I once spent an enjoyable lunch discussing the (for me previously unconsidered) merits of tidal power for electricity generation. My friend’s position was one of incredulity that a potentially free, non-polluting ” either in terms of emissions, noise or aesthetics ” could be so far behind the curve of other renewable energy technologies. It should be no surprise that he lives in Guernsey which at over 20 ft has one of the highest tidal ranges in the world. My friend can see the power of the sea going to waste every day from his bedroom window. Some amazing claims have been made on the power generation potential from Guernsey’s tides. Martin Bruger, CEO of renewable energy specialist Blue Energy Canada has gone on record as saying Guernsey could generate 25,000mw of electricity. Since most versions of tidal power generation do not accumulate silt (unlike hydro and coastal barrages) the investment can be re-paid over a long life cycle. Bruger suggests 100 years. Personally, we’d like to know what materials will contribute to that 100 year turbine life cycle!
So why hasn’t tidal power taken off? It’s not as if the technology is completely unproven. Britain recently installed a tidal power generator fixed to the seabed in Northern Ireland’s Strangford Lough. It is claimed to be the first commercial tidal turbine although there are many previous examples on a much smaller scale. But at 1.2mw, the 300 ton Strangford Lough generator will eventually be capable of powering 1000 homes. Marine Current Technologies, the firm behind the project says they plan to build a production line making the generators which act much like an underwater windmill. They intend to install a new generator in 24 hours, we can pop them out like Smarties the CEO said. On a more commercial production run, power generation costs will be about 5.5 cents/kilowatt hour for units of 10mw or more. This is comparable or cheaper than wind power and much less than solar power.
This technology requires a current of 5-7 knots which limits the use of underwater turbines in North America to the Pacific Northwest, San Francisco Bay, New York Harbor and rivers with strong currents. But the University of Michigan is working with the Detroit River Authority on a different technology harnessing the vortex induced vibrations in column shaped bars to generate electricity from tidal ranges. Their technology, called VIVACE, can work with currents as low as 2 knots. The first project is going in this year to power the lights for a new wharf between Hart Plaza and the Renaissance Centre. Project director Mike Bernitsas says an array of 1000 cylinders could eventually produce the same power as a large nuclear power station.
Technologically none of these concepts require advanced science; none have pollution issues, long term resource issues like fossil fuels or legacy issues like the disposal of nuclear waste. Unlike wind or solar, the tides are utterly predictable decades in advance. There are environmental concerns about the impact on marine life but the expectation is like earlier concerns about bird life and wind power the impact will be limited. One hindrance has been the permitting. In the US, between 25 and 35 different federal, state and local regulatory agencies claim some jurisdiction over marine deployment. In the UK, there are just two. Consequently, Roger Bedad, ocean energy leader at EPRI, Palo Alto, CA says it could be 2025 before big deployment takes place in the USA. Even Canada may be an earlier adopter as the approach tends to be more collaborative north of the border rather than adversarial in the US people are worried about being sued said Verdent Power’s president Trey Taylor. If the new administration is going to invest in renewable technologies it would be a shame if tidal power did not get a good hearing. A strong US led development of the technologies would undoubtedly bring the cost of production down for everyone. The issue then would be the cost of taking that power, sometimes from remote sites, to the areas of consumption. Which brings us to smart grids and the subject of another article in the future.