黑洞社区

However what must equally not be forgotten is the comparison of the quantities of fuels consumed with the quantities of biofuels that can be produced in the UK, always bearing in mind that we ought to grow as much food locally as is possible. This kind of comparison suggests, for instance, that rapeseed oil should be reserved for transport.

In 1999, the basic statistics relating to building energy use, excluding electricity, were: available arable land for fuel and food production, 6.4 Mha; Oil and gas equivalent used in buildings, 65 MTe; arable land needed for 65 MTe rapeseed oil, 65 Mha; arable land needed for 65 MTe willow coppice, 15 Mha.

Basically, the UK is overpopulated by a factor of more than three for food production and nearer six for sustainable biofuel plus food. Bearing this in mind, the GLA鈥檚 鈥�10%鈥� for buildings, often thought of as a start point, should be considered close to the current realisable maximum, and be constituted wherever possible from waste, solar or wind. The rapeseed oil is needed for transport.鈥�

John Moss, consultant to Arup R&D

Andrew Robertson responds

John Moss鈥檚 comment concerning the need to compare quantities of fuel consumed against our ability to grow both food and energy crops is correct. However, I disagree that the figures support his claim that oilseed rape should only be used as a transport fuel.

The 2004 Defra agricultural census suggests the total arable land including set aside land is around 6.4 MHa. The government鈥檚 2010 鈥淕reen Fuels Obligation鈥� commits the UK to replace 5% of transport fuel with biofuels, which will require 2.57 billion litres of biodiesel according to the DoT鈥檚 Partial (RIA) Biofuels report. The amount of arable land required to produce 2.57 billion litres of biodiesel based upon DEFRA鈥檚 oilseed rape yields is 2.0 MHa of arable land 鈥� around 30% of UK arable land. If all the 560,000 Ha of set aside land was used to produce 726 million litres of biodiesel and the current 100 million tonnes of waste vegetable oil was made into 113 million litres of FAME biodiesel, this would still leave a balance of 1.73 billion litres of biodiesel produced from oilseed rape grown on 1.3 MHa of arable land, based on DEFRA鈥檚 yields.

Considering domestic heating oil demand, It is possible that B20 biodiesel could become a future domestic heating biofuel. This market consumes around 2.7 billion litres/year of kerosene. Assuming 113 million litres of FAME biodiesel is used as B20 heating biodiesel, the amount of additional biodiesel required to supply the B20 biodiesel heating market will be around 427 million litres from oilseed rape grown on 0.33 MHa of set aside arable land, or around 5% of arable land.

Currently, Defra does not allow food crops to be produced from set aside land, therefore B20 heating oil produced from waste vegetable oil (FAME biodiesel) and 0.33 MHa of oilseed rape grown on set aside land will not impact on the food industry as suggested by John Moss.

The bulk of transport biofuels consumed in the UK over the next few years will probably be imported to reduce the food crop impact. I鈥檝e demonstrated that B20 biodiesel heating oil can be produced without any need to import, which supports UK farming and the UK economy as a whole.

Andrew Robertson MIDHEE (andrewrobertson@cleanenergy.wanadoo.co.uk)