Wave Power

Way back in the 1970s, in the oil crisis era, and around about the time I was experiencing carless days in the South Pacific, a Professor Stephen Salter of the University of Scotland, was trying to find a way to harness the exhaustless power of the sea – and convert it to electricity.

In September 1973 I caught ‘flu. My wife said to me, with callous indifference to my misery, “Stop lying there looking sorry for yourself. Why don’t you solve the energy crisis?” – Professor Salter, in the University of Edinburgh Bulletin, Volume 11, Number 2, 1974

Some, including Professor Salter, believe he just may have – although, the eventual outcome of his research and experimentation was somewhat shrouded in mystery….

Miniature Salter’s Duck in test tank

His invention, Salter’s Edinburgh Duck, continues to be the machine against which all others are measured. In small scale controlled tests, the Duck’s curved cam-like body can stop 90% of wave motion and can convert 90% of that to electricity. While it continues to represent the most efficient use of available material and wave resources, the machine has never gone to sea, primarily because its complex hydraulic system is not well suited to incremental implementation, and the costs and risks of a full-scale test would be high….

According to sworn testimony before the House of Parliament, The UK Wave Energy program was shut down on March 19, 1982, in a closed meeting, the details of which remain secret. The members of the meeting were recruited largely from the nuclear and fossil fuels industries, and the wave programme manager, Clive Grove-Palmer, was excluded.

An analysis of Salter’s Duck resulted in a miscalculation of the estimated cost of energy production by a factor of 10, an error which was only recently identified. Some wave power advocates believe that this error, combined with a general lack of enthusiasm for renewable energy in the 1980s (after oil prices fell), hindered the advancement of wave power technology. – Wikipedia

Some even go as far to say that Salter’s Duck was a very inconvenient solution that was intentionally killed by nuclear lobbyists.

Harnessing the combined forces of wind, the earth’s spin, and the
moon’s gravitational pull

Waves are not short on power. In fact, the sheer potency of the ocean is a serious issue for engineers. How do you build something that can withstand the constant wear and tear of the enormous weight of ocean surges? And, once you have that figured, add in extra fortification for stormy conditions, and top it off with protection against the incredibly corrosive effects of salt.

The outcome was that many regarded such technology as prohibitively expensive. Even prototypes, if they were to offer a half-decent impression of what the real thing could do, were pricey enough to discourage a rush in investment.

But, as we all know, oil prices only fell so far – and have since turned around to rush right back at us again. Renewable energy options are back on the table, and some believe wave power is one of the soundest environmental options – at least for those nations with an accommodating coastline (most of the best sites are on the western coastlines of continents and islands between the 40′ and 60′ latitudes, above and below the equator).

Some perceived pros and cons:

Pros:

• If properly located, more consistent power source than wind or solar
• Cheap to maintain
• A potentially highly efficient wave-to-electricity conversion ratio
• The sheer force/density of water compared to wind equates to far fewer generators being required compared with wind turbines
• Low negative impact on ecosystems
• Visually inconspicuous

Cons:

• High initial startup costs
• Must be able to withstand very rough weather
• Needs a suitable site, where waves are consistently strong
• Difficulty to transfer energy back to land

Today there are several kinds of Ocean Power devices either in use, in construction, or being experimented with. Although the Salter’s Duck design is regarded as having the highest power conversion ratio, other designs have their own benefits. Where local geographic features allow, some designs have been successfully integrated into cliffs and shorelines, removing the problem of electricity transfer back to land – and providing better maintenance access.

Here are a few examples of different kinds of Ocean Power designs:

Limpet (Land Installed Marine Powered Energy Transformer): A third of the energy requirements of the Isle of Islay, off the western coast of Scotland, are powered from one of these guys. Power is generated as waves enter the open cavity, concentrating and forcing air through a chamber on the top (or rear depending on the design) of the installation. The forced air turns a turbine, which turns a generator.

You can see how it works here:

Pelamis: This long, hinged tube (about 160 metres long) is appropriately named after the Pelamis sea-snake. As it bobs up and down in the waves, the hinges bend and pump hydraulic fluid which drives generators.

Scottish engineers built the Pelamis wave farm in Portugal, and it was announced last year that a much bigger farm will be built in Scottish waters. The completion date should be 2011. Learn more about the Pelamis here.

 

A report on the Pelamis off the coast of Oporto, Portugal – the world’s first wave farm implementation:

And here’s another variation for good measure:

https://www.youtube.com/watch?v=DLJ2eUHP2PI

Mighty Whale: This monster device is the latest incarnation of a long line of experimentation in ocean power technologies in Japan. A Mighty Whale prototype, complete with painted mouth and eyes, was launched in Japan in 1998, and has been the subject of open sea tests since. More info here and here.

As in every area of power generation, whether coal-fired, nuclear, wind or solar – energy storage issues are still a thorn in the energy industry’s side. Being able to feed Ocean Power into established power grids, with its generally more consistent generation, has the potential to supply a significant percentage of energy needs – for those countries with appropriate westerly facing shorelines (e.g. west coasts of Scotland, northern Canada, the U.S. northwest and northeast seaboards, southern Africa, Australia and New Zealand in particular).

There are also other potential applications for Ocean Power installations, in addition to generating electricity, like the generation of hydrogen for vehicles, or water desalination.

Back in the ’80s government and industry in the UK, apparently, stalled progress in ocean power development. Today, competitive industry influences with their long established relationships, including Solar and Wind industries, will still seek to gain contracts in the place of the lesser known ocean power technologies – but, it’s also certain that the tide is turning. Professor Salter may not have fulfilled his wife’s request to solve the world’s energy crisis, but his work was certainly more than just a drop in the ocean.

In combination with a much needed reduction in consumption levels, such technologies could help some countries mitigate energy shocks as we head into an era of energy descent.

A few of several different Ocean Power designs

There are new designs for wave power systems coming out all the time. The clip below is an example of such: