[The Vector] Harnessing the Ocean for Energy: the New Frontier?

The world’s oceans are a new frontier in the renewable energy world. Ocean energy is emerging and will be ‘make or break’ in the next five years, says the firm Pike Research that focuses on research and analysis of renewable energies. “The ocean energy business is right on the cusp,” says Pike’s managing director Clint Wheelock. He says more than 300 projects and tests are in the works around the world. (Press release, Pike Research. “Ocean Energy Could Reach up to 200 Gigawatts of Power Generation by 2025.” January 19, 2010.)

A researcher at Frost and Sullivan, another market research firm, agrees. “It is projected that commercialization of wave and tidal energy will take place in the next 5-10 years as the technology evolves and production costs decline,” notes Frost’s Technical Research Associate Chin Wai Loon. “Wave and tidal energy are expected to be deployed on a commercial scale due to its large promising resource and high market potential; it is crucial for technology developers to push through into the commercialization phase.” (Press Release, Frost & Sullivan. “Hydro, Wave and Tidal Power Outlook Bright.” July 14, 2010.)

SO WHAT EXACTLY IS OCEAN ENERGY?

Many of us have long been familiar with hydrokinetic or hydropower in the form of man-made dams or the old mills powered by a river and paddle wheel. Hydropower, unlike ocean energy, has been used in the U.S. since the early 1880’s. According to the EIA, 6% of our energy in the U.S. came from hydropower (mainly dams) in 2008, and within the renewable energy category (which supplies 7% of all U.S. energy needs), 67% is hydropower. Many experts today separate the category of hydropower from ocean energy, though in the end, the power of water is involved in generating power.

Ocean energy includes wave energy, ocean current energy, tidal energy, offshore wind, thermal gradient energy, hydrogen production, aqua biofuels and more.

Ocean energy is not well understood and has not been given the attention and focus that solar, onshore wind, biofuels and batteries have been given so far in the renewable energy world, in my opinion. Even the 2010 REN21 Midyear Renewable Energy report card  on renewable energy has little to say about ocean energy other than it is the least mature of the renewable energy technologies, that interest is growing and that the existing energy producers tend to be in Europe so far.

I must point out that some forms of ocean energy are indeed in use. For instance, the La Rance Station in France is a tidal energy plant that began making electricity in 1966 – yes, more than forty years ago – producing enough energy from tides to power 240,000 homes (240 MW). It has more than 10 times the power than the next largest station in the world (a station in Canada). Only a handful of tidal energy facilities exist or have been developed. Even with La Rance’s success, there was no scramble to jump on the ocean energy bandwagon, with some saying it is costly and others saying the source of energy is ‘uneven,’ while the real reason may be that fossil fuels are cheap and there hasn’t been much motivation – perhaps until now.

Any new technology takes capital investment and focus to help bring it forward, along with government policies, public support and true feasibility. As we transition from fossil fuel-based energy, there is no question that we must look at all sources of viable energy, especially abundant domestic sources. Ocean energy, along with wind, solar, biomass, etc. are all sources that can and should be developed in the U.S.  They certainly are being developed elsewhere.

Let’s take a look at a summary of each category of ocean energy.  Vector followup stories in the days to come will highlight actual Ocean Energy projects, both domestically and abroad, as we look closer at this exciting and emerging industry:

Offshore Wind energy.

This category is the most researched and the most advanced in testing /use in ocean energy, because of advances in onshore wind energy. Some suggest offshore wind energy is a hybrid between ocean energy and wind energy, and statistics may sometimes appear in the wind energy category.

Wind is produced by the sun’s uneven heating of the earth’s surface. Offshore wind (over water) tends to flow at higher speeds than onshore, allowing more production of electricity. As wind flows over and pushes the blades of a wind facility, a generator is turned which ultimately produces electricity. Undersea collection cables connect the turbines and transport the electricity to a transformer where it is converted to high voltage for transmission via cables to a substation. At the substation, electricity is connected to the electricity grid.  Denmark and the U.K. are global leaders in offshore wind energy so far.

According to the Ocean Energy Institute, 61% of U.S. offshore winds occur 10 to 20 miles within landfall, with enough energy to generate 1,533 GW of potential energy. The total U.S. electricity capacity today is at 1,100 GW of energy. In other words, the Institute contends there is enough offshore winds (if all were able to be captured) to power the entire U.S. electricity needs. This does not include wave and tidal power or the other types of ocean energy. The chart below is courtesy Ocean Energy Institute and Matthew Simmons, illustrating U.S. wind resources.

The U.S. offshore market is in its infancy: at the beginning of 2009, there were 5 offshore wind projects in the U.S. and by the end of 2009, there were 20. 83% of all offshore turbines are manufactured in Europe – an area that sorely needs U.S. development.

By contrast, European offshore wind is having a record year. 118 new offshore turbines were connected to the grid in the first half of 2010 alone with a capacity of 333 MG, according to the European Wind Energy Association (EWEA). Another 151 turbines were installed in the first half of 2010 but are not yet connected to the grid. 577 MW was installed in Europe in 2009. 16 offshore farms are under construction (in Denmark, Germany and the U.K.)  There was 1,901 MW of cumulative capacity installed by 2009, reports EWEA, and 3,001 cumulative capacity should be in place by the end of 2010.

Strong offshore winds are found in the U.S. northeast, where 8% of the U.S. population lives (about 55 million people) and where electricity costs are high.   Great Lakes winds are strong, too, and in fact, a $1B project is planned over the next 5 years that could product a significant amount of power there, if successful.

To note: Offshore turbines are typically taller and larger than onshore turbines, with longer blades and higher capacity – the further from the shoreline, the most expensive. Offshore turbines do have added technical needs not necessary for onshore turbines, because they are exposed to more demanding climates, need to cope with strong waves, and have a greater need for corrosion protection. The access platforms are typically brightly colored (for ships at sea and for location by maintenance teams), and the equipment has high-grade exterior paint as well as built-in service cranes. There can be a higher risk of lightning strikes, and systems minimizing this risk are essential. Aerial and warning lights are usually integrated as well. Ongoing maintenance is essential.

Wave energy.

Ocean wave energy technology essentially captures waves directly from or below the surface. Waves essentially do all the work to move or turn a turbine or device which generates electricity. There are, according to OREG (Ocean Renewable Energy in Canada), five configurations of wave energy devices today:

• Buoys: floating structures are carried up and down or side to side in the waves to move a generator.
• Surface Following: floating structures hinged together follow surface movements (typically rectangular in shape) that power a generator by moving against each other.
• Oscillating Water Column: an enclosed column of air rises and falls with the motion of the waves, pushing and sucking air through a turbine.
• Terminators: a line of floating structures are placed facing oncoming waves, and are forced to move against each other to power the generator.
• Overtopping: an offshore reservoir is created as waves flow up a ramp into a structure, then flow back out through a turbine that drives the generator.

The EPRI (Electric Power Research Institute) says the energy in waves can travel thousands of miles before dissipating – however, waves cannot be effectively harnessed everywhere and in fact vary considerably around the world. The most wave-rich areas are found in western Scotland, northern Canada, southern Africa, Australia and the northwestern coasts of the U.S. The northeast of the U.S. also has acceptable wave strength, too. Some experts estimate that wave energy could one day supply a tenth of the world’s renewable energy.

Norway and the U.K. are leaders in this area of implementing wave technology, along with Portugal who established a wave facility in 2006. The first U.S. wave energy power farm launched a test program this spring in Oregon. Wave power projects are also being developed in Spain, Scotland, England, Western Australia and Hawaii.

A recent report (mid July) from The European Ocean Energy Association (EU-OEA) says 15% of Europe’s energy needs could be met by wave and tidal energy alone by 2050. “A number of large-scale utilities, energy agencies and industrial players…have already made significant investments in the sector,” says the executive director of EU-OEAA Nathalie Tousseau. “The successful growth of the ocean energy industry now depends on swift and targeted policy actions and EU support…” (Press release, EurActive. 20 July 2010.)

The U.S. has vast coastlines and more real estate than Europe, with great wind and ocean energy potential, but is terribly behind.

Ocean Current energy. 

The relatively constant and known flow of the world’s ocean currents carries energy that could be captured and converted. Ocean currents are generally driven by wind and solar heating of waters near the equator, and are usually flowing in one direction only (unlike tides near the shoreline.)  Examples of currents are the Florida Straits, the Gulf Stream and the California Current. The map below outlines major currents, courtesy GENI (Global Energy Network Institute).

A 2006 white paper from the U.S. Department of the Interior (“Wind Energy Potential on the U.S. Outer Continental Shelf”), estimated that worldwide power in ocean currents to hold about 5,000 GW. The constant density near the Florida Straits alone is such that capturing just 1/1,000^th of the available energy there could supply Florida with 35% of its electrical needs, says the white paper. The Florida Straits currents provide 21,000 times more energy than Niagara Falls, to put it in perspective. This large current of energy (the Florida Straits) is close to heavily populated areas with high energy demands.

Tidal energy. 

Tidal energy refers to the tides, the mass of water that rises and falls, moving with speed and direction caused by the gravitational pull of the sun and moon. The moon exerts roughly twice the tide rising force as the sun, so there is a constant pull and dance.

Tides are strongest where water passage is constricted, such as in channels, narrows, fjords and around islands. For tidal energy to work well, it needs large increases in tides – optimal is 16 feet between low tide and high tide.

The three main types of tidal devices today are:

Cross-flow or Vertical axis turbines: the turbine is placed in the tidal stream flow, and as water flows past, the blades are pushed to rotate like a children’s carousel, which turns a generator inside.

Axial or Horizontal axis turbines: the turbine is similar to the wind turbine. As tidal streams flow past, the blades rotate like a wind turbine, which moves the generator.

Reciprocating hydrofoils: these work like a fish’s tail and are controlled by pitch. The hydrofoils are forced up and down by the stream (like a kite in the wind), and the up and down movement drives the generator.

The map below is courtesy the book “Ocean Energy: Tides and Tidal Power” by R.H. Charlier and C.W. Finkl (Springer Press, 2009), showing current tidal installations. 

As mentioned earlier, the French La Rance plant is the largest and oldest using tidal energy. Two other installations, Kislaya Bay (Russia) and Hog’s Island (Bay of Fundy, Canada) are almost as old, and all have performed well over time. Test installations are functioning in Russia, Canada and China and a number of smaller sites are in play (especially in China)  – but there has not been a big rush to build or develop other major plants yet – some say due to cost and efficiency.

The East River in Manhattan is serving as a pilot station for river tides now, to be discussed in an upcoming Vector story.

Ocean Thermal energy.   

Ocean thermal (usually referred to as OTEC or ocean thermal energy conversion) is not a new idea, says authors Charlier and Finkl in their book “Ocean Energy: Tides and Tidal Power.” Using the temperature of water to make energy dates back to at least 1881 when a French engineer, Jacques d’Arsonval first developed a plan for ocean thermal energy conversion. Differences in the ocean temperatures– the water gets colder the deeper you go – can be tapped to make energy.

A heat engine is placed between the warm water collected at the surface and the cold water below. “Like a ball rolling downhill, heat flows from the warm reservoir to the cool one. The greater the temperature difference, the stronger the flow of heat that can be used to do useful work such as spinning a turbine and generating electricity.” (ScienceDaily. “Generating Energy from the Ocean Waters Off Hawaii.” August 4, 2010.)  About a 38 degree Fahrenheit differential is needed.

A new study at the University of Hawaii says the Leeward side of the Hawaiian Islands could in fact be ideal for OTEC, as discussed in a recent issue of Journal of Renewable and Sustainable Energy.  The chart below, courtesy Hawaii National Marine, shows world temperature differentials, which are needed for OTEC.

 

 

Hydrogen generation.

Hydrogen is an energy carrier, not an energy source. Hydrogen can store and deliver energy produced by ocean energy technologies. Hydrogen could be key in storing wind, solar and wave energy for use at night or at times when energy is not produced by those sources. Testing and research at many locations, including MIT, are working on using hydrogen to store energy.  We could potentially rely on the waters of our abundant oceans as a resource of hydrogen in storing of renewable energy.

Electrolysis is used to separate hydrogen from oxygen – it is the dissociation of water into hydrogen and oxygen by passing a current through an electrochemical cell, a technology already long available. At this time, hydrogen is not being used to store or transport energy from ocean energy technology, but future applications are probable.

However, electricity-created hydrogen can be combined with nitrogen (3 Hydrogen and 1 Nitrogen) to create liquid ammonia or NH3, which is a usable fuel – combustion engines can use it today.

While there is potential for any and all of these technologies, Pike Research says the outcome of pilot projects will determine the next steps. If there is limited success, costs are too high, financing too hard to get, competition from other renewable energies steps in, or public policy doesn’t support it, ocean energy could move slowly and be relegated to “niche” status.

As far as policy and federal support, there may be some positive signs. As reported in The Vector last month, the U.S. Department of the Interior and its Bureau of Ocean Energy Management formed the Atlantic Offshore Wind Energy Consortium with a number of northeastern state governors. They hope to advance offshore wind in cooperation.

At the July 2010 grand opening of the Ocean Energy Institute offices, founder Matt Simmons (author of “Twilight in the Desert: The Coming Saudi Oil Shock and World Economy” who recently retired from his energy investment firm), said, “The Ocean Energy Institute’s mission is to quickly fill the knowledge void and let our oceans supply us the energy that fossil fuels have provided for the last hundred years.” (July 20, 2010. Press Release.)  It seems there is a void to fill, and much potential to be tapped.

Simmons has outlined, in one of his many presentations, which categories of ocean energy he believes have the most potential for the U.S., and what should be pursued in order. Because of the potential, testing to date and costs in each technology, he believes offshore wind should be pursued first, then waves and then tidal.  See the chart below, courtesy Matt Simmons and Ocean Energy Institute.  

The tide appears to be turning (so to speak) in favor of ocean energy, according to Jeff Deyette, an energy analyst at the Union of Concerned Scientists. “There’s a growing awareness that our current energy system is unsustainable. There is an interest in finding ways to generate electricity from cleaner, reliable energy sources.”