| Oil | | | | such as windfarms. |
| The main criteria of a car's eco-friendliness is generally | | | | Electric cars are not subject to road tax and, as an |
| seen as the energy it uses in its operation. Cars have | | | | added bonus for London drivers, they enjoy 100 per |
| primarily run on oil-based fuel in the form of petrol or | | | | cent congestion charge discount. Drivers living in areas |
| diesel for over a century. But we are now at the point | | | | where they have to pay for residential parking permits |
| where demand for oil is rising so much, and reserves | | | | might also find that they get a discount on this cost. |
| are declining, that oil is actually running out. Oil prices | | | | Electric cars are often regarded as the ideal |
| have always been volatile and they react to | | | | non-polluters, but it's not quite that simple. They're |
| speculation about events ranging from terrorism to | | | | obviously good for lack of tailpipe emissions and are |
| hurricanes, but rising demand and diminishing reserves | | | | near silent, but they need to carry rechargeable |
| mean that overall, oil is just going to keep on getting | | | | batteries. These batteries are not really energy |
| more expensive. However despite this, most cars | | | | sources, they are energy storers. This creates two |
| today still rely on oil as their primary source of energy; | | | | issues. Firstly they are heavy and bulky with very low |
| and oil is obviously a key contributor to carbon | | | | energy densities. Secondly, the original source of |
| emissions, and climate change. | | | | energy, for recharging, has to be questioned, because |
| Petrol | | | | if it's not renewable, those vehicles will indirectly |
| Petrol has been the most popular fuel for cars in the | | | | contribute to climate change. There is a further |
| UK for years; petrol engines are generally quiet and | | | | drawback; if their batteries are lead or cadmium-based, |
| smooth, they are responsive and their performance is | | | | there is a serious pollution problem if they are not |
| good. Petrol is currently slightly cheaper than diesel. | | | | properly disposed of at the end of their life. |
| Petrol engines emit around 10% more carbon dioxide | | | | The only electric car available in the UK at the |
| (CO2) than diesel. However petrol cars pump out less | | | | moment, although this is about to change, is the G-Wiz, |
| toxic emissions than diesel. Unfortunately at the | | | | a small car for about-town use, claimed to be the |
| moment there is no single source of fuel which can | | | | greenest, most energy-efficient and cheapest car to |
| compare with petroleum in terms of its instant bulk | | | | run in the UK. It has two front seats plus two children |
| availability, energy density and (relative) cheapness. | | | | size seats, which can be folded down for luggage. It is |
| Diesel | | | | in insurance group 1, exempt from VED and the |
| Diesel engines are more economical than petrol | | | | London Congestion Charge, and qualifies for free or |
| engines, therefore they emit less CO2. New 'common | | | | discounted parking in some London areas. The G-Wiz |
| rail' diesels are approximately 10% more efficient than | | | | is claimed to consume just one quarter of the energy |
| older diesels, and direct-injection diesel engines give the | | | | of a similar-sized petrol car and costs around just |
| best fuel economy, diesels emit more particulates than | | | | £1.64 a day to run, equivalent to around 600 |
| petrol - but diesel engines with a particulate trap help | | | | miles per gallon. |
| prevent emissions of sooty particulates - ie. the clouds | | | | Goingreen, the company behind the G-Wiz, should be |
| of smoke that you'll experience if you follow old buses | | | | commended on their efforts in bringing such a vehicle |
| through towns. So diesel engines will generally provide | | | | to the market, and for some people, in the centre of |
| you with more miles per gallon than their equivalent | | | | London for example, it can provide motoring with very |
| petrol models - just look at the differences between | | | | low running costs. However it's not practical for |
| similar vehicles in our Green Car Guide. Diesel is | | | | everyone - its drawbacks include the fact that it needs |
| currently more expensive to buy than petrol, and the | | | | a 6 hour recharge - you literally need to plug it in! - and |
| forecasts are that diesel prices will continue to rise | | | | its range and speed are limited. Apart from all that, its |
| more steeply than petrol in the near future. | | | | design is just not as cool, trendy and sophisticated as |
| Diesel engines have always been seen as slow and | | | | cars such as the Smart or even the Toyota Aygo. |
| noisy, however technology has seen some remarkable | | | | In summary, viable electric vehicles are still around the |
| advances in recent years; for instance Honda has | | | | corner while hybrids, bio-diesel and bio-ethanol vehicles |
| developed their own diesel engine that is designed to | | | | are here now. |
| be quiet, refined, clean and with instant response - | | | | Biofuels |
| fighting against all the old stereotypes. | | | | Biodiesel |
| LPG | | | | Biofuel has traditionally been in the form of biodiesel, |
| Over recent years, LPG (liquefied petroleum gas) has | | | | currently available in various types and qualities, |
| been a viable fuel option in the UK. LPG produces | | | | primarily from vegetable oils, such as from recycled |
| fewer emissions than petrol and diesel but fuel | | | | cooking oils, and from crops such as rapeseed oil, both |
| consumption is worse. It's been possible to convert | | | | of which avoid the carbon emissions of mineral diesel. |
| many existing cars to run on LPG by after-market | | | | However there is no wide availability, unless in industrial |
| conversions, and some manufacturers such as | | | | quantities, and it is more commonly used to blend with |
| Vauxhall have had new cars in their range that are | | | | normal diesel. There's at least one company that is |
| dual-fuel, which are designed to run primarily on LPG | | | | currently building up a world-wide biodiesel production |
| with petrol back-up. There is a reasonable network of | | | | and refining capacity but it's not ready yet. |
| filling stations. | | | | A wide range of car manufacturers supply cars rated |
| LPG, and natural gas in heavier vehicles, has been an | | | | as totally compatible with biodiesel and even older |
| attractive proposition in the past primarily due to its | | | | models may be compatible. It's recommended that if |
| cheaper cost, as it has enjoyed less fuel duty. | | | | your fuel runs through rubber pipes they must be |
| However there is no guarantee that the Chancellor will | | | | replaced with plastic equivalents. Biodiesel will remove |
| maintain this in the future, and although there are some | | | | dirt in the engine left by previous use of petro-diesel |
| emissions improvements over petrol, LPG is still | | | | and deposit it in the filters, therefore the filters need to |
| derived from a fossil fuel and therefore still releases | | | | be changed after the biodiesel has been used for a |
| greenhouse gases into the atmosphere. | | | | while. Biodiesel will work in most modern diesel engines |
| CNG | | | | (but not petrol!) but there are warranty implications - all |
| Some vehicles, usually heavier vans or trucks that | | | | vehicles should be checked for their compatibility for |
| normally run on diesel, but also cars such as the Volvo | | | | running on biodiesel. |
| (V70 Bi-Fuel), can run on CNG (Compressed Natural | | | | D1 Oils is a British company which recognises the |
| Gas), which again results in lower CO2 emissions than | | | | increasing demand for biodiesel and aims to become a |
| standard petrol cars, but the fuel is not as efficient as | | | | global, sustainable, low cost supplier of crude vegetable |
| diesel. Finding CNG for refuelling can be a challenge. | | | | oil and biodiesel refiner. It has developed plantation |
| Petrol-Electric Hybrids | | | | rights and established refinery operations in several |
| Petrol-electric hybrid vehicles run on a combination of a | | | | international regions, creating a supply chain from seed |
| conventional petrol engine and an electric motor | | | | selection through to the sale of biodiesel to end users. |
| powered by an energy storage device such as a | | | | Currently it has four operations centred in the UK, |
| battery pack. In simple terms they work on the principle | | | | South Africa, Asia Pacific and India. There are also |
| that an electric motor provides the power at low | | | | projects in Madagascar and Saudi Arabia. The main |
| speeds such as in urban driving, and they switch to | | | | plant source is the Jatropha tree which can grow in |
| petrol for driving at higher speeds. The batteries are | | | | desert areas with a minimum requirement for water. |
| recharged while driving and hybrids use regenerative | | | | Grassolean is a US site where you can find |
| braking, which means that energy is put back into the | | | | information on starting your own Biodiesel project. |
| battery when braking, which improves energy | | | | Green Fuels Ltd was formed to bring affordable and |
| efficiency. | | | | sustainable biodiesel technology to the UK and |
| Hybrid technologies improve fuel efficiency and | | | | European marketplace. They market decentralised |
| therefore provide considerable fuel savings compared | | | | plant for making biodiesel on a scale suitable for home, |
| with a normal petrol vehicle - as well as carbon | | | | business or locality. They also provide training. |
| emissions savings. While models might cost more than | | | | Low-Impact Living Initiative (LILI), a non-profit |
| conventional cars, running costs can be two-thirds that | | | | organisation helping to protect the environment by |
| of equivalent petrol-fuelled vehicles. | | | | promoting sustainable alternatives. They run hands-on |
| Because of their lower CO2 emissions, hybrids also | | | | courses throughout the year including several on |
| benefit from reduced vehicle excise duty and are | | | | making your own biodiesel and there's even one on |
| treated favourably in Budgets. In addition they are | | | | vegetable oil as a motor fuel. They can also supply |
| exempted from the London Congestion Charge. | | | | and deliver biodiesel to your home. |
| However at the moment there are a limited number of | | | | Bio'petrol' - Ethanol and Methanol Vehicles |
| hybrid vehicle choices; there are currently just four | | | | Ethanol and Methanol are viable vehicle fuels which |
| hybrids available in the UK; the Toyota Prius, Honda | | | | are an alternative to petrol in internal combustion |
| Civic hybrid, Lexus RX400h and Lexus GS450h. As | | | | engines, giving considerable carbon emission benefits if |
| they are still a relatively new technology, there aren't | | | | the fuel is derived biologically. It's cleaner inside the |
| many available second-hand and so they are quite | | | | engine as well as outside. Vehicles usually require |
| expensive. | | | | adaptation to convert from petrol to ethanol if the |
| Toyota's first Prius (launched in Japan in 1997) didn't sell | | | | concentration exceeds 10% (E10) (manufacturers tend |
| in great numbers, however a new model has been | | | | to be conservative and warranties usually state that |
| introduced and this is now proving more successful. | | | | no more than 5% ethanol should be added, however, |
| Although it looks like a normal car, it is designed around | | | | most cars seem to run on E10). The required engine |
| energy efficiency, and has many clever technological | | | | modifications to convert from petrol to ethanol are |
| features that assist fuel consumption, including air | | | | more extensive than those to convert diesel to |
| conditioning and brakes powered by electricity rather | | | | biodiesel. Several manufacturers are working to |
| than by sapping energy from the petrol engine. Lexus, | | | | produce vehicles that will run on an 85% proportion |
| part of Toyota, has introduced a hybrid version of the | | | | (E85) and in the Americas and Canada, Flexible Fuel |
| RX300, known as the RX400h. This is an SUV and | | | | Vehicles (FFVs) can run on E85 as well as gasoline |
| because of its size, it still only returns around 35mpg | | | | (petrol). Where ethanol can be produced in abundance, |
| compared to the Prius's 65.7mpg. | | | | notably Brazil, the fuel is used widely. The alcohols also |
| Although the official fuel economy figures for cars | | | | have potential for the raw source in fuel cells. |
| such as the Toyota Prius at 65.7mpg sound great, | | | | Recently, biofuels that can run with petrol have been |
| they only really achieve maximum economy benefits in | | | | introduced in the UK. The Saab BioPower and the |
| built-up areas where they primarily run on electric | | | | Ford Focus Flexi-Fuel are the only two new vehicles |
| rather than petrol although the Prius can only drive for | | | | on the market that are designed to run on biofuel. For |
| around a mile on battery power before needing to | | | | more information see items in our News section. |
| revert to petrol; in real-world motoring it seems difficult | | | | Hydrogen |
| to attain the official figures. On a motorway run, a | | | | Hydrogen fuel cells are seen as the fuel of the future. |
| good diesel is likely to be more economical. | | | | Although they are charged with very bulky hydrogen, it |
| Nevertheless hybrids are still one of the best options | | | | can be supplied in a liquid hydrocarbon compound and |
| that the consumer has today to achieve better fuel | | | | that way, theoretically, the density problem can be |
| economy, especially if much driving is done in towns, | | | | solved. To be climate-friendly the compound must be |
| along with the financial benefits such as lower tax and | | | | renewable (bio(m)ethanol for example), not petroleum |
| escaping London's Congestion Charge. | | | | based. One of the biggest attractions about hydrogen |
| Only petrol-electric hybrids are currently available; | | | | is that the only waste it produces is water. |
| diesel-electric hybrids will achieve even better fuel | | | | Various manufacturers are developing prototype cars |
| consumption - watch out for these appearing in the | | | | powered by hydrogen fuel cells however they still |
| not-too distant future. | | | | demand much research and development to be |
| Battery-Electric cars | | | | commercially viable in vehicles and it will be a number |
| Electric cars use a battery and electric motor to | | | | of years before they are widely available, together |
| power the vehicle, meaning they have no emissions at | | | | with the fuel, in the UK. |
| the point of use. Due to the capacity of the battery, | | | | Other technologies |
| their range is normally limited to about 40-60 miles | | | | Citroen has developed 'Stop & Start' technology, |
| between recharges, which means they are only really | | | | currently used in two of its models. The normal petrol |
| suitable for city-based users. | | | | engine shuts down if the car stops in traffic in normal |
| Electric vehicles can be recharged by plugging them | | | | driving. You still pay a premium over standard models |
| into an existing electrical socket, and some city councils | | | | for this technology, but they are cheaper than hybrids - |
| are installing electric recharging points in car parks or | | | | but the fuel savings are not as great - the fuel |
| on-street. However, they are only truly 'green' if they | | | | consumption does not improve significantly at all; like |
| are recharged with electricity from renewable sources | | | | hybrids, they offer greatest benefit in urban areas. |