Australian company Energetech is one of the growing number of companies building systems to turn the motion of the ocean into usable energy -- something we've taken to calling "hydrokinetic power." Waves, tides even undersea currents can, in principle, be tapped to generate electricity; the technology is in transition from real-world experiments to early adoption, and the preliminary signs are that the systems can indeed produce usable amounts of power at competitive prices.

Energetech has taken their system a step beyond power generation, however. Working with a company called H2AU, Energetech added a small desalination system to a test deployment of a wave energy system at Port Kembla in Australia. Happily, the combination works splendidly:

Most desalination installations use electricity to create the pressure needed to drive a reverse osmosis system but the two Sydney-based, privately owned companies' combined technologies use wave pressure directly to power a reverse osmosis desalination plant. This unusual project avoids the multiple energy losses in converting wave energy to electricity before using the electricity to drive pressure pumps. [...]

"The main expense with desalination is building up the pressure needed to force the water through the separation membranes," says David Murdoch, managing director of H2AU. "With normal water desalination, that pressure energy is lost but our systems incorporate energy recovery technology, which allows us to transfer most of the pressure from the outgoing brine to the incoming seawater."

The Port Kembla test system has met its initial goals, and is now gearing up for longer-term operation. Energetech estimates that it will produce at least 500 MWh annually -- possibly up to 1,500 MWh -- and about 2,000 liters of fresh water every day. At full production, an Energetech wave power system should produce electricity at a cost of less than five cents US per kilowatt-hour. A full report of the Port Kembla test results can be downloaded from Energetech (PDF).

(Thank you, Tim Dutoit!)

Could they use wind-power too? Or both? I mean, how do they funnel a come-and-go pressure and turn it into the higher-and-higher pressure needed for reverse osmosis? (Not that I understand the process, though.)

Posted by: Lucas Gonzalez on November 22, 2005 2:46 PM

What an elegant turbine! The Helix mirrors the great source of biochemical human intelligence- DNA. It is therefore fitting such a spiral design would power society through the kinetic and chemical energy present in the environment.

This reading caused a thoughtstorm in my mind:
What about adding wind turbines on top of the water turbines?
What about adding rain-catching solar philm on these promethean power plants?
What about using silica aerogel to float these badboys in the ocean?
What about integrating OTEC (ocean thermal energy conversion)?
What about adding hydroponic biomass producing modules using the desalinized dihydrogen monoxide? Floating H20/biomass/energy plants...what more do you need besides water, food, energy, and fiber?

http://Spoey.com - Grid of Renewable Integrated Networked Transport

Posted by: David Spoey on November 22, 2005 6:11 PM

good stuff & not before time, esp given almost the entire Australian population lives along the coasts. (& there's been a big stink about building an energy hungry desalination plant there that potentially also reduces water quality).

re: nomenclature:
Tides = lunar power
Waves = solar power

a circuit of the deep ocean current can take 1,000 years, + there are suspected atmospheric/oceanic cycles every 10,000 yrs or so. How amazing is nature? No wonder we can't be figure out where much of the extra CO2 has gone.

Posted by: Flannel Flower on November 23, 2005 5:04 AM