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PG&E, San Francisco and Golden Gate Energy to Explore Tidal Power Options in SF Bay

Lunar Energy RTT Turbine. One of the different technology options available for tidal in-stream energy conversion (TISEC). Click to enlarge.

Pacific Gas and Electric Company today signed an agreement with the City and County of San Francisco and the Golden Gate Energy Company to conduct the most comprehensive study yet undertaken to assess the possibilities for harnessing the tides in San Francisco Bay to create a new source of zero-emissions, renewable electric power for California energy customers.

The multifaceted study, the initial phases of which will begin this summer and are estimated to take approximately twelve months, will include thorough analyses of the Bay’s energy potential, the existing and emerging technologies to capture energy from tidal flows, the possible environmental impacts associated with such a project, as well as the economic feasibility and other costs and benefits of tapping this new energy supply.

If findings in the initial rounds of research affirm the feasibility and promise of tidal in-stream energy conversion (TISEC), future plans could ultimately lead to the development of a full-scale commercial project.

The study effort will bring together and draw on the combined resources and expertise of PG&E, CCSF and Golden Gate Energy. Specifically, PG&E is committing to provide up to $1.5 million to fund research by third-party experts, dovetailing with up to $346,000 contributed by CCSF for feasibility studies and stakeholder outreach. Golden Gate Energy, which currently holds key federal regulatory permits necessary to study the San Francisco Bay location, will work cooperatively to support the effort.

In addition to being clean and renewable, tidal power offers the advantage of being highly predictable and reliable. In addition, tidal power technology would be situated on the sea floor, avoiding the land-use and visual impact considerations associated with many other forms of power generation. In a 2006 study, the Electric Power Research Institute identified San Francisco Bay as one of the world’s most abundant potential resources for electricity generation using tidal power technology.

The EPRI report grouped TISEC water turbine technology into two types (like wind turbines):

  • Horizontal axis turbines in which the axis of rotation is horizontal with respect to the ground and parallel to the flow direction; and

  • Vertical or cross-flow axis turbines in which the axis of rotation is perpendicular to the flow direction.

Subsystems include rotor blades which convert the energy to rotational motion, a drive train and a supporting structure. Devices vary by:

  • Design of the support structure: gravity base bottom mounted, attached to a monopole foundation, or anchored and moored and allowed to float in the tidal stream;

  • Open vs. shrouded rotors;

  • Fixed versus variable pitchblades;

  • Yaw control versus fixed yaw angle; and

  • Drag vs. lift water foil (vertical axis only).




There's already work on a similar project in New York City waterways.


And here in BC:



The tidal turbines in NY are so simple: basically a fixed blade wind turbine dropped underwater! It bothers me that no one ever thought of these years ago!


It was not thought of years ago because people didn't believe that water under water moved!

Kinda like asbestos and mercury were safe to play with 30+ years ago...times change


If that where true one can only wonder what blatantly obvious things we are miss today; but I'm pretty sure they knew tidal waters move: anyone could see bays filling and emptying in a day! The problem was back then they built a few huge megaplants and artificial bays to optimize energy usage but also optimize price into the extremely expensive range, making it impractical for large scale use. Small scalable arrays may be the answer.


Good news abounds these days. This is a necessary step toward capturing energy that is abundant, clean, renewable and there for the taking. I expect to see more innovation in wave action and tidal capture systems soon.

There are some Aussies that are doing fantastic work on underwater bio-mechanical systems. They are simply reproducing what nature has done for millennia with great success.


Great news indeed, hopefully this moves along faster than is typical of projects in SF. This would tie in nicely with SF's plans for Community Choice Aggregation! According to the Chronicle, there's a potential 38 MW to be tapped compared to 10 MW in the East River.


Sorry, but these were thought of long ago. The difference is that none of the developers thought that they would be able to get it past the environmentalists. What happens when whale meets turbine? How many salmon are going to get chopped up in these things? Thankfully for the big investors, all they need to do is protect their profits with their mantle of green and make sure that certain regulators get their big bonus at Christmas time. The key is to make sure that there's lots of good exposure from gullible Fox News reporters that know where their paycheck comes from and get your foot in the door before Clinton gets in.


New ! thats a laugh , the french built a system in northern France
in the 1960´s and its still going strong today!



the BC Racerocks project claims 2.1 - 4.5 million kWh per turbine dependent on size and current flows. Does this sound plausible?


gr: I can't say for sure, but I do know that the turbine has been in the water there (I have a friend that worked on it) and that the currents at race rock are way wicked.

deut: It is possible to build these in such a was as to not "chop up" anything.


The turbines don't actually spin fast enough to "chop up" things: 10-30 revolutions per minute.


You are really scaring me. What drives people to defend such reckless technologies? I am similarly incredulous when I see people cheering on Genetically Modified Organisms that voraciously devour compounds as ubiquitous as cellulose, but have no idea how our "test case" organisms like BT corn have hybridized (evolved) and now deal death to a variety of non-target species. Are we willing to give up the wild things so that we can have our plasma screens?

Tidal power may help "solve" the Global Warming problem, but this may just get us out of the frying pan and into the fire. The tip speed of a huge rotor can run faster than anything that swims. Tell me how a whale or a salmon will avoid even one of these things at night, much less 99 of them stretched across the Golden Gate?

Personally I am willing to put up with windmills killing birds, since most of the birds can be counted. As this particular technology moves forward we will see a few dead whales on beaches, but I say that most of the pulverized sea life will float to the bottom and disappear into the bellies of a few scavenger species, and some of those may be exotics. Maybe that's good enough for you?


I'd just like to know who this "Golden Gate Energy Company" is. As far as I can tell, they don't even have a website. Probably a Halliburton subsidiary...

Frank Ferrano

Yeah you would think that this could have been thought of years ago. I like the direction though. Anything with less emissions works for me. Since “green” businesses are popping up left and right, I love that The Social Venture Network is holding a contest to reward business leaders of socially responsible companies! If you know a CEO or high-level person in such a company, please send them to the Social Venture Network site and look for the "Imagine Whats Next" contest.They are holding this contest to reward business leaders for starting or running socially responsible companies. This seems to be a growing trend, and a colleague of mine who works at a non-profit sent it to me.

Vince Monahan

I was on the Social Venture Network’s website today and came across that contest for socially responsible business leaders. It looks like a great way to reward new businesses for working toward the greater good.

Mick Marshall

A colleague of mine who works at a non-profit sent that Social Venture Network website to me. I’m trying to start a non-profit myself and I can use all the help I can get!

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