Road transport in the UK and elsewhere relies almost exclusively (~98%) on oil for energy. This results in significant emissions of greenhouse gases, which are rising as a function of an increased vehicle fleet and higher annual mileage. Although different grades of fuel are available, almost all fuel used in the UK is either petrol or diesel. Alternative fuels occupy only a small portion of the market (1-2%). (1)
There are a range of fuels that could potentially be used to power vehicles:
- Battery vehicles and some hybrids that require electricity
- Biofuels can be introduced either as blends in current fuels and used in current vehicles and hybrids, or potentially as pure fuel with small vehicle modifications
- Hydrogen is required for fuel cell vehicles and could also be used in internal combustion engines
There are different types of biofuels (2):
Biodiesel. Crop oils including oilseed rape, sunflowers and soybeans, as well as from waste cooking oils. Environmental Benefits: Depending on the production method and source, it is generally accepted that biodiesel gives a maximum of 60% carbon dioxide reduction, which means a 3% reduction in a 5% blend. Potential Impacts: Using 100% biodiesel can potentially create problems with engine performance, unless the vehicle has been modified to use this fuel. Current Use: Biodiesel is currently in use in the UK and production is primarily from esterification of waste vegetable oil and rapeseed. Britain’s first large-scale biodiesel plant opened in Scotland in March 2005, with the capacity to produce 50 million litres of biodiesel per year from waste cooking oil and animal fats. Outlook: In the longer term, biofuels are likely to come from sources such as wood, grass, straw and even organic waste materials in the form of second generation biofuels.
Bioethanol. Generally produced from starchy crops like wheat, sugar beet, sugar cane etc. In theory, it can be made from virtually any organic substance (grass, wood, green bits of municipal solid waste), but the technologies for doing so are not proven at commercial scale. Bioethanol is generally used as an additive (up to 5%) in petrol. As with biodiesel, it can be used at higher blends, but not without some, relatively cheap, vehicle modifications. Emissions: Emissions from bioethanol blends are generally slightly lower than from petrol, except for NOx emissions, which may be slightly higher because of the higher combustion temperature of oxygenated fuels. Environmental Benefits: Carbon dioxide savings can be achieved through the use of biofuel, with ethanol from wheat straw giving the biggest savings of up to 90% compared to petrol. Potential Impacts: As with biodiesel, there are growing concerns that a drive to increase the production of bioethanol worldwide will lead to increased deforestation, reduced food stocks and land converted from food to fuel production. This would have devastating impacts in countries already experiencing food shortages and environmental degradation. Current Use: Ford and others are already producing ‘E85 flex-fuel vehicles’ which can run on any petrol containing anything from zero to 85 per cent ethanol. The supermarket chain Morrisons opened the first 10 bioethanol refuelling stations in March 2006. Outlook: Plants to supply a total UK annual capacity of over 450 million litres of bioethanol— equivalent to 1.75% of 2005 total petrol sales—are either already under construction, or in the planning process.
Pure Plant Oil. Pure Plant Oils (PPO) are made by crushing and filtering oil-based crops such as rapeseed, palm or nuts. Emissions: All emission levels are generally lower than for fossil diesel. The only parameter which in general is unchanged is the NOx emission.
Environmental Benefits: Depending on the production method, Pure Plant Oil gives a greater carbon dioxide reduction than biodiesel. PPO contains no traces of carcinogens (benzene) and heavy metals, such as in conventional diesel fuels.
PPO is a fuel that UK farmers can grow and refine to fuel grade quality and therefore has potential benefits for the economies of rural areas. Potential Impacts: Currently in Europe however, the majority of PPO adapted vehicles use rapeseed oil which is produced in Europe and are therefore not relying on crops such as palm oil or soya which are often grown in cleared areas of biologically diverse tropical forest. In addition, the by products of PPO production can be used as high protein animal feed, thereby reducing the need to import protein from abroad. Current Use: Pure plant oil technology is used all over the EU but most specifically in Germany, where many cars are converted to run on PPO and there is also an established refuelling network. Outlook: Pure Plant Oil is highlighted as a potential contributor to the Renewable Transport Fuel Obligations.
A Renewable Transport Fuel Obligation (RTFO) is being considered as an instrument to increase the use of renewable transport fuels by road transport in the UK. The short term objective of an RTFO will be to ensure that biofuels constitute 5% by volume of all fuel being sold on UK forecourts by 2010. The RTFO expects to reduce the carbon emissions from road transport in 2010 by about 1 million tonnes which is equivalent to a 2-3%
reduction in the current levels of carbon emitted from road transport.
For biofuels to have a significant impact on reducing carbon emissions, domestic production is critical yet there is debate as to whether UK agriculture’s spare land capacity is sufficient to supply for the forthcoming biofuel demand. If 100% of the UK obligation were to be produced domestically it would involve approximately 20% of UK arable land – 1.2 million ha of 5.9 million ha (UK arable land 2004). This figure does appear high and such figures have been used to undermine UK ability to supply for this market and raises concerns that biofuel production will divert agricultural production away from food crops.
However, the UK agriculture market is currently not at productive capacity. The projected extra land required to meet the 5% RTFO is in the region of 900,000 ha. The UK has a current average exportable wheat surplus of 375,000 ha (or 3 million tonnes) and mandatory set-aside of 559,000 ha. If this land was used for biofuel production (934,000 ha in total) it could provide more than the 5% required as well as producing a significant amount of animal feed / biomass.
- Hart, D., A. Bauen, et al. (2003). Liquid biofuels and hydrogen from renewable resources in the UK to 2050: a technical analysis. An assessment of the implications of achieving ultr-low carbon road transport, UK Department for Transport.
- Francis, A. and H. Bell (2008). The Impact of Transport. Sustainable Transport Report. Wallington, BioRegional Consulting Ltd.