Fleets of Wave Power Ships Could Harvest Cheap Energy from the Motion of the Ocean

[txlibdem]

Fleets of Wave Power Ships Could Harvest Cheap Energy from the Motion of the Ocean
by Daniel C Jones, 07/21/11

"One of the major concerns over the current crop of renewable energy technologies is that they're pretty expensive compared to dirtier, more conventional fossil fuels. However researchers at Boston University and the Fraunhofer Center for Manufacturing Innovation think they've found a way of producing cleaner, cheaper wave generated energy on demand. Their idea would send a fleet of wave-powered ships out into the middle of the ocean, where they would drop anchor and start gathering energy from the movement of the surrounding waves. This energy would then be stored in on-board batteries, and once fully charged the ships would return to shore where the energy could be distributed into the grid.

The concept was recently presented at the Clean Energy 2011 conference and expo in Boston. It would do away with the need for expensive transmission cables that currently take electricity from offshore power generation projects to the mainland. These cables typically cost more than $500,000 per kilometre and account for a significant fraction of the cost of conventional wave-generated electricity.

As reported by New Scientist, the 50-metre-long ships would harvest wave energy via buoys attached to their sides by pivoting arms. While the hull remains relatively stable, the buoys bob up and down on the waves, causing the arms to pivot back and forth and drive a generator producing up to one megawatt (MW) of electrical power. The batteries are planned to have a capacity of 20 MW/hours, so the ships would have to stay at sea for at least 20 hours to be fully charged.

The plan could produce electricity at $0.15 per kilowatt hour (kWh), which is far cheaper than energy produced from existing wave technology, which costs between $0.30 and $0.65 per kWh. In comparison, offshore wind energy costs from $0.15 to $0.24 per kWh, and solar power around $0.30 per kWh."

http://inhabitat.com/fleets-of-wave-power-ships-could-harvest-cheap-energy-from-the-motion-of-the-ocean/

See the graphic at the link.

[krispos42]

1. As long as the ships are electrically powered...

...we're all set. Might as well throw some solar panels on them as well, right?

[muriel_volestrangler]

2. 20 MWh at $0.15/kWh = $3000 of electricty for one trip lasting over a day

Is that really worth it? When you've paid the crew?

[RC]

3. How dare you inject reality into pie in the sky ideas.

Hmph, the every idea...

[petronius]

8. It sounds like these are the same sorts of buoys that have been proposed

for mooring in a near-shore environment, so I'm not sure what problem is being solved here (except perhaps for the not-in-my-viewshed! complaint). On the other hand, it seems to create a lot of potential costs and inefficiencies... :shrug:

[Ready4Change]

4. #1: They need a less toy looking graphic.

It really looks like a bath tub toy with the colors they've chosen. Also, the floats being purely round, would hinder the ships movement in the water, slowing it down and making it waste energy. They either need to be little boat hulls themselves, or there needs to be crane infrastructure to lower them into place once the ship is on station, then raise them again when it's time to go home. And that takes me to #2.

#2: Idea of running out to sea to collect energy in batteries, then return to port to off-load, doesn't seem likely to pan out. However, the idea of using the difference between wave motion and a large ships hull motion to generate power IS interesting, and could be useful in driving the ships own engines. I'm not up on their tech, but it seems likely that many ships today would operate like diesel electric trains, using turbine or piston engines to turn generators, then using that power to spin the electric engines that turn the props. Perhaps such a design could use the energy in waves to supplement or replace the energy from fossil fuel burning engines. (Although I secretly yearn for the end of fossil fuels to cause a rebirth of Clipper ships.)

[txlibdem]

6. Agreed, the graphic they chose looks like it's made out of Lego's :-)

I think you're right about the crane needed to raise and lower the buoys. Being round as they are they would without doubt impede the ships movement.

The idea does not pan out economically... today. But once the truth leaks out that we hit worldwide peak oil in 2005 all heck is going to break loose. I don't believe that the USA would find it desirable but perhaps a nation with lower energy needs and access to the coast would be able to.

The article did say "a fleet" of the ships, at 20 MWh apiece (more in the future as more advanced batteries are developed) perhaps a fleet of 100 ships, each out to sea for 20 days and at port for 1 day... 5 ships at port and the rest out to sea... it gives a possibility of 100 MWh being put into the grid each day. The average American family uses 30 kWh per day (serving 3333 households) but Europeans use only 14 kWh IIRC so the number of homes serviced would be larger.

I read the article with the idea in the back of my mind that this is only a part of their energy picture and would supplement solar, wind, and maybe geothermal if they have any.

[FBaggins]

5. Doesn't seem to make sense.

Why pay a crew to run the thing... plus use up energy running in and out... plus pay for expensive battery storage?

If the energy conversion technology works out, just anchor them offshore permanently and run a cable out to a bunvh of them. There's no way that that's more expensive than operating ships.

[Dragonbreathp9d]

7. Liquid karma?

Pimps do not commit suicide