Like analog TV and Marshall Tucker fans, solar power is a holdover from the Carter administration. Yet, for modern businesses like Google and General Motors, it's a promising alternative energy source. So far, "promising" is as far as it's gotten: the density in data centers and in the typical office complex -- lots of demand in a small area -- turns solar arrays into a pipe dream. At Google HQ, for example, nearly every rooftop is covered with solar panels, and they have plans for more coverage, but the array can only provide for about 30 percent of peak power usage.

Yesterday morning Sir Richard Branson of Virgin Atlantic Airway pulled up to the IAC Building in a hydrogen fuel-cell-powered Chevy Equinox SUV. There he was joined by executives from GM and Rolls Royce to announce a smorgasbord of environmental initiatives. A clear theme was hard to distinguish, other than the color green.

Heres an odd PR move making the blog rounds today: Bob Lutz, the General Motors Vice Chairman whos driving the charge to build the Chevy Volt plug-in hybrid, was recently quoted in D Magazine calling global warming a crock of s**t.

Talk about irony. I'm driving one of the world's most environmentally responsible cars into Las Vegas, the world capital of excess.

My ride is the HydroGen1, General Motors' zero-emission fuel-cell-powered development vehicle, and I'm taking it over for the last leg of a 230-mile endurance run dubbed Challenge Bibendum by organizer Michelin. Participating are a host of alternative-fuel vehicles, including nine fuel cell cars.