How natural gas vehicles work: A look under the hood

car lightYou’ve probably heard about how natural gas vehicles (NGVs) are a key component of a clean transportation infrastructure and are growing in popularity. But what’s under the hood of NGVs that allows them to operate with fewer emissions? Before learning about how natural gas vehicles work, one must first understand the history and makeup of this clean fuel.

The history of natural gas

Natural gas has been used around the world for decades as a reliable fuel for heating and cooking. But until now, the idea of natural-gas powered vehicles has been somewhat impractical; refueling infrastructure was nearly absent, rendering NGVs a problematic day-to-day transportation option. Now, though, natural gas is steadily becoming a serious alternative to gasoline, with more than 14.8 million NGVs on roads around the world, according to the U.S. Department of Energy.

What is natural gas?

Natural gas consists of methane and other gasses and exists, as its name suggests, primarily in gaseous form. For use as a motor fuel, it must be either compressed or liquefied in order to be space-efficient – typically, a CNG filling station has its own compressor to pressurize gas delivered through conventional lines. In that form, it is transferred to NGVs at special filling stations into cylindrical fuel storage tanks underneath the vehicle. New “fast-fill” stations allow drivers to refuel their CNG-powered vehicles at roughly the same speed as a gasoline-powered vehicle. At-home filling stations, like the one offered by Honda, rely on a slower filling method, so motorists who refuel at home often do so overnight.

How natural gas vehicles work

Once the compressed natural gas leaves the fuel tank, its pressure is lowered for use in an internal combustion engine almost identical to those found in gasoline-powered vehicles. There, the gas is mixed with air in the engine’s cylinders and ignited by spark plugs, forcing pistons up and down in the motor– just like in a gasoline engine.

NGV fuel tanks have traditionally been fairly bulky, taking up trunk space and even requiring chassis design modifications to allow for extra room for the tanks. However, significant improvements have been made recently to minimize the size of tanks, and some companies are already looking for even more creative ways to make fuel storage more efficient.

Key benefits of NGVs

While the basic process is nearly identical for both natural gas- and gasoline-powered cars, natural gas burns much cleaner, resulting in lower emissions. In fact, the U.S. Environmental Protection Agency named the natural gas Honda Civic GX the cleanest internal-combustion vehicle on earth.

For many motorists, safety is also a top concern. Fuel tanks for NGVs are made from durable composite materials and insulated with absorbent foam to protect against collisions. They meet or exceed the most stringent safety regulations in the world, and are much stronger than gasoline tanks. And in the highly unlikely event of a leak, the fuel would disperse upwards rather than form pools of flammable liquid like gasoline.

As an added bonus, NGVs offer cost-savings over gasoline-powered cars and in many places, NGVs are eligible for single occupancy use of the HOV lane.

NGVs vs. traditional vehicles

Even while being eco-friendly, NGVs perform comparably to gasoline engines in all categories, including top speed and acceleration. Volkswagen, a leading manufacturer of NGVs, has set out to demonstrate these performance capabilities through the Scirocco R-Cup racing series, which pits top drivers against one another in natural-gas powered racecars fueled exclusively by Gazprom.

Some drivers have chosen to take advantage of bi-fuel vehicles as the network of filling stations continues to expand, which can switch from natural gas to gasoline power when necessary. However, dedicated NGVs tend to offer better performance and fuel economy, and with the introduction of more and more fueling stations, they are growing in popularity. As more and more consumers and fleet owners gain a better understanding of how natural gas vehicles work, this trend will continue to grow.

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