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Cleaner Fuels

Global Transport and the Environment

In 1994, world motor vehicle numbers were estimated at 750 million. Recent projections indicate they will reach 1 billion by 2006, having become an integral and essential part of modern life.

They are also a major source of air pollution. We have to face the fact that motor transport poses serious problems in terms of our environmental well being. Most countries, aiming to pump less pollutant into the air, need to control the exhaust emissions of vehicles.

If vehicle users will not or cannot walk, cycle or use public transport, the only other option is to change vehicle technology to reduce emissions. This can be done by making vehicles more fuel-efficient, or by using non-polluting fuels.

Why Alternative Fuels?

In the UK, road transport creates around 20% of the C02 (carbon dioxide) that we release. There are many ways to improve C02 emissions apart from just choosing more fuel-efficient vehicles. 25 years of technical advances has already led to the introduction of unleaded fuel and catalytic convertors but this is not enough.

EU emissions directives have resulted in the elimination of the most harmful emissions (around 90% of hydrocarbons, carbon monoxide, nitrogen oxides and low-level ozone) from new petrol engine vehicles.

Despite this, without further measures it is estimated that by 2010 emissions will once again begin to increase - driven purely by traffic growth.

In August 1996 the UK Government admitted people are being killed by air pollution from traffic, particularly from diesel vehicles. Maximum concentrations for eight known cancer-causing or lung-affecting pollutants were reported. Up to 25 people a day were dying as a result of minute particles in air, mostly from vehicle exhausts.

Since then the Government Car Service stated that it will be converting or changing its fleet of 160 cars to alternative fuel. In looking for low emission vehicles, we do not have to wait until the next millennium.

Most government action plans include a requirement to have a percentage of certain types of vehicles, e.g. city centre buses and taxis, operating on alternative fuels within an agreed time span. Much can be accomplished by using alternative fuels.

Fuels Available

Alternative fuels all have advantages and disadvantages when compared with petrol and diesel.


Many sing the praises of electric vehicles, especially for city centres. The electric car itself gives zero emissions. But when you consider the electricity has to be generated at a power station, then transferred by charging the batteries, the overall emissions are not so favourable. The only benefit is that the emissions are at least produced away from city centres.


Hydrogen has been called ‘the fuel of the future’. Due to storage and refueling problems, perhaps it always will be! At least until water (H2O) can be split into Hydrogen and Oxygen cheaply and efficiently.

Natural Gas

Natural gas, the ‘cleanest’ fossil fuel, represents an attractive alternative thanks to the absence of impurities and residual combustion products.

Natural gas has become accepted in many parts of the world as the third most popular vehicle fuel. However, globally natural gas accounts for only 0.2% of vehicle fuel used.


Autogas is the name applied to Liquid Petroleum Gas (LPG) when used as vehicle fuel. The same gas is often used in rural areas for cooking and central heating.

There is nothing new about gas-powered vehicles - some of the earliest stationary internal combustion engines were fuelled by gas. During the Second World War, vehicles could be seen with a large box shaped balloon on the roof containing coal gas (also called town gas). During the post war years, the ready availability of petrol reduced the need for gas.

Happily, nowadays the gas technology does not rely on a giant balloon on the roof! The gas is stored under pressure in liquid form, in purpose-made tanks. Being liquid under high pressure gives Autogas an advantage over Natural Gas, which only turns liquid at extremely low temperatures. Therefore, with Autogas, more fuel is stored in the same weight and volume than with Natural Gas.

LPG for automotive use is normally a mixture of propane and butane in equal proportions, although some countries, depending on ambient temperatures, use different ratios. In the UK it is mainly propane: Autogas demand is small compared with industrial and domestic use so tankers deliver the same gas mix to all supply outlets.

Autogas Emissions vs Diesel and Petrol

Autogas is very much cleaner when compared with diesel.

Nitrogen dioxide (No2) emissions from Autogas are less than a tenth of the level of diesel emissions.

Particulate emissions from Autogas vehicles are almost eliminated compared to diesel engines – less than 6% of diesel levels. Recent studies show that particulates contribute towards 10,000 deaths every year in the UK. This is now the most harmful exhaust emission, only subject to legislation since 1993. These particulates are actually visible – they cause the haze on a hazy sunny day.

Autogas emits significantly less carbon monoxide (CO) and hydrocarbons (HC) than petrol.

Countries already switched on to LPG

The New Zealand Government started the alternative fuels initiative with a grant scheme. The vehicle owner received a grant that was a substantial proportion of the conversion costs. As a result, around 57% of current LPG usage in New Zealand is for automotive use.

The largest consumer of LPG for vehicles is Japan, which uses over 1.8 million tonnes annually. Not surprising for a country with such a high population density. Over 90% of all the taxis in Japan run on Autogas. A stringent NOx (Nitrogen oxides) limit in designated areas of major cites promotes the use of alternative fuels. The aim in Japan is to have 2,000 service stations selling ONLY alternative fuels by the year 2000.

Running on Autogas

Autogas benefits:
  • Autogas enters the engine as a gas, which burns more evenly than a liquid, and results in quieter and smoother performance than petrol.
  • Autogas is clean burning, containing no additives or contaminants to cause build up on spark plugs.
  • Unlike petrol, Autogas has no corrosive impurities associated with it.
  • Using Autogas there is no washing away of upper cylinder lubricants during the enriched starting and warm up period.
  • This increases engine life and reduces running costs.
  • Autogas is 100% lead free and combusts cleanly. Greenhouse gas and toxic emissions are far less than with traditional fuels.
  • Autogas can be conveniently stored as a liquid. This liquid expands about 250 times when it becomes a gas, so that a large quantity of fuel can be stored in a relatively small space.
  • Autogas gives more power than diesel over a much wider range.
  • Overall, Autogas is much quieter and maintenance is a great deal cheaper.
Autogas in the UK Now

UK businesses have changed their attitudes recently as commercial rewards for good environmental practices have been prioritised. Increasingly, it is the polluter who is required to pay for damage caused, so for many companies there are financial advantages from choosing a greener route:
  • Taxation on conventional fuels is planned to increase by at least 6% above inflation for the foreseeable future.
  • Preferential rates have been introduced for alternative gaseous fuels, which burn cleaner and create less pollution.
  • A new system of vehicle excise reduction for smaller, fuel-efficient cars (and commercial vehicles that can meet stringent emission standards) has just been introduced.
Such incentives provide many companies with sufficient justification to switch from petrol or diesel to Autogas.

As it costs nearly 50% less than petrol and diesel, changing to Autogas not only helps the environment, but can also help companies and individuals save thousands of £'s in fuel and taxes.

LPG Association web site

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