01 Dec 2008: Report

Capturing the Ocean’s Energy

Despite daunting challenges, technology to harness the power of the waves and tides is now being deployed around the world – from Portugal to South Korea to New York’s East River. These projects, just beginning to produce electricity, are on the cutting edge of renewable energy’s latest frontier: hydrodynamic power.

by jon r. luoma

Way back in Napoleonic Paris, a Monsieur Girard had a novel idea about energy: power from the sea. In 1799, Girard obtained a patent for a machine he and his son had designed to mechanically capture the energy in ocean waves. Wave power could be used, they figured, to run pumps and sawmills and the like.

These inventors would disappear into the mists of history, and fossil fuel would instead provide an industrializing world with almost all its energy for the next two centuries. But Girard et fils were onto something, say a growing number of modern-day inventors, engineers, and researchers. The heave of waves and the tug of tides, they say, are about to begin playing a significant role in the world’s energy future.

In the first commercial-scale signal of that, last October a trio of articulated, cylinder-shaped electricity generators began undulating in the waves off the coast of Portugal. The devices look like mechanical sea snakes. (In fact, their manufacturer, Scotland’s Pelamis Wave Power Ltd.,
Pelamis Wave Power Ltd.
A Pelamis wave energy 'snake' now
operating off the Portuguese coast
takes its name from a mythical ancient Greek sea serpent.) Each Pelamis device consists of four independently hinged segments. The segments capture wave energy like the handle of an old fashioned water pump captures the energy of a human arm: as waves rock the segments to and fro, they pump a hydraulic fluid (biodegradable, in case of spills) powerfully through a turbine, spinning it to generate up to 750,000 watts of electricity per unit. Assuming the devices continue to perform well, Portuguese utility Energis expects to soon purchase another 28 more of the generators.

The completed “wave farm” would feed its collective power onto a single high voltage sea-floor cable, adding to the Portuguese grid about 21 megawatts of electricity. That’s enough to power about 15,000 homes.

In a world where a single major coal or nuclear plant can produce more than 1,000 megawatts of electricity, it’s a modest start. But from New York’s East River to the offshore waters of South Korea, a host of other projects are in earlier stages of testing. Some, like Pelamis, rely on the motion of waves. Others operate like underwater windmills, tapping the power of the tides.

Ocean-powered technologies are in their infancy, still technologically well behind such energy alternatives as wind and solar. Necessarily designed to operate in an inherently harsh environment, the technologies remain largely unproven and — unless subsidized by governments — expensive. (Portugal is heavily subsidizing the Pelamis project, with an eye to becoming a major European exporter of clean green power in the future.) Little is known about the effects that large wave or tide farms might have on marine ecosystems in general.

Despite the uncertainties, however, proponents say the potential advantages are too striking to ignore. Eight hundred times denser than air, moving water packs a huge energy wallop. Like solar and wind, power from moving seas is free and clean. But sea power is more predictable than either wind or solar. Waves begin forming thousands of miles from coastlines and days in advance; tides rise and fall as dependably as the cycles of the moon. That predictability makes it easier to match supply with demand.

Roger Bedard, who leads ocean energy research at the U.S. utility-funded Electric Power Research Institute (EPRI) in Palo Alto, says there’s plenty of reason for optimism about the future of what he calls “hydrodynamic”

More From Yale e360

Click below to read more from Yale Environment 360 on renewable energy innovation.

Deep Geothermal: The Untapped Energy Source | Solar's Time Has Finally Arrived
power. Within a decade, he says, the U.S. could realistically meet as much as 10 percent of its electricity needs from hydrodynamic power. As a point of reference, that’s about half of the electricity the U.S. produces with nuclear power today. Although he acknowledges that initial sea-powered generation projects are going to be expensive, Bedard believes that as experience grows and economies of manufacturing scale kick in, hydrodynamic power will follow the same path toward falling costs and improving technologies as other alternatives.

“Look at wind,” he says. “A kilowatt hour from wind cost fifty cents in the 1980s. Now it’s about seven cents.” (That’s about the same as producing electricity with natural gas, and only about three cents more than coal, the cheapest — and dirtiest — U.S. energy choice. Any future tax on carbon emissions could narrow that gap even more, as would additional clean-power subsidies.)

For some nations, wave and tide power could pack an even bigger punch. Estimates suggest, for instance, that the choppy seas surrounding the United Kingdom could deliver as much as 25 percent of its electricity. British alternative energy analyst Thomas W. Thorpe believes that on a worldwide basis, waves alone could produce as much as 2,000 terawatt hours of electricity, as much as all the planet’s major hydroelectric plants generate today.

Although none are as far along as Pelamis, most competing wave-power technologies rely not on the undulations of mechanical serpents, but instead on the power captured by the vertical bobbing of large buoys in sea swells. Ocean Power Technologies (OPT), based in New Jersey, drives the generators in its PowerBuoy® with a straightforward mechanical piston. A stationary section of the mostly submerged, 90-foot buoy is anchored to the ocean floor; a second section simply moves up and down with the movement of sea swells, driving pistons that in turn drive an electrical generator. The Archimedes Wave Swing, a buoy-based system developed by Scotland’s AWS Ocean Energy, harnesses the up-and-down energy of waves by pumping air to spin its turbines. Vancouver-based Finavera Renewables uses seawater as its turbine-driving hydraulic fluid.

Although Pelamis beat all of these companies out of the commercialization gate, OPT appears to be right behind, with plans to install North America’s first commercial-scale wave power array of buoys off the coast of Oregon as early as next year. That array — occupying one square-mile of ocean and, like other wave power installations, located far from shipping lanes — would initially produce 2 megawatts of power. OPT also announced last September an agreement to install a 1.4-megawatt array off the coast of Spain. An Australian subsidiary is in a joint venture to develop a 10-megawatt wave farm off the coast of Australia.

Meanwhile, Pelamis Wave Power plans to install more of its mechanical serpents — three megawatts of generating capacity off the coast of northwest Scotland, and another five-megawatt array off Britain’s Cornwall coast.

The Cornwall installation will be one of four wave power facilities plugged into a single, 20-megawatt underwater transformer at a site called “Wave Hub.” Essentially a giant, underwater version of a socket that each developer can plug into, Wave Hub — which will be connected by undersea cable to the land-based grid — was designed as a tryout site for competing technologies. OPT has won another of the four Wave Hub berths for its buoy-based system.

Other innovators are trying to harness the power of ocean or estuarine tides. Notably, in 2007, Virginia’s Verdant Power installed on the floor of New York’s East River six turbines that look, and function, much like

Verdant Power

Verdant Power
VIDEO: Verdant Power demonstration
of underwater turbines
stubby, submerged windmills, their blades — which are 16 feet in diameter — turning at a peak rate of 32 revolutions per minute. The East River is actually a salty and powerful tidal straight that connects Long Island Sound with the Atlantic Ocean. Although the “underwater windmills” began pumping out electricity immediately, the trial has been a halting one. The strong tides quickly broke apart the turbines’ first- (fiberglass and steel) and second- (aluminum and magnesium) generation blades, dislodging mounting bolts for good measure.

Undeterred, in September Verdant Power began testing new blades made of a stronger aluminum alloy. If it can overcome the equipment-durability problems, the company hopes to install as many as 300 of its turbines in the East River, enough to power 10,000 New York homes.

A scattering of similar prototype “underwater windmill” projects have been installed at tidal sites in Norway, Northern Ireland, and South Korea. (In addition, interest in moving into freshwater sites is growing. Verdant itself hopes to install its turbines on the St. Lawrence River. At least one other company, Free Flow Power of Massachusetts, has obtained Federal Energy Regulatory Commission permits to conduct preliminary studies on an array of sites on the Mississippi River south of St. Louis.)

The environmental benefits of hydrodynamic power seem obvious: no carbon dioxide or any other emissions associated with fossil-fuel-based generation. No oil spills or nuclear waste. And for those who object to wind farms for aesthetic reasons, low-profile wave farms are invisible from distant land; tidal windmill-style turbines operate submerged until raised for maintenance.

There are, however, environmental risks associated with these technologies.

New York state regulators required Verdant Power to monitor effects of their its turbines on fish and wildlife. So far, sensors show that fish and water birds are having no trouble avoiding the blades, which rotate at a relatively leisurely 32 maximum revolutions per minute. In fact the company’s sensors have shown that fish tend to seek shelter behind rocks around the channel’s banks and stay out of the central channel entirely when tides are strongest.

But a host of other questions about environment effects remain unanswered. Will high-voltage cables stretching across the sea from wave farms somehow harm marine ecosystems? Will arrays of hundreds of buoys or mechanical serpents interfere with ocean fish movement or whale migrations? What effect will soaking up large amounts of wave energy have on shoreline organisms and ecosystems?

“Environmental effects are the greatest questions right now,” EPRI’s Bedard says, “because there just aren’t any big hydrodynamic projects in the world.”

Projects will probably have to be limited in size and number to protect the environment, he says – that’s a big part of the reason he limits his “realistic” U.S. estimate to 10 percent of current generation capacity. But the only way to get definitive answers on environmental impact might be to run the actual experiment — that is, to begin building the water-powered facilities, and then monitor the environment for effects.

Bedard suggests that the way to get definitive answers will be to build carefully on a model like Verdant’s: “Start very small. Monitor carefully. Build it a little bigger and monitor some more. I’d like to see it developed in an adaptive way.”

POSTED ON 01 Dec 2008 IN Business & Innovation Climate Energy 


This is a fantastic idea yet it holds another benefit that was not mentioned in this article.

An article that I have read about the erosion of the beaches in Chicago and it's solution could be combined with this system at no additional cost. Chicago placed piers perpendicular to the beaches and found that this stopped the currents from causing beach erosion.

This generation system would actually work much in the same manner if it was placed near the shorelines. Also, as the ocean waves near the beach, they are pushed up increasing the wave height which would also increase the efficency of these wave power generators.

C. Jeff Dyrek, North Pole Expedition Leader.
Posted by C. Jeff Dyrek on 04 Dec 2008

Jeff's comments are right on the mark and align with what I was thinking when reading up on H20 kinetic power.

Why not use these as artificial harbors instead of rock breakwaters?

an array of these would attenuate the waves making a quite zone inside.

I remember a story from the bible of an array of wood tree trunks placed in an array to form a inner shelter for boats.

and combining what Jeff had mentioned with floor based deflectors between the kinetic generators would focus the wave energy onto the generators while still creating a harbor and/or beach erosion benefits. place these at angles to the most common wave front directions to maximize the energy and spread out the phase magnitude generated by the sum total for array for the smoothest, continuous power generation. Throw in some small percentage near shore to create optimum wave shape for surfing enthusiast and you have a holistic win-win for all. Perhaps the angled sections could both smooth out power generation and focus and shape waves for surfers? Hey Surfrider what do-ya think?

Posted by Ron Davison on 05 Dec 2008

This, of course, is an interesting idea. The problem has become NIMBY principles - look at the Kennedy family in Nantucket sound with CapeWind. The credit crisis is not helping wind projects either - because of their long payback period. What we really need is reliable, affordable electricity to power our next generation over vehicles: hybrids, especially plug ins. Concepts such as carbon capture and storage will help ensure coal continues to play a major part in our energy portfolio. Renewables can help too, but their inherent limitations make them more supplemental than alternative.
Posted by Jude C on 09 Dec 2008

The thing with Carnegies system (CNM) is that it is deployed underwater completely hidden so this takes wave energy, cuts down on erosion without being unsightly which is a big selling point in my opinion as most other systems are visible
Posted by jack petreski on 16 Dec 2008

Whenever tried, tidal turbines macerate all living things in the tidal areas except crab life.

I am constantly amazed at the ecological disasters that are ignored in the name of saving the planet.
Posted by Dahun on 16 Mar 2009

In Australia a company called Carnegie wave energy is developing an interesting bouy actuated energy production unit. The benifits seem to be numerous, for example no moving parts underwater that are detremental to sea life, totally submerged, electrical generation is on land (in my opinion safer to marine enviroment is the long term),can be set up as sanctury zones with the benifit of its arrangement creating an increased habitat for marine life,can create enough pressure for direct desalination with zero emitions they are using materials that have already been proven in the oil and gas industry to have handled 20 to 30 years in that enviroment and the way the energy is transfered would seem to have the same impact as if sponges and seaweed were to be growing and moving with the tide or waves.
Definately an interesting project if are interested and believe in the ocean being the answer.

Posted by Scott Newman on 08 Aug 2010

Ancient Water Discovery In Depths Of Iron Range Mine « CBS Minnesota


Posted by Sarah C Hawkinson on 16 May 2011

Comments have been closed on this feature.
jon r. luomaABOUT THE AUTHOR
Jon R. Luoma, a contributing editor at Audubon, has written about environmental and science topics for The New York Times, and for such magazines as National Geographic and Discover. His third book, The Hidden Forest: Biography of an Ecosystem, has been released in a new edition by Oregon State University Press. In his last article for Yale Environment 360, he wrote about the promising state of solar power.



A Tale of Two Northern European Cities:
Meeting the Challenges of Sea Level Rise

For centuries, Rotterdam and Hamburg have had to contend with the threat of storm surges and floods. Now, as sea levels rise, planners are looking at innovative ways to make these cities more resilient, with new approaches that could hold lessons for vulnerable urban areas around the world.

A Tale of Two Northern European Cities:
Meeting the Challenge of Sea Level Rise

For centuries, Rotterdam and Hamburg have had to contend with the threat of storm surges and floods. Now, as sea levels rise, planners are looking at innovative ways to make these cities more resilient, with new approaches that could hold lessons for vulnerable urban areas around the world.

African Lights: Solar Microgrids
Bring Power to Kenyan Villages

Small-scale microgrids are increasingly seen as the most promising way to bring electricity to the 1.3 billion people worldwide who currently lack it. In Kenya, an innovative solar company is using microgrids to deliver power to villages deep in the African bush.

How 'Third Way' Technologies
Can Help Turn Tide on Climate

In a Yale Environment 360 interview, Australian scientist and author Tim Flannery explains how the development of technologies that mimic the earth’s natural carbon-removing processes could provide a critical tool for slowing global warming.

Will Tidal and Wave Energy
Ever Live Up to Their Potential?

As solar and wind power grow, another renewable energy source with vast potential — the power of tides and waves — continues to lag far behind. But progress is now being made as governments and the private sector step up efforts to bring marine energy into the mainstream.


MORE IN Reports

For Storing Electricity, Utilities
Are Turning to Pumped Hydro

by john roach
High-tech batteries may be garnering the headlines. But utilities from Spain to China are increasingly relying on pumped storage hydroelectricity – first used in the 1890s – to overcome the intermittent nature of wind and solar power.

On Thin Ice: Big Northern Lakes
Are Being Rapidly Transformed

by cheryl katz
As temperatures rise, the world’s iconic northern lakes are undergoing major changes that include swiftly warming waters, diminished ice cover, and outbreaks of harmful algae. Now, a global consortium of scientists is trying to assess the toll.

The Haunting Legacy of
South Africa’s Gold Mines

by mark olalde
Thousands of abandoned gold mines are scattered across South Africa, polluting the water with toxics and filling the air with noxious dust. For the millions of people who live around these derelict sites, the health impacts can be severe.

The Sushi Project: Farming Fish
And Rice in California's Fields

by jacques leslie
Innovative projects in California are using flooded rice fields to rear threatened species of Pacific salmon, mimicking the rich floodplains where juvenile salmon once thrived. This technique also shows promise for growing forage fish, which are increasingly threatened in the wild.

A Delicate Balance: Protecting
Northwest’s Glass Sponge Reefs

by nicola jones
Rare and extensive reefs of glass sponges are found only one place on earth – a stretch of the Pacific Northwest coast. Now, efforts are underway to identify and protect these fragile formations before they are obliterated by fishing vessels that trawl the bottom.

As the Fracking Boom Spreads,
One Watershed Draws the Line

by bruce stutz
After spreading across Pennsylvania, fracking for natural gas has run into government bans in the Delaware River watershed. The basins of the Delaware and nearby Susquehanna River offer a sharp contrast between what happens in places that allow fracking and those that do not.

Will Tidal and Wave Energy
Ever Live Up to Their Potential?

by sophia v. schweitzer
As solar and wind power grow, another renewable energy source with vast potential — the power of tides and waves — continues to lag far behind. But progress is now being made as governments and the private sector step up efforts to bring marine energy into the mainstream.

The Rapid and Startling Decline
Of World’s Vast Boreal Forests

by jim robbins
Scientists are becoming increasingly concerned about the fate of the huge boreal forest that spans from Scandinavia to northern Canada. Unprecedented warming in the region is jeopardizing the future of a critical ecosystem that makes up nearly a third of the earth’s forest cover.

Northern Forests Emerge
As the New Global Tinderbox

by ed struzik
Rapidly rising temperatures, changes in precipitation, and increased lightning strikes are leading to ever-larger wildfires in the northern forests of Alaska, Canada, and Siberia, with potentially severe ecological consequences.

For U.S. Tribes, a Movement to
Revive Native Foods and Lands

by cheryl katz
On ancestral lands, the Fond du Lac band in Minnesota is planting wild rice and restoring wetlands damaged by dams, industry, and logging. Their efforts are part of a growing trend by Native Americans to bring back traditional food sources and heal scarred landscapes.

e360 digest
Yale Environment 360 is
a publication of the
Yale School of Forestry
& Environmental Studies


Donate to Yale Environment 360
Yale Environment 360 Newsletter



About e360
Submission Guidelines

E360 en Español

Universia partnership
Yale Environment 360 articles are now available in Spanish and Portuguese on Universia, the online educational network.
Visit the site.


e360 Digest
Video Reports


Business & Innovation
Policy & Politics
Pollution & Health
Science & Technology


Antarctica and the Arctic
Central & South America
Middle East
North America

e360 VIDEO

The 2015 Yale e360 Video Contest winner documents a Northeastern town's bitter battle over a wind farm.
Watch the video.


The latest
from Yale
Environment 360
is now available for mobile devices at e360.yale.edu/mobile.

e360 VIDEO

A 2015 Yale e360 Video Contest winner captures stunning images of wild salmon runs in Alaska.
Watch the video.

e360 VIDEO

Colorado wildfires
An e360 video goes onto the front lines with Colorado firefighters confronting deadly blazes fueled by a hotter, drier climate.
Watch the video.


A three-part series Tainted Harvest looks at the soil pollution crisis in China, the threat it poses to the food supply, and the complexity of any cleanup.
Read the series.

header image
Top Image: aerial view of Iceland. © Google & TerraMetrics.