Should we be moving more of our renewable energy efforts offshore?

From the Tide Mill at Woodbridge to the Rance in Britanny, we have been harnessing the power of the tide for centuries. MARK ASPINALL, director of 4NRg, based at OrbisEnergy in Lowestoft and managing director of Scour Prevention Systems Ltd, explains why this ancient concept is still relevant today.

NOTHING seems to divide opinion like renewable energy.

Whilst the science behind the projections for global climate change is almost incontestable, opinion on what should be done, if anything, is very divided.

In this country in particular, building renewable energy resources is almost bound to upset someone and getting projects through planning is almost impossibly difficult. Getting sufficient electricity generation built before we start shutting down the old coal fired power stations now looks extremely unlikely.

Given that none of us wants to be left sitting in the cold and dark, what can be done to change the situation?


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The obvious answer is to build resources in places that don’t create the same problems: but where, what, and can we afford it?

The answer might be to follow the offshore wind turbines.

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The energy companies have spent billions of pounds in the last few years installing thousands of turbines off Britain’s shores. More importantly, they’ve built a whole infrastructure of cables, sub stations, port facilities and vessels. They’ve developed a sophisticated supply chain and spent millions on training people with the skills to work in this difficult environment. If all these resources could be used to support new energy opportunities, not only could we generate a lot more power (and a lot more jobs), we could also bring down the cost of that electricity and remove one of the biggest objections we have to renewable energy at the moment: the price.

Britain leads the world

So, where should we get the power from? Offshore, in addition to the wind there are three other possible sources of energy: wave, tidal range and tidal flow.

The world’s first practical wave energy device was created in the mid 70s by Professor Stephen Salter at Sheffield University. Salter’s Duck (as it became known) bobbed up and down on top of the waves and extracted an incredible 80% of the energy available: it is still the standard by which other wave energy devices are measured.

Closer to home, Trident Energy in Suffolk have developed a linear generator (coils of wire passing over a magnetic pole ) and created a highly efficient, low cost wave energy device which will attach to offshore wind foundations. The generators have been successfully tested on-shore and the technology shows great promise. Trident Energy is planning to undertake sea trials of the generators later this year. Steve Packard, Trident’s CEO explains, Marine energy has so much potential and should feature strongly in the Uk’s future energy generation mix. Like the wind industry of 10 years ago, costs are high but this will change as developers learn from their experiences and start serial production of machines. I believe that the UK can be the leader in this new market, create product export potential and thousands of jobs in the new green economy.”

Tidal energy comes from the movement of the sea - the tide - created by the moon revolving around the earth. As long as the moon is in the sky there is a virtually limitless supply of energy. Perhaps more importantly it is highly predictable with high tide occurring twice a day every day, meaning that unlike wind or sun, which can vary unpredictably, the amount of energy and exactly when you’ll get it can be calculated hundreds of years in advance: a real boon for the energy companies who are constantly battling to balance supply and demand.

Tidal range energy comes from capturing the sea as the high tide comes in, then releasing it in a controlled way through turbines to generate electricity. Britain has some of the largest tidal ranges (in excess of 11m) in the world and could create an astonishing amount of energy from it. And it’s not new: there has been a tide mill at Woodbridge since at least 1170. Large scale tidal schemes are not new either: La Rance in France has been running since 1966 generating 240MW at peak. That energy has cost France 1.6c per KWh, compared to nuclear at 2.4c, and without the prohibitive decommissioning costs at the end of life.

Tidal flow takes the speed of the water and turns it directly into energy. Again, the UK has a huge resource as the whole of the Atlantic tries to squeeze in and out of the North Sea twice a day. This squeezing action forces the water to accelerate, giving speeds in excess of 3m/s around the north of Scotland, and that’s why European developers have placed the European Marine Energy Centre (EMEC) on Orkney - remote but perhaps the best place in the world to try out new technologies. In fact, over half of all the world’s largest full scale tidal energy devices under development are based in the UK.

Back in Suffolk, 4NRg recently tested their latest device, the Tidal Harvester (TH2), on Lake Lothing in Lowestoft and demonstrated that tidal devices, scaled for the North Sea, could easily generate clean energy on a commercial basis. Dave Watson, the inventor of the Tidal Harvester said, “The most exciting finding was that the device produced 25% more power than originally predicted. And the testing allowed me to identify more ways in which to make the device simpler, more robust and more efficient. The next few years are promising to be very exciting as we develop this further”.

So what happens next? Well, Suffolk has done very well out of the original development of offshore wind farms and we have a wealth of experience and knowledge that is equally applicable to marine energy. As individuals, businesses, and as a community, we need to make sure that we continue to be at the forefront of these developments: create the networks, support the businesses, lobby local and national government, and most importantly, be vocal in our support of these new technologies and ensuring that they come to Suffolk rather than go elsewhere. In return we can expect a healthier economy, a better trained workforce, and more good jobs for our kids over the next thirty years.

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