Liquid biofuel crops

The two main markets are for biodiesel and bioethanol as a petrol substitute. In the UK the main crops grown for these are oilseed rape, cereals, sugar beet and fodder beet. They have the potential to cut carbon dioxide emissions by 50-60% as well as reducing other pollutants such as smoke particles. 

There are no special agronomic requirements of these crops grown for biofuels. Any oilseed rape variety can be used for biodiesel and wheat is the favoured cereal for bioethanol as its starch yield is higher than barley. British Sugar have a bioethanol plant at their Wissington factory which can also use wheat. 

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The assessment of the sustainability of the cultivation of energy crops includes the input and recycling of nutrients, the application of pesticides, the water-use efficiency, the consumption of fossil fuels and the balance of soil carbon. The aim is to recycle the nutrients, which is simple in the case of anaerobic digestion by applying the digestate to the field. If crops are combusted many of the minerals can be returned via the ash. In the case of liquid biofuels, exported nutrients are lost and have to be replaced. The application of pesticides, mainly herbicides, can often be reduced in comparison to food production, but the energy yield per hectare might be reduced if the share of weeds exceeds certain thresholds. Water use efficiency,... 

Energy crops such as short-rotation woody crops, herbaceous woody crops, grasses, starch crops, sugar crops, forage crops, oilseed crops, switchgrass, and miscanthus can be converted to liquid biofuels by thermochemical and biochemical conversion processes. 

Turley, D.B., Boatman, N.D., Ceddia, G., Barker, D., Watola, G., 2002. Liquid Biofuels — Prospects and Potential Impacts on UK Agriculture, the Fanned Environment, Landscape and Rural Economy. Central Science Laboratory, Report prepared for DEFRA, Organics, Forestry and Industrial Crops Division, York, UK. 

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

Since late 2007, the Energy Biosciences Institute in Berkeley has been the center for cooperation between scientists from the University of California and the Agricultural Department of the University of Illinois for the production of fuels from so-called energy crops like switch grass. In this second-generation biofuel project that is financed over a 10-year period with 500 million by oil company BP, biomass is converted with the help of synthetic catalysts, for example, organometallic compounds, in a special solvent medium, better known as ionic liquids, into hydrocarbons with properties close to automotive fuels. 

Biomass can also be converted to a liquid fuel, such as ethanol, which is then used as a gasoline blend. Today, the major biofuel is ethanol produced from corn, which yields only about 25 percent more energy than was consumed to grow the corn and make the ethanol.32 The future holds the promise of ethanol from sources other than corn, dedicated energy crops such as switchgrass, which can be grown and harvested with minimal energy consumption so that overall emissions are near zero (see Chapter 8). 

An alternative to the utilization of food crops in biofuel production is lignocellu-lose, which can for instance be utilized in biomass-to-liquid (BTL) processes. That way, a direct competition between food and fuel production can be avoided. This feedstock is much more abundant than vegetable oils or sugar and starch crops. 

Biofuel Liquid fuels that are most commonly derived from plant material, such as sugar and starch crops (ethanol), or vegetable oils and animal fat (biodiesel) and used as a replacement for or additive to traditional fossil fuels (petrol). 

Apart from biofuels for transport, bio-liquids for heating and electricity, and biomass crops, there are a number of other important uses for industrial crops. These include ... 

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