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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.
Battery
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
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
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. |
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