem with the policies now imposed on transportation fuels in an attempt to control CO2 emissions. The issue has to do with how carbon is counted when the policies are defined.

Good accounting needs to reflect the fact that motor fuels are liquids that contain carbon as their molecular backbone. By nature, liquids flow. That's one main reason why they are so valuable for fueling cars, trucks, ships and planes. Carbon flows with the fuels, and it's the rate at which the carbon flows to and from the atmosphere in the form of CO2 that matters for global warming.

Note the "to and from" in the previous sentence. A big focus of climate policy is reducing CO2 emissions, e.g., reducing the rate at which carbon flows into the air due to energy use. But the from part is also important, and in fact, the CO2 problem is best described as an imbalance in the global carbon cycle due to human activities that cause carbon to flow into the atmosphere faster than natural processes can remove it.

The Global Carbon Cycle
(Source: www.esrl.noaa.gov Carbon Cycle Toolkit)

The adjoining figure illustrates the global carbon cycle. As suggested by the relative thickness of the arrows depicting the flows, the overall cycle is much larger than the excess from fossil fuel use. In round numbers, the natural CO2 flow amounts to circulation of about 200 PgC/yr (petagrams, i.e., 1015 grams, or billion of metric tons, of elemental carbon per year) between the atmosphere and the earth's surface (both land and sea). The total flow into the atmosphere from fossil fuel consumption has been steadily climbing and is now about 10 PgC/yr. Roughly another 1 PgC/yr of emissions are due to deforestation. (The latest data can be found at the Global Carbon Project.)  

The carbon cycle matters a lot when biofuels enter the picture. To protect the climate, biofuels must increase the from part of the carbon cycle; that is to say, they have to increase the net rate at which CO2 is removed from the atmosphere. After all, they don't decrease the to part of the cycle because simple chemistry tells us that a given biofuel emits essentially the same amount of CO2 as the fossil fuel it replaces. As I've put it elsewhere, if biofuels have a benefit, it's not when they're burned.

Bread & Circuses vs. Getting the Prices Right

Two researchers just published an analysis showing something that many casual observers have long realized about the political challenges of using taxes to address externalities. Liddle & Lung (2015) find that countries whose citizenries consume a lot of fuel tend to tax fuel at lower rates than countries with relatively lower consumer demand for fuel. In other words, the nations having a greater need to "get the prices right" through some form of consumption tax are, politically speaking, less likely to pursue the types of taxation that economists would recommend.

The paper is:

Liddle, Brant and Lung, Sidney, The Endogeneity of OECD Gasoline Taxes: Evidence from Pair-Wise, Heterogeneous Panel Long-Run Causality Tests. Transportation Research A: Policy and Practice, 73: 31-38, 2015. DOI: 10.1016/j.tra.2014.12.009; available at SSRN: http://ssrn.com/abstract=2557780

Flawed studies underpin low-carbon fuel policies

Nearly all of the studies used to promote biofuels as climate-friendly alternatives to petroleum fuels are flawed and need to be redone. This conclusion is just one of the findings of my advanced review paper, "The Liquid Carbon Challenge: Evolving Views on Transportation Fuels and Climate," recently published online by Wiley Interdisciplinary Reviews: Energy and Environment. The unhappy assessment is based on an in-depth review of the literature published on the topic over the past two decades.

Once the erroneous carbon accounting methods are corrected, the results will show that policies used to promote biofuels -- such as the U.S. Renewable Fuel Standard (RFS) and California's Low-Carbon Fuel Standard (LCFS) -- actually worsen the buildup of CO₂ in the atmosphere rather than reducing emissions as promised. 

The Liquid Carbon Challenge

In addition to reducing how much fuel gets burned, cutting the climate risk from gasoline and other liquid fuels requires balancing their CO₂ emissions by removing additional CO₂ from the air in locations other than the transportation sector. 

Options for addressing carbon dioxide emissions from liquid transportation fuels

It's easy to take for granted just how important liquid fuels are in everyday life. Gasoline, diesel and jet fuel remain crucial for transportation. Petroleum fuels are the world's most widely used form of energy and rank second to coal as a source of global CO₂ emissions, a situation unlikely to change for at least two decades. Although some worry about peak oil, in reality the world is not about to run out of fossil hydrocarbons that can be turned into convenient liquid fuels at an affordable price.

The RFS and the climate challenge

The Renewable Fuel Standard (RFS) confronts many issues but perhaps its ultimate test is how well it helps meet the climate challenge. The world isn't running out of oil and so the business case for renewable fuels hinges on their role in reducing CO₂. That role is much more restricted and farther into the future than RFS advocates, including many green groups, have assumed. From a carbon perspective, the very premise of the RFS is fatally flawed.

Recent analysis reveals that fuel lifecycle models, such as those used in policies including the RFS and California's Low-Carbon Fuel Standard (LCFS), make a serious mistake in their baseline assumptions. This error cuts to their very core but is only just now coming to light. This isn't another debate about net energy or processing efficiency. Rather, it's about how these policies build in an assumption of carbon neutrality without first verifying the conditions under which it is true. 

The RFS assumes that just because biomass recycles carbon, then substituting a biofuel for a fossil fuel automatically neutralizes the CO₂ coming out the tailpipe. That's not true for the biofuels now produced at market-meaningful scale.

Does a corn field absorb more CO2 from the atmosphere when it
is harvested for fuel than when it is harvested for feed or food? 

Let's think about what occurs when you substitute ethanol for gasoline, and let's start with the facts on the ground. There, the threshold question is this: does a harvest keep more CO₂ out of the air when it's used for fuel than when it's used for other purposes? For example, does corn that goes into biofuel remove more CO₂ from the atmosphere than the corn that goes into cornmeal? The answer is no.

Now, if we grew feedstocks on barren land, say in a desert where nothing was growing before, then that would absorb more CO₂ than was otherwise being absorbed. But that's not what's happening. The vast majority of renewable feedstock is harvested from land that was already in production.

You might argue, well, doesn't carbon stay in the ground when you use a biofuel instead of gasoline?  Yes, carbon stays in the ground, but that doesn't necessarily mean that less gets into the air. A reduction occurs only if you increase the net rate at which CO₂ is removed from the air in other locations. 

Remember that at the car, the amount of CO₂ directly emitted varies little among liquid fuels. And so as far as climate is concerned, if biofuels have a benefit, it's not when they're burned. 

It always comes down a question of how much more CO₂ gets taken out of the air somewhere else. Lifecycle models completely gloss over that question. Because they leave existing land use out of the equation, their carbon balance calculations are incorrect. This problem is more fundamental than the issue of indirect land-use change (ILUC), which only adds to the uncertainties involved. 

In short, lifecycle policies such as the RFS and LCFS are a mistake as far as climate is concerned. They risk doing more harm than good. Policymakers need to go back to the drawing board and do the careful homework that was never done before these programs were put in place. 

This post reflects remarks made at the SAE Government-Industry Meeting panel on "Crosscutting Challenges for the Renewable Fuel Standard," held in Washington, DC on January 23, 2014. Supporting information is available in a technical brief released that day, and the remarks also draw on the paper, "Biofuel's carbon balance: doubts, certainties and implications," published in
Climatic Change 121(4): 801-814, http://dx.doi.org/10.1007/s10584-013-0927-9. 

Back and forth on biofuels

Several comments on my Yale e360 piece on alt fuels policy take the common view that biofuels are "essentially carbon neutral" and "inherently sustainable," as Mr. Lloyd puts it. However, nothing is inherently sustainable, and the carbon balance of any system is something that must be verified. My piece asks "Where's the climate benefit?" and for biofuels at market scale, it is not possible to answer to that question in an verifiable manner.

Simply substituting biomass carbon for fossil carbon does not suffice to ensure a net CO2 reduction, as shown by the example my article gives for corn ethanol. It may leave more fossil carbon in the ground, but that doesn't mean less carbon overall went into the air. A formal analysis of this issue is given in my new paper on "Biofuels Carbon Balance."

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.