Harnessing the Ocean’s Power for Electricity

9 Jun

Finavera Technology\'s AquaBouy, which is to be deployed off the coast of CaliforniaThis week’s Economist contains a couple of interesting articles in its Technology Quarterly outlining a variety of approaches to harnessing natural and renewable sources of energy for human consumption. Specifically, it focuses on technologies capturing power from the ocean.

Wind

The first looks at new technology for off-shore wind farms which would allow them to be located much further off the shoreline, generating more energy from higher-velocity winds and fewer complaints from nearby residents whose views have been blocked.

the stronger winds out at sea can generate more electricity, and hence more revenue: wind blowing at 10m/s can produce five times as much electricity as wind blowing half as fast, and this greatly favours building more offshore wind far

Instinctively, this seems like a winning combination: it moves electrical generation out of “my backyard,” where so few people are willing to have it, while also improving the economics of wind energy by tapping a more reliable, stronger source of wind.

The ability to get the electricity generated offshore back to where it is consumed, and the amount of energy lost in transmission would seem to be major barriers to the technology’s success. As would the cost of the turbines and maintenance, which would both seem considerably greater than a traditional land-based wind farm.

Wave

The second looks at the approaches to harnessing wave power which are showing the most promise.

YOU only have to look at waves pounding a beach, inexorably wearing cliffs into rubble and pounding stones into sand, to appreciate the power of the ocean.

Unlike wind and solar energy installations, wave energy sites could theoretically be located far from the coastline if an easy means of transporting the electricity were developed, once again eliminating the “not in my backyard” objections of most other forms of electrical generation.

Alas, harnessing it has proved to be unexpectedly difficult. In recent years wind farms have sprouted on plains and hilltops, and solar panels have been sprinkled across rooftops and deserts. But where the technology of wind and solar power is established and steadily improving, that of wave power is still in its infancy.

The article outlines a number of different designs and approaches to capturing wave energy, but none appear to be the obvious choice for the future. Each faces obstacles that have thus far kept them from widespread adoption.

A recurring problem, ironically enough, is that new devices underestimate the power of the sea, and are unable to withstand its assault. Installing wave-energy devices is also expensive; special vessels are needed to tow equipment out to sea, and it can be difficult to get hold of them… Another practical problem is the lack of infrastructure to connect wave-energy generators to the power grid. The cost of establishing this infrastructure makes small-scale wave-energy generation and testing unfeasible; but large-scale projects are hugely expensive.

The Role of Silicon Valley

Will the innovation of offshore wind and wave technologies happen in the same place so much technological innovation has occurred in the last twenty years? Interestingly, the article mentions that PG&E, the Bay Area electrical utility, is one of the first adopters of wave technology.

In December Pacific Gas & Electric, an American utility, signed an agreement to buy electricity from a wave farm that is to be built off the coast of California and is due to open in 2012

The PG&E project will involve deploying the Aquabouy, which is produced by Finavera Renewables of Vancouver.

Each Aquabuoy is a tube, 25-metres long, that floats vertically in the water and is tethered to the sea floor. Its up-and-down bobbing motion is used to pressurise water stored in the tube below the surface. Once the pressure reaches a certain level, the water is released, spinning a turbine and generating electricity.

Could this early adoption of wave technology, along with San Francisco Mayor Gavin Newsom’s well-known interest in alternative energy, mean that the Bay Area has an early lead in the development of this, the latest of alternative energy technologies?

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