KEY POINTS:
New Zealand drivers will soon be able to get ethanol-blended petrol at some service stations. Using ethanol-blended petrol results in lower overall greenhouse gas contributions than ordinary petrol, as ordinary petrol is completely fossil fuel-based.
Ethanol-blended petrol also burns more cleanly, and can help reduce pollution and improve air quality.
The difference it makes to air pollution depends on the design and condition of the engine and how it is driven. It's a move to introduce renewable energy into our transport fuels and to reduce the millions of tonnes of carbon dioxide emitted by New Zealand vehicles.
Ethanol is an alcohol derived from corn and is used, in general, for two basic reasons: economics and to reduce pollutants introduced into the environment. Ethanol is mixed with fuel in three common formula ratios, though depending on your location in the world, the ratios can be different.
Fuel ratios are expressed in the mixture of ethanol to petrol, with the letter E and a number. The number indicates the percentage of ethanol in the fuel mixture.
E10, which is a mixture of 10 per cent ethanol and 90 per cent petrol, can be used in internal combustion engines of most modern vehicles. E10 is available in North America and along with E85, is the only type of petrol sold in Minnesota. As of the spring of 2006, due to the phasing out of methyl tertiary butyl ether (MTBE), which was used as a petrol additive in the place of lead, E10 has become very common throughout North America.
Similar blends to E10 include E5 and E7, which are generally safe for engines that normally run on pure petrol. Some regions mandate that locally sold fuels contain at least some ethanol. It is in this situation where these smaller ratio fuels may be sold.
E15 is generally the highest ratio of ethanol to petrol that is recommended by vehicle makers selling vehicles in North America in vehicles that do not carry the designation of E85 or flex-fuel.
E20 is not yet widely used in North America, but will be mandated by Minnesota for all petrol sold by 2013. Since February 2006, E20 is the required mixture for all petrol sold in Brazil.
E85 is generally the highest ethanol fuel mixture found in the US It is common in Sweden, and is gaining in popularity across North America.
E95 contains just is used in some diesel engines where high compression is used to ignite the fuel, as opposed to the operation of petrol engines where spark plugs are used. This is because as octane ratings increase, compression ratios must also increase to cause the fuel to ignite.
E100 is straight ethanol used in Brazil and Argentina. Ignition in temperatures below 15C causes problems when using pure or neat ethanol. A common cold-weather solution is adding a small petrol reservoir to increase the petrol content momentarily so ignition can occur and the engine can start. Once started, the engine can be operated on pure ethanol. In Brazil, ethanol fuel is hydrated ethyl alcohol, which is a mixture of 96 per cent ethanol and 4 per cent water. This distillation creates the purest form of ethanol.
To clearly know which vehicles are designed to operate on which types of fuel, refer to the vehicle owners manual, fuel fill cap, signage on the vehicle, or vehicle makers service information.
Regardless of the vehicle maker, the use of ethanol-blended fuels can cause driveability issues from using ethanol-based fuels with ethanol concentrations above 10 per cent in non flex-fuel vehicles, or from a condition called phase separation. Phase separation occurs when water saturation occurs to ethanol-blended fuel.
Using fuel in vehicles that are not capable of handling ethanol ratios above 1 per cent can damage parts from the fuel pump to the engine. Depending on the age of the vehicle and the vehicle maker, flex-fuel-specific parts can include the fuel tank, fuel pump, fuel sending unit, non-metallic fuel lines and hoses, fuel filter, fuel injectors, and parts of the exhaust system.
When water is absorbed by the ethanol, the alcohol in the fuel begins to be removed, therefore lowering the octane rating of the fuel. When enough moisture is absorbed into ethanol-based fuels the fuel can no longer absorb water and the extra water separates and settles to the bottom of the fuel tank.
What occurs as a result are poor driving conditions, such as knocking, pinging, sluggish performance, or a hard or no-start condition. From the effect of the alcohol being removed, the air-to-fuel ratio becomes lean and combustion chamber temperatures increase. Increased combustion chamber temperatures will lead to premature wear.
With ethanol fuels being used more in North America, the opportunity for water entering an open fuel system may become a concern for repair facilities. Water contamination of a fuel system may become a problem for vehicles that are stored for extended periods of time in environmental conditions that are humid or wet.
But a word of warning, with the ever-changing design of motor fuels and the evolution of vehicles capable of burning different types of fuel, filling a vehicle with the wrong fuel can lead to driveability problems not commonly experienced.
- Additional information I-CAR Advantage Online
