Changing an industrial standard that is over century old is not an easy task. Such an ambitious goal will not only attract hopeful capital but also a boatload of skeptics. It's no wonder why natural gas engine innovator Westport Innovations (WPRT 0.34%) has attracted both.

The bear necessities
Today I'd like to address those skeptics, which in Westport's case are more than just doubters. As of the end of last month more than 20% of the float was sold short. These are investors who are betting directly against the success of Westport, hoping to profit from its demise. 

It's not that short sellers can't make money on short-term volatility -- there certainly are risks to Westport's long-term bullish investment thesis. The company is not yet profitable and gross margins have actually been contracting. The longer-term thesis could really derail if natural gas prices spike high enough to negate the economic benefits of switching, or if a competitor comes in with a better, cheaper alternative. 

That's likely why shares have been so volatile and why bears are hungry for more. That being said, I think investors will make more money over the long term by taking the other side of that trade. Here are two simple trends that could very well propel Westport's stock higher in the years to come.

CNG is really starting to catch on
Westport, along with joint venture partner Cummins, just announced a massive contract for 900 new buses fueled by compressed natural gas. The deal is just one example of the growing list of companies converting their fleets to natural gas. In fact, several transit operators have pledged to convert 100% of their fleets to run on natural gas.

They are not alone: Refuse companies in particular are making the same switch. Waste Management (WM 0.60%), for one, is committing 85% of new truck purchases to those fueled by natural gas. The company will see payback in as little as one year. Because of this, refuse companies are really "thinking green" when it comes to switching to natural gas.

America's Natural Gas Highway awaits
Until recently, natural gas as a transportation fuel was limited to fleets that returned to base. That's beginning to change as Clean Energy Fuels (CLNE 4.53%) continues its quest to build America's Natural Gas Highway. This is a potential game changer, as the lack of refueling infrastructure is one of the things holding back the more than 3 million class-8 trucks nationwide that could be replaced by those fueled by natural gas. Even natural gas producers like Chesapeake Energy (CHKA.Q), which owns a stake in Clean Energy, and Encana (OVV 1.13%) are getting into the act of building natural gas stations. In both cases its not only about making money on those stations, it is also spurring more demand for natural gas.

It's estimated that by 2017 nearly 35% of the new trucks entering the highway could be fueled by natural gas. This could mean a growth of 75,000 annual units, which would be explosive growth from the current rate of just 1,700 trucks. Having more refueling stations will help make it easier for truckers to commit to the switch, and with its industry leading patent portfolio, Westport is poised to take its share of the profits as this becomes a reality.

My Foolish take
An investment in Westport isn't an investment in a certain future, but instead one in what hopes to be a better future. Natural gas is an abundant, cheap, clean, and American-sourced fuel. As we find more ways to harness its power, investors will be among many who reap those rewards.