While many alternative (non-petroleum-using) vehicles continue to struggle as viable approaches for making transportation greener, mostly due to cost and practicality concerns, one alternative fuel has been quietly succeeding in expanding its usage in recent years: natural gas.
Worldwide, there are approximately 15 million natural gas vehicles (NGVs). Most are concentrated in the Middle East and Latin America, while other countries, such as Italy and Australia, are tightly hanging onto their coattails. Australia, for instance, boasts the highest market penetration of natural-gas powered buses in the world.
In fact, most NGVs are buses. The reason is simple, and it starts underground.
Add heat and pressure, then mix in time, dead animals and composting plants, and Mother Nature blends these ingredients to create natural gas. Humankind tries to do one better – substitutes for natural gas can be made from methane and carbon dioxide, which emanate from rotting landfills and stinky sewers. Both gases can be used for the same applications, such as fueling internal combustion engines.
Automobiles can use two forms of natural gas: compressed natural gas (CNG), which is stored at 21-25 MPas and often used for passenger bus fleets, and liquid natural gas (LNG), a cryogenic liquid, which is stored at -162 degrees Celsius. Twice as dense as CNG, LNG is often used for Class 7 and 8 heavy-duty trucks.
Since the debate around natural gas in homes is heated already, it’s no wonder that the same concerns would apply to NGV vehicles. Natural gas was first fed to cars out of necessity, though. Italy, the Axis-turned-Ally country, suffered petroleum starvation during World War I. Because of this, innovative motorists powered their engines using “coal gas” stored in giant balloons which they mounted to their vehicles.
Then crude oil boomed, and natural gas never returned to the spotlight. But now, with dependence on foreign oil at the forefront of Western politics, natural gas is being looked at once again. Transportation fleets use natural gas for a host of reasons. Natural gas costs significantly less than petrol (gasoline). It is safer when spilled, and natural gas engines are quieter than diesel engines – and it reduces engine wear, lessens carcinogenic particulate emissions and decreases carbon dioxide emissions. Most importantly, natural gas is an important ally against dependence on foreign oil. In countries such as Australia and the United States, it is often extracted from domestic coal beds and shale oil.
Unfortunately, transportation fleets can make sacrifices that passengers can cannot. For one, filling up with CNG takes 2-3 times longer than with petrol, and many fleets use slow-fill LNG stations that require up to eight hours to refill a tank. In a way, the gas balloons of the 1920s have never left. Natural gas tanks are large, unwieldy and heavy, and hold little energy compared to gasoline tanks. The Honda Civic GX, for instance, has a maximum range of less than 200 miles, and yet its tank takes up half the trunk!
Another obstacle to widespread CNG or LNG adoption is infrastructure. In order to be cost efficient, natural gas must be transported in pipelines, yet few countries can stomach the costs of a nationwide natural gas pipeline system. In Europe, however, countries come smaller, and petroleum costs more. So Fiat makes a profit from its six bi-fuel hatchbacks, and Volkswagen’s suite of bi-fuel models are a common sight. In contrast, the Honda Civic GX is the only public NGV vehicle sold in America.
Yet is natural gas the fire to oil’s frying pan? Exempting biogas, natural gas is a non-renewable fossil fuel. Though cheap and clean, it can only last so long, and some argue it is not being put to its best use. Some experts say that burning natural gas in an electric power plant for use in an electric vehicle would be twice as efficient. Pump: The Movie, which opens in September 2014, asks the same question: How best to fuel America’s cars?
Then, of course, there is the controversial practice of fracking, which has been a primary force behind falling natural gas prices in recent years. The procedure, which involves inserting high-pressure chemicals into rock formations to access the fossil fuels below ground, has as many opponents as it does supporters, and the EPA is actively studying fracking’s ecological impact. No matter the environmental drawbacks, the production of natural gas has continued to increase from just over 21.1 million cubic feet in 2008 to more than 25.6 million cubic feet in 2013.
Most likely, NGVs will have the most success gaining ground in urban public transit and long-distance transportation fleets. Due to infrastructure costs and fuel storage requirements, however, NGVs may always struggle to overcome their status as minor players in passenger transportation.
