Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of natural gas fuels specialist Clean Energy Fuels (Nasdaq: CLNE) powered up to a 13.4% intraday gain on moderately heavy volume.

So what: Westport Innovations (Nasdaq: WPRT) and a subsidiary of Royal Dutch Shell (NYSE: RDS-A) just announced a joint project to promote the use of liquid natural gas in heavy-duty commercial vehicles. Shell mainly produces the fuel, Westport builds LNG-friendly engines, and not-so-innocent bystander Clean Energy Fuels may get to build refueling stations.

Now what: It's exciting to see cleaner and more sustainable fuel technologies slowly making their way into the mainstream. Yeah, LNG is still a petrochemical product just like the oil, diesel, and gasoline we all know and loathe, but a less-exploited and somewhat more eco-friendly one. If Shell and friends can make this work for commercial vehicles at first, we'll have a low-cost alternative to gas-and-battery hybrids for the consumer market soon enough. When the natural gas runs out, let's just hope we'll have cold fusion reactors in every home already.

Fool contributor Anders Bylund holds no position in any of the companies discussed here. Motley Fool newsletter services have recommended buying shares of Westport Innovations. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool is investors writing for investors.