Power generation based on the "motion of the ocean" offers significant long-term value, and arguably could eventually displace solar and wind generation for large-scale renewable energy projects. Hydrokinetic power (encompassing wave, current and tidal power) doesn't have the "intermittency" problems facing solar and wind, nor are there as many issues about ruined views and overrun landscape. Costs remain high, however. There are numerous ocean power projects in testing, and while most show promise, I don't believe we've yet seen the real breakout project putting ocean power at the front of the renewable energy race.

The latest contender is the "Manchester Bobber," an ocean power platform design from the University of Manchester. The up-and-down motion of the water surface drives a generator; a full-size unit should be able to produce a mean power output of around 5 megawatts:

[Professor Peter Stansby, co-inventor of the Manchester Bobber :] "Energy from the sea may be extracted in many ways and harnessing the energy from the bobbing motion of the sea is not a new idea. It is the hydrodynamics of the float employed by the Manchester Bobber that provides the vital connection to generating electricity."

The devices unique features include:

The vulnerable mechanical and electrical components are housed in a protected environment well above sea level, which makes for ease of accessibility.

All mechanical and electrical components are readily available, resulting in high reliability compared to other devices, with a large number of more sophisticated components.

The Manchester Bobber will respond to waves from any direction without requiring adjustment.

The ability to maintain and repair specific 'Bobber' generators (independent of others in a linked group) means that generation supply to the network can continue uninterrupted.

One interesting proposal is that the Bobbers be built on decommissioned oil rigs. Aside from reducing the construction costs, this idea has a significant symbolic value.

Phase 1 tests of a 1/100th working model completed early this year, and Phase 2 tests of a 1/10th scale version are now underway. The university group is working on a preliminary design of the full-size version, and hope to have a time frame for construction by the end of this year.

(Via We Make Money Not Art)

I'm pleased to see so many new university research projects involved in renewable energy production. I believe that hydro energy production is even more promising than wind or solar because it is more concentrated energy source. It is also a steady source of power as opposed to the intermittancy of wind and solar. Another benefit is the proximity of large urban centres to large bodies of water.

Posted by: Chris Richards on September 27, 2005 4:28 PM

Tides and current are probably pretty consistent, but depending on where you are in the world, waves may indeed be intermittent.

It often strikes me, here in southern California, how well named the "Pacific" really is. We've got 2.3 feet at this moment:

http://www.ndbc.noaa.gov/station_page.php?station=46230

Posted by: odograph on September 27, 2005 6:03 PM

Jamais (or whomever), forgive my ignorance, but how does the electricity generated by these reach shore? Surely we're not talking about wires stretched from rigs out at sea into cities? Are they run along the seafloor? This part of the technology seems rife with potential difficulties to me, but as I said, I don't know what the latest plans are...

Posted by: Justus on September 27, 2005 6:39 PM

Undersea cables are used to get the power to land.

Same as with offshore windfarms.

Posted by: wintermane on September 27, 2005 8:48 PM

Can anyone please tell me something more about Manchester Bobber???

Posted by: andrew on September 27, 2005 9:55 PM

A variety of sources combined with advanced demand-side management should be fine; that's the gist of the article Jamais linked to (intermittency)

Posted by: Daniel Haran on September 28, 2005 1:47 AM

Power to area ratio is the important number.
If you can fit 10 wind turbines in the area of
one bobber than you are compare 20 mega watts to
5 mega watts. How about a Wind tubine like system
on the see floor ? using ocean currents rather than wind ?

Posted by: VK on October 2, 2005 5:06 AM

If one had several hundred/thousand of these
manchester bobbers stretching from England to
the Netherlands, than on top you could build a
road/rail bridge. Perhaps this would make the
whole thing worthwhile?

Posted by: V Narayan on October 5, 2005 5:04 AM