By 2020, the UK aims to source 15 per cent of its energy from renewable sources. In 2017, renewables generated 11.3 per cent of UK energy, from offshore wind, solar power and biomass.
That percentage is growing. However, one source of renewable energy remains untapped: the UK has yet to fully exploit and develop marine energy to generate electricity.
Marine-energy technologies seek to harness energy from waves and tides. They include wave, tidal-stream and tidal-range power, along with ocean thermal, ocean current, run of river and salinity-based technologies.
Harnessing the tides offers predictability. The gravitational pull of sun and moon creates continuous tides, rising and falling twice a day. Having a near-continuous supply of clean energy would overcome the uncertainty that comes with wind and solar-based renewables.
Marine energy could generate up to 10 per cent of the world’s electricity by 2050, according to Marine Power Systems. It says wave and tidal technologies could create a £46 billion market in Europe and generate 4,000 TWh a year globally, worth £76 billion.
The International Energy Agency says marine energy could generate 337GW globally by 2050.
Water, the UK has in abundance. The main island has a 17,820 km coast, according to Ordnance Survey. England and Wales have 68,000 km of rivers.
The Bristol Channel has among the world’s widest tidal ranges. Estimates suggest the UK could generate a third of Europe’s marine energy. So what’s stopping us?
The answer is lies in the costs and in worries about the environmental impact of this new energy source.
So far, the UK has invested nearly £500 million in marine energy, becoming a world leader testing and developing new technologies. On Orkney in Scotland, the European Marine Energy Centre (EMEC) tests wave and tidal-stream energy converters. It has four test sites, including two that feed energy to the National Grid.
By year-end, 20 companies had tested 30 prototypes there. Orbital Marine, formerly Scottish Renewables, launches its third prototype there in the coming year, having last year generated 3GW/hr from its second.
Pembroke Dock-based Marine Energy Wales is developing and testing wave power and tidal technologies, tapping the Welsh government’s EU-backed €100 million marine-energy R&D fund.
Marine-energy developer Minesto has successfully tested an EU-funded tidal-stream project, using a subsea kite to generate electricity off Holyhead. It will reactivate the project this spring.
“Tidal-stream projects have come furthest so far in the innovation space,” says Marine Energy Wales project director David Jones. “Offshore wind has had great success in the UK, but we have other innovative technologies. We need a more strategic approach to renewables.”
But with less than a year to go to meet that 2020 renewables target, the UK government has yet to get behind a live marine-energy project.
Last June, it decided not to back a £1.3 billion tidal lagoon in Swansea Bay, ruling that it didn’t offer value for money, and supporting nuclear power instead. Supporters called the decision “a huge mistake”.
“We have more than 20 wave-power developers and 20 tidal power developers,” says RenewableUK head of policy Barnaby Wharton. “Some incredibly exciting ideas have been coming through. The UK is a maritime nation, with the best marine-energy industry in the world.
“The danger is that if the government won’t back this industry, Canada and France will take our lead in tidal energy and grab a larger chunk of the future market. That’s business that we could be getting.”
Having secured a development consent order (DCO), Swansea Bay was the UK’s most advanced marine-energy project.
Now, the sector’s future looks uncertain. Two years ago, the government scrapped subsidies for marine energy, forcing bidders to compete against other renewables for contracts-for-difference (CFD) funding. CFD guarantees the purchase price of energy over an agreed timeframe, to enable investment against a risk profile appropriate to the project to support private sector involvement.
Meanwhile, Brexit rules out future access to European Union cash. “Marine energy has been fraught with problems, relating first to cost and second to politics,” says one industry source, speaking firmly off the record.
However, coastal landowner the Crown Estate believes the UK could generate 118GW from marine energy. Crown Estate believes that Scotland could generate 27GW, additional tidal-stream projects in England, Wales and Northern Ireland bringing the total to 32GW.
And this, says Arup associate director Henrietta Ridgeon, is why it’s a question of when – not whether – the UK harnesses marine energy.
Further endorsement came two years ago, from the Charles Hendry Report. “This concluded that tidal-range projects really could contribute to UK energy,” Ms Ridgeon says.
Production costs remains a barrier. Industry sources estimate that tidal-range projects cost £250 per MW/hr. Arup says recent studies indicate costs of £100 per MW/hr – and could drop to £60 per MW/hr “with longer-term financing arrangements and market readiness”.
But marine-energy projects face sizeable up-front costs. It will take at least five years to secure permits, test and order technology and build. Projects don’t make a penny until they generate first power, and the UK has yet to test this technology on a commercial scale.
Then there are environmental concerns. Turbines work by stepping, not stopping, the tides, but this can impact the impounded water body’s hydro-ecological characteristics, including the sediment regime. Projects will need to factor in local shipping and leisure interests. Developers of all project types will need to study impacts on wildlife and movements of fish.
“Another problem with securing investment is that no one knows what’s around the corner,” says Cardiff University emeritus professor of water management Roger Falconer. “We don’t know what other technologies are coming – such as advances in nuclear fusion – which creates real reluctance to invest on that long-term scale.”
Supporters counter that marine-energy projects’ 120-year life expectancy means they will more than recoup their costs. A nuclear power station has a lifespan of 30-60 years; offshore wind turbines last up to 30 years.
Few corporate investors are that long-sighted in these risk-averse, shareholder dividend-driven times. However, Arup argues that energy co-ops and low-carbon initiatives such as Zero West could step into the breach.
Industry sources say marine-energy costs must come down “well below £90/MWhr – to £60-£70/MWhr – to come close to wind and solar”.
“BEIS told us we need to come in at around £50 – and if we can’t, to go away and don’t come back until we do,” the backer of one barrage-based project told The Environment.
Mr Wharton argues that tidal-stream projects will replicate technologies, in time bringing costs down significantly. Projects that generate 1GW of capacity can slash their costs to less than £90 per MW/hr, comparable to other large-scale energy projects, he claims.
RenewableUK wants the government to back Innovation Power-Purchase Agreements (IPPAs) enabling developers to find buyers at a price to bring the project to market. The buyer will receive tax breaks in return.
“Marine energy employs 1,500 people. We think it could bring in £1.5 billion a year, supporting 4,000 jobs. And that’s just in the UK – tidal-stream power could become a global market, with export potential,” Mr Wharton says.
Ms Ridgeon maintains that marine energy offers competitive whole-lifecycle costs and comes closest to making the UK energy-secure.
“The tricky thing is the five-year cycle of politics,” she says. “The world’s first tidal plant, La Rance in France, is still producing energy 60 years on. It paid off the investment within 25 years.”
One option is to develop marine energy as part of a wider project. Several proposed schemes are multipurpose projects, generating power and improving coastal flood defences.
These include the £7 billion North Wales Tidal Energy and Coastal Protection lagoon between Llandudno and Rhyl, and the £400 million barrage-based Wyre Tidal Gateway in Fleetwood, Lancashire.
Projects that combine flood defences and power generation make a much stronger case, Prof Falconer says.
“These projects will be judged on case by case, depending on how many homes and businesses we can demonstrate they will protect, and depending on how much land we can protect that can then be developed,” says Arup associate Robin Campbell.
“The days of pure energy or environmental or flood-risk management projects are over. These days, authorities are in the business of delivering multiple benefits. It’s about doing more for less.”
So can the UK realise its marine-energy ambitions? Some predict progress starting this year, during the CFD auctions this spring.
Ms Ridgeon says the best-case scenario will see the first project launch “within six years”, although a 10-15 year time-frame is more likely. Mr Campbell is more bearish, given the environmental concerns, red tape and uncertainty about new technology and funding.
“The government is very tied up with Brexit,” Ms Ridgeon concludes. “There is not a lot of headspace for this.
“At the same time, we have the potential to source 10 per cent of our energy needs from a wholly renewable source, where we know that we will get power twice a day.
“We should lay this down as a challenge to government – lots of enthusiastic people are trying to get this off the ground and so many different things are going on. But we are not developing this industry in a productive, supportive or economic way. We need to embrace marine energy to make it happen in the best possible way.”
Mr Wharton makes an impassioned case for the UK to press ahead with marine energy. “The regions that stand to benefit most from this have been hard-hit by deindustrialisation – south and west Wales, southwest England and Scotland,” he concludes.
“This creates a real opportunity to invest in these coastal communities. We need to make that case, to the national and the regional authorities. This is something the UK does really well: we need to back it.”
Tidal stream – turbines are placed in fast-flowing water, generating electricity from tidal power
Tidal range – barrages are built across tidal rivers, bays or estuaries to generate electricity by allowing water to spill over the top or through turbines. The barrage gates open as the tide rises, closing at high tide and releasing the water through the turbines to generate energy at a controlled rate. Tidal lagoons are similar to barrages but with the barrier built along the natural coastline or estuary, the turbines working as the lagoon fills and empties to generate continuous power.
Dynamic tidal power – new technology to harness tidal power, using enormous dams built straight from shore to open sea
Next month, exclusive to The Environment: angling and wildlife campaign groups have their say, regarding marine energy
Whether you are studying, actively looking to progress your career, or already extensively experienced, our membership will add value and recognition to your achievements.Become a member
CIWEM organises a wide portfolio of UK and international thought leading events, providing an industry recognised forum for debate, Continuing Professional Development (CPD) and sector networking.Find out more