Mike the Mad Biologist

A completely new concept of underwater wave energy using a simple 7 ton kite turbine design has been developed by Minesto; which is a spinoff from the Swedish military and aircraft design firm Saab. The Deep Green underwater turbine captures the power of the ocean just like a kite in wind....

Originally Saab was working on a kite design for a wind turbine, but found that the concept would actually work better in water, which is 832 times more dense than air.

The kite twirls in a repeating figure eight pattern (video) that increases the ocean velocity ten-fold. The first stage increases the relative flow speed entering a turbine. When the tide hits the wing it turns down, which creates a lift force. The kite is mounted to the ocean bed with a tether and is controlled by a rudder to gently nudge it in the desired trajectory.

According to Minesto's website, each megawatt-worth of kite(s) would weigh 14 tons, so it would seem that each 7 ton kite is a 500 KW unit. According to CEO Anders Jansson's estimate, these could probably produce power for somewhere between $0.09 cents and $0.20 cents per kwh.

Certainly because these are such extremely simple-tech structures they would be cost effective - costing less in materials per power produced, and costing less in transporting them to the site, in installing them and even in ongoing maintenance costs.

I wonder if this technology might have been developed in the U.S. had we not deployed so much of our brainpower and resources to the housing boom. Because that worked out really well.

Also, this little bit shocked me (italics mine):

The system could generate 18 terawatthours of energy annually, enough to provide nearly 4 million British households with reliably green electricity every year. UK households now use about a third of what average US households use in energy.

We might want to do something about that too. Nonetheless, kudos to Saab. You've come a long way baby:

(from here)