Ocean Floor Carpets Can Harness Wave Energy, But Could They Slow Global Warming?

Photo: Pelamis Wave Power / Rhonda J. MillerOcean waves are coming into sharper focus as a source of renewable energy as warnings about climate change and sea level rise intensify in nations around the globe. Scientists at the University of California Berkeley are developing leading edge technology for an ocean-floor carpet to harness wave energy.

“There is a vast amount of untapped energy in the oceans and with increasing worldwide demand for power, the need to find cleaner alternatives to fossil fuels is critical,” said UC Berkeley Assistant Professor of Mechanical Engineering Reza Alam in a statement. “We are also seeing greater population growth along coastal cities, so the ocean-based system we are developing would produce electricity in a carbon-neutral way right where it is needed.”

Researchers at the Theoretical and Applied Fluid Dynamics Laboratory at UC Berkeley are working to realize potential in the analysis by the London-based Carbon Trust that wave energy could provide more than 2,000 terawatt hours of electricity per year, or about 10 percent of global electricity needs.

“The benefit of having a system underwater is that there is minimal visual and physical impact on boats and sea life,” said Alam. “Our system would work with no problem in stormy conditions because the water column above the carpet buffers the impact momentum of surging waves. In fact, our carpet is even more efficient when ocean waves are stronger.” Alam’s research team is dong extensive testing at its UC Berkeley wave tank laboratory to harvest wave energy reliably, as well as economically.

In Europe, projects to utilize wave energy to produce power are in the water at several sites as the Scottish company Pelamis Wave Power expands its collaborations to deploy its wave energy machine. Pelamis works with project developers, energy companies, and utilities that want to harness wave energy to meet the global need for clean, sustainable, renewable power generation.

The Pelamis is an offshore wave energy converter that uses the motion of waves to generate electricity. The machine operates in water depths greater than 50 meters, or about 180 feet, and is typically installed two to10 kilometers from the coast. One machine can provide sufficient power to meet the annual electricity demand of approximately 500 homes.

So far, Pelamis Wave Power has produced six full-scale Pelamis machines. Two of the latest have been built for utility customers E.ON, one of the world’s largest investor-owned power and gas companies based in Duesseldorf, Germany, and Scottish Power Renewables, one of the world’s largest wind energy developers based in Glasgow, Scotland.

Scottish Power Renewables has consent at the European Marine Energy Centre in the Orkney Islands, UK to test a wave energy generation device and recently purchased a Pelamis P2 to be berthed and tested at the facility.

The project, using Pelamis technology, utilizes existing electrical subsea cables, substation and grid connection at EMEC. The Scottish government has provided funding for the project through the WATES scheme and consent through a portion of the Electricity Act, according to the Pelamis project report on its website.

The order from ScottishPower Renewables is the second commercial order for the second generation P2 Pelamis machine and was installed at EMEC in May 2012. ScottishPower Renewables and E.ON have put in place a unique joint working agreement to maximize the learning from operating and maintaining the machines as a wave farm. The project will serve as the foundation for plans by Scottish Power Renewables to install 66 Pelamis machines in a 50 megawatt project off Marwick Head in Orkney, for which a lease agreement has already been awarded, according to Pelamis..

A Perth, Australia-based company, Bombora Wavepower, is also developing technology to use ocean wave energy, according to Science Network Western Australia. The wave energy converter developed by Bombora Wavepower is intended to be a highly-economical means for harnessing wave energy from relatively small ocean waves. The technology uses a V-shaped device that sits on the seabed near the shore at depths of between five and 15 meters, with arms designed to capture the energy of waves as they move closer to shore and become concentrated into a smaller column of water.