Today, oil is the No. 1 source of fuel worldwide, followed by coal, which is the main fuel for generating electricity in the United States. But by 2040, natural gas will overtake coal as the No. 2 fuel, as transportation, power and other fuel users seek a cleaner alternative. They're also taking advantage of the relatively new fracking methods that have made natural gas abundant in regions such as the Fort Worth area's Barnett Shale.
Among the companies leading this transition is Fort Worth-based BNSF, which is taking a real close look at converting at least some of its locomotives from diesel- to natural gas-powered.