The Tide Is High

Here's news to warm the hearts of wonky environmentalists: Tidal power in San Francisco has been declared officially feasible. And not only feasible, but also a damn good fit for the city's electrical needs and geographic circumstances — or at least, so says a new report by the Electric Power Research Institute, a nonprofit R&D outfit based in Palo Alto.

Tidal is electric power we can feel good about, because it's generated without causing asthma, black lung, global warming, or foreign wars. And S.F. is the place to pursue it because we've got the Golden Gate strait, a narrow channel with strong tides that rush in and out twice a day. According to Jared Blumenfeld, director of the city's Department of the Environment, “We're definitely in the top 10 on the planet” in terms of our tidal resources. That's right — San Francisco is almost as cool as the Bay of Fundy.

Here's how it works: Turbines would sit 60 feet below the Golden Gate Bridge, on the seabed; you wouldn't be able to see them even if you were leaning waaaay over the edge of the bridge. Researchers don't expect them to harm the fish — the rotors revolve slowly, so fish could swim through the turbines without being chopped into fish-kabobs.

That's the dream, anyway. Tidal power advocates have waited years for the technology to be ready to go. This summer, a pilot project goes into the water near Scotland. It's the moment S.F. has been waiting for, Blumenfeld says. “San Francisco doesn't want to be an R&D facility; we want to be the first commercial deployment. We don't want to be working out the kinks; we want to get something that works.”

Not surprisingly, financing is the sticking point. While the city and state could probably pull together the $7 million required to build a 1.5-megawatt pilot project, the European companies blazing the tidal trail won't bring a team here for such small potatoes. Portugal, Spain, France, and the United Kingdom are all considering serious, large-scale investments in ocean power (which includes both tidal and wave power, a technology that isn't as far along). To entice the companies across the pond, California needs to make some big promises. “We need the same level of commitment that has been put into hydrogen, wind, and solar to be put into ocean energy,” says Blumenfeld. If California pledged to build a full $90 million system in the Golden Gate, for example, then we might find some takers.

The start-up capital costs are higher than they would be for a new natural gas or coal power plant, by at least 20 percent. But when you combine capital and operational costs over 20 years, a tidal system costs the same as a natural gas plant. After all, the tide comes in for free, while natural gas costs money. And the benefits are obvious. Most of our power is piped up from the southern Peninsula, especially now that the Hunters Point power plant is closed. But the city is responsible for generating about 200 megawatts of its power load. Right now, Mirant's Potrero Power Plant supplies that power, but the natural gas facility has been accused of polluting the bay, and it certainly emits greenhouse gases. Many environmentalists — not to mention Gavin Newsom — have talked of closing down Mirant and replacing it with a portfolio of smaller, renewable energy systems. Tidal would contribute at least 35 megawatts to the mix, according to the EPRI report.

And while that may not seem like much, there's at least one less tangible benefit: It's good bumper-sticker fodder. “This will be very boutique,” says Blumenfeld. “People will want to say, 'I get my energy from waves and tides.'”

View Comments