A short history of wave energy

The production of energy, in particular through the burning of fossil fuels, accounts for an estimated three-quarters of global greenhouse gas emissions. Widely recognised as a key driver of climate change, global superpowers are now uniting to mastermind an energy transition moving rapidly towards green, renewable forms of power production.

Wave power is set to play an important role in this future renewable energy mix. While it remains an emerging sector, it continues to make significant progress with several global developers aiming to harness the full potential of this dense and consistent power source.

Importantly, it offers a series of major benefits compared to more established renewable energy sources, for example offsetting the intermittency of wind and solar. Essentially, this adds stability to the electricity system at times when it is most needed, when it is not sunny or windy, reducing over-capacity in generation plus grid and storage capacity – significantly lowering the overall cost for zero-carbon electricity systems of the future.

Harvesting energy from ocean waves has proved a challenging pursuit with many devices either breaking in storms or simply not producing enough power to make them a viable business prospect. The complexity of the process has led to a host of designs, including writhing snake-like attenuators, bobbing buoys and devices mounted on the ocean floor. Some devices generate electricity on the spot and transmit it via undersea cables to shore, while others pass the mechanical energy of the wave along to land before transferring it into electrical energy.

The idea of using waves as an energy source however is far from new with attempts documented as early as 1799. Shortly before the turn of the 19th century French inventor Girard obtained a patent for a machine he and his son had designed to mechanically capture the energy of ocean waves, to power heavy machinery including mills and pumps.

Later in 1868, San Francisco began its experimentation using wave action to power boats, with a self-propelling vessel built and tested in North Beach. The state subsequently became a leader in ocean powered technologies with records showing four separate wave motor patents registered in the 1870s, all invented by Californians.

Later in the century, wave energy converters and motors were being developed all over the world as people searched for new innovations to solve local problems. Back in California, an extreme drought in Santa Cruz, during the winter of 1897-98, led to dust flying on the wagon roads greatly affecting travel. The city struggled to propose a cost-effective way to sprinkle the passageways with water to settle the dust, inspiring the Armstrong brothers to build a simple wave motor inside the coastal cliff area to power irrigation. The idea was to have the rock protect the motor. The prototype consisted of two 35-foot wells drilled down into the cliffs of West Cliff Drive, a series of pipes, pistons, pumps, a 600-pound float, and a 5,000-gallon water collection tank.

For many years the wave power pursuit continued, although it took the oil crisis in 1973, to attract real academic interest. At the time, American oil consumption was rising, and domestic supply could not keep up with demand forcing America to import foreign oil. Rising tensions caused members of the Organization of Petroleum Exporting Countries (OPEC) to impose an embargo against America in retaliation for the US’ decision to resupply the Israeli military and to gain leverage in the post-war peace negotiations. The fallout from the embargo forced America to reevaluate its dependence on fossil fuels and push efforts to explore renewable energy sources.

America was not the only nation participating in wave energy development. European university academics such as Stephen Salter, Johannes Falnes and Kjell Budal were critical in the exploration of wave energy and its potential.

Within the Nordic countries, a political consensus was reached in the 1970s on the division of energy sector research, with Denmark focusing on wind power, Norway on wave power and Sweden on bioenergy.

UK Professor Salter, who had a career in design engineering, became concerned about the limited nature of oil resources shifting his focus to renewable energy and wave power. As a result of the 1973 oil crisis, he created Salter’s Duck, a device that converts wave power into electricity. It was later officially renamed the Edinburgh Duck, and was one of the earliest generator designs proposed to the Wave Energy programme in the United Kingdom. The device was designed to absorb 90% of the energy from incoming waves. After initial enthusiasm of the project, the programme was shut down due to oil prices drastically plummeting.

Meanwhile, Falnes and Budal spearheaded research and development of wave energy in Norway in the 1970’s. Falnes and Budal theorized the ‘antenna effect’ which draws inspiration from the radio antenna’s ability to absorb radio waves. Theoretically, the surmised that a floating-point absorber could absorb far more wave energy from the sea. They also developed the latching control strategy to maximize energy extraction. Similar to Salter, the decrease in oil prices led to a decrease in public interest for problems concerning the environment and resources.

While both nations initially seemed to agree that phase control was the key to functioning wave power plants, opinions later diverged. The Norwegian ‘school of thought’ was to focus on smaller, cost-effective power plants, while the British focused efforts on large-scale installations in the 10+ Megawatt class. The following years were characterized by dwindling support for wave energy development.

However, the emergence of a bright young mind in Jørgen Hals Todalshaug, a student of Professor Falnes, helped spark further innovation which coincided with the renewed interest in the field. Dr. Hals Todalshaug shortly went on to join CorPower Ocean and continues to take a central role driving the company’s highly innovative technology.

During CorPower’s early stages, it adopted ‘latch control’ to achieve phase control, developed by Budal and Falnes. But it was not until Dr Hals Todalshaug invented the WaveSpring in 2012, that the final, crucial piece of the puzzle fell into place. Now it is finally feasible to apply phase control in industrial equipment, allowing the buoy to move in optimal phase with the waves. In scientific terms, this enables CorPower to approach the theoretical maximum absorption for a given floating structure. The phase-control technology strongly amplifies the response to waves in terms of the motion and power capture. For instance, in a 1-meter wave, the CorPower buoy may move 3 meters up and down due to the resonance phenomena. The technology has been shown to produce five times more electricity per ton than any other known wave technology.

It has taken several centuries of inquiring minds to solve the conundrum of effective wave energy extraction –combining efficient electricity production, with survival capabilities and economic competitiveness. And these solutions are needed more than ever before.

While we continue to navigate the global energy transition, it is worth remembering that the ocean remains one of the largest and least explored energy sources on earth. By 2050, ocean energy could provide 500GW of power – equivalent to 10pc of Europe’s current electricity needs – and stimulate a market worth €53billion annually, while creating hundreds of thousands of jobs.

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