Algae towers, geothermal mushrooms and fog flowers. These may sound like the stuff of science fiction but some Bay Area architects say it could be the city's green future.

"We tried to think of what was next," says Lisa Iwamoto of the IwamotoScott architecture firm.

IwamotoScott entered a design competition to create the city of the future, 100 years from now. And they took home the top prize in the regional competition, beating out seven other local firms.

"It's kind of like iron chef of architecture," Iwamoto said. "They give you one week to design a city which is not much time to design anything let alone a city."

But design the did, coming up with HydroNet. A plan that would connect water and power through an underground system.

"We began by saying what are people going to need. One is fresh water. Some people speculate it’s more valuable than oil in 100 years," Iwamoto said. "Another is power and for us we thought of not fossil based fuels by hydrogen based, a really clean burning energy and a lot of research now on how to make it store it make it cost effective for every day use."

So they designed an underground network of carbon nanotube walled tunnels where people travel in hydrogen fueled cars that can fly.

"Some other proposals moved toward mass transit,." Iwamoto says. "But we think Americans aren’t going to want to give up personal vehicles. we also felt like auto tech would change, smaller, hydrogen based and faster.

The hydrogen would come from Algae towers along the Bay side of San Francisco. The idea would be to turn the algae into hydrogen, work which is already being done by scientists. Work is now underway to store hydrogen in a safe and efficient manner, and that's where the nanotubes would come in.

"The tunnel walls being built with nanotubes would store hydrogen in safe manner." says Craig Scott, also of IwamotoScott. "The microstructure of nanotube can put it in solid form not gaseous state."

Now San Francisco was just one of the cities competing to build the City of the Future. Contests were also held in Washington, D.C. and Atlanta. Now the winning teams from all three regions are pitted against each other for the grand prize.

For more on the competition and to cast your own vote, head to click here