Electric vehicle are increasing with popularity as battery technology advances, and counties and consumers try to reduce their reliance on fossil fuels. Electric cars are powered by an electric motors (DC or AC) which draws its power from an on-board battery packs which act as an energy store. Batteries, usually Nickel metal-hydride or Lithium-ion are charged by simply connecting the vehicle to a mains power supply, and is usually charged overnight for a full charge, or within a matter of ours if dedicated charging points are installed. A feature of most modern electric cars is the regenerative braking system which allows the battery to be topped up when the brakes are applied.
Until recently electric vehicles available in the UK were smaller 2 seater cars from small bespoke manufacturers with a range of of 40 to 80 miles and a top speeds from 25 to 45 mph. More recently, electric cars are from mainstream manufacturers are larger car with five seat and distance ranges in excess of 100 miles.
Electric cars are favoured by city drivers given their limited range and current charging infrastructure, and are more popular in cities where a congestion charge is in force such as London. Huge savings can therefore be made from avoiding the congestion charge, free road tax, no petrol costs and in may cities, free parking and even charging.
Electric Cars are sometimes referred to as zero emission cars, but this refers to tailpipe emissions. Emissions are produced during the generation of electricity unless a renewable energy supplier is used.
Hybrid cars generally use a combination of two power sources. The most common hybrids currently available on the market use both electric motors and the petrol combustion engines however certain manufacturers are now offering diesel hybrid cars.
Batteries are charged and act as a storage device to power an electric motor, usually working when the vehicle is travelling at low speed or in traffic, therefore making it ideal for city driving. The petrol or diesel engine, usually a small efficient unit then powers the car when more power is needed such as at higher speeds or under hard acceleration allowing the combustion engine to only operate at its more optimum efficient speeds.
The combustion engine is used to recharge the battery cells along with regenerative braking, therefore hybrid cars do not need to be plugged into an external power supply. This combination of battery power and internal combustion engine produces less pollution and CO2 as no gases are released when the electric motor is running.
2012 saw the launch of plug-in hybrid cars which means rather than the electric motors being charged and powered by the conventional engine, they are charged by plugging the vehicle in to a mains plug. This is more efficient and eliminates the inherent problems on pure electric cars such as range and charge times. As such, plug-in hybrid cars benefit from up to £5k in UK government grants.
Biodiesel is produced from renewable energy sources such as rapeseed, sunflower or soybean oil. Biodiesel is green as it has the potential to be carbon-neutral, that is to say all the carbon dioxide emitted during use of the fuel when emitted from the vehicle is balanced by the absorption from the atmosphere during the fuel crop’s growth.
Biodiesel in some instances can be a direct replacement for diesel, however most manufacturers remain cautious about engine wear and recommend a blend of between 5% to 30% biodiesel although some modern engines are capable of running on 100% biodiesel.
Ethanol, also known as grain alcohol is produced from plants, usually sugar cane. The fuel has a high octane rating which in turn means increased engine efficiency. Ethanol is widely used globally as a fuel and is increasing in popularity in Europe. A number of manufactures have developed flexi-fuel vehicles (FFVs) currently available on from Ford, Saab and shortly Volvo cars.
Flexi-Fuel vehicles can run on a blend of ethanol and petrol, usually up to E85 (85% Ethanol, 15% Petrol) which is the most common blend in the UK or just petrol. This gives drivers flexibility as the current ethanol filling station in the UK is limited.
Bioethanol is green as it has the potential to be carbon-neutral, that is to say all the carbon dioxide emitted during use of the fuel when emitted from the vehicle is balanced by the absorption from the atmosphere during the fuel crop’s growth.
Liquefied Petroleum Gas (LPG) is a natural hydrocarbon fuel made up of propane and butane. LPG produces far less carbon dioxide than petrol and fewer particulates and nitrogen oxides than diesel. It can be used within a modified internal combustion engine after conversions which cost around £1,500-£2,000. A conversion includes the installation of a second fuel tank for the LPG which means the vehicle can switch between petrol or LPG.
LPG has the special property of becoming liquid when under pressure, and reverting to gases at atmospheric pressure. This means it can be easily and conveniently stored as a liquid. About 60% of the world supply of LPG comes from the separation of natural gas products, and 40% is a by-product from the refining of crude oil. In the past, LPG has been considered as waste and flared off; now it is recognised as a major energy source and currently offered by about 10% of refuelling stations.
Fuel cells are electrochemical energy conversion devices which produce energy from an electro-chemical reaction. Electricity can constantly be produce as long as the flow of reactants is available. Although the technology is now available, the technology is still being developed and is current expensive. One problem is that hydrogen can still not be produced efficiently to make viable as an alternative fuel just yet.
Compressed Natural Gas is a fossil fuel sourced from reserves deep under the Earth’s surface. It has lower CO2 emissions compared to petrol/diesel but is still a greenhouse gas.
Similarly to LPG it requires a conversion so that the car can be switched between gas and petrol. The gas is compressed in a cylinder rather than being stored as a liquid form. The gas mixes well with air prior to combustion and has a high octane rating and therefore is fuel efficient.
CNG is popular worldwide and increasing in popularity in the UK. There are a number of aftermarket conversions available and options also available from the factory from manufacturers such as Volvo.
Petrol engine cars are the most common car available. They are generally cheaper than their diesel or alternative fuel counterparts to buy. Petrol powered cars release carbon dioxide into the atmosphere and burn non-renewable energy sources. We all know this is bad for the environment but there are obviously some petrol cars which are less harmful (greener) than others.
The most efficient petrol cars return the best miles per gallon (mpg) of fuel and therefore produce the lowest CO2 emissions. These are usually the smaller super mini’s as they are lighter and therefore have smaller engines. These cars are usually the cheapest Green Cars to buy and running cost are low. Concessions are made with lower road tax rates for producing less harmful emissions and they are usually cheaper to insure and you will notice savings on fuel because of their efficiency.
Diesel cars sales are on the rise in the UK as consumers are more cost conscious and demand more efficient vehicles. Across Europe, diesel sale amount to nearly half of all new vehicle sold. Diesels operate on average 30% more fuel efficiently than petrol powered vehicles by using higher compression ratios and higher combustion temperatures.
Diesel still release carbon dioxide into the atmosphere and is a non-renewable energy sources but this is usually less so than in petrol cars. However other compounds such as nitrous oxides and particulate matter is released which have harmful effects to the ozone and humans.
You you may think then diesel cars are not so green then but they certainly can be greener and by buying the most efficient in terms of good miles per gallon (mpg) of fuel and the lowest CO2 emissions will help the environment.