This Company Could Kill the Gas Engine -- for Huge Investor Profit

The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.

NEW YORK (StreetAuthority) -- Every now and then I run across a statistic or a fact that makes me feel really stupid. I kick myself: "Why didn't I already know that?"

What got me is that my red Dodge Ram 1500 is technically classified as a "light truck." I was mortally offended by this. My pickup has a 5.7-liter Hemi V-8 and is as loud as the Space Shuttle and almost as fuel efficient. It doesn't feel like a light truck. But it is.

Millions of semis are driven an incredible amount of miles, getting about five miles to the gallon, burning through billions of gallons of diesel a year.

The thing that matters more than light trucks, though, are the larger semi trucks that roll down the highway. There are millions of them, they drive an incredible amount of miles and they get about five miles to the gallon, burning through billions of gallons of diesel a year.

Now, it's a myth that diesel is dirtier than gas. It might seem like it because of the exhaust, but the two fuels are actually pretty close to equivalent in terms of energy content and emissions. But the fact remains that we use a vast quantity of diesel, and if we could replace it with something else, it would be a serious game-changer. If that fuel were cleaner than gas and diesel, there would be reduced emissions from moving stuff around. But if this new fuel were also cheaper, the diesel dominos would begin to fall, and quick.

The fact is, all of those various kinds of trucks -- and cars, too -- can get the same energy out of a fuel that costs half as much as diesel. That fuel is natural gas, which is abundant, clean and can be domestically sourced. Natural gas has the ability to displace billions of gallons of diesel, not only on the road but in marine applications, which also burn through billions of gallons every year, and for heavy equipment.

That's coming. And I've found a stock that is the strongest pure play on this trend.

That stock is Westport Innovations(WPRT) .