Millions of drivers in the developing world are embracing natural gas as a cheap and relatively clean alternative to petroleum fuels. Will high oil prices prompt the United States and Europe to follow suit?
 | Making the switchA mechanic installs a bottle of compressed natural gas (CNG) into a vehicle at a garage in Bangkok, Thailand. (Photo: Reuters) |
Sometimes one must choose the lesser of two evils. Natural gas is a fossil fuel that releases greenhouse gases when burned. However, it releases up to 20-percent less greenhouse gases than gasoline or diesel, and as much as 90-percent less smog-forming pollutants. That is because natural gas is mainly methane, which has less carbon in it than petroleum-based fuels. It also requires less energy and is cheaper to produce.
Worldwide, natural gas vehicles have grown by 30 percent annually since 2000, with Asia and South America leading the way. Argentina has over 1.6 million gas-powered vehicles on its roads. Iran is one of the world’s largest oil producers, yet it imports gasoline and diesel. Now it is switching to cheaper, cleaner natural gas. By law, 60 percent of new passenger cars and 80 percent of public transport vehicles must use natural gas.
Oil-addicted North America and Europe have been slower to embrace gas-powered cars. Despite being named the “greenest vehicle in the country” by the American Council for an Energy Efficient Economy for the last five years, the natural gas-powered Honda Civic GX is the only natural gas car available in the country.
Natural gas vehicles operate the same way as conventional gasoline vehicles. The fuel is mixed with air, and ignited by a spark plug to move a piston. Consequently, drivers can convert their vehicles to run on natural gas. They must install pressurized cylindrical tanks to store the gas in either compressed (CNG) or liquefied (LNG) form.
If these tanks are ruptured in an accident, the gas rapidly disperses, making it safer than petroleum fuels that are liquid and so remain on the scene and a fire hazard. The tanks, however, are large, heavy, and expensive. The Civic GX, which runs on CNG, gets about the same mileage as the conventional Civic, but costs about 5,000 dollars more.
 | Animation (click on the image to enlarge)Ten ways to make cars more efficient (Animation: Allianz) |
However, CNG can be 1.50 dollars cheaper per gallon than gasoline, so over the long-term the extra expense may be worth it. One U.S. trucking company uses LNG in diesel engines for a fleet of 50 trucks that are cheaper to run than similar diesel trucks. They also emit 20 percent fewer emissions.
A critical problem for natural gas vehicles is that they require a new network of filling stations to supply the fuel. This infrastructure exists in countries like Argentina, but elsewhere, it is a barrier to widespread adoption. There are only about 1,600 CNG filling stations in the United States, compared with up to 200,000 gas stations.
One way that CNG users can get around that is to fill up at home. With the right equipment, drivers can tap into their domestic gas supply, making the fuel even cheaper. Another option is a bi-fuel vehicle with one tank for gasoline/diesel and one for natural gas.
Natural gas vehicles have been around for nearly 20 years, but an era of cheap oil made progress difficult. Times have changed, and now even Texas oil billionaire T. Boone Pickens is campaigning to convert U.S. vehicles to natural gas. In Europe, Italy now has the fourth largest fleet of natural gas vehicles in the world with over 400,000 on Italian roads.
Looking further ahead, renewable natural gas is the next step for this alternative fuel. Today’s natural gas is not sustainable because it gives off extra greenhouse gases and it takes a lot of energy to extract from the earth. However, the main ingredient of natural gas, methane, also forms in places such as landfills, dams, sewage plants, and agricultural waste pits, from where it leaks into the atmosphere as a potent greenhouse gas.
This biomethane could instead be captured and used as a renewable fuel, something that has been tried in Sweden. By developing the infrastructure for natural gas vehicles now, some countries are paving the way for renewable methane as a fuel of the future.
editor: James Tulloch
publishing date: October 9, 2008
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