Bill Totten's Weblog

Sunday, April 08, 2007

Biofuels - facts and fiction

The claims made for biofuels make it seem truly a wonder crop. Mark Anslow separates the wheat from the chaff.

by Mark Anslow

The Ecologist (March 2007)

Claim One - You get more out than you put in ...

For more than fifteen years, David Pimentel, Professor of Ecology and Agriculture at Cornell University in New York, and his colleague, Professor Tad Patzek at Berkeley, have published peer-reviewed research showing that biofuels give out less energy when burnt than was used in their manufacture.

By using a 'cradle to grave' approach - measuring all the energy inputs to the production of ethanol from the production of nitrogen fertiliser, through to the energy required to clean up the waste from bio-refineries - they have shown that while it takes 6,597 kilocalories of nonrenewable energy to produce a litre of ethanol from corn, that same litre contains only 5,130 kilocalories of energy - a 22 percent loss.

Their work has been fiercely attacked by the biofuel lobby, who argue that Pimentel and Patzek include too many 'energy input' costs, and fail to give credit to the other, useful 'co-products' created in the process of refining biofuel.

Neither objection stands up under closer scrutiny. In fact, corn uses more herbicides, insecticides and fertiliser than any other crop; and 99 per cent of all cornfields used for producing bioethanol are heavily fertilised with nitrogen.

Pimentel and Patzek have shown that although the energy costs involved with fertiliser production have fallen, most of the factories producing nitrate fertiliser in the USA today were built in the 1960s and are highly inefficient. As such, they estimate that the energy costs of nitrogen fertiliser manufacture account for over thirty per cent of the total energy needed to grow corn. When the energy costs of labour, machinery, petrol and diesel, other fertilisers, herbicides, insecticides and corn seed production are figured into the equation, merely growing corn using intensive agriculture accounts for 38 percent of the energy needed to produce a litre of ethanol.

To make their energy costs appear more favourable, proponents of biofuels frequently 'off set' the energy value of other substances produced during the refining process against the total energy used to produce the fuel. For bioethanol, these co-products include animal feed and carbon dioxide gas. For biodiesel, they include animal feed and glycerine, a component of soap. They argue that, by calculating the energy that would have been required to produce these substances by themselves, the amount of energy accounted for in the biofuel production process can be reduced. In some studies, the energy value of co-products has been calculated at 150 per cent more than the energy required to produce the fuel.

But the energy and monetary value of these co-products is highly subjective. In the UK, the production of glycerine, which biodiesel producers had hoped to sell to cosmetics companies to offset the costs of production, has reached such levels that supply is exceeding demand. Some refiners have been forced to simply burn it. In the US, the value of the grains left over after ethanol distillation has been much touted as an animal feed. But research has shown that this grain contains less energy than normal animal feed (usually made from much less fertiliser-intensive soya), and that production of soya has not fallen as ethanol production has risen, indicating that livestock farmers have been reluctant to change the their animals' diet and use the new feed. David Morris, a biofuel lobbyist, has even admitted that it may benefit refiners more to burn the animal feed as fuel than to sell it.

Some ethanol distilleries have bottled the carbon dioxide that is given off during the fermentation process and sold it to carbonated drinks manufacturers, counting the value of the by-product against their overall energy costs. Most, however, have not.

Energy offset benefits can only be counted if the co-products are genuinely used in substitute for another product. Refining ethanol produces roughly equal parts ethanol, carbon dioxide and animal feed. Given that US corn-based ethanol production in 2005 peaked at 16.2 billion litres, this means that an almost equivalent amount of co-products (by volume) must have been produced. If these products are, as market figures suggest, unwanted, then instead of providing a useful 'offset', they are set to become a serious waste problem.

Claim Two - It makes economic sense

In 2006, the American government handed out between $5.1 and $6.8 billion in ethanol subsidies. These include payments made to farmers, tax breaks given to refiners and payments made under carbon reduction programmes. But instead of these subsidies finding their way into farmers' pockets, they are instead swelling the accounts of several large biofuel manufacturers.

One company, Archer Daniel Midlands, one of the world's largest agribusiness companies, accounted for nearly 28 per cent of the US ethanol industry in 2006.

According to attorney Arnold Reitze, Professor of Environmental Law at George Washington University Law School, every dollar of Archer Daniel Midlands's profit has cost US taxpayers $30. To ensure the continuation of ethanol subsidies, the Renewable Fuels Association, of which Archer Daniel Midlands is a member, had reportedly contributed $772,000 to Republican coffers between 1991 and 1992.

Biofuels have already been taken out of the hands of farmers and turned into big business. Where the demand for ethanol has benefited corn farmers, it has done so only at the expense of cattle farmers, for whom the cost of animal feed has vastly increased. Ethanol production from corn has been estimated to add $1 billion to the cost of beef production.

In the USA, a litre of petrol costs roughly 33 cents to produce; a litre of ethanol can cost up to $1.88. At present, these differentials are disguised behind subsidies, tax breaks, levies and laws. Germany subsidises biofuels to the value of 47 cents per litre, and France to the value of 33 cents per litre.

In his recent pre-Budget report, Gordon Brown reduced the tax on UK blended biofuels from 53 pence per litre to eight pence per litre. In Brazil, although subsidies of ethanol officially ended in the mid-1990s, a number of 'incentives' still exist. Personal diesel-engined vehicles have been banned, to encourage the uptake of ethanol burning models, despite the greater fuel economies of many diesel cars. In addition, new 'flex-fuel' cars - models that can run on both ethanol and petrol - have been made available at a reduced rate of VAT.

Behind this raft of measures, it is difficult to see whether biofuels could ever compete with fossil fuels without continued subsidies, covert or otherwise. It is important to remember exactly what is being subsidised as well - excessive motor transport. As Michael O'Hare, Professor of Public Policy at UC Berkeley, pointed out in a recent article: 'Driving your car with a gallon of ethanol doesn't do fifty cents worth of good for society, it just does less damage than driving it with gasoline'.

Claim Three - It is the solution to our energy problems

Recent figures show that if high-yield bio-energy crops were grown on all the farmland on earth, the resulting fuel would account for only twenty percent of our current demand. The Organisation for Economic Cooperation and Development (OECD) published research which shows that more than seventy per cent of Europe's farmland would be required for biofuel crops to account for even ten per cent of road transport fuel.

But there are more basic reasons why biofuels cannot be the answer to our energy problems. A normal petrol engine cannot run on more than a fifteen per cent ethanol blend, and it is considered too expensive to modify a car after manufacture. Given that the average life expectancy of a vehicle is fourteen years, it would take approximately this long to replace the current petrol fleet. By 2021, however, it could already be too late to make a difference to serious global warming.

The European Union Biofuels Directive requires that all EU member states have a blend of 5.75 per cent biofuel in their road transport fuels by 2010. However, a litre of biodiesel contains twelve per cent less chemical energy than an equivalent litre of mineral diesel, and is five per cent less fuel-efficient when burnt in an engine. A litre of ethanol contains 33 per cent less energy than a litre of petrol, and a blend of 85 per cent ethanol to fifteen per cent petrol (known as E85) can see vehicle fuel consumption rise by 31 per cent. The UK uses approximately 26 billion litres of petrol each year. If this were to be blended with 5.75 per cent bioethanol, the net energy contained in a litre of pump fuel would drop by approximately two per cent. In addition, ethanol blended fuels cannot be transported by pipeline, as the ethanol attracts water, which would render it ineffective as a fuel. It must, therefore, be transported by road. This means that an extra 521.5 million litres of fuel would need to be transported annually to make up for the energy deficit - equivalent to an extra 16,478 tanker journeys in the UK each year, which could increase the carbon emissions involved in distribution from refinery to tanker terminals by 38 percent.

Claim Four - It's clean and safe

The biofuels ethanol and biodiesel are often referred to as 'clean-burning' fuels, and much has been made of their lower emissions of carbon monoxide. However, analyses of exhaust emissions from cars burning ethanol show an increase in nitrogen oxides, acetaldehyde and peroxy-acetyl-nitrate.

Likewise, cars burning biodiesel have been shown to emit higher levels of nitrogen oxides than those burning mineral diesel. Nitrous oxides are powerful greenhouse gases and can lead to the depletion of atmospheric ozone. At low levels they can react with volatile organic compounds (VOCs) and create low-level ozone, which can give rise to urban smog and respiratory problems.

When ethanol is blended with gasoline it makes the entire fuel more volatile. This means that it is more likely to evaporate, especially in the summer, through rubber and plastic parts of the fuel system. A study by the California Air Quality Board in 2004 found that blending ethanol with petrol increased fuel evaporation by fourteen to eighteen per cent. This means a higher quantity of hydrocarbon and nitrogen oxide emissions, as the fuel dissipates from vehicle tanks.

Ethanol is a solvent, and corrodes soft metals including aluminium, zinc, brass and lead. This means that existing underground storage tanks designed for fossil fuels and made from metal or even fibreglass could leak if filled with ethanol-blended fuel, leaching pollutants into groundwater. If this happens there is evidence that pollution would be even more widespread with a petrol-ethanol blend than with petrol alone. The presence of ethanol in the mix increases the persistence of the toxic substances benzene, toluene, ethylbenzene and xylene, and can cause them to travel 2.5 times farther in groundwater than would have been the case with a non-ethanol blended fuel.

Biodiesel is also a natural solvent, whereas mineral diesel is not. This means that parts of the fuel system, particularly in older cars, may start to corrode when biodiesel blends are used. This can lead to a build-up of deposits in the fuel system and engine, which in turn could reduce vehicle performance and increase fuel consumption.

Biodiesel also solidifies at around four to five degrees Celsius. This means that it must be pre-heated on cold winter mornings before it will flow from the tank. One biodiesel information website recommends the use of highly toxic 'anti-gelling' compounds mixed in with the fuel-or a 'heated garage'. It is this kind of solution that typifies the utter dependence of biofuels upon the continuing extravagant use of fossil energy.

Claim Five - It's good for the environment

A bio-refinery is an extraordinarily wasteful facility. For every litre of bioethanol produced in a modern refinery, thirteen litres of waste water are generated. This waste water contains dead yeast and small amounts of ethanol, and has what is known as a Biological Oxgen Demand (BOD) - which means that the effluent competes with various other organisms in the water for available oxygen.

If effluent with a BOD is discharged into a watercourse, microorganisms in the water use oxygen in the water to break down, or oxidise, the pollutants, thus making the oxygen less available for other species. In extreme cases, fish and other aquatic organisms can suffocate from lack of oxygen.

The BOD of raw sewage is around 600 milligrams per litre; that of bio-refinery waste water can be between 18,000 and 37,000 milligrams per litre. This must be treated before it can leave the refinery, which requires an energy input of around 69,000 kilocalories, roughly equivalent to 306.7 cubic feet of natural gas per 1,000 litres of ethanol produced.

In sugarcane ethanol plants, which are particularly common in Brazil, twelve cubic feet of a thick, dark red, acid substance called 'vinasse' is left behind for every cubic foot of ethanol that has been produced. It is piped from the refinery to settlement ponds, where it is allowed to cool. If vinasse is left in the pools, anaerobic breakdown will lead to the production of methane, a greenhouse gas.

Some refinery operators have chosen to dilute vinasse at a ratio of up to 1:400 with water for use as a fertiliser on the sugarcane plantations. But it is so potent that the soil has to be carefully monitored to make sure that plants are not scorched or waterways polluted. Some farmers have used vinasse as a 'binding agent' on gravel drives, only to find that it corrodes the underside of vehicles that frequently drive over it.

Ethanol refineries also produce significant amounts of nitrous oxides (a greenhouse gas more than 300 times more potent that carbon dioxide), carbon monoxide and volatile organic compounds (also linked to the destruction of the ozone layer and damage to human health). Their emissions are so high that in March 2006, the Environmental Protection Agency in the USA was forced under political pressure from the biofuels lobby to propose raising the threshold for facilities considered to be 'minor source of emissions' from 100 tons per year to 250 tons per year.


Mark Anslow is a reporter for The Ecologist. An annotated version of this article is available on our website,

Bill Totten


  • Some very good points are made in the article, but many of the debates are directed towards few sources of biofuels, such as ethanol. What about emerging sources such as jatropha and algae?

    With current biofuels we cannot rid our dependency on fossil fuels, but would the writing not agree that globally we are moving in the right direction in at least experimenting with alternate fuels, combined with pushing for greater efficiency in how we use current supplies?

    Regardless we still need to push conservation to reduce our overall dependency.

    By Anonymous Anonymous, at 8:14 AM, April 10, 2007  

  • Great article. Thanks for the insight.

    By Blogger Unknown, at 12:24 PM, April 11, 2007  

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