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What is ethanol?
Ethanol is an alcohol fuel usually made by fermenting sugar or starch in wheat, corn, sugar beet, sugar cane and other crops. Yeasts feed on the sugars, creating ethanol and carbon dioxide. The ethanol is then concentrated by distillation. Ethanol is seen by many as a replacement for oil and other fossil fuels because it is a renewable energy supply that can reduce reliance on oil imports.
The (purported) benefits of ethanol
- Lower transport-related carbon emissions: When crops are harvested and ethanol is burned in an engine, CO2 is released into the atmosphere – just as it is when oil and other fossil fuels are burned. The difference with ethanol is that as new crops grow, they absorb CO2 from the atmosphere and the overall concentration of CO2 in the atmosphere stays the same. When fossil fuels are burned, the CO2 stays in the atmosphere and the concentration of CO2 continually increases, contributing to global warming.
- Energy security: Because crops for ethanol can be grown over and over, ethanol has the potential to reduce dependence on oil imports and replace dwindling oil reserves.
Unfortunately, there are some serious drawbacks with ethanol. Some of these are listed below.
10 reasons why ethanol fuel is bad for you and the environment
- Lower fuel efficiency: Ethanol has less energy than gasoline. At higher blend levels (including E85) fuel efficiency will be noticeably lower than for gasoline.
- Agricultural subsidies: Although the price at the pump may seem favourable compared to gasoline, this is partly due to incentives and subsidies paid by governments to farmers, especially in the US and Europe. Not only does this mean that ethanol is effectively subsidised by taxation, the subsidies distort markets and hurt farmers in the third world who can’t compete on the world market.
- Deforestation and habitat destruction: Increasing demand for ethanol crops increases demand for agricultural land. Clearing forests to make more cropland destroys habitat and releases large amounts of carbon into the atmosphere.
- Higher food prices: The land needed to make enough fuel for one car could be used to feed seven people. Ethanol producers buy grain in the same global markets that supply grain for food. Increasing the demand for agricultural land and grain increases the price of food worldwide, and this has a disproportional impact on the poorest people in society.
- Increased use of pesticides: As with most modern farming systems, farmers that grow crops for ethanol rely on pesticides that can contaminate soil, water and air.
- Increased use of artificial fertilisers: To increase yields, farmers use artificial fertilisers made from non-renewable petroleum, natural gas and phosphate minerals.
- Soil erosion and declining water quality: Land clearing and cultivation exposes soil to wind and water erosion. Soil, fertilisers and pesticides are washed into waterways where they can affect ecosystems and contaminate water used for drinking, crops and stock.
- Greenhouse gas emissions: As well as emissions from land clearing and the manufacture of fertilisers and pesticides, there are also emissions from farm machinery. The distilling process also uses a lot of energy. At present much of the energy to distil ethanol comes from coal-fired power stations. The overall reduction in greenhouse gases from using ethanol is relatively small and might sometimes be negative.
- Ethanol can only be a small part of the solution: It takes about ten acres of corn to supply enough fuel for one car. It would take the whole land area of the United States to make enough ethanol to fuel all cars in America today.
- Increased water use: Irrigation to grow crops comes from groundwater or streams and this adds to the overall environmental and social impact of ethanol by reducing water available to ecosystems, food farmers and town drinking water supplies.
So the catch is that ethanol isn’t very good at lowering carbon emissions or improving energy security – but it does cause a lot of problems. In some ways, mining of oil has been replaced with mining of soil and water. And the risk of oil spills has been replaced by the risk of denuded soils, declining water quality and soil fertility. It’s no surprise that ethanol from grains has been called “subsidized food burning”.
Fortunately, it might not be all bad news for ethanol. In this post, we only looked at ethanol from grain and sugar. It might soon be possible to efficiently manufacture ‘cellulosic’ ethanol made from crop residues, wood chips and fast-growing energy crops (like switch grass). If it becomes viable, cellulosic ethanol looks like it might be much more sustainable than ethanol from grain and sugar crops.
Another ‘renewable’ liquid fuel source gaining popularity is biodiesel . Biodiesel is a replacement for normal diesel fuel that is made from vegetable oils or animal fats, including used fats from cooking.
We’ll take a look at both cellulosic ethanol and biodiesel in future posts…
UPDATE: New post – The trouble with biodiesel