California utility Pacific Gas & Electric is developing the electricity grid of the future, one that will look more like the Internet - distributed, interactive, open-source - than the dumb, one-way network of today that pushes dinosaur molecules from a carbon-spewing power plant to your home. Here are some of the technologies and energy sources that utilities will tap: solar power stations; solar buildings with solar cells integrated into rooftops, walls and windows; wind power; wave power; cow power (methane gas extracted from cow manure powers electricity-generating turbines); car power (plug-in hybrid cars that not only have rechargeable batteries but also feed power back to the grid); clean-coal plants; and smart grids that communicate with household appliances. (See the full story.)