One of the main criticisms of the first-generation biofuels is that they appear incap­able of supplying the large quantities of transport fuels required without compromis­ing food crops. The first-generation biofuels were not intended to completely replace fossil fuels but rather to demonstrate that alternative fuels could be used in the inter­nal combustion engine and for electricity generation. Any calculation of the land required to replace 100% fossil fuel would indicate this. It was the development in the second and third generation that was intended to supply the bulk of the fuel. In addition, the introduction of some new fuels may require the installation of a new infrastructure which will take some time to install. The sustainable systems for elec­tricity generation such as wave and wind power can be integrated into the current electricity supply systems, but the introduction of new transport fuels will incur high costs if these fuels are not compatible with current supply infrastructure. To be com­patible with present infrastructure, the non-fossil fuels should be liquid as this fits the engine technology and supply systems. Gaseous fuels such as hydrogen and DME will require either the introduction of a new infrastructure or significant modification of the present systems. Once the first-generation biofuels were shown to be suitable for present engine technology their introduction was driven by the legislation produced under the Kyoto Protocol for carbon dioxide reduction.

The primary sources of transport fuels are all agricultural crops such as wheat and maize, apart from wood, woody and organic wastes, and many of these are food crops. Therefore, a conflict may occur between food and fuel crops.

The yield of fuel obtained per hectare varies depending on the crop, growth conditions, and climate. The yields of oil for biodiesel range from 5000 t/ha for oil palm to 1000 t/ha for rapeseed and 375 t/ha for soybean, which is mainly grown for its protein content. A number of studies have been carried out on the effect of biofuel crops on agriculture (Azar, 2005; Johansson and Azar, 2007). The detrac­tors of biofuels have perhaps been too simplistic in their approach to biofuels, and as a consequence biofuels have been blamed for food shortages and increases in food prices (Johansson and Azar, 2007). The adoption of large-scale production of

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first-generation biofuels has been recognized as having some unfortunate conse­quences in addition to their obvious advantages (OECD, 2007). The consequences are mainly the conflict between the growth of food crops and those for biofuels. This has been suggested as the reason for the shortage of certain foods and the rise in the price of others. However, food prices on a large scale are subject to a large variety of factors so that the reasons for price rises are complex and cannot be solely due to biofuels.

Producing biofuels on a large scale will require large land areas in countries where the land is required for food production. In two scenarios produced by the Inter­national Food Policy Research Institute (IFPRI), they predict that the price of maize and oilseed will increase by 26 and 18%, respectively, if the production of biofuels continues as currently planned. If biofuel production doubles, the price of maize would increase by 72% and oilseed by 44%. This increase in food prices would affect the poor populations who spend a higher proportion of their income on food. The use of non-food-producing land is the obvious solution to this problem but the yields on poor land will naturally be reduced. If the price of biofuel crops exceeds food crops, farmers will plant energy crops on normal agricultural ground. The outcome, at least for the US markets, will be that farm gate prices for all crops will increase substantially with a doubling of wheat prices. Increases in the farm gate prices are predicted not to affect food consumption as the price is low compared with commodity prices. How­ever, if biofuels are produced from lignocellulose the increase in the value of lignocel — lulose crops may stimulate the use of marginal land for non-food crops. Thus, the development of second and third generation biofuels needs to be pursued with some urgency to avoid conflict with food crops.

In order to reduce carbon dioxide emissions, carbon tax and trading schemes have been introduced, for example, €90/t carbon in the EU. However, once biofuel crops reach a certain price, driven by the carbon tax, commercial growers will use the most productive land for biofuel crops, replacing food crops. The conclusion was that at a carbon price of US$70/t carbon energy crops will dominate other agricultural options (Johansson and Azar, 2007).

To supply anywhere near the total requirement for liquid fuels either globally or in the UK will require the introduction of a mixture of fuels and propulsion systems coming from multiple sources rather than a single source. Perhaps one answer would be to stop using liquid fuels, abandon the internal combustion engine for alternative power sources such as fuel cells, and electric motors. However, liquid fuels are sup­ported by a vast infrastructure and industries which supply all the various compo­nents and employ a large number of people. Any change from our present position on fuels will need time, legislation and money and should go through a number of intermediate stages. A fossil fuel such as diesel may still be required for some time, as it is the motive force for the largest transport systems such as ships and trains, but we need to act now to mitigate the problem of global warming and fuel supply.