Currently more than 40 per cent of the US corn crop goes into producing ethanol, which is mostly mixed with gasoline to fuel conventional cars. Even though this raises food prices and reduces the US surplus that can be sold on world markets, the ethanol industry is supported by a $6 billion subsidy scheme aimed at cutting greenhouse gas emissions. In Europe, biofuels are similarly supported with ‘environmental’ subsidies and fuel mandates. All these supports and promotion schemes for liquid biofuels should be scrapped, because of overwhelming scientific evidence that using land to produce energy crops delivers no climate benefits at all once agricultural emissions and land-use change are taken into account. This is obvious in the most egregious example of all: the clearing of tropical rainforest in Malaysia and Indonesia for oil-palm plantations, at least a third of which are used to produce feedstocks for biofuels (the rest goes into processed food, from chocolate to cooking oil, and cosmetics). Overall, 1.7 million hectares of Indonesian forest were converted to oil-palm plantation between 1990 and 2005, and the rate of destruction is accelerating. Scientists have calculated that the burning of peatland rainforest to free up land for plantations churns out more than 1,500 tonnes of carbon per hectare. Biofuels derived from cleared rainforest land should not just be discouraged – they should be outright banned.
Estimates of future land take for biofuels production range up to well over a billion hectares globally, more than double the 400 million hectares that remain if we are to respect the proposed planetary boundary. Once the need to produce more food is taken into consideration, it is clear that biofuels can only ever be a marginal contributor to world energy supplies. This conclusion has important implications. Most critically, liquid fossil fuels used in the world’s vehicle fleet of cars and trucks cannot simply be replaced with liquid biofuels. Instead, surface transport must be almost entirely converted to electricity. This is starting to happen already: all-electric cars or plug-in hybrids are beginning to hit the mass market, and will be particularly appropriate for urban or suburban drivers where the limited range of current battery technology is less of a concern. In the medium to long term, however, countrywide electrical-charging infrastructure will need to be built that allows electric cars to deliver all the range and refuelling convenience of petrol vehicles.
The only likely exception to the rule against biofuels in transportation is the urgent need to decarbonise air transport, where low-carbon alternatives to liquid hydrocarbon fuels remain a distant prospect. Whilst aviation has been demonised by environmentalists (myself included) in the past because of the climate-change impact of aircraft emissions, in terms of fuel efficiency per passenger kilometre the latest large aircraft like the Airbus A320 and the Boeing 787 now compare favourably with small family cars. The reason why per capita emissions from an intercontinental flight are counted in the many tonnes of CO2 is the enormous distances covered: no one drives from London to Sydney.
Therefore, with over 2 billion people using air travel every year already, and rapid uptake in developing countries like India and China, technical substitutes for high-carbon aviation must rapidly be found. If they can be sourced fairly sustainably, biofuels look promising, particularly ‘second-generation’ biofuels like algae that do not directly compete with food crops. (pdf) British Airways has led the way with its pioneering commitment in February 2010 to build a plant in the UK that will convert 500,000 tonnes of waste material into 16 million gallons of jet fuel annually. This may seem like a large amount, yet it represents only about 2 per cent of flights from London’s Heathrow Airport. This is the scale challenge of aviation, and demonstrates why biofuels may need to be almost exclusively reserved for air transport.