Raise your hand if you flew this holiday. Yeah, me too. Feel guilty about the carbon emissions? Stop. There’s hope. Read on.

By Alastair Bland

Automobiles that thrive off of alternate energies. Car companies show off how fast and furious can be green and clean.

Reynolds, Indiana doesn't look like the town of the future. But the little Midwestern town has one thing going for it. Hog manure. Lots of it. Until last year, that didn't seem like a plus for the town where hogs outnumber people 3 to 1. But then the state government got the idea to turn the town's biggest problem into its biggest asset. The result? BioTown, USA.

There's no way around it: Your car is contributing to global warming. In fact, it's almost certainly the single most environmentally harmful component of your lifestyle. The transportation sector is responsible for nearly 40 percent of nationwide greenhouse gas emissions, not to mention plenty of ozone-damaging and smog-forming pollutants. The good news is that new clean-car technologies are emerging at a rapid pace – not just behind the scenes, but in the showrooms of car dealerships near you. Efficient hybrid-engine cars like the Toyota Prius and the Ford Escape SUV can't keep up with demand. Meanwhile General Motors and Ford are ramping up their development of flexible-fuel vehicles that can burn both standard gasoline and biofuels such as ethanol. So if you're in the market for a climate-saving, planet-positive vehicle, which should you choose -- better mileage or biofuel?

A new biofuel for jet engine could be in the works. Researchers in North Dakota say they have been working for four years on a process that converts soybean or canola oil into aviation turbine fuel or