Wave Power

Waves contain large amounts of energy, particularly large waves and ocean swell. Wave energy is in reality a stored and concentrated form of solar energy, with the wind as the intermediary.

Wave energy research was pursued intensively during the 1970’s and early 80’s, especially in Britain. Interest in it was then revived in the mid 90’s as one of the options to reduce fossil fuel dependency and address global warming. During these last 30 years a large number of devices such as the nodding duck, the Osprey, tethered buoys, bottom standing oscillating water columns, over-spilling systems, floating bags, articulated rafts, submerged pressure chambers, and many others have been tried with varying degrees of success. However, wave technology is now slowly maturing, and the day of commercial viability is approaching.

There are two basic types of wave technology: fixed onshore and floating offshore. Up to very recently most of the research and development has been focused on fixed devices onshore or in shallow waters. Now, however, there is increasing interest in the much greater offshore resource with a variety of floating devices being developed.

The greatest wave energy resource is in the mid-latitudes, between 40 and 60 degrees N & S. This is where winds blow most consistently, while in more tropical areas there are often long periods of calm weather in between severe storms.

Global Highlights

• The World Energy Council has estimated the global wave energy potential to be 2,000 GW. (New Scientist, Sept.20, 2003)
• The economically recoverable wave energy resource for the UK has been estimated by the Ocean Power Delivery Company to be 87 TWhrs/year.
• A 500 kW fixed device called the Limpet has been operating on the island of Islay off the coast of Scotland since November 2000. It was built and installed by Wavegen, and was the first commercial-scale grid-connected wave energy device installed anywhere. Its output is being sold to the local utility for 5.95 pence/kWhr. (Environmental Science & Technology, No.3, 2001)
• In February 2004 ocean testing began of the 750 kW Pelamis, also called the Sea Snake, which is the first deep-water grid-connected wave power generator in the world. It is 120m long, 3.5m wide and weighs 750 tonnes. It is built and operated by the Ocean Power Delivery Company of the UK.

What’s Happening in BC

In 2001, the Green Energy Study of BC, Phase 1, was completed for BC Hydro. It stated that 8.25 GW of wave power is incident on western Vancouver Island, and Winter Harbour and Ucluelet were identified as suitable sites for installations, each with a potential of 200 MW. The study estimated that by 2009/10, Vancouver Island could have 75 MW of installed wave capacity, generating 156 GWhrs/year, and by 2019/20 there could be 225 MW generating 468 GWhrs/year. All of it would be at less than 7 cents/kWhr.

In June of 2001, BC Hydro announced a 20 MW Vancouver Island Green Energy Demonstration Program, of which wave energy was to be a part. About a year later Ocean Power Delivery of the UK and Energetech of Australia were selected to develop demonstration projects of 2 MW each. However, in April 2003, BC Hydro pulled out of these projects, saying that the success of their more recent Call for Private Green Power Proposals eliminated the need for BC Hydro to be involved in funding demonstration projects.

What Does it Cost?

According to the World Energy Council, costs are currently in the 12-16 CAN cents/kWhr range, but within 3-5 years they can be expected to come down to the 5-7 cents range.

Energy from the Limpet is sold by Wavegen for 5.95 pence/kWhr (14cents/kWhr).

BC Hydro’s Green Energy Study for BC, Phase 1, estimated the future price of wave energy to be in the 4-9 cents/kWhr range.

When we look at these costs and compare them to conventional technologies, it should be kept in mind that electricity from fossil fuels will only get more expensive in the future as supplies dwindles, and also that fossil fuel energy does not include the cost of externalities such as pollution and greenhouse gas emissions.

Environmental Matters

Fixed wave energy devices can disturb shoreline ecosystems, and siting must be done with careful attention to sensitive areas. On the other hand, these fixed devices tend to be located on exposed rocky sites rather than in more sensitive estuarine areas.

Offshore floating devices can be navigational hazards and must have adequate lighting and radar warning equipment.

Technical Matters

The size of the global wave energy resource has been mapped, but it is important to notice that the values given (40-70 kW/linear metre for good sites) are for deep-water locations. As you get closer to shore, breaking waves and friction along the rising seabed reduce the energy to about a third. This is why even companies such as Wavegen, which has until now focused only on fixed onshore devices, recognizes that the long term future of bulk wave energy generation lies in using the offshore resource rather than the onshore. (Tom Heath, Wavegen website, and New Scientist, Sept.23, 2000)

Ocean Power Delivery of the UK, with its Pelamis Sea Snake, is a leader in offshore technology, and its vision is one of large wave farms where each square km can generate 30 MW.

Price, Policy & Political Matters

The history of the development of wave energy technology clearly shows that government support is necessary. When such support abruptly stopped, as in the UK in 1982, technological advances also stopped, or at least slowed down dramatically, only to pick up again once public support was reinstated.

BC was on the cusp of developing experience and expertise in wave energy in 2001, until BC Hydro abandoned their program, at which time all wave activity stopped. Unless some support is reinstated, little wave development will occur here until the technology is developed further in other countries. Then we will have once again missed a chance of participating in the development of an emerging new industry, and all its attendant economic benefits.

Can I Do it at Home?

Some of the older devices are quite small in scale, but most are not available commercially. You would also need a foreshore lease.

Links

Energetech (Australia)
European Commission, Atlas Programme
Finavera Renewables (Vancouver, BC)
Ocean Power Delivery Ltd. (UK)
Ocean Renewable Energy Group (OREG)
Wavegen Co (UK)

Credits

Written by Bo Martin for the BC Sustainable Energy Association, 2005.