Info!
UPDATED 1 Sept: The EI library in London is temporarily closed to the public, as a precautionary measure in light of the ongoing COVID-19 situation. The Knowledge Service will still be answering email queries via email , or via live chats during working hours (09:15-17:00 GMT). Our e-library is always open for members here: eLibrary , for full-text access to over 200 e-books and millions of articles. Thank you for your patience.

Energy Insight: Wave Energy

As climate change rises up the global political agenda, and given the finite nature of fossil fuel resources, countries all around the world are gravitating towards renewable forms of energy such as wave energy. Wave resources are particularly worth investigation as they are more consistent and predictable than some more commonly-deployed renewables like wind or solar. Although deploying wave devices comes at high initial cost, this consistency could allow wave power producers to enjoy different or greater market opportunities than are currently available for more variable renewables. The UK is in a unique position to benefit from wave energy, with strong expertise in offshore operations and a wave resource that is one of the greatest in Europe. Nevertheless, opportunities for wave energy remain largely untapped both in the UK and globally.


By the Numbers

  • Only 7.2 MW of wave energy projects were installed worldwide by the end of 2017 with a further 10.5 MW reportedly planned to be deployed in the near future.
  • Global theoretical wave energy potential is estimated at 32 PWh/yr, more than 1.5 times the global electricity consumption in 2016. Estimates of what can practically be recovered vary from 5.5 PWh/yr to as low as 2 PWh/yr
  • Between 32 and 42 TWh/yr of energy could be practically extracted from UK waters, equating to an installed capacity of roughly 10 to 13 GW.
  • 35% of Europe’s total wave resource lies in the UK.
  • Power output of wave energy converters is 35% more predictable than for wind turbines.
  • Waves are available 90% of the day on average, compared to 20-30% for wind and solar.


Burning Question

As of 2011, the general industry consensus was that commercial readiness was three to five years away for wave energy. Eight years on, the technology remains some distance away from commercialisation. Could 2019 be the year for wave energy, or is its future looking more and more like that of fusion power: perpetually 20 years away from commercialisation?


Wave Energy Conversion Explained

Winds are the underlying mechanism of wave formation. The sun heats air differentially, giving rise to winds blowing across the water surface. The energy from the winds is then transferred to the water body where the waves grow. The amount of energy that the waves carry depends on their height and time period between successive peaks. Wave power has high seasonal variability with outputs significantly increasing during the winter, but less short-term variability with similar output levels from one hour to the next.

A wave energy converter (WEC) is a machine that captures and converts the energy from waves to do useful work – for example, electricity generation, water desalination or water pumping. Depending on the design, WECs may be deployed offshore or along the shoreline. Shoreline devices provide easy access and generate energy close to the point of use, but can only access limited flows as 90% of the wave’s original energy is lost by the time it hits the shore. In contrast, offshore devices are typically deployed far from land in waters tens of metres deep. While allowing the capture of stronger waves, installation and maintenance costs are much higher for offshore devices given the difficulty of access. Engineering offshore devices is also more complex since they are more likely to be damaged by extreme weather conditions.

Similar to a wind farm, a wave farm is a group of WECs deployed in the same location. The deployment of WECs, especially as a farm consisting many of them, can have various impacts on the surrounding environment. WECs remove energy from the ocean, leaving less available for natural processes – i.e. current flows, water mixing, sediment transport – at the site. Migratory species and marine mammals can be disturbed by the physical presence of WECs as well as the noise and lighting they may create. WECs also introduce large, hard structures in the water which create new habitats. This is sometimes argued to be a positive impact; for instance, when underwater elements of WECs act as artificial reefs. Studies are underway to properly assess how the deployment of WECs will alter the host environment, including this three-year project led by the European Marine Energy Centre (EMEC).


Visually

Global Wave Energy Resource

Reference: World wave energy resource map by Ingvald Straume

The extent to which the waves build in height depends on how long the prevailing winds blow for and the expanse of water over which they travel. Locations with suitable shorelines for wave energy include the western coasts of Europe; the northern coast of the UK; the Americas, including Canada, the US and the southern parts of South America; Southern Africa; and Australia and New Zealand. Practically, systems are unable to extract all the potential wave power and some power is lost during conversion from mechanical energy to electricity.

Various Concepts Considered for Wave Energy Conversion

 

Reference: Wave energy concepts overview numbered by Ingvald Straume (modified)

Concepts considered for wave energy conversion can involve devices moving up, down or side-to-side. A prominent example is the Oscillating Water Column (OWC) which uses the motion of the waves to force the air within a compression chamber to flow through a turbine to generate electricity. Wave motion is highly idiosyncratic and the ocean is a tough operating environment, with challenges including wind stress, temperature fluctuations, storm surges, currents, corrosion, wave slam, marine life and electrical issues. Industry efforts have focused on establishing and testing a design that can capture the energy from waves in a reliable, efficient and robust way. A device that works well in one location may also not suit another, adding further to the difficulty of developing a single optimal design.

Projects tested at sea, either as pilot plants or prototypes include: 

As can be seen from this list, a wide number of competing concepts exist in wave technology. There are also many concepts that have been in development for years but have so far failed to progress to sea trials. The European Marine Energy Centre (EMEC) publishes a comprehensive list of wave developers.


State of the Market Explained

So far, attempts to commercially exploit wave energy have been limited to small systems and progress is far from that made with some other renewable technologies. Currently, the cost of producing energy from waves is too high to be economically competitive with conventional energy or more established renewable sources. The World Energy Council reports on the analysis by Bloomberg New Energy Finance (BNEF) which estimated the levelized cost of electricity (LCOE) of wave energy to be approximately US$500/MWh in 2015. While there has been minor change in the cost of wave energy since then, most other forms of renewable generation have dramatically reduced in cost, including offshore wind (US$118/MWh), solar PV (US$70/MWh), and onshore wind (US$55/MWh), based on BNEF’s analysis for the first half of 2018. Unless further projects lower the cost of extracting, transmitting and/or storing the energy from waves at scale, the future for wave energy may be limited to niche installations in remote locations such as powering offshore installations.

Active projects (installation or operation activities in the preceding 18 months) for wave energy in the UK at the end of 2017 amounted to less than 1 MW with most of it located at the European Marine Energy Centre (EMEC) in Orkney, off the coast of Scotland. Subject to the full force of the Atlantic Ocean, EMEC has hosted more ocean energy deployments than at any other single site in the world since opening in 2003, and continues to offer developers a variety of grid-connected test sites exposed to real sea conditions. WaveHub, launched in 2010 off the coast of Cornwall, is another wave power research project in the UK. There, developers can connect their devices to the hub’s 30 MW undersea “socket” that is meant to feed the electricity into the National Grid. However, WaveHub has not met their expectations for wave energy development, having hosted only one device by April 2018, and is now planning to diversify to offshore wind. Ocean Prospect, Ocean Power Technologies, Fred Olsen, Ocean Energy, Fortum, Carnegie and Gwave who were potential clients for WaveHub have all decided against their plans to use the site.


Timeline

1799: First wave power technology patent is issued.

1973-1984: Oil crisis leads to significant investment in wave energy research. Number of large-scale wave energy concepts are developed.

1984: Investment in wave energy drops with no viable technologies identified.

1984-2000: Small-scale wave energy projects are developed. Two key players enter the market: the US’s Ocean Power Technologies and the UK’s Pelamis.

2000: LIMPET (Islay, Scotland) – world’s first commercial grid connected WEC – is installed.

2003: EMEC (Orkney, Scotland) – world’s first marine energy test facility – is opened.

2004: Pelamis’ device becomes the world’s first offshore WEC to generate electricity and feed into the grid.

Late 2000s: New market entries including E.ON, Scottish Power and Voith Hydro (WaveGen)

2010s: Sector sees job losses, large companies falling into administration and many planned projects cancelled as initial expectations about cost reductions are not met.

…: Growing concern regarding climate change, energy security and oil prices. 94 MW of wave energy projects in early planning and 725 MW of early concepts in development as of 2016.


Quotable

“If wave power offers hope to any country, then it must offer hope to the United Kingdom and Ireland – flanked on the one side by the Atlantic Ocean, and on the other by the North Sea,” according to David MacKay in his 2009 book, ‘Sustainable Energy: Without the Hot Air’.


Leading Developments in the UK

Voith Hydro Wavegen's 500kW LIMPET OWC was installed in 2000 on the island of Islay, off the west coast of Scotland. After clocking up over 50,000 generating hours, the plant has now been decommissioned as the company ceased its wave operations in the UK.

Pelamis were EMEC’s first clients and their 750kW sea snake – an example of a hinged contour device – started testing in 2004. E.ON placed an order for their next generation device, known as the P2, which was installed at EMEC in 2010 and remained operational until Pelamis went into administration in 2014. A second P2 device, previously owned by EMEC, now belongs to Orkney Islands Council who are seeking to find potential alternative uses for the machine.

Aquamarine Power’s Oyster – a buoyant, hinged flap which is attached to the seabed near shore at around ten metres depth – was also tested at EMEC. Deploying two full-scale devices (315kW followed by the second-generation 800kW) costed the company in excess of £3m. The company ceased trading in 2015, ending the 3-year test programme of their 800kW device at EMEC. Currently, the LAMWEC consortium led by Belgium-based Laminaria is working to produce their WEC at full-scale to be deployed at EMEC in 2019 for sea trials, following successful tank tests.

EMEC recently saw the 1MW Penguin device by the Finnish WEC developer Wello sink during demonstration at one of its test sites.


Leading Developments around the World

In 2011, a 296 kW OWC based on LIMPET’s design was installed in Mutriku, Spain and has since been supplying power to the local grid. In 2016, the Sotenäs project – a joint effort between Seabased, Fortum, and the Swedish Energy Agency – has delivered the world’s first grid-connected multiple unit wave power plant (36 WECs) located off western Sweden. Despite cancelling plans to expand the Sotenäs wave farm, Seabased signed a 100 MW wave power plant contract with Ghana in 2018 and will set up two 20 MW wave energy parks in the Caribbean with the phase one expected to be operational by the fall of 2019.

The US-owned company Ocean Power Technologies (OPT) have developed a PowerBuoy wave generation system which uses a "smart," ocean-going buoy to capture and convert wave energy into electricity. In 2018, PowerBuoy has successfully been deployed in the Adriatic Sea to advance Eni’s R&D project aiming to demonstrate suitability of wave energy technologies for remote offshore applications such as autonomous vehicle charging, subsea equipment powering and monitoring oil and gas operations. OPT currently has many projects underway around the world to supply PowerBuoys across various industry sectors.


Short Story: The Prize that “cannot be won”

In 2008, the Scottish Government launched the Saltire Prize worth £10 million to be awarded for innovation in marine energy technology to push the sector towards commercialisation. By March 2013, there were five companies in the competition. Today, a decade after the launch of the prize, two of the major competitors – Pelamis and Aquamarine Power – have gone bust and no competitor was able to meet the original prize deadline of June 2017. Shortly after the news about the latter calling in administrators in 2015, the Scottish government acknowledged the need for reviewing the prize and looking into options to reshape it “…in the likelihood that, because of the criteria set, it cannot be won."

A different support scheme, Wave Energy Scotland was established  in 2014 at the request of Scottish Government with a budget of £10m for wave energy technology development projects in 2015-16 and £13.5m per year thereafter. Unlike previous UK wave energy RD&D funding schemes, this offers 100% funding throughout procurement while also requiring that concepts meet stringent criteria before being eligible for next steps of funding. The scheme has already funded 86 contracts and invested £38.6m for wave energy development. A leading example is CorPower Ocean who have been successful in the scheme’s Stage 3 Power Take-Off call and completed their C3 WEC’s demonstration at EMEC. The company is currently working with industrial partners to develop their first commercial scale machines.


Further Reading

Ocean Energy Technology Brief, IRENA

A Review of Wave Energy Converter Technology by B Drew, A R Plummer and M N Sahinkaya

Wave & Tidal Energy: State of the Industry, Report to ClimateXChange

World Energy Resources 2016, Chapter Marine, World Energy Council

Energy Insight details


Subjects: Wave power

Please login to save this item