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Sep 22, 2010 at 10:13 AM |
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Natural gas as a vehicle fuel has many of the same advantages that natural gas enjoys in other areas of energy use. Natural Gas is a DOMESTIC energy source with over 95% of the natural gas we use in the United States coming from North American production. ENVIRONMENTALLY, using natural gas produces less CO2 and pollutants than any other readily available form of energy (electricity for example is efficient at the plug, but produces extreme levels of pollution at the source where coal and other fuels are very inefficiently used to produce most of the electricity we consume in this country). EFFICIENCY, the process of converting natural gas to BTU’s of energy is very straightforward and efficient in a direct use application. These items produce a significant cost advantage for natural gas over other fuels as well. The current equivalent cost of natural gas for the energy in one gallon of gasoline is $1.25. For these reasons, natural gas has become a common source of vehicle fuel in some areas of the world. However, transportation fuels present unique problems that are not present in normal stationary fuel applications. In the United States, the convenience of large on board storage tanks (vehicle range) and the supply infrastructure already in place for gasoline and diesel fuel have greatly limited the use of natural gas in the vehicle fuel market.
The advantages of converting vehicles to natural gas use, or buying factory built dedicated natural gas vehicles are:
- Fuel Costs—On an equivalent amount of energy basis residential natural gas currently costs about $1.25 per equivalent of gasoline (without any road taxes).
- Engine Wear and Maintenance—Natural gas is a very clean burning fuel; engines that have run many thousands of miles on natural gas have been taken apart and the internal parts of the engine often look brand new.
- Environmentally Friendly—Natural gas emits far fewer pollutants than either gasoline (conventional auto engine), or coal (the base fuel you are actually using if you use a plug-in electric vehicle).
- Domestic Fuel—All but a very small percentage of natural gas used in the United States is produced in North America.
- Natural Gas supply—recent advances in the production of natural gas from shale formations have unleashed a domestic supply of natural gas that will meet our needs for natural gas for decades (probably centuries) into the future.
- Dual Fuel—Vehicles can be adjusted to run on both natural gas and gasoline with a switch to change back and forth.
There are also some challenges to be overcome in using natural gas as a motor fuel:
- Storage of natural gas—The best answer currently available to storage of natural gas onboard the vehicle is the use of Compressed Natural Gas (CNG) cylinders. These cylinders store natural gas at several thousand psi pressures, but are a little bulky for the amount of energy they will hold. The end result of this problem is that most conversion natural gas vehicles have a limited range between fill-ups on the order of 100 miles. The dedicated natural gas Honda Civic appears to have a range of just over 200 miles. The US Dept of Energy is doing work, and had some recent success, on creating new storage options that will greatly increase the amount of fuel that can be stored onboard a vehicle.
- Cylinder fill—Filling the CNG cylinders requires a high pressure compressor. Quick fill requires only a high pressure compressor and time (usually 8 hours or so).
- Engine Performance—An engine dedicated to running purely on natural gas will have acceleration slower than performance of the same engine on gasoline (The Honda Civic is rated at 140 HP on gasoline and 113 HP on CNG). Engines operating on the dual fuel mode have to be adjusted between optimal settings for either fuel and thus lose more performance in either natural gas or gasoline mode. Some new engine developments are ongoing that increase engine compression ratios to better match the octane of natural gas, and limit or eliminate this performance problem.
- Availability of product—Currently there are no public natural gas vehicle refueling stations in the service area of Middle Tennessee Natural Gas and a limited number of these nationally. Some advance in Public Station availability is occurring in California and other states, and many other countries of the world are far ahead of the United States in this area. Nationally, there are fleet operations that use natural gas for vehicles that return to a given central location each night. There has been a residential level slow fill compressor on the market that can refill your vehicle at home. This product is not currently available in Tennessee.
- Vehicle first cost - In time first cost may not be a large factor but, at present, dedicated CNG vehicles are several thousand dollars more expensive to buy than similar gasoline models.
In conclusion, we are optimistic that natural gas will become one of the primary alternate fuels used to wean Americans off of the environmental and economic problems associated with foreign oil. However, at present, the products and infrastructure are not available in Middle Tennessee to easily make this conversion. Middle Tennessee Natural Gas will continue to monitor this issue and provide you information as the situation changes. One near term positive development is that new dedicated high compression ratio CNG vehicles for the North American market are under design at several automobile companies.
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