The European Commission has announced its proposals for limiting average new car CO2 emissions to 120 grams per kilometre by 2012. The proposals include fines on car makers who fail to meet the target.

It is estimated that 20,000 people die per year in the UK due to pollution related causes of which vehicle emissions is the major contributor. This compares to around 3,000 road fatalities every year. Climate Change is recognised as one of the greatest threats to mankind, cars account for 1/3 of all climate emissions.

There are two commonly available electric vehicle designs for cars: Battery Electric Vehicles, which convert chemical energy to electrical energy in batteries; and Hybrid vehicles, which convert chemical energy to electrical energy via an internal combustion engine and a generator.

Technology

Electric vehicles use electricity stored in a battery as their primary source of motive power.

A hybrid vehicle has a powertrain incorporating an energy storage mechanism, either electrical or mechanical, which is able to act as a complementary or alternative source of motive power.

Batteries

The battery powered car is charged with a charge cable which plugs into the side of the vehicle and into your mains electricity at home or elsewhere. Electric Vehicles are carbon neutral with zero emissions.

The most popular Electric Vehicle (EV) in the UK is the G-Wiz (seen in picture) with over 900 G-Wiz on the road in London and over 2,000 worldwide.

The G-Wiz is powered by electricity (8 x 6v Lead Acid Batteries) and provides up to 48 miles range on a full charge (typically 35 - 40 miles in normal road conditions), with a certified top speed of 50mph.

If electricity is brought from a regular supplier representing the average mix of electricity production in the UK, CO2 emissions work out at 64g CO2 / km. This is 2/3 less than the UK car average of 176g CO2 / km and around 40g CO2 / km less than the nearest clean hybrid or diesel cars.

Electric motors often achieve 90% conversion efficiency over the full range of speeds and power output and can be precisely controlled.

EV’s are much quieter than a conventional car, minimising local noise pollution.

There will be 200 + charging points for EV’s in London from Spring '08.

To find out more visit www.goingreen.co.uk

Hydrogen fuel cells

Unlike a battery, a fuel cell does not run down or require recharging. It will produce energy in the form of electricity and heat as long as fuel is supplied.

A fuel cell consists of two electrodes around an electrolyte. Oxygen passes over one electrode and hydrogen over the other, generating electricity, water and heat.

Since the fuel cell relies on chemistry and not combustion, emissions from this type of a system would still be much smaller than emissions from the cleanest fuel combustion processes.

Fuel cells run on hydrogen, the simplest element and most plentiful gas in the universe. Hydrogen is colorless, odorless and tasteless. Hydrogen is the lightest element, yet it has the highest energy content per unit weight of all the fuels. Hydrogen is always combined with other elements such as oxygen.

Because hydrogen is such a light gas, it is difficult to store a large amount in a small space. That is a challenge for auto engineers who want to match today's 300-mile vehicle range.

The first public hydrogen refueling station was opened in Reykjavík, Iceland in April 2003. The station produces all the hydrogen it needs, with an electrolysing unit, and does not need refilling: all that enters is electricity and water.

Image: Shell Hydrogen’s Reykjavik fuelling station uses an onsite electrolyser powered by Iceland’s early unlimited geothermal resources.

Fuel cell vehicles have a similar performance to vehicles with internal combustion engines and are not as limited in range as most battery electric vehicles.

Fuel cell vehicles can be either 'pure' or 'hybrid'. The hybrid design includes a battery for peak power loading. This enables the vehicle to use regenerative braking which can reduce fuel consumption by up to 20%.

Most fuel cell designs are fragile to freezing conditions and cannot survive in such environments at startup but since heat is a byproduct of the fuel cell process, freezing conditions are not a problem once it is running.

When fuelled directly by pure hydrogen fuel cell vehicles emit only heat and water vapour. However, energy is used to produce the hydrogen, so in order to be carbon neutral the hydrogen should be produced using a renewable energy source such as wind or solar. Hydrogen can be derived chemically from a feed stock, such as methanol, but can also be produced electrochemically from water, currently this process is quite inefficient so costs are high.

Costs

At present fuel cell vehicles are not yet commercially available, although most vehicle manufacturers have fuel cell programmes and believe these vehicles will outsell other vehicle types in the next 15 years.

Fuel cells are much more expensive to produce than conventional engines, it is estimated that manufacturing costs need to fall by 10-30 times in order to be commercially viable.

Scientists are studying how to produce inexpensive fuel cells that are robust enough to survive the bumps and vibrations that all automobiles experience.

In order to distribute hydrogen to cars, the current fossil fuel fueling system would need to be replaced, or at least significantly supplemented with hydrogen fuel stations.

The electirc G-Wiz car mentioned above costs from £8995. It is believed that the savings made from purchasing an electric car over a conventionally fuelled car are:

• £500 - £1000 on fuel for 4,000 miles a year. This would cost £40-£50 in a G-Wiz in electricity - less than the average price of a tank of petrol.
• Free road tax
• Group 1, the lowest insurance category

For the G-Wiz 80% charging capacity is reached within 2 1/2 hours. A full charge takes 8 hours, uses 9.6kWh of electricity and costs about 50p depending on the electric tariff, equalling about a penny a mile to drive.

Image: Ford Hydrogen Fuel Cell at the Eden Project’s Green Car Show, Cornwall.

The Future

Nissan and Renault, who make up the fourth largest car making alliance, say they plan commercial sales of electric cars using lithium ion batteries by 2012, while Honda introduced the fuel-cell powered FCX Clarity at the Los Angeles International Auto Show. Honda's first production version of the FCX Clarity will be available to retail customers in the US next summer. Initially, the cars will only be available to customers in Southern California in areas where hydrogen filling stations are available. The technology is particularly suitable in the US where78% of cars do less than 40 miles a day - well within the range of electric power - and where off-peak, overnight supplies of electricity are abundant and cheap.

New breakthroughs in storage technology could remove a key barrier to the adoption of cars running on hydrogen. UK scientists have developed a compound of the element lithium which may make it practical to store enough hydrogen on-board fuel-cell-powered cars to enable them to drive over 300 miles before refuelling. Achieving a greater driving range is considered essential if a mass market for fuel cell cars is to develop in future years. This has not been possible using current hydrogen storage technologies.

Image: An electric car that moves. Powered by lithium-ion batteries, the Eliica is an 8 wheeled vehicle that goes from 0-60 mph in just 4.2 seconds and tops out at 230mph (Source: www.gadgetreview.com).