AUG 30, 2015 4:29 PM PDT

Hawaii's Making Clean Power From Ocean Water

WRITTEN BY: Andrew J. Dunlop
Hawaii made history recently, as it threw a switch connecting the world’s first ocean thermal energy conversion power plant to its power grid.

The on-shore portion of Hawaii's OTEC plant

This is one in a series of renewable energy projects Hawaii has been rolling out over the past few years. Currently the state depends on expensive imported fossil fuel to provide most of its power, but this is in the process of changing. Hawaii has embarked on an ambitious plan to be using 100 percent renewable energy by 2045. It has already installed a number of wind frams, plenty of rooftop solar panels, several sophisticated smart grid systems which make the most efficient use all of the energy generated there, and, now they have the first fully closed-cycle Ocean Thermal Energy Conversion (or OTEC) plant in the U.S.

What is an OTEC plant? It is a system that generates electricity by exploiting  the difference in temperature between the warm ocean surface waters in tropical areas and the much colder water in the ocean depths below. The two streams of water are pumped through a heat exchanger, which creates steam. The steam drives a turbine which produces clean, reliable, scalable electricity.

The OTEC current plant has a capacity of 105 kW, which is enough to power 120 Hawaiian homes per year. That may not seem like a lot, and it’s not, but this is a demonstrator-sized plant. It’s estimated that about seven industrial scale plants of this type could power the entire state. 

Scaling up the technology could be done tomorrow, if the funds were available. The engineering isn’t in question. How to scale up the technology in a way that makes economic sense is. Figuring out how to do this will be the job of the Ocean Energy Research Center, where the plant is located. The Center will be working on plumbing the potential of this type of technology. There are already many other locations that are interested in acquiring an industrial scale version of this sort of plant, places like Okinawa and Guam, which like Hawaii, are also currently dependent on expensive imported fossil fuels for most of their energy needs.

Makai, the maker of this plant, has just signed on to develop a 1 MW version of the plant on the island of Kyushu in Japan. Makai has also been working in concert with Lockheed Martin to plan a 100 MW OTEC plant in either Hawaii or Guam. According to Makai a plant of this size, could produce enough electricity for 100,000 Hawaiian homes at a rate of only 20 cents per kWh.

Once the mechanics of building an industrial scale version of an OTEC plant are worked out, it could be the perfect energy source for tropical areas near large bodies of water. It’s not as risk-heavy as harnessing wave power. It’s extremely stable. It always produces energy, regardless of whether it's night or day or if the wind is blowing. It can also be easily ramped up and down quickly to accommodate fluctuating demand and intermittent power surges from solar and wind farms.

Sources: TechExplore, TreeHugger
About the Author
Bachelor's (BA/BS/Other)
Andrew J. Dunlop lives and writes in a little town near Boston. He's interested in space, the Earth, and the way that humans and other species live on it.
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