Hybrid cars aren't the only thing that's going green. By 2009, Australia's Solar Sailor is planning to set up solar-powered ferry boats to sail across San Francisco Bay, carrying tourists and passengers alike.

Solar Sailor CEO Robert Dane introduced the idea after making successful runs of its own solar-powered ferry boats in Australia. Hornblower Yachts is currently looking into the possibility of such a transport service by asking the permission of the local Coast Guard.

If all goes well, the boat will be ferrying passengers in two years time. The boat still runs on diesel, but it mostly gets around on wind or solar power. The proposed design will rely on one big solar sail, which acts like a conventional sail to drag it using the wind currents.

The sail will be made with the assistance of a German company and will be lighter than typical silicon solar panels. Solar Sailor has already been successfully contracted to deliver a set of sails for a 150-passenger boat in Shanghai, as well as a 100-person ferry in Hong Kong.

The San Francisco boat will approximately be 15 meters high and will only have one sail, as opposed to its original eight sail design in Australia. The boat will cost around US% 8.5 million, US$ 1.5 million of that dedicated to the solar sail alone.