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Is Ethanol a Cost Effective Solution to Climate Change?

John Miller's picture
Owner-Consultant Energy Consulting

During my Corporate career I provided manufacturing with power generation facilities’ technical-operations services and held different technical and administrative management positions.  In order...

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  • Jan 17, 2013

Ethanol has been strongly supported as a solution to U.S. energy security, and recently, reducing carbon emissions.  Historic Government subsidies and blending mandates made ethanol one of the most successful renewable energy sources in the U.S.  Although the Government subsidies expired a year ago, increased ethanol is now being advocated possibly as a part of the EPA’s developing climate policy.  Is increased corn ethanol a reasonably economical solution to reducing future U.S. carbon emissions?

Brief History of U.S. Ethanol Blending – Ethanol has been used as motor fuel-component since the dawn of the automobile.  Until the 1990’s ethanol use was limited due to relatively poor economics compared to petroleum fuels.  Besides having a lower vehicle fuel efficiency than petroleum (lower unit volume energy content), ethanol is corrosive and requires special handling.  These factors further increase ethanol’s production-consumption costs.  The Clean Air Act was amended to require reformulated gasoline ‘oxygenate’ blending during the early 1990’s.   Although the oxygenate mandate was initially met by blending methyl tertiary butyl ether (MTBE), increasing ground water contamination issues totally replaced MTBE with ethanol by the early 2000’s.

The oxygenate blending requirement was effectively replaced by the first ‘renewable fuel standard’ (RFS1) created in 2005.  The RFS1 mandated blending up to 7.5 billion gallon per year ethanol by 2012.  The required blending level was further increased in 2007 when the new ‘RFS2’ was established.  Refer to the following bar chart:

ethanol production

Data: RFS2 is from EISA (P.L. 110-140), Section 202.  EtOH – ethanol, BioDsl – biodiesel

Conventional corn ethanol mandated blending has effectively tripled since 2005 and is scheduled to increase up to 15 billion gallons/yr. in 2015.  Cellulosic (advanced) ethanol biofuel was mandated at increasing volumes beginning 2010 under the RFS2.  The Ethanol Industrial, however, struggles to produce cellulosic ethanol at levels approaching the original RFS2 targets due to ongoing technology and developmental gaps.

Ethanol ‘Lifecycle’ Energy Balance – Conventional corn ethanol initially consumed more fossil fuel energy during cultivation-production than yielded in the finished biofuel, 10-20 years ago.  Over the years significant improvements were made in the efficiency of corn and ethanol production, and its overall ‘lifecycle’ energy balance.  To illustrate, refer to the following ‘well-to-wheel’ (WTW) diagrams:

climate change graphic

Total fossil fuels energy consumption based on the GREET model.  Petroleum gasoline WTW fossil fuels consumption has been corrected (1.13 vs. 1.23 million Btu) using improved data.

The energy balances show that 0.78 million Btu (MBtu) and 1.13 MBtu of fossil fuels are consumed in the overall WTW lifecycles of corn ethanol and petroleum gasoline respectively (for every 1.0 MBtu of finished motor fuel produced-delivered).  The petroleum gasoline fossil fuels energy consumption has been corrected to represent more accurate data developed by my detailed analysis of the GREET energy balance.  Details covered in the following ‘GREET Model Peer Review’ section.

The two WTW energy balances are formulated somewhat differently since corn ethanol is a renewable biofuel and petroleum gasoline is a fossil fuel.  Refer to the following table:

ethanol transportation table

Lifecycle energy balance details based on GREET and Peer Review adjusted data.  WTT – well-to-tank, TTW – tank-to-wheel, DDGS – dried distiller’s grains and solubles, and NEV – net energy value

The corn ethanol lifecycle balance basically only includes the ‘well-to-tank’ energy consumption steps.  As shown, total energy consumption (fossil fuel + non-fossil fuel power) is actually 6% greater than the heating value of the finished ethanol fuel (1.06 MBtu total energy consumed vs. 1.00 MBtu in the finished EtOH product).  However, the net energy consumption of ethanol is normally adjusted by an ‘energy credit’ for the co-products yielded during corn-ethanol conversion.  This energy credit is subtracted from the total energy consumption since the (DDGS) co-product displaces the energy required to produce an equivalent amount of (DDGS) animal feed elsewhere in the country.  Since ethanol is a renewable fuel, no final energy consumption and associated CO2 emissions (TTW) are included in the overall WTW lifecycle balance.  In other words, all of the CO2 emissions from consuming the finished ethanol biofuel are assumed to be ‘zero’ and fully offset by the CO2 captured from the atmosphere during the growth of the corn feedstock.

The petroleum gasoline lifecycle balance is formulated differently since it is not a renewable biofuel.  All of the energy, including the WTT + TTW, is included in the overall lifecycle WTW balance.  Technically excluding the final TTW energy consumption, petroleum gasoline has an actual NEV of 0.86 MBtu/MBtu; over 7-times corn ethanol’s NEV.  This factor is a major reason why ethanol generally costs more than petroleum gasoline.  But since petroleum gasoline is a fossil fuel, the overall balance includes the TTW energy consumption for determing the total lifecycle CO2 emissions.

GREET Model Peer Review – Federal Agencies (DOE, EPA, etc.) use the Argonne National Laboratory energy lifecycle GREET model for renewable-fossil fuels studies.  The ‘original’ GREET model output shows the petroleum gasoline WTW fossil fuels consumption is 1.23 MBtu/MBtu.

In 2010 I evaluated some corn ethanol production business investment opportunities.  During this evaluation I reviewed the latest version of the GREET model and published lifecycles.  Based on my 30+ year’s petroleum-refining experience, a couple unusual data points caught my attention; the EERE published gasoline lifecycle balance illustrated using ‘residual oil’ downstream of petroleum refining and the 0.23 MBtu WTT energy consumption level.  Residual oil use is not significant within the U.S. (commonly used internationally due to lower environmental standards) and the WTT energy consumption value was double my experience with Upstream crude oil production and Downstream refineries.

To evaluate the GREET model petroleum lifecycle energy balances I performed a detailed (Peer Review) analysis based on my experience with U.S. Refining performance surveys, Upstream & Downstream crude-petroleum oil supply chains, and available (non-proprietary) EIA data.  Based on this analysis the following detailed petroleum gasoline WTW fossil fuel energy balance was developed:

ethanol peer review table

Industrial (proprietary) data based on Oil Company performance and energy-yield surveys conducted by Solomon Associates

Using more accurate Industrial/EIA data found that overall WTW fossil fuels consumption was 1.125 MBtu/MBtu.  As originally suspected, much of the available documentation on GREET data found it to be based significantly on international refining and transportation data.  U.S. refineries are generally more efficient than international refineries and ‘crude/gasoline transportation’ (primarily via pipelines) is also more efficient.  Note: I attempted to contact the Argonne National Lab in order to reconcile the ‘unaccounted (energy) consumption’ in their published petroleum gasoline WTW balances.  No response was received.

My evaluation of the GREET corn ethanol WTW energy balance in 2010 found the published 0.78 MBtu/MBtu fossil fuel consumption to be reasonably accurate. 

Renewable Fuel Standard Carbon Reduction – The total WTW fossil fuels consumption of corn ethanol vs. petroleum gasoline is 0.78 MBtu vs. (uncorrected) 1.23 MBtu & (corrected) 1.13 MBtu respectively.  Based on average U.S. Power sector fossil fuels-renewables mix and the natural gas + petroleum consumed in the overall corn ethanol and petroleum gasoline WTW balances, the total carbon emissions for producing and blending 15 billion gallons per year ethanol was compared to petroleum gasoline.  Refer to the following table:


Table based on 2008 EPA RFS2 analysis (slide 4), ‘original’ GREET model and the Author’s Peer Review ‘corrected’ data. MMT – million metric tons

Based on EPA ‘original’ estimates, replacing 10.4 billion gasoline (Btu equivalent) gallons with 15 billion gallons of corn ethanol would reduce U.S. carbon equivalent (CO2-e) emissions by 30 MMT/yr.  The ‘corrected’ petroleum gasoline WTW balance reduces the overall ethanol CO2-e emissions reduction to 20 MMT/yr.

While the lower level of carbon emissions reduction makes the RFS2 program a less effective solution towards climate change, it also identifies a potential regulatory compliance issue.  The RFS2 requires (slide 3) all new corn ethanol bio-refineries “must show 20% GHG (CO2-e) reduction compared to gasoline”.  The ‘original’ EPA determined 24% GHG reduction becomes 18% after the petroleum gasoline WTW balance is ‘corrected’.  This Peer Review analysis indicates that RFS2 GHG maximum target compliance could be problematic for some new corn ethanol plants built since 2007.

Other Corn Ethanol Impacts – Consumption of corn for ethanol production has been a growing controversy due to impacts on animal feed and general food market prices, and water usage.  In 2012 ethanol reportedly consumed 40% of the total U.S. corn crop.  This reported 40% figure is a little misleading.  Almost 1/3rd of the total mass of the corn ethanol feedstock is converted to the DDGS co-product.  After correcting for the DDGS co-product yield off-set, ethanol did directly accounted for about 28% of the total 2012 crop.

The CBO has estimated that corn ethanol has only contributed to 10-15% of total food cost increases during the latter 2000’s.  However, since 2005 actual corn prices have more than tripled.  The escalated corn prices not only affect animal feed and ‘human’ food markets, but also impact the less efficient corn ethanol bio-refinery economics; as witnessed by a number of recent plant shutdowns.  How much of the recent corn market price escalation is due to increased demand and how much is attributed to the 2012 drought is difficult to ascertain.

Corn Ethanol Carbon Credit Value – After correcting the petroleum gasoline WTW balance, 15 billion gallons of corn ethanol production-blending more accurately reduces U.S. total carbon emissions by 20 MMT/yr.  On average ethanol costs about $1.00/gallon more than petroleum gasoline (Re. page 3, Table 2, gasoline equivalent gallons).  Base on these data the value or cost of carbon credits generated by corn ethanol would be $750/MT.  This carbon credit value is huge compared to alternative carbon reduction strategies.  Carbon reduction strategies such as replacing coal power with nuclear/natural gas/wind, efficiency upgrades and replacing petroleum gasoline with EV’s should generate carbon credits at about $100/MT.

Ethanol Advocate Claims – Various Advocacies have very successful supported corn ethanol by obtaining many $10’s Billions in Government subsidies and tax credits over the past couple decades.  Although the subsidies ended January 1, 2012, the Federal RFS2 blending requirement is still in place.  Advocates appear to be regrouping and focusing on carbon credits as a possible strategy to restore some ethanol financial support.  The Renewable Fuel Association (RFA) has apparently embarked on a new campaign to support ethanol.  Their strategy appears to address the EPA’s climate policy and possible future U.S. carbon trading.  The RFA recently petitioned the EPA to revise their corn ethanol RFS2 lifecycle energy and carbon balances.  This action would apparently reduce the level of carbon emissions generated in the overall WTW corn ethanol lifecycle as previously determined by the EPA.  If successful, the level of carbon credits generated for the production of corn ethanol would increase.

Review of the RFA report indicates their proposed ethanol lifecycle adjustments could help compensate for the reduced carbon emissions of a ‘corrected’ petroleum gasoline (Peer Reviewed) WTW lifecycle fossil fuel consumption balance.  The RFA proposal could eliminate the possible current RFS2 compliance risk of some recently built corn ethanol plants by directionally increasing current reduced GHG emissions performance estimates up to the minimum 20% RFS2 requirement.

Ethanol vs. Natural Gas Motor Fuels – Another viable alternative to petroleum gasoline and reduced carbon emissions is natural gas.  Domestic natural gas production is increasing fairly rapidly, has become relatively inexpensive and generates significantly less carbon emissions then petroleum gasoline.  These factors make natural gas an attractive alternative motor fuel.  The overall WTW lifecycle fossil fuels consumption for natural gas is also much lower than petroleum gasoline.  Comparing the natural gas WTW lifecycle to corn ethanol finds that natural gas has a WTT NEV 8-times greater than ethanol, and generates about 25% less WTW carbon emissions than conventional ethanol.  In addition, the average natural gas cost is less than half of ethanol (Re. page 3, Table 2; gasoline equivalent gallons).  These factors make natural gas possibly a much more superior alternative to displacing petroleum gasoline than corn ethanol. 

In Conclusion – The majority of the energy available in conventional corn ethanol comes from fossil fuels consumed during the overall cultivation-production of this biofuel.  Even if the RFA successfully persuades the EPA to adjust corn ethanol’s WTW lifecycle carbon emission balances, the generated carbon credits would still have a relatively high cost of about $500/MT.  This carbon credit value is extremely expensive compared to natural gas, further efficiency upgrades, or other more cost effective Power and Transportation sectors carbon reduction strategies.

The primary incentive to continue producing and blending large volumes of conventional corn ethanol is the Federal RFS2 ‘renewable fuel standard’ mandate.  Without the RFS2 requirement the probability of ethanol competing in a free market based on economically displacing equivalent fossil fuels or generating reasonably priced carbon credits appears to be relatively small.

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Rick Engebretson's picture
Rick Engebretson on Jan 17, 2013

Just yesterday I had an argument with a corn farmer who thinks I am anti-ethanol. So today I'm supposed to sound like I'm pro ethanol to an oil guy.

The problem is neither of you know what the issue is. I suggest you install SuSE Linux 9 on an old computer and run the screensaver "molecule" with all the features enabled. The program draws a few biomolecules, drugs, etc. and labels them. It is capable of running files from the "protein data base."

The complexity and sophistication of biomolecules is never part of the oil story. The only way to make most biomolecules is biology. And yeast can make biomolecules if you feed it right. But, like all biology, there is waste.

So the oil industry finds it difficult to understand yeast waste as a fuel. No, it is not energy, it is food production waste. And right now be thankful you (and billions others) can buy protein to eat.

The recent fear of the "dairy cliff" reflected that 1949 milk prices would be double today's price. And that is with a small fraction of the protein market we feed today.

Rick Engebretson's picture
Rick Engebretson on Jan 17, 2013

In a separate comment I hope I can figure out how links work to provide a picture the corn farmer tried to insult me with;

Maybe the link tool doesn't work on my linux browser? (a java script) But that is the URL emailed me with the greeting "So you think it's new?"

I replied how I actually knew the microbiologist who started the modern frenzy, and spent 6 months in a federal pen for it. Then George McGovern helped him. A long story that deserves better than it gets.

There is no way to untangle the misinformation, so why volunteer anything new?

J Elliott's picture
J Elliott on Jan 17, 2013

Your gasoline crude well-thru-vehicle gasoline consumption fossil fuels energy balance seems to indicate that with the exception of some smaller adjustments to crude oil production/transportation and gasoline T&D adjustments, the major difference with the Argonne Nat Lab balance is the refining energy usage.  Are foreign refineries really 40% less efficient than American refineries?

John Miller's picture
John Miller on Jan 17, 2013

EMB, The reason for the large difference of energy consumption between my gasoline WTW balance and the Argonne National Laboratory is due to a combination of thermal energy efficiency and the crude oil refining-conversion process yields.  Besides the significantly increased thermal efficiency of average U.S. refineries vs. International refineries (EU, Asia, etc.), a major contributing factor is due to the ‘liquid volume yield gain’.  The Argonne National Lab appears to have missed the importance and impact of liquid volume yield gains when developing the petroleum motor fuels module(s) in their GREET model.  The error or gap is due to the fact when complex U.S. refineries process heavier crude oil into lighter, cleaner burning motor fuels, including reformulated gasoline, ultra low sulfur diesel, jet, etc., the total net products volumetric yields average about 5% greater than the volume of crude oil feedstock (i.e. 1.00 barrel of crude yields about 1.05 barrels of products).

The refined products volume gain is due to the technology and processes used to convert heavy crude oil into lighter petroleum oil products.  Common processing technologies include fluid catalytic cracking, hydrocracking and thermal cracking (or coking).  Besides breaking down the heavier crude oil hydrocarbon molecules into lighter gasoline and distillate hydrocarbons, most intermediate petroleum products are further hydrotreated to remove contaminates such as sulfur and heavy aromatics (critical processes required to produce cleaner burning fuels).  The combination of converting heavy hydrocarbons into lighter products and hydrotreating (chemically adding large amounts of hydrogen to the fuels), increases the total volume yields of processing a given crude oil.  The gain in products net volume over crude oil feeds adds significantly to the overall lifecycle energy efficiency and reduces the fossil fuels energy consumption per 1.0 MBtu of petroleum products produced .  

Stanley Seibel's picture
Stanley Seibel on Jan 17, 2013

 Very good. Thank you.

 We don't need to,and with the drought and population growth we shouldn't use farm land to grow fuel. There are plenty of better options, like-, safe new nuclear, and that we should support and fast track.
But the RFS mandates stifle better options by forcing us to use billions of gallons,of corn ethanol and other land source energy. 
 But I don't think the National corn growers association will let the corn ethanol mandate end, with out a fight.
 Everyone should sign the PLEDGE at .
     The highly respected OECD said. "The rush to energy crops threatens to cause food shortages and damage to biodiversity with limited benefits … Government policies supporting and protecting domestic production of biofuels are inefficient [and] not cost effective … The current push to expand the use of biofuels is creating unsustainable tensions that will disrupt markets without generating significant environmental benefits … Governments should cease creating new mandates for biofuels and investigate ways to phase them out." -  Richard Doornbosch and Ronald Steenblik, "Biofuels: Is the Cure Worse Than the Disease?," in Round Table on Sustainable Development (OECD, Sep 11-12, 2007).

John Miller's picture
John Miller on Jan 17, 2013

Stan87, you are probably correct that the RFS2 is not likely to be significantly changed in the foreseeable future.  Besides the strong support by agricultural and ethanol special interests, the Federal ethanol blending mandate was passed by a (based on today’s Political standards) very rare ‘bipartisan’ Congressional-Administration action (EISA 2007 regulation).  Hopefully with ongoing concerns of the current slow economic recovery, increasing federal deficits and realization that our resources are indeed limited, the EPA will not aggressively pursue unreasonable future increases in ethanol or other expensive-inefficient biofuels blending mandates.

There use to be a sound business philosophy that if producing a specific commodity was a good idea, that it would be commonly duplicated throughout the markets.  In the case of ethanol, the U.S. & Brazil produce and consume the vast majority of this biofuel.  The level of ethanol produced and consumed by other OECD countries is relatively small.  Brazil has a unique advantage that makes ethanol production attractive; tempered weather, fertile land and relatively high rain fall.  These environmental factors make growing sugar cane and producing ethanol from this sugar crop the most efficient biofuel industry in the world.  Outside of Hawaii, the U.S.’s ability to grow sugar crops (cane or beets) is much more limited and relatively energy intensive-costly.  To meet Federal RFS blending mandates and within existing cultivation-farming industry capabilities, corn was found to be the most efficient source of conventional ethanol bio-refinery feedstock (i.e. sugar from the converted starch).  Corn ethanol, however, is much more energy intensive and costly compared to Brazilian sugar cane ethanol.

Rick Engebretson's picture
Rick Engebretson on Jan 18, 2013

Since the US is a large food exporter and oil importer, perhaps your oil experience is better applied to improving your industry. You may not understand or care to understand the food - ethanol link, but it is paying your bills right now, and feeding you too. The bottom line.

John Miller's picture
John Miller on Jan 18, 2013

Rick, as you are aware fermentation of sugars into ethanol is a natural process that goes back to the dawn of mankind.  The ‘saccharification’ of corn starch by enzymes into sugars that can then be fermented with yeasts into ethanol is a more recent development; or starting about the time when IBM cards and mainframes were still popular.  Yes, ‘dry mill’ bio-refineries produce proteins and corn oil found in many processed food products.  Less capital-operating expensive ‘wet mill’ bio-refineries do not separate the corn kernels into different co- or byproducts (i.e. produce only DDGS) that is normally used for animal feed markets (cattle, poultry, etc.).

You may be confusing ‘cellulosic’ ethanol, which produces a bio-waste that has no value as an animal or human food.  The dried bio-waste is only valuable as a solid fuel for generating heat (steam and/or power).  Without the conversion of the cellulosic bio-waste into some form of usable energy, producing cellulosic ethanol would be extremely inefficient (and probably violate the RFS2 60% GHG reduction target requirements; Re. slide 3) compared to producing conventional corn ethanol in a state-of-art bio-refinery.

John Miller's picture
John Miller on Jan 18, 2013

Perhaps you should refer to my reply to your first comment (below).  Suggest we continue this discussion outside this post.

J Elliott's picture
J Elliott on Jan 18, 2013

The Federal Government recently extended the wind power subsidies and discontinued the ethanol subsidies at the end of 2011.  This indicates that the wind power should continue to grow and ethanol may not.  Shouldn’t the Federal Government reconsider extending the ethanol subsidies?  As you indicate, the ethanol industry has made good progress in reducing the energy consumption, increasing the NEV and also reducing the carbon emissions over the years.

Rick Engebretson's picture
Rick Engebretson on Jan 18, 2013

John, I'm not "confusing" anything. Of the 21 L-alpha-amino acids that make up protein we require, many can't be produced in a laboratory or in crops. IIRC, some have tried GMO soybeans. Years ago, one of the requirements for a recombinant DNA microbial experiment (commonly E-Coli) was tryptophan synthetase genetic deletion so the organism could not escape the lab and required tryptophan to live. Before the ethanol boom I worked in a place where synthetics were blended to create "milk replacer" for veal calves taken from their milking mother dairy cow. Agriculture is a big, sophisticated industry. Take a look at just what amino acids are, then add in nucleic acids, and vitamins. Since there is no longer the cropland and pasture to feed everybody the required nutrients previously provided by ruminants and their stomach microbiology, the corn starch digester was invented that can use manufactured precursors. You complain that the ethanol waste cuts into your fuel market. Rather funny, the food diversity that we ingest for our complex lives and some get angry about burning waste liquid fuel in a car engine. So there are laws to deal with it.

But I don't have anything at all to do with corn or ethanol. In fact I warned my friends that they are buying fertilizer and seeds from the same people they sell the product to. And there is no farm bill. This looks like a bubble. So I have no sides here. I simply resent your all too common misinformation.

What is interesting is at "". If you ever get past the oversimplifications, they do a great job doing computer biophysical chemistry. Maybe some day we will see "solar fuels" and then you will complain.

Leo Klisch's picture
Leo Klisch on Jan 18, 2013
From my on line R&D newsletter 

Photovoltaics beat biofuels at converting sun's energy to miles driven
Thu, 01/17/2013 - 10:51am

In 2005, President George W. Bush and American corn farmers saw corn ethanol as a promising fossil fuel substitute that would reduce both American dependence on foreign oil and greenhouse gas emissions. Accordingly, the 2005 energy bill mandated that 4 billion gallons of renewable fuel be added to the gasoline supply in 2006. That rose to 4.7 billion gallons in 2007 and 7.5 billion in 2012.

Since then, life cycle assessments (LCAs) have shown that corn ethanol has modest if any effect on reducing carbon dioxide emissions and may actually increase them, while posing a threat to natural habitats and food supplies, as food stocks are turned to fuel and marginal lands are put under the plough to keep up with demand. In 2010, fuel ethanol consumed 40% of U.S. corn production, and 2012 prices are at record highs. Since the U.S. also accounts for 40% of the world's corn, U.S. ethanol production has affected corn prices around the planet.

As electric vehicles (EVs) increasingly enter the market and charging stations are built to serve them, EVs are competing with alternative-fuel vehicles. Using electricity generated by coal-fired plants to power the cars defeats the purpose to some extent, but what if the energy comes from the ultimate clean and renewable source—the sun itself? How would that compete with ethanol in terms of land use, life-cycle emissions, and even cost?

The question, says UCSB Bren School of Environmental Science & Management Professor and LCA expert Roland Geyer, is which makes more sense, growing fuel crops to supply alternative-fuel vehicles with ethanol and other biofuels or using photovoltaics (PV) to directly power battery electric vehicles (BEV)?

"The energy source for biofuels is the sun, through photosynthesis," he says. "The energy source for solar power is also the sun. Which is better?"

To find out, Geyer joined former BrenSchool researcher David Stoms and James Kallaos, of the Norwegian University of Science and Technology, to model the relative efficiencies of the technologies at converting a given amount of sunlight to miles driven.

The results, which appear in a paper titled "Spatially Explicit Life Cycle Assessment of Sun-to-Wheels Transportation Pathways in the U.S." and published in Environmental Science & Technology, showed photovoltaics (PV) to be much more efficient than biomass at turning sunlight into energy to fuel a car.

"PV is orders of magnitude more efficient than biofuels pathways in terms of land use—30, 50, even 200 times more efficient—depending on the specific crop and local conditions," says Geyer. "You get the same amount of energy using much less land, and PV doesn't require farm land."

The researchers examined three ways of using sunlight to power cars: a) the traditional method of converting corn or other plants to ethanol; b) converting energy crops into electricity for BEVs rather than producing ethanol; and C) using PVs to convert sunlight directly into electricity for BEVs.

Because land-use decisions are local, Geyer explains, he and his colleagues examined five prominent "sun-to-wheels" energy conversion pathways—ethanol from corn or switchgrass for internal combustion vehicles, electricity from corn or switchgrass for BEVs, and PV electricity for BEVs—for every county in the contiguous United States.

Focusing the LCA on three key impacts—direct land use, life cycle greenhouse gas (GHG) emissions, and fossil fuel requirements—the researchers identified PV electricity for battery electric vehicles as the superior sun-to-wheels conversion method.

"Even the most efficient biomass-based pathway…requires 29 times more land than the PV-based alternative in the same locations," the authors write. "PV BEV systems also have the lowest life-cycle GHG emissions throughout the U.S. and the lowest fossil fuel inputs, except in locations that have very high hypothetical switchgrass yields of 16 or more tons per hectare."

PV conversion also has lower GHG emissions throughout the life cycle than do cellulosic biofuels, even in the most optimistic scenario for the latter. "The bottleneck for biofuels is photosynthesis," Geyer says. "It's at best 1% efficient at converting sunlight to crop, while today's thin-film PV is at least 10% efficient at converting sunlight to electricity.

Finally, while cost was not a key component of the study, Geyer says, "The cost of solar power is dropping, and our quick calculations suggests that with the federal tax credit, electric vehicles are already competitive."

What does this mean for the future?

"What it says to me is that by continuing to throw money into biofuels, we're barking up the wrong tree," Geyer explains. "That's because of a fundamental constraint, which is the relative inefficiency of photosynthesis. And we can't say that right now, biofuels aren't so great but they'll be better in five years. That fundamental problem for biofuels will not go away, while solar EVs will just continue to get more efficient and cheaper. If they're already looking better than biofuels, in five years the gap will be even greater. A search for a silver bullet is under way through "synthetic photosynthesis," but using genetic engineering to improve the efficiency of photosynthesis is a pipe dream. If there is a silver bullet in energy, I think it's solar power."

Source: University of California, Santa Barbara


Rick Engebretson's picture
Rick Engebretson on Jan 18, 2013

Imklisch, I agree with much of what you say but want to add some concepts.

First, let's forget corn ethanol as a biofuel, because it is simply food production waste put to good use.

Next, let's look at fire itself. In chemical kinetics is the concept of "activation energy." It is often represented as an energy hill separating reactants and products. There is a reason wood or other biofuels don't burn until they get red hot, and then perpetuate a cycle. The red hot is the activation energy. Activation energy is how enzymes effect chemical kinetics and reaction specificity.

The nice thing about red hot is solar energy concentration can do it. By simply removing the activation energy requirements, solar energy is stored into an intermediate high energy fuel. Destructive distillation of methanol has a long history.

So biofuel does not have to be grown from photosynthesis. It is just a carbon source and can be landfill waste. Photosynthesis is an entirely different process creating negative entropy; order from chaos.

The interesting thing about the "" molecular dynamics group is they understand the quantum physics of water. They model proton tunneling and optical wavelengths and all the rest that you now associate with electrons in silicon. We don't want to get locked into electrons in silicon when far bigger solar energy solutions are a global focus.

John Miller's picture
John Miller on Jan 18, 2013

EMB, renewable wind or biofuels subsidies and other forms of financial support are most often needed for developing many innovative and new technologies to reduce the U.S. reliance on petroleum fossil fuels and reducing carbon emissions.  Depending on how the financial support is managed and issued the results and benefits to the general public or the country overall can be both positive and negative.  Without the very significant past Government subsidies, neither ethanol or wind power would likely have developed and expanded to the current supply capacity levels.  This is obviously the positive benefit.  The potentially negative outcome is that excessive subsidy levels or financial support carried out over unreasonably long time periods can actually encourage the development and continued operation of technologies and production facilities that are very inefficient and unsustainable without perpetual government support. 

Since wind power generation subsidies of 2.2 cent/KWH only represents about a 20% price increase in current average residential retail power costs, these subsidies appear to be reasonable as long as they are eventually terminated in the foreseeable future.  A possible wind power subsidy phase-out strategy has been recently recommended by the American Wind Energy Association.  

The ethanol industry has benefited from subsidies of over 50 cents/gal., which has historically represented well over 25% price increase vs. average gasoline.  Ethanol has also benefited from large additional agriculture subsidies, blending mandates, imports protections, etc.  The different Government supports are somewhat complex and have cost taxpayers and the general public $50-100 Billion over the past 20 years.  Termination of the consumption financial subsidies a year ago appears to be a very reasonable decision.

The problem statement for excessive and perpetual Government subsidies for specific renewable energy types (such as ethanol) is that they distort the process of identifying and developing the truly most cost effective alternative energy sources to fossil fuels.  In the case of ethanol, other options including wind/solar, natural gas, EV’s, etc. appear much more promising and cost effective compared to conventional corn ethanol production. 

John Miller's picture
John Miller on Jan 18, 2013

Lmklisch, your added information on ‘sun-to-wheel’ comparison of solar PV-EV vs. conventional and advanced ethanol is very informative.  Your referenced studies arrive at the same conclusion from a different research perspective; other renewable energy options are generally more cost effective and reduce carbon emissions to greater levels than conventional corn ethanol.

While I agree that solar power used to power EV’s is a better solution to the costs/benefits of corn ethanol, my research has shown that wind power may be more competitive to solar PV based on the current levels of technologies development and costs.  Granted, solar PV panel costs have come down substantially in recent years, but so have the delivered per KWH cost of wind turbines.  As you are probably aware, wind turbines have the advantage of larger average ‘capacity factors’ compared to solar PV.  Solar PV is, however, much less impactful on local avian/bat populations.  Which technology will ultimately be the most cost effective awaits further future technology and reduced manufacturing-construction cost developments.

If you have identified similar studies comparing ethanol-wind or wind-solar, further references would be much appreciated. 

Leo Klisch's picture
Leo Klisch on Jan 20, 2013


 you may be interested in the following studing in the "Journal of Power Sources" having to do with the cost and possibility of 90% + renewables powering a major eastern US grid.

James Thurer's picture
James Thurer on Jan 20, 2013

Although the federal government has discontinued ethanol subsidies, it has continued the mandate.   As a consequence, the consumption on ethanol. will not be reduced.  This simply shifts that portion of the costs of ethanol from the taxpayer to the consumer.

James Thurer's picture
James Thurer on Jan 20, 2013

Corn ehtanol is not an effective solution to climate change, as its production results in a net increase in greenhouse gasses.  This is due to the requirement to use large amounts of nitrogen fertilizer to cultivate corn, which results in the release of nitrous oxide, a greenhouse gas 300 times more potent than CO2.  In addition, more recent work by Paul Crutzen  indicates that the impact of nitrous oxide released by corn cultivation is about three times that, or about 1000 times that of CO2.

There are other environmental problems associated with intensive corn cultivation, such as nitrate runoff and contamination of aquifers (including the Ogalalla Aquifer that the Obama administration pretends to care so much about), and the creation of  "dead zones"  in oceans.  Al Gore wrote about these environmental problems in "Earth in the Balance" in 1992, before supporting corn ethanol subsidies while running for president.

Sugarcane ethanol, in contrast, would reduce greenhouse gasses, as sugarcane requires very little nitrogen fertilizer, but high tariffs on sugar result in an artifically high sugar price that  precludes producing sugarcane ethanol commercially in the U.S.  These subsidies were emplaced in the 1930's, and are politically sacrosanct.

The bottom line is that the primary obstacle to responsible biofuel policy in the United States is political, not technical.


John Miller's picture
John Miller on Jan 20, 2013

James, although the Federal renewable fuel standard blending mandate continues, the market price of ethanol does not appear to have increased to replace the lost per gallon subsidy value.  As measured by average E-85 ethanol vs. retail gasoline prices between Oct. 2011 (just before the 50 cent/gal. subsidy expired at yearend) and Oct 2012 the prices of ethanol and gasoline motor fuels both increased by about  9%.  Although the lost subsidies cost should have been expected to shift from the taxpayer to consumers as you state, the cost difference does not appear to be reflected in the cost of ethanol vs. petroleum gasoline fuels over the past year.   Average crude oil costs actually dropped by 1% Oct. 2011-12, which could account for a small percentage of the lost subsidy, but this may have been offset by increased corn feedstock costs ethanol producers experienced during the same period.  Where’s the lost subsidy?  Your guess is as good as mine.

James Thurer's picture
James Thurer on Jan 20, 2013

The lost subsidy was reflected in an immediate increase of retail gasoline prices, as the ethanol producers themselves predicted.  Remember, the retail gasoline price includes the cost of the ethanol that has to be blended in by mandate.

If the mandate did not exist, then the elimination of the subsidies would have resulted in a decrease in the price of ethanol.  With the mandate in place, the increased cost for ethanol was simply passed on to the consumer. 

Ask yourself two simple questions:  How much did you last pay for a gallon of gasoline?  I bet you can tell me within a penny or two.  Now, how much did you pay for the ethanol in the gasoline?  I bet you have no idea.

This is why the ethanol mandate, which is simply a wealth transfer program to inflate corn prices, has been so successful politically.  The consumer never sees the cost explicitly.

John Miller's picture
John Miller on Jan 20, 2013

James, you make some very good points relative to corn cultivation and nitrogen fertilizer greenhouse gas emission impacts.  Besides identifying additional probable gaps in the Argonne National Lab. GREET model (corn ethanol carbon-equivalent generation balances), you raise the very important issue of how politics can and has distorted the U.S. (and other countries) abilities to actually control and reduce greenhouse gas emissions.  Since Congress has not passed any legislation on climate change, this regulatory arena has been taken up by the EPA and their discretion on how to address future carbon reductions.

Coincidentally, one of the major issues raised in the recent Renewable Fuels Association’s (RFA) petition to the EPA is commonly referred to as ‘land use change’ (LUC) impacts.  The petition claims that the EPA’s original assessment over estimated the greenhouse gas impacts of corn cultivation, which should have included the issue of nitrogen fertilizers; as you have raised.  The RFA, of course, claims that the current corn ethanol lifecycle greenhouse gas total balance should be reduced, which is the opposite conclusion of your referenced Paul Crutzen work.

Besides the contradiction of actual corn cultivation run-off contaminating the Ogalalla Aquifer vs. the exaggerated risk impacts of the Keystone XL pipeline project last year, politics has been a major factor in nearly all renewable energy source regulations, including biofuels and addressing climate change.  If the EPA were fully supportive of reducing carbon emissions, they would overcome political influences and truly focus on objective science and engineering.  Unfortunately politics is a strong and dominate force within the EPA, and they may continue to overlook the full lifecycle LUC impacts including nitrogen fertilizer use and run-off contamination factors.

In the meantime, no one, Congress or the Administration, holds the EPA accountable for their actions or lack of effectively enforcing many current regulations.  Ignoring the impacts of excessive corn cultivation and run-off pollution appears to potentially violate the Land Use Control Policy of 1998

Instead of making many possible value added actions, the EPA uses its authority somewhat arbitrarily to make regulatory decisions, such as denying the recent request to waive the renewable fuel standard due to the severe 2012 drought and the large economic impacts on animal feed and food markets. 

Do you think politics had a little influence on this EPA decision?  Of course you need to consider that the request was primarily related to market and consumer economics, a subject the EPA is not known to put much priority on historically.

Simon Friedrich's picture
Simon Friedrich on Jan 21, 2013

Thank you for a very informative analysis of theGreet Model Peer Review’.

The paragraph on the life cycle balance shows the incorrect assumptions in the Greet model from an emissions reduction perspective. For example, it gives greenhouse reduction credits for the DDGS co-product.  This inexpensive feed will only promote the expansion of flatulent cattle herds.  It well known that on the global scale methane emitting cattle are a significant source of greenhouse gases.

The arbitrary exclusion of carbon dioxide from the combustion of biofuel ethanol from the greenhouse gas emission inventory, because it is a renewable energy source is even a bigger problem.  

Regrettably, governments and international organizations have embraced the “carbon neutral” assumption under which emissions resulting from land use changes caused by biofuels demand are ignored.  The time parameter for removing greenhouse gases by photosynthesis is also ignored. Hopefully, one day they will realize that there is only limited arable land and water for the 9 billion humans who will be on the planet by mid century and that nature (by photosynthesis) does not use humanity to remove carbon dioxide from the atmosphere.  Further, forests and grasslands can store more carbon than agricultural lands. Massive use of biofuels has no clothes.  


John Miller's picture
John Miller on Jan 21, 2013

Simon, the issue of cattle flatulence was raised a couple years ago when the EPA was beginning to develop their plans to control carbon emissions.  For various reasons (political?) the EPA decided to exempt the cattle industry.  Even some initial discussions on applying carbon taxes to cattle became a political hot point (although the EPA vigorously denied its consideration) and was quickly killed by other Federal agencies (Farm, Ag., etc.) and special interests.

The issue of how valid the application of DDGS co-product credits should be was also strongly debated about 10 years ago.  Carbon emissions were not much of a consideration at the time.  The main point of the debate was the net energy value (NEV) of corn ethanol in replacing an equivalent amount of petroleum gasoline.  As you can see from my lifecycle energy balances, without the co-product energy credit state-of-conventional corn ethanol production processes still have significantly negative NEV’s.  The ethanol and agricultural lobbies helped influence adoption of the co-product energy credits.  The final decision to include the fairly generous co-product credits included minimal concern for carbon emission impacts at the time. 

James Thurer's picture
James Thurer on Jan 21, 2013

I don't want to be picky, but I'd like to correct a common misconception about  methane generation by ruminant (multi-stomached) animals, such as cattle, sheep, and goats.

The great bulk of the methane generation from ruminant animals is from coughing, not from flatulence.  Ruminant animals transfer the rumen. or "cud," from one stomach to another by coughing up the rumen to their mouths, and then swallowing it again.  The coughing expels stomach gasses, one of the principal components of which is methane.

If I remember correctly, the IPCC report on greenhouse gasses concluded that methane generation from ruminant animals produces a greater greenhouse gas effect than thre burning of fossil fuels for all forms of transportation combined.

My advice to those who are worried about greenhouse gasses:  Eat more chicken!

Something I have wondered about is what the global impact on greenhouse gas generation would be if we all were simply to change from consuming dairy milk to soy milk.  I've never seen any numbers on this, but I bet it would have a very significant impact  and would be far cheaper than producing biofuels or building and charging electric cars.

John Miller's picture
John Miller on Jan 21, 2013

James, thanks for helping clarify the impacts of animals on greenhouse gas emissions.  You are correct that living styles or eating habits have very significant impacts on greenhouse gas emissions.  Not too long ago a contact asked me how much U.S. CO2 emissions could be attributed to people breathing.  This individual had a hard time accepting that we all exhale what is now defined as a major world pollutant.  Based on 2000 calorie per day per individual assumed food consumption-digestion, the U.S. total population exhales CO2 equivalent to roughly 3% of total 2011 carbon emissions based on EIA MER data.  Your suggestion of switching our diets from beef to chicken could probably reduce this level of resident carbon exhale emissions (and obesity/general health) significantly.

But on a more serious note, a factor rarely discussed by the IPCC or Developed countries’ governments concerning climate change is that the world population is a major factor to total anthropological greenhouse gas emissions, both directly and indirectly.  To my knowledge China is the only country to regulate this factor.

Richard Rodriguez's picture
Richard Rodriguez on Jan 23, 2013

Hello John and thanks for your effort and summary of the economics and viabiity of ethanol. I realize carbon neutral is the goal in generating corn ethanol or as close as possible to neutrailty.. Therefore I would bring another grass biomass substitute to your attention. Giant King Grass is very similar to corn stalk but is more productive and low in the sugar content than other biomass produces. Other then wood biomass Giant King Grass produces the least ash content of proven feedstocks. Could provide you much more information but research is your business.thanks again,


John Miller's picture
John Miller on Jan 24, 2013

Richard, giant king grass looks like a possible improvement over alternatives, such as switch grass, as a possible cellulosic ethanol feedstock.  As you are aware, cellulosic ethanol still faces major development challenges to get the costs under control, and improve yields, NEV’s and carbon balances.  I have not studied or evaluated cellulosic developments recently.  Are successful developments-improvements being made in the areas of pretreatment (lignocelluloses separation) and enzymatic hydrolysis processes for giant king grass?  These were and may still be the major barriers to successfully developing cellulosic ethanol from switch grass, stover or wood.

Stanley Seibel's picture
Stanley Seibel on Jan 25, 2013

As much as I really like solar and wind energy,there are some big problems, I feel that we are over looking. The energy and carbon it take to build the equipment, build the infrastructure because of the large area needed on land, or at sea,and to maintain it ( for instants the best place for solar is in dry dusty areas and would need to be cleaned constantly )  all this I think, ends up being more energy used and carbon produced, than energy produced or carbon reduced over the life of the panels and turbines. That's why I feel we need to push for these new energy technologies.   sugar production for biofuels

 From the book Prescription for the planet. free at The Science, under the Books, Videos, Audio link.
Here are a couple of quotes from an article on what is scheduled to be the largest solar energy “farm” yet, a 4,500 acre,500 MW array of Stirling solar-thermal dish generators in the Mojave Desert in southern California:
[…D. Bruce Osborn, Stirling Energy's new CEO, says,] “a dish farm of 11 miles square could produce as much
electricity as the 2,050 MW from Hoover Dam.”…Theoretically, Stirling dish farms with a total area of
100 miles square could replace all the fossil fuels now burned to generate electricity in the entire U.S.76
A casual reader might be forgiven for interpreting that “11 miles square” figure as the more usual “11 square miles,” but in reality it denotes 121 square miles. That is a LOT of dishes. It’s also a wildly inaccurate calculation, since at a capacity of 500 MW per 4,500 acres it would take approximately 29 square miles of dishes—not 121—to equal that 2,050 MW Hoover Dam output. While this may look good at first glance, that would be around 80,000 dishes
(each 37 feet in diameter), which will soon allegedly cost $150,000 each (they cost much more than that now) and could, we are told,drop to half that cost with true mass production. Not to get bogged down in figures here, but even at the theoretical greatly reduced target figure of $75,000 each that would come to a tab of about six
billion dollars. Not exactly chump change.The second figure quoted above is pretty close to right on (it
seems the reporter is better at math than the solar guy), if by fossil fuels you also (incorrectly) include nuclear power. But 100 square 76 Otis Port, "Power from the Sunbaked Desert," Business Week Sep 12, 2005.miles isn’t what they’re talking about there. Notice it’s “100 miles square” which is actually 10,000 square miles, an area larger than
the state of Vermont. Oh heck, as long as I’ve got my calculator out I’ll do the math for you. That would take about 28 million dishes and run up a bill of around $2.14 trillion. Plus the cost of all the feather dusters you’d need to keep them clean and shiny
John Miller's picture
John Miller on Jan 25, 2013

Stanley, very good point about the huge physical footprint of solar power facilities, relatively high costs and the need for continuous maintenance.  Another factor that many advocates often overlook is the environmental impacts of solar facilities.  Unlike the common perception that solar power facilities are installed on waste lands, the truth is that these installations destroy very fragile arid or desert environments and adversely impact local wild life.  Although many renewable energy advocates routinely chose to emphasize the macro-negative environmental costs of fossil fuels, they often overlook the negative impacts of renewables.  In the case of corn ethanol, land and water use are not inconsequential.  The same is true of wind power on local avian/bat populations.  The bottom line is that all forms of energy have environmental impacts, which involve positive and negative impacts or trade-offs.  

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