Direct Injection

The first improvements manufacturers concentrate on are inefficiencies in fuel combustion. Direct injection technology has produced cars that can travel a third further for the same amount of petrol, which means less output of carbon dioxide and this is achieved with 10% more power. Ultralean air/fuel mixture of 50/1 compared with 14.5/1 in conventional engines make this possible. New catalytic converters have to be developed however to cope with these systems since the production of NO_x's is increased.

Liquid Petroleum Gas

Liquefied Petroleum Gas is obtained through the distillation of oil from crude oil and from "wet" North Sea gas and contains no lead. When it is pressurised it becomes a liquid and in this form is pumped into the fuel tank. The major constituent for LPG is propane whereas compressed natural gas (CNG) is predominantly methane.

In the UK the traditional fuels at the petrol station are still the familiar 4 star, unleaded or super unleaded and Diesel. We are not perhaps as aware of the fuel alternatives that exist as other countries, which may be surprising since the UK government is in favour of LPG and in the 1998 budget, excise duty was raised on every fuel except LPG.

It is interesting to know perhaps that a litre of LPG will set you back 30p compared with unleaded petrol at 70p so maybe it will become more popular. Currently there are only 150 LPG "filling stations" nationally but since cars can run on both LPG and petrol at the flick of a switch, this may not be such a problem.

Almost 7% of all Dutch cars run on LPG, which is about 380.000 private and business motorists and over 75,000 Natural Gas Vehicles are on U.S. roads. NGVs have a long-established record in Europe, Canada, New Zealand and Australia, as well. Italy has been using natural gas as a transport fuel since the 1940s, with more than 300,000 NGVs. In Canada, nearly 40,000 NGVs operate with a network of 125 public fuelling stations. Argentina has over 400,000 NGVs, and Russia has more than 200,000, with plans to convert one million vehicles by the end of this decade. Japan predicts the number of NGVs will increase to 200,000 by 2000. World-wide over one million NGVs are in use, in countries now including Uzbekistan, Venezuela, Mexico, the Philippines and Indonesia.

Benefits & Issues of LPG/CNG systems

• If LPG is installed properly, carbon monoxide emissions can be reduced by up to 80% less than petrol and 40% less than diesel.
• Hydrocarbon emissions are around 60% less than petrol and 50% less than diesel
• NOx emissions are around 80% less than petrol and 90% less than diesel.
• The life of the engine is also extended as a result of the absence of acids and carbon deposits.
• The system used for filling is 'closed', therefore fuel spillage and the resulting ground pollution associated with filling stations is not an issue.
• LPG easily and instantly mixes with air so that combustion efficiency is at its peak the minute the engine is started unlike petrol engines.
• For short trips involving a cold start, LPG is preferred by far over petrol. The results of a study carried out by Renault in May 1993, show the reduction of harmful exhaust fumes:
  reduction of carbon monoxide (CO) 94%
  reduction of hydrocarbons (CH) 88%
  reduction of nitrogen oxides (NOX) 75%
• Dedicated NGVs also can reduce carbon dioxide exhaust emissions by almost 20 percent

Biofuels

The most important difference between normal fossil fuels and biofuels is that biofuels are renewable. Plus the carbondioxide (CO₂) produced by burning biofuels in theory doesn't actually add to the CO₂ present in the earth's atmosphere because the plants used to make the fuel have already absorbed enough CO₂ during their lifetime to balance the output. In addition fuels can be used in most modern diesel engines without modification. Biofuels is the general term for vegetable oil fuels and is produced from oilseed crops. These fuels are used as diesel substitutes or extenders but not petrol. In certain areas of France the diesel fuel sold in service stations is mixed with up to 30% rapeseed oil. In Austria rapeseed oil is used extensively to power agricultural tractors whereas in Switzerland it is used to run some city buses. Most of these types of fuel have been in use in some form over a long period of time but major improvements need to be carried out if they are to be introduced on a larger and more significant scale.

• There are no sulphur dioxide emissions from biodiesel, since biodiesel does not contain sulphur.
• Soot emissions from biodiesel are 40-60% less
• Carbon monoxide and hydrocarbon emissions are cut by between 20% and 60%. Biodiesel does not however reduce NO_x's

Several companies in Europe are building Biodiesel plants; each of these plants will produce up to 5.7 million litres (1.67 million gallons) of fuel per year.

Solar Power

Currently it does not appear that we will be racing around in solar powered cars. Photovoltaic (solar) cells produce too little power and are not practical to run a full- sized car. It is possible that some photovoltaics could be used to help charge the batteries of electric cars but even this would be insufficient to provide fully charged batteries. Although some cars have been manufactured these have been specifically for solar powered racing events. As extremely light vehicles, generally less than 180kg (400lb) these vehicles are not strong enough to be in traffic, are pretty uncomfortable since the driving position is almost horizontal and they tend not to be particularly manoeuvrable.