Alternative Fuels

One of the biggest impacts of vehicle use is exhaust emissions. These days most attention is focused on Carbon Dioxide (CO2) as these are a major contributor to global warming. CO2 emissions are generally related to fuel type and engine size. Stricter European emission standards are driving down the level of CO2 emissions.

Different Fuel Types Emit Different Levels of CO2:

Diesel:

Diesel engines have lower CO2 emissions and offer better value for money than petrol engines, but emit other pollutants such as Nitrogen Oxides (Nox) and other substances that affect air quality. When and where you use a diesel engine is important when considering how to tackle air quality issues. For example, when driving at speed on a major road, a diesel engine is likely to have less of a negative impact due to lower CO2 emissions. However, when driving in a congested urban area, a diesel engine is likely to have more of a negative impact due to emissions particulates.

Liquid Propane Gas (LPG):

LPG gives good fuel value for money but the advantage it had of lower CO2 emissions has been wiped away in recent years by the increased efficiency of petrol and diesel engines due to the requirement to meet Euro IV emission standards by 2007. LPG is much cleaner than diesel when it comes to Nitric Oxides and fine particulates. On average, a diesel vehicle emits around 120 times as many as an LPG powered vehicle.

Electric Cars:

Electric cars are cars that are recharged from an electrical output. Electric cars have no exhaust emissions and are free from local pollution and CO2 emissions. They aren't completely pollution-free however, especially if they are recharged from an electrical power grid that burns large quantities of fossil fuels such as coal.

Fuel Hybrid:

Fuel hybrid vehicles use a parallel hybrid system in which a petrol engine provides the main power to the vehicle with an electric motor assisting as needed. The efficiency of this technology leads to lower CO2 emissions than ordinary petrol or diesel vehicles. Examples of hybrid vehicles are the Toyota Prius, Honda Insight and Lexus GS 450h.

Hybrid vehicle prices are considerably more expensive than conventionally powered cars. It is expected that prices will fall as the technology becomes more commonplace.

Biofuels:

The "Renewable Transport Fuel Obligation" (RTFO) places an obligation on fuel suppliers to ensure that a certain percentage of their sales are up on biofuels from April 2008.

Biodiesel:

Biodiesel uses vegetable oil as a substitute for conventional diesel and can reduce CO2 emissions by around 50%. However these can increase Nox too. Most diesel engine cars will operate well on a 5% mix (B5) but manufacturers warranties may be invalidated by 100% biodiesel (B100) due to possible damage to certain materials.

Biogas:

Biogas is a renewable alternative fuel which is produced by breaking down organic matter by a process of microbiological activity. In simplest terms, this means rotting municipal waste, food waste or sewage and turning it into gas by means of "anaerobic conversion" in a digester.

Biogas gives an average 95% carbon dioxide reduction in comparison to diesel whilst also delivering 80% lower Nox emissions and zero particulate emissions. The use of biogas creates a carbon reduction of greater than 100% as the organic matter would have naturally released methane, a greenhouse gas 21 times more potent than carbon dioxide into the atmosphere.

Bioethanol:

Bioethanol is a liquid biofuel made from fermented distilled starch plants such as corn and sugar and is widely used in Brazil. It can be used alone or blended with petrol, although higher E85 blends require modification of the vehicle. Bioethanol produces a 70% carbon dioxide reduction compared to petrol. A 5% blend produces 3.5% less carbon emissions, whilst an 85% blend (like E85) would achieve a 50% reduction. Availability of bioethanol is set to increase as car manufacturers begin to produce vehicles that can run on all blends up to 85%.

Alternative Fuel Development:

There is growing interest in developing alternative fuels and technologies and much investment in these areas at the moment. Hydrogen and electric technologies are likely to move forward, as well as the development of hybrid vehicles running on combinations of any or all of the above, but not without some controversy.

Biofuels have come under scrutiny recently as crop production threatens to compete with food production. There is also a lot of debate within the scientific community as to whether the CO2 produced in growing the necessary crops negates any benefit from lower exhaust emissions.

As the situation stands, Biogas offers the least environmentally damaging prospect as it is created from waste material that would otherwise have had a negative impact on the land and atmosphere.