Pros: Potential to offer large CO2 savings. Already on the market. Certain bio-diesel blends compatible with existing diesel cars. Does not require change to current refuelling infrastructure.
Cons: Today's cars are only guaranteed to run on a maximum of 5% bio-diesel and 95% fossil-diesel. Cultivating the crops for bio-diesel has potential to upset and even destroy natural habitats. Hard to quantify actual CO2 savings.
Bio-diesel is a fuel derived from different types of plant oils, such as palm oil, rapeseed oil and soybean oil. It can be blended with mineral-diesel or used neat, and the advantages are that it reduces CO2 emissions and our dependence on fossil-fuels. The extent to which it does both of these things depends on the amount of 'bio-matter' contained in the fuel. For example, the term 'bio-diesel' can refer to anything from a blend of 5% bio-matter and 95% fossil-diesel, 100% bio-matter and no fossil-diesel, or any mix in-between. Commonly-used blends are B5 (5% bio-diesel, 95% fossil-diesel), B30 (30% bio-diesel, 70% fossil-diesel) and B100 (100% bio-diesel). The warranties of today's diesel cars only allow them to run on B5, however. Indeed, the current European fuel standard for diesel (EN590) can contain up to 5% bio-diesel by volume, and certain fuel retailers (such as two of the UK's largest supermarket chains of Tesco and Morrisons) already sell B5 as standard diesel. Some car companies, notably the French, guarantee their cars and vans to run on B30, although this fuel is not widely available for sale in the UK. The Government's Renewable Transport Fuel Obligation (RTFO) requires that bio-diesel makes up 5% of all road transport diesel by volume by 2010. This could potentially require widescale changes to our agricultural landscape. One significant risk, however, is that tropical rainforest can end up being cleared for this potentially profitable cash crop (some forests have been cleared in Malaysia and Indonesia to grow palm oil for fuel), more than eliminating the CO2 gains and destroying habitats and eco-systems. Friends of the Earth has expressed concern on this issue, saying that the cultivation of palm oil for food has led to widescale deforestation (apparently one in ten products on supermarket shelves now contain palm oil)and they therefore oppose any further expansion in demand for the crop. In response, oil companies say they would use crops from sustainable sources.
