RenewableEnergyWorld “Ocean Energy 2009” Excerpts

MARSHA W. JOHNSTON, RenewableEnergyWorld.com, March 2009

One hundred and forty-one years ago, the relentless sea off Scotland’s coast inspired the following observation from native son and author George MacDonald:

I climbed the heights above the village, and looked abroad over the Atlantic. What a waste of aimless tossing to and fro! Gray mist above, full of falling rain; gray, wrathful waters underneath, foaming and bursting as billow broke upon billow…they burst on the rocks at the end of it, and rushed in shattered spouts and clouds of spray far into the air over their heads. “Will the time ever come,” I thought, when man shall be able to store up even this force for his own ends? Who can tell.”

In the United States, permitting may be an even bigger hurdle to marine energy deployment than financing. Between 25 and 35 different U.S. federal, state and local regulatory agencies claim some jurisdiction over marine power deployment. In the UK, two agencies handle permitting.

Today, we can certainly say, “Yes, the time will come.” The only question remaining is how long it will be before humankind routinely and widely uses electricity generated from the kinetic power of ocean tides, currents and waves.

If one defines “commercial ocean energy” as several tens of megawatts, the world cannot yet boast a commercial ocean energy installation. Indeed, only two installations of either wave, tidal or in-stream current devices are grid-connected and can generate over 1 megawatt (MW) of power. One is Pelamis Wave Power’s 2.25-MW Aguçadoura project off of Portugal’s northern coast and the other is Bristol-based Marine Current Turbines’ (MCT) SeaGen, a US $20-million commercial-scale tidal-energy project under development in Northern Ireland’s turbulent Strangford Narrows. In December, SeaGen boasted the first tidal turbine to hit a capacity of 1.2 MW.

(The biggest exception to commercial ocean energy production is the world’s longest running tidal power plant, the 240-MW La Rance, in France. But the plant’s barrage technology, which traps water behind a dam and releases it at low tide, has fallen out of favor due to its perceived higher environmental impact than underwater turbines. Nova Scotia has also been operating a 20-MW barrage Tidal Generating Station in the tidal-rich Bay of Fundy since 1984.)

The rest of the world’s wave, tidal and current installations, some of which have been in the water as far back as the 1990s, are experimental and prototype units ranging in size from 35 kilowatts (kW) to 400 kW. Because these units operate only intermittently and are not typically connected to any grid, it is not possible to determine their total power generation.

Many of these units are prototype demonstration units for the much bigger installations that are under development and that will begin to realize significant exploitation of the world’s ocean energy resource. For example, Ocean Power Technologies Inc. will use the 150-kW PowerBuoy it has been testing since the mid-90s as the “workhorse” for the 270-MW, four-site wave energy plant off California and Oregon coasts that it has partnered with Lockheed Martin to develop, says CEO George Taylor.

And Inverness, Scotland-based WaveGen expects to use 40 units of the 100-kw turbine it just installed off the Island of Islay for a 4-MW farm off of Scotland’s Isle of Lewis. Meanwhile, Pelamis says if its 750-kw “sea snake” devices, which were installed last year, make it through the winter, it will put 37 more of them in the water, generating 30 MW.

All of the wave, tidal, ocean and river current power around North America that can be practically extracted could together provide 10% of today’s electrical consumption in the U.S., says Roger Bedard, ocean energy leader at the Electric Power Research Institute (EPRI) in Palo Alto, CA. He adds that the total water resource could, it is sometimes said, possibly power the world twice over, but a lot of it is out of reach. “Hudson’s Bay, off the Arctic Circle, has HUGE tidal power, but it is thousands of miles from where anyone lives. We have HUGE wave resources off Aleutian Islands, but the same problem,” he says.  See EPRI’s U.S. Offshore Wave Energy Resource Map, below.

What will be the “magic” year for large-scale ocean energy deployment? Most developers indicate 2011-2012. Trey Taylor, co-founder and president of Verdant Power, which is moving into the commercial development phase of its 7-year-old Roosevelt Island Tidal Energy project, says the firm aims to have “at least 35 MW” in the water by the end of 2011.

Bedard is more circumspect. “I think it will be 2015 in Europe and 2025 in U.S. for big deployment,” he says, adding that the year cited depends entirely on the definition of “big” and “commercial,” which he defines as “many tens of megawatts.”

Verdant’s Taylor expects greater initial success in Canada. “The fundamental difference between Canada and the U.S. is that the underpinning of processes in Canada is collaborative and in the U.S. it is adversarial. It’s just the nature of Canadians, collaborating for community good, whereas in the U.S. people are afraid of being sued,” he said.

Bedard says the U.S. could catch up to Europe earlier, if the Obama Administration walks its big renewable energy infrastructure investment talk. “But if it’s business as usual, it could be later, depending on the economy,” he says.

Since the global economy began to melt down last September, many ocean energy companies have had to refocus their investment plans. With venture capital and institutional monies drying or dried up, firms are turning to public funds, strategic partners such as utilities and big engineering firms, and angel investors.

In November, MCT retained London-based Cavendish Corp Finance to seek new financing. Raymond Fagan, the Cavendish partner charged with MCT, said although tidal energy is not as advanced as wind or solar, he has seen a “strong level of interest so far from large engineering-type firms in MCT’s leading position.” Because MCT holds patents and is delivering power to the grid ahead of its competitors, Fagan thinks Cavendish can bring it together with such strategic partners.

In addition to the economic climate, he notes that the drop in oil and gas prices is further slowing renewable energy investment decisions. “Six to 12 months ago, people were leaping into renewable energy opportunities,” he says, adding that the UK government’s recent call for marine energy proposals for the enormous Pentland Firth zone north of Scotland will improve Cavendish’s chances of getting financing. Though it has yet to make a public announcement, MCT is widely viewed as a prime operator for the zone.

Monies are still available. Witness Pelamis Wave Power’s infusion of 5 million pounds sterling in November, which it says it will use for ongoing investment in core R&D and continuing development of its manufacturing processes and facilities.

In the U.S., permitting may be an even bigger hurdle to marine energy deployment than financing. Between 25 and 35 different U.S. federal, state and local regulatory agencies claim some jurisdiction over marine power deployment. In the UK, two agencies handle permitting. Bedard notes however, that streamlining the process in the U.S. may have begun with the recent opening of a new six-month process for licensing pilot marine energy plants.

Marine energy experts agree that there are more opportunities for wave power than for tidal, as there are simply fewer exploitable tidal sites. In technology terms, however, tidal turbines have benefited from a quarter century of wind turbine development, says Virginia Tech professor George Hagerman. Despite more widely available wave resource, wave energy developers face the challenge of needing many more devices than do tidal energy developers, and have a higher cabling cost to export the power.

As Christopher Barry, co-chair of the Ocean Renewable Energy panel at the Society of Naval Architects and Marine Engineers, explains: “The major challenge [to ocean energy] is not pure technology, but the side issues of power export and making the technology affordable and survivable.”

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Push for Clean Energy Spurs Tidal Power Globally

Bloomberg via The Economic Times, February 2, 2009

LONDON: Three decades ago, engineer Peter Fraenkel created an underwater turbine to use river power to pump water in Sudan, where he worked for a charity. Civil war and a lack of funding stymied his plans. Now, his modified design generates electricity from tides off Northern Ireland.

“In the 1970s, the big snag was the market for that technology consisted of people with no money,” said Fraenkel, the 67-year-old co-founder of closely-held Marine Current Turbines. “Now it’s clear governments are gagging for new renewable energy technology.”

MCT last year installed the world’s biggest grid-connected tidal power station in Strangford Lough, an Irish Sea inlet southeast of Belfast. The SeaGen project’s two turbines, which cost 2.5 million pounds ($3.6 million), can produce as much as 1.2 megawatts of electricity, enough to power 1,140 homes. The company is one of more than 30 trying to tap tidal currents around the world, six years after the first project sent power to the grid.

Investors may pump 2.5 billion pounds into similar plants in Europe by 2020 as the European Union offers incentives for projects that don’t release carbon dioxide, the gas primarily blamed for global warming. In the US, President Barack Obama plans to increase tax breaks for renewable energy.

“Tidal energy has an enormous future, and the UK has a great resource” if construction costs come down, said Hugo Chandler, renewable energy analyst at the Paris-based International Energy Agency, which advises 28 nations. “It’s time may be just around the corner.”

While tides are a free source of energy, generating power from them is three times more expensive than using natural gas or coal over the life of a project, according to the Carbon Trust, a UK government-funded research unit.

Including capital expenses, fuel and maintenance, UK tidal current power costs 15 pence per kilowatt hour, compared with 5 pence for coal and gas and 7 pence for wind, the trust says.

Designing equipment to survive in salty, corrosive water and installing it in fast-moving currents boosts startup costs, said MCT Managing Director Martin Wright, who founded the Bristol, England-based company with Fraenkel in 2002. MCT raised 30 million pounds for SeaGen and pilot projects, he said, declining to break out the expenses.

Gearboxes and generators have to be watertight. The machinery must withstand flows up to 9.3 knots (10.7 mph) in Strangford Lough, which exert three times the force of projects that harness wind at similar speeds, Fraenkel said.

“The forces you’re trying to tap into are your enemy when it comes to engineering the structure,” said Angela Robotham, MCT’s 54-year-old engineering chief.

The project consists of a 41-meter (135-foot) tower with a 29-meter crossbeam that is raised from the sea for maintenance. Attached to the beam are two rotors to capture incoming and outgoing flows. The turbines convert the energy from tidal flows into electricity, differing from more established “tidal range” technology that uses the rise and fall of water.

Positioned between the North Sea and Atlantic Ocean, the British Isles have about 15% of the world’s usable tidal current resources, which could generate 5% of domestic electricity demand, the Carbon Trust estimates. Including wave power, the ocean may eventually meet 20 percent of the UK’s energy needs, the government said in June.

OpenHydro, a closely held Dublin company, linked a donut-shaped device with less than a quarter of the capacity of SeaGen to the grid at the European Marine Energy Centre in Orkney, Scotland, last May.

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MCT Demonstrating Tidal Energy in Nova Scotia

MendoCoastCurrent, January 23, 2009

Marine Current Turbines Ltd, the Bristol based UK tidal energy company, in now in partnership Canada’s Minas Basin Pulp and Power Company Ltd to demonstrate and develop tidal power technology and facilities in Canada’s Bay of Fundy, Nova Scotia. Minas Basin Pulp and Power Company Limited (MBPP) of Hantsport, Nova Scotia is a leading sustainable energy and resources company.

Working in partnership with MBPP, Marine Current Turbines (MCT) will participate in the tidal power demonstration centre established by the Province of Nova Scotia. MBPP and MCT intend to deploy a 1.5MW tidal generator when the in-stream tidal energy centre enters full operation and is connected to the Nova Scotia grid. 

MCT installed the world’s first offshore tidal current device in 2003 off the south west coast of England (the 300kW SeaFlow) and during 2008, it installed and commissioned its 1.2MW SeaGen commercial prototype tidal current turbine in Strangford Narrows in Northern Ireland. SeaGen generated at its full output of 1.2MW onto the local grid in December 2008, becoming the most powerful marine energy device in the world. It has the capacity to generate power for approximately 1,000 homes. 

Notes on the SeaGen Technology from MCT: SeaGen works by generating power from sea currents, using a pair of axial flow turbines driving generators through gearboxes using similar principles to wind generator technology. The main difference is that the high density of seawater compared to wind allows a much smaller system; SeaGen has twin 600kW turbines each of 16m diameter. The capture of kinetic energy from a water current, much like with wind energy or solar energy, depends on how many square meters of flow cross-section can be addressed by the system. With water current turbines it is rotor swept area that dictates energy capture capability, because it is the cross section of flow that is intercepted which matters. SeaGen has over 400 square meters of rotor area which is why it can develop its full rated power of 1.2MW in a flow of 2.4m/s (5 knots).

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Tidal Energy Limited Gets Boost from Propeller and Wind Technologies

ALOK JHA, Guardian UK, January 5, 2009

Tidal Energy's DeltaStream

Propellers on ships have been tried and tested for centuries in the rough and unforgiving environment of the sea: now this long-proven technology will be used in reverse to harness clean energy from the UK’s powerful tides.

The tides that surge around the UK’s coasts could provide up to a quarter of the nation’s electricity, without any carbon emissions. But life in the stormy seas is harsh and existing equipment – long-bladed underwater wind turbines – is prone to failure.  A Welsh renewable energy company has teamed up with ship propulsion experts to design a new marine turbine which they believe is far more robust.

Cardiff-based Tidal Energy Limited will test a 1MW tidal turbine off the Pembrokeshire coast at Ramsey Sound, big enough to supply around 1,000 homes. Their DeltaStream device, invented by marine engineer Richard Ayre while he was installing buoys in the marine nature reserve near Pembrokeshire, will be the first tidal device in Wales and become fully operational in 2010.

To ensure the propeller and electricity generation systems were as tough as possible, the tidal turbine’s designers worked with Converteam, a company renowned for designing propulsion systems for ships. “They’ve put them on the bottom of the Queen Mary … and done work for highly efficient destroyers, which is exactly the same technology that we’re looking at here,” said Chris Williams, development director of DeltaStream.

DeltaStream’s propellers work in reverse to a ship’s propulsion system – the water turns the blades to generate electricity – but the underlying connections between blades and power systems are identical to those on the ship.

Tidal streams are seen as a plentiful and predictable supply of clean energy, as the UK tries to reduce its greenhouse gas emissions. Conservative estimates suggest there is at least 5GW of power, but there could be as much as 15GW – 25% of current national demand.

A single DeltaStream unit has three propeller-driven generators that sit on a triangular frame. It weighs 250 tonnes, but is relatively light compared with other tidal systems which can be several times heavier. The unit is simple to install and can be used in closely packed units at depths of at least 20m. Unlike other tidal turbine systems, which must be anchored to the sea floor using piles bored into the seabed, DeltaStream’s triangular structure simply sits on the sea floor.

Duncan Ayling, head of offshore at the British Wind Energy Association and a former UK government adviser on marine energy, said that one of the biggest issues facing all tidal-stream developers is ease of installation and maintenance of their underwater device. “Anything you put under the water becomes expensive to get to and service. The really good bit of the DeltaStream is that they can just plonk it in the water and it just sits there.”

Another issue that has plagued proposed tidal projects is concern that the whirling blades could kill marine life. But Williams said: “The blades themselves are thick and slow moving in comparison to other devices, so minimising the chance of impact on marine life.”

The device also has a fail-safe feature when the water currents become too powerful and threaten to destroy the turbines by dragging them across the sea floor – the propellers automatically tilt their orientation to shed the extra energy.

Pembrokeshire businessman and sustainability consultant Andy Middleton said: “People are increasingly recognising how serious global warming really is, and in St David’s we are keen to embrace our responsibility to minimise climate change. DeltaStream is developing into a perfect example of the technology that fills the need for green energy and has the added benefit of being invisible and reliable.”

The country’s first experimental tidal turbine began generating electricity in Strangford Lough, Northern Ireland last year, built by Bristol-based company Marine Current Turbines. SeaGen began at about 150kW, enough for around 100 homes, but has now reached 1,200kW in testing. It had a setback early in its test phase, with the tidal streams breaking one of the blades in July.

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Harnessing Energy from the Oceans

GLOBE-NET NEWS, May 29, 2008

Forever moving – our restless oceans have enough energy to power the world. As long as the Earth turns and the moon keeps its appointed cycle, the oceans will absorb and dissipate vast amounts of kinetic energy – a renewable energy resource of enormous potential. But harnessing this resource has proven more difficult than first thought. In this the latest installment of the GLOBE-Net Series on Renewable Energy – we look at how the power of the oceans might eventually find its place among other forms of renewable energy.

Ocean Energy – What is it?

According to the United Nations, 44% of the world’s population lives within 150 km of an ocean coast. In Canada and Australia the number is much higher at 80%. In the United States 53% of the population lives in close proximity to an ocean.

Thus it is only natural that many countries look to the oceans as a source of energy to be harnessed. How they seek to exploit this resource varies according to factors of geography and available technologies.

The two main forms of energy associated with our oceans are tidal power and wave power – born of the same source, but different in how they turn energy into electricity.

Tidal Power

Tidal power coverts the energy of tides into electricity utilizing the rise and fall of the ocean tides. The stronger the tide, either in water level height or tidal current velocities, the greater the potential for tidal electricity generation.

Tidal generators act in much the same way as do wind turbines, however the higher density of water (832 times that of air) means that a single generator can provide significant power at velocities much lower than those associated`with the wind power generators.

Tidal power can be classified into two main types; Tidal Stream Systems and Barrages.

Barrages are similar to hydro-electric dams but are placed in an estuary bay or river mouth, where they act as barriers that create artificial tidal lagoons. When water levels outside the lagoon changes relative to water levels inside, turbines in the barrages are able to produce electrical power. There are only three such structures in the world: the Rance River in France, Canada’s Bay of Fundy, and Kislaya Guba, Russia.

Tidal stream systems make use of the kinetic energy of moving water to power turbines. This technology simply relies on individual turbines which are placed in the water column; moored to be suspended, floating or anchored to the ocean floor. As the tide flows in or out, electrical energy is produced as water moves through the turbine.

Tidal power boasts several advantages over other types of renewable energy technology, because tides are more predictable and reliable than wind energy or sunny days for solar power. Tidal energy has an efficiency ratio of approximately 80% in terms of converting the potential energy of the water into electricity. Tidal stream system turbines are only a third the diameter of wind rotors of the same power output.

As with wind power, location is important factor in terms of being able to harness the earth’s natural energy. Tidal stream systems must be located in areas with fast currents where natural flows are concentrated between natural obstructions, for example at the entrances to bays and rivers, around rocky points or headlands, or between islands and other land masses.

Wave Power

Ocean surface waves are also a considerable source of energy potential, but energy that is not as restricted in terms of location as tidal energy systems. Typically wave energy is captured using buoys which generate mechanical energy as they oscillate vertically from wave motion.

Terminator devices extend perpendicular to the direction of wave travel and capture or reflect the power of the wave. Water enters through a subsurface opening into a chamber with air trapped above it and wave action causes the captured water column to move up and down like a piston to force the air though an opening connected to a turbine.

A point absorber is a floating structure with components that move relative to each other due to wave action (e.g., a floating buoy inside a fixed cylinder). The relative motion is used to drive electromechanical or hydraulic energy converters.

Attenuators are long multi-segment floating structures oriented parallel to the direction of the waves. The differing heights of waves along the length of the device causes flexing where the segments connect, and this flexing is connected to hydraulic pumps or other converters.

Overtopping devices have reservoirs that are filled by incoming waves to levels above the average surrounding ocean. The water is then released, and gravity causes it to fall back toward the ocean surface. The energy of the falling water is used to turn hydro turbines.

Wave power varies considerably in different parts of the world, and wave energy can’t be harnessed effectively everywhere. According to the Ocean Renewable Energy Group, a Vancouver based organisation that promotes the development of ocean energy in Canada, regions considered to have “good” wave energy resources are generally those found within 40 to 60 degrees of latitude, where the strongest winds are found. Wave-power rich areas of the world include the western coasts of Scotland, northern Canada, southern Africa, Australia, and the northwestern coasts of the United States.

Projects Underway

Ocean energy company Clean Current Power Systems estimates a potential global market for 67,000 Megawatts (MW) of tidal and wave action equipment worth $200 billion. At 20 cents/kW hour, the market for tidal electricity could be $27 billion annually. According to Finavera, world-wide wave energy could provide up to 2,000 TWh/year, 10% of world electricity consumption.

It comes as no surprise then, that interest in ocean energy has been building momentum in the past few years as these nations scramble to meet renewable energy targets.

For instance, in November 2007, British company Lunar Energy announced that it would be building the world’s first deep-sea tidal-energy farm off the coast of Pembrokshire in Wales. Eight underwater turbines, each 25 metres long and 15 metres high will provide electricity for 5,000 homes. Construction is due to start in the summer of 2008 and the proposed tidal energy turbines, described as “a wind farm under the sea”, should be operational by 2010.

Plans for a ten-mile barrage across the River Severn, which could generate 5% of the UK’s electricity needs, are currently under development. According to the UK Sustainable Development Commission, a barrage across the Severn would produce clean and sustainable electricity for 120 years. This would have a capacity of 8,640MW and an estimated output of 17 terawatt hours a year.

Scotland boasts roughly 25% of the entire European Union’s tidal power potential and 10% of its wave energy potential and could produce more than 1,300 megawatts by 2020, enough to power a city the size of Seattle. In 2007, Scotland announced $26 million worth of funding packages to develop marine power in the nation. So far $8 million has been procured to develop 3 MW of tidal power.

UK based Marine Current Turbines is developing a tidal stream system off the coast of Ireland. The 1.2-megawatt turbine will be tested for 12 weeks before feeding power into the Northern Ireland grid where it will operate for up to 20 hours per day, producing enough electricity to power 1,000 homes.

Both Scotland and England are planning wave energy projects. Scotland will be developing a 3MW array and England will be developing a 20 MW Wave Hub off the north coast of Cornwall, England. The Cornwall project will power up to 7,500 homes.

Canada has the world’s longest coastline and has always been serious about harnessing ocean energy. In early 2008 the Government of Nova Scotia gave the green light to three tidal energy testing projects in the Bay of Fundy to help establish a permanent tidal energy farm (see GLOBE-Net Article Nova Scotia to fund tidal power research). Irving Oil is also studying 11 potential sites in the Bay of Fundy to develop tidal energy farms.

The Government of British Columbia estimates there are more than 6,000 megawatts of potential wave energy that have been identified so far in the province and projects are already underway to develop wave energy systems. In 2006 Vancouver based Clean Current Power Systems began developing a pilot tidal power project near Victoria to demonstrate the potential for tidal power.

PG&E and Vancouver-based Finavera Renewables is developing America’s first commercial wave power plant off the coast of Northern California. The plant is scheduled to begin operating in 2012, generating a maximum of 2 megawatts of electricity.

In March, 2008, the U.S. Department of Energy announced would be offering up to $7.5 million in grants for hydro-kinetic energy such as wave and tidal power. The department is seeking partnerships with companies and universities to develop the technologies and plans to award up to 17 grants.

Portugal is planning the world’s first commercial wave farm, the Aguçadora Wave Park near Póvoa de Varzim. If successful, a further 70 million euro is likely to be invested before 2009 on a further 28 machines to generate 72.5 MW.

The Challenges

Despite the enormous potential of ocean energy, there remain many pitfalls (if such a word can be used in a watery context) that have proven difficult to overcome, and which explains why ocean energy remains the least developed of all forms renewable energy. Problems still exist regarding cost, maintenance, environmental concerns and our still imperfect understanding of how power from the oceans will impact on the world’s energy infrastructure.

For example, turbines are susceptible to bio-fouling; the growth of aquatic life on or in the turbine. This can severely inhibit the efficiency of energy production and is both costly and difficult to remove. Turbines are also prone to damage from ocean debris.

In the Bay of Fundy, project developers are particularly concerned with ice floes the size of small apartments, and cobblestones the size of watermelons constantly being tossed across the Bay’s terrain by the power of the Bay’s water flows.

Turbines may also be hazardous to marine life and the impacts on marine life are still largely unknown, but concern is warranted.

Barrage systems are affected by problems of high initial infrastructure costs associated with construction and the resulting environmental problems. For example, independent research on the economics of building the proposed Severn Barrage in the UK revealed that, taking environmental costs into account, the structure could cost as much as $12 billion to create – $4 billion more than previously estimated.

Barrage impacts include a decrease in the average salinity and turbidity within a barrage, significantly altering associated ecosystems.

Wave power systems present their own set of challenges. Most electric generators operate at higher speeds, and most turbines require a constant, steady flow. Unfortunately wave energy is slow and ocean waves oscillate at varying frequencies.

The rough realities of the marine environment have also proven difficult to deal with, especially for companies seeking to remain cost-effective. Constructing wave devices that can survive storm damage and saltwater corrosion add to development costs.

The Future

Modern advances in ocean energy technology may eventually see large amounts of power generated from the ocean, especially tidal currents using the tidal stream designs. The technology is still in its infant stage and most projects that exist or are that are in project development stages are mainly pilot projects. But the promise remains.

“It’s not as well-established as solar, thermal, wind and biomass, but it [ocean power] shows a lot of promise,” said Philip Jennings, professor of energy studies at Western Australia’s Murdoch University.

“As the technology develops and becomes more affordable, which it will over time, we can continue to expand pretty much anywhere where there is an ocean,” said Chief Executive Officer Phil Metcalf of Pelamis Wave Power.

The market potential for tidal power still remains unclear [says who?]. Sector analysts believe Initial Public Offerings (IPO) for wave and tidal power projects will be much harder to price than for comparable wind power projects, because wave firms cannot give exact estimates on the scale of benefits and few have technologies that are up and running.

Regardless, both ocean wave and tidal power have attracted growing interest from investors and power utilities looking for the next long-term play in renewable energy.

“Water covers more than 70 percent of the Earth’s surface,” said Andy Karsner, assistant secretary for energy efficiency and renewable energy at the DOE. “Using environmentally responsible technologies, we have a tremendous opportunity to harness energy produced from ocean waves, tides or ocean currents, free-flowing water in rivers and other water resources to…provide clean and reliable power.”

According to Jennings ocean power could not match fossil fuels for electricity production but could be competitive with other forms of renewable energy.

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