“The economics are very powerful,” says Mark Little, director of GE Global Research. “Diesel fuel is somewhere on the order of 10 times more expensive than natural gas, per unit of energy. There’s switching going on all over the place.”So, why the natural gas power plants are still growing slower than diesel fired smaller power gen market?
Diesel engines can be made to run on natural gas with relatively small modifications (see “Swiss Researchers Make an 80-mpg Hybrid”). In a diesel engine, fuel and air are ignited not with a spark, as in gasoline engines, but by compressing them until they get hot enough to combust. Compression ignition, as the process is called, doesn’t work well with natural gas alone. It’s too difficult to control exactly when combustion occurs, and the natural gas can detonate—explode like a bomb—damaging the engine. In a dual-fuel engine, the problem is solved by injecting a small amount of diesel into the engine to trigger combustion.
While dual-fuel technology could facilitate a transition to natural gas, a comprehensive changeover will be held up by the high cost of natural gas engines and the lack of fueling infrastructure. There are still few natural gas pumping stations, especially stations that make the liquefied natural gas (LNG) that’s best for long-distance trucking and rail.