Feature

Time for tidal power?


George Giles

George Giles from Siemens Industry looks at some of the issues surrounding tidal power.

As the race to find commercial and technical solutions for alternative renewable energy sources that can help power a low carbon and sustainable energy future continues, could the more predictable nature of tidal power mean it's time to take closer look at how the sea can help fuel the nation in years to come?

It is clear that if the UK is to achieve its challenging carbon reduction targets then much work is still needed to create, develop and utilise alternative and sustainable energy sources for the nation's energy needs. The impending access to cheaper forms of energy such as shale gas has fuelled the debate concerning the appropriate energy generation mix. This will see, in due course, the phasing out of the significant energy contribution currently made by high energy intensive coal fired power stations, to be replaced with low carbon and infinitely more sustainable energy sources such as wind and tidal.

It's time to take a closer look at how the sea can help fuel the nation in years to come, suggests George Giles from Siemens Industry.

However, when assessing the worth of such options and the mounting evidence that supports the claims of green energy alternatives, this only emphasises the central role that renewable energy sources can play in helping to safeguard our energy future. The case is already being made for tidal technology energy solutions as it is clear that while the removal of coal power stations is a laudable aim, it can only be done if the energy alternatives offer a safe, predictable and manageable delivery of energy source for the UK's needs. In this context the time is now right to look seriously at the contribution tidal or marine energy can make to our energy mix over the coming decades.

Marine or tidal energy – energy from tidal and current oceans – has unlimited potential as the ultimate green energy source. The UK is uniquely positioned to take advantage of tidal power. The UK and Irish waters are especially promising due to the island configuration and the energy source potential from the surrounding sea currents. It is estimated that the UK and Ireland could provide between 25-50% of total European tidal energy, according to a recent report from RenewableUK; making it not only a highly significant contributor to energy needs, but an income generator as well. The same report predicts that the tidal energy industry will be worth some £6.1 billion to the UK economy by 2035, and could displace up to half a million tonnes of CO2 every year by the end of this decade.

The most advantageous factor for tidal energy is its very predictability, certainly compared to alternative green technologies such as wind power. This is the key to its future energy contribution. While wind power can be significant it is very hard to rely upon it as an energy provider as its strength will ebb and flow. This is a serious issue if it is to replace base load sources such as coal fired power stations. Tidal, on the other hand, can offer accurate predictions of energy contributions as tidal and current behaviours are well known and reliable and, most importantly, create a higher averaged output than wind.

Comparisons between the two technologies see that while wind as an energy source delivers between 15-30% of its capacity due to unpredictable wind conditions, the potential of tidal can see it produce 50-60% of capacity depending upon tidal flows and technology solutions, with up to 20 hours per day of predictable tidal flow. It is this certainty that points to tidal as a primary energy answer.

The issues

While the case for the invaluable contribution tidal energy can make to our generation mix is strong, we are now at a critical point in its development. Investment in the best technology solutions as well as the current wide-ranging number of solutions, rather than settling on a single recognised answer, is confusing matters somewhat. To realise the potential, we have to encourage an integrated and solution focussed strategy that brings tidal power up to match the development progress made by other green technologies such as wind.

While it is believed that tidal development trails wind by some 15-20 years, that gap can be cut to 5-10 years with proper investment, quicker technology development and Government support. Turning tidal potential into an energy source is expensive to do and the Government recognises this fact.

Incentives are helping. Renewable Obligation Certificates (ROCs) have been increased for tidal energy with five available for every MW installed. This outstrips wind generation considerably. However, this incentive only lasts until 2017 when a longer timeframe is needed, and is capped at 30 MW schemes. But nonetheless it does provide cause for optimism for the establishment of a viable and commercially attractive solution for tidal energy generation. The current cost of generation of each MW remains very high at approximately £7 million per MW. This needs to be cut by at least 50% to prove financially successful and attractive.

A large number of companies, including Siemens, are now heavily involved with tackling the technology challenges tidal energy presents. As mentioned, many potential technologies are under development in the absence of a single preferred solution as seen in the case of wind.

The majority of current schemes are small-scale – up to 2MW – and they need to prove their viability, while at the same time research and development continues apace. However a lack of investment support continues to hamper the progress of many, with institutions somewhat reluctant to provide the necessary funding for next stage development. Overlap that could see the deployment of existing oil and gas sector technologies are currently deemed to be too expensive.

Allied to investment issues as a challenge to bring tidal energy more to the fore is that of skills. One of the primary challenges is the recruitment of skilled engineers into the sector and the promotion of the tidal energy industry as an attractive source of employment when compared to other green technology arenas. It is proven that skills will follow a commercially vibrant enterprise with the North Sea oil boom a prime example, and it will be difficult to entice such skills to a newer market. In many ways, the tidal sector continues to compete with the mature oil and gas markets in this regard.

It is hoped that the success of exciting tidal energy developments currently underway in locations such as Bristol and the Orkney Isles will act as catalysts, so that the increasing momentum for tidal energy technology can continue and the skills required to turn its potential into reality can be secured. While the challenge to engineer the tidal power projects is strong, it is also clear that the UK has the skill sets and knowledge base which can help develop and lead this important market.

While the tidal energy sector remains in its infancy, it has many positive facets. It is a predictable, safe and green source of energy that can make a substantial contribution to our future energy needs and balanced generation mix, while offsetting our reliance upon carbon. There is a real need for greater investment across the board if we are to accelerate its technology development progress and cut the gap to the current status of other green technologies such as wind. With such investment, continued Government support and incentives, and the skills of engineers to help secure a more focussed technological tidal energy solution, the UK can begin to reap the benefit from a critical energy source that will never run out.

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Energy infrastructure  •  Policy, investment and markets  •  Wave and tidal energy

 

Comments

Anonymous said

25 August 2013
Existing state-of-the-art Tidal Stream Generators (TSGs) convert <4% of the total resource into varying in length pulses of electricity. The Springs/Neaps'cycle accounts for the variation of 8/8ths to 1/8th and back to 8/ths every 14 days or so.

This makes real time generation from tidal streams unviable. Gentec venturi converts almost all the resource into heat in the first instance, and stores it. Over 10 times more load following electricity, out of real time, can be generated 24-7-365 from thermal storage when compared to simplistic electromechanical TSGs.

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