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Promising wave power

David Crisp, Orecon, UK

UK-based Orecon has developed an innovative buoy to harness wave energy. The company’s chief executive, David Crisp, gives his views on how to kick-start investment that will allow the UK to be a world leader in wave power.

A limitless power source to end our reliance on fossil fuels and, with it, a reduction in the effects of global warming may sound fanciful but this is the reality on offer from the sea. It is a vast, mostly untapped, power source that could well hold the key to our energy needs for the future.

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According to the World Energy Council (WEC) only 0.2 per cent of the energy contained in the oceans could power the entire world. It represents a renewable supply of energy forever lapping at our shores.

The idea of wave power is nothing new and for centuries engineers have been using the power from water to drive pumps and other mechanical plant. It was in the 1970s that the idea of harnessing commercial quantities of energy from the waves really took off.

The UK led the way with its ideal climatic conditions complemented by a supportive government and national entrepreneurial spirit. The ‘Edinburgh Duck’ created by Professor Stephen Salter sparked a storm of interest when small-scale tests showed it could efficiently convert wave energy into electricity. However, as the years passed, interest and momentum was lost and along with it the vital central funding. Professor Salter’s project was shut down in the early 1980s.

Now, the tide has turned. Renewable energies are very much back on the power map with supporters warning that an invaluable opportunity will be missed if action is not taken now to harness this valuable resource.

In the UK alone it is believed there are 87 000 GWh up for the taking every year à‚— this is enough to satisfy a quarter of the UK’s power needs. It is a prospect that has spawned a crop of new wave power systems, the first of which are now tantalisingly close to becoming commercial realities.

Simple and robust technology

One of those leading the field is Orecon, originally a spin-out of the University of Plymouth, UK. Orecon has developed a steel wave energy buoy consisting of three multi-resonant chambers (MRC) held in place by a gravity base which forms a tension mooring system, designed to compensate for the tide but resist movement caused by waves. Orecon’s technology was developed by marine engineer Fraser Johnson who credits his problem-solving success to learning the hard way.

Orecon’s director of engineering Fraser Johnson
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“I decided not to do A-Levels and joined the Merchant Navy instead. For a number of years I worked as a deck officer on vessels involved in the oil and gas industry. Those vessels don’t tend to carry their own engineers so when something went wrong it was a steep learning curve and extremely hands-on. It taught me more about the problems of coping with the damage caused by extreme offshore conditions than I could ever have hoped to learn anywhere else,” recounts Johnson.

It was experience that Johnson put to good use on completion of his Marine Engineering degree when he opted to study for a PhD à‚— his topic of choice was wave energy systems.

He explains: “After all my time at sea and my knowledge of the power industry, it was a subject that held a great fascination for me although I did seem to approach it from a rather different perspective to the academics around me.

“While they were all hell-bent on creating the biggest, most technologically impressive system that would generate the most power, I looked at the mechanics already proven in the oil and gas industries, and concentrated on producing a device that would actually survive the environment it was intended for.”

The result was the MRC, a device designed from day one to be simple, robust and to remain in operation on site for a minimum of 25 years.

Power and efficiency

Like other systems before it, the Orecon buoy is based on oscillating water columns (OWC). However, unlike its predecessors, Orecon’s device contains three 500 kW OWC chambers, which are identical in cross-section but different in length. The result is a device a third more efficient than earlier models and, through the varying lengths of the chambers, is equipped to extract maximum energy across all seasonal sea states. The control system strategy further increases efficiency by keeping the chambers in resonance. Current ratings mean that each buoy will be capable of generating 1.5 MW, which is enough power to satisfy around 1000 homes.

While conventional OWC systems use Wells turbines to convert bi-directional airflow into energy, Orecon has devised a power system using a new impulse turbine providing it with a far higher efficiency and a broader band of operation to overcome the issue of changing conditions. As waves rise and fall within each of the three chambers they act like pistons, driving air backwards and forwards through the air turbine, which is linked to a 500 kW generator. The power produced is then fed through a converter to a step-up transformer, emerging at a grid code compliant 33 kV for transmission to shore.

Former world champion dinghy sailor and Orecon’s Environment Manager Nikki Meek and David Crisp, CEO and founder of Orecon
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The company’s use of a patented tension mooring system is also a huge plus. Not only does it reduce the risk of entanglement with marine life and traffic, but it helps the environment by eliminating scour of the seabed.

Perhaps most importantly for customers, the vertical mooring system is also of tremendous commercial benefit à‚— the mere fact that the buoys do not ‘bob’ up and down increases power capture by 90 per cent compared to catenary moored devices which rely on long mooring chains giving them a footprint an order of magnitude larger.

Simplicity is at the heart of Orecon’s entire philosophy. The 40-m buoys are deliberately low-tech with few moving parts and none that come into contact with the water. Only the turbines and drive shafts rotate, and they are housed in the machinery room contained within the structure of the buoy. The tension mooring system ensures the buoy does not disturb the environment as there is no continual sweeping and scouring of the sea bed. Its synthetic material tendons are highly visible to sea life and their deliberately open arrangement in the sea means larger mammals can pass freely around them without danger of being ensnared.

Maintenance is made easy as the lack of complex mechanics means there will be no enforced shutdowns in severe weather conditions and it also has the benefit of ensuring that all maintenance work can all be carried out on site with no requirement for large, complex support vessels.

Testing times

Final tank testing will be completed this year. Quarter-scale models have been produced to test the turbine, generator and power conversion systems and so far, according to the project team, the only surprises have been good ones. An early offshore test of a scale model produced equally pleasing results and Orecon’s designers are confident that MRC’s components will perform well under even the most extreme conditions.

Orecon’s multi-resonant chamber wave energy system is designed to remain in operation on site for a minimum of 25 years
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The first full-size buoy will be deployed, probably off the coast of Cornwall, in April 2010. After further tests additional buoys will be added to create the UK’s first commercial array.

Attracting investment

It is a prospect that is likely to prove irresistible to the world’s energy companies as they attempt to reduce their reliance on oil and gas in favour of more renewable sources. According to Orecon the cost of power produced from waves will be around $0.08/kWh making it just as attractive as wind power. Where the MRC outperforms is in power density with a yield of 100 MW of power for every km2 of ocean compared to around 11 MW for offshore wind power.

However one looks at it, the figures do add up, a fact that has not escaped some of the globe’s most influential energy investors. A deal was closed in February 2008 for à‚£12 million ($21 million) of venture funding from a syndicate led by Advent Ventures (UK) and including Venrock (USA), Wellington Partners (Germany/Europe) and Northzone Ventures (Scandinavia). The only funding problem the company faced was the fact that at one point there were too many people hoping to join the syndicate.

The tension mooring system ensures the buoy does not disturb the environment by eliminating scour of the sea bed
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David Crisp, Orecon chief executive said: “We see ourselves as sensible professionals rather than persistent headline grabbers. For us it is all about doing what is most important rather than what is most interesting.”

It was this philosophy that prompted Orecon’s decision to invite the scrutineers from Det Norske Veritas (DNV) to be on board from day one. DNV is an independent body dedicated to the safeguarding of life, property and the environment.

Its classification rules are based on a wealth of experience accumulated over more than 140 years of research and development.

For many organizations the constant monitoring by DNV would be seen as too intrusive during the all important development stage. For Orecon it was a chance to draw on DNV’s experience, with the company happy to make use of proven technology and known by DNV to be working well in the harshest ocean conditions.

As a result the entire MRC is being built to DNV classification rules (DNV à‚— OSS-312).

“We are not out to re-invent the wheel at every turn. Why would we try and redesign every single part we need when most of them have already been created by engineering experts with far greater knowledge than us and come with long track records of working well in the conditions in which we would like to use them?” observed Crisp.

Delivering on promises

But there are still many hurdles to overcome, not least of which is winning back the support of government. Most of the major power companies are playing a waiting game and the wave industry is still heavily reliant on private investors to fund the development. It is vital work that could reap billions of pounds in the future and a point made by Crisp when he chaired London’s first ever Wave Energy Summit in June 2008.

Crisp told the conference: “It is time for government and all political parties to put real support into the industry. Political and regulatory uncertainty is a significant risk and, as such, a deterrent for investors. The government must now send out the right signals and make real commitments to the industry, commitments that the industry and its investors can rely upon.”

Significant political support, he said, could produce dramatic results for the UK wave industry with substantial, positive knock-on effects for the rest of the UK economy for years to come.

Delegates who travelled to the conference from around the world were told how Orecon is working hard to make the South West of England the centre of the wave industry in much the same way that Silicon Valley in California is the centre of the hi-tech world. “Wave energy represents a multi-billion pound global industry for decades to come. The UK has the lead. We must not give it away as happened with wind; the lessons to be learned are very clear,” said Crisp.

Crisp explained his view of raising capital from the private sector: “If provided with a commercial environment, where investors can see wave being profitable, I believe we can attract the risk capital needed for the industry’s development. I am certain that private equity can be persuaded to take the technology risk provided they can see a reward, this way we can avoid putting public money at risk. A further benefit of this approach is that it is left to industry to sort out, with government support, which technologies are viable and which are not, something industry is experienced at and designed to do properly.”

With innovative technology and an experienced team of experts with years of working offshore, Orecon has a goal to prove that the UK has the expertise required to be a world leader for wave power.

Fraser Johnson, Orecon director of engineering said: “What I want to see is Orecon delivering on its promises. For years now a lot of people have been talking about commercial wave power, a lot of money has been invested in the idea of it, but so far no-one has delivered a commercial energy device that is 100 per cent up to the task. We believe our device will be and we fully intend to deliver.”