Abstract
Although advanced vehicle concepts such a fuel cells and hybrid electric vehicles offer potential for the future, developments of conventional vehicle technology will provide most of our transport needs for the next several decades. The introduction of lower sulphur fuels will help achieve the full potential of new vehicle technologies, whereas changes to other fuel parameters have only a small impact on future emission levels. Alternative fuels do not offer major advantages for widespread use, but are valuable for special applications. The potential of biofuels to contribute to energy supplies and greenhouse gas (GHG) reductions is limited, since the energy input to produce biofuels means that not all the theoretical energy and GHG savings are achieved in practice. If all EU15 set-aside land were used for biofuel production, the energy and GHG savings would be only 1.5% of current transport fuel levels. Considerable uncertainty surrounds calculations of GHG emissions, particularly field N2O emissions and soil sequestration effects, and when these factors are included, actual GHG savings may be even less. Costs of GHG reduction through biofuels appear very high relative to other ways of reducing GHG emissions. Other uses of biomass, such as direct use as a source of heat and power merit investigation, and may give greater benefits. Continued study is needed to provide guidance for future fuel and energy choices.
The conclusions of the paper are:
1. To achieve overall energy efficiency and CO2 reduction, fuel and vehicle need to be considered together in a well-to-wheels analysis
2. Developments of conventional vehicle technology will provide most of our transport needs over the next twenty years. Lower sulphur fuels, as proposed by the European Commission can help achieve the full potential of new vehicle technologies: other fuel parameters have only a small impact on future emission levels.
3. The contribution of biofuels to EU15 GHG reduction and supply diversity is small. {nThe introduction of 5% biofuels (on an energy basis) into the market would at best displace energy equivalent to around 1.6% of gasoline and 2.8% of diesel. The GHG savings would amount to 1.9% of gasoline emissions and 2.9% of diesel emissions. These GHG savings may be substantially less when the effects of field N2O emissions and land change effects are included.
{nThe land needed to achieve these modest savings would exceed the available EU15 setaside land area. {nA focus on efficient use of biomass resources rather than road fuel production could produce larger and more cost-effective GHG and energy savings.
4. Many uncertainties surround estimates of biofuel well-to-wheels balances. Continued study is needed in this area to provide guidance for future options.