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Marine Current Turbines' SeaGen project is a mini-farm off the coast of Ireland, which features two turbines attached to a tower, producing 1.2 MW.  (Source: Marine Current Turbines)
Companies race to harvest the ocean's bountiful green energy, but can they make it affordable?

In the U.S., President Obama has launched an ambitious initiative to have the U.S. seize the lead in the global alternative energy industry.  With options such as nuclear, solar, and wind on the table, one key technology the administration is focusing on is tidal power.  Similarly, European efforts to harvest tidal and wave power are heating up in part to help the EU fulfill its alternative energy and emission cut promises.

The new push is validating many technologies that were thought up decades ago, but never fully explored.  For engineer Peter Fraenkel, founder of Marine Current Turbines, it was a plan in the 1970s to pump water in Sudan via tidal power.  Civil war and lack of funding temporarily killed his dream, but the alternative energy boom revived it, and his company now has slightly modified versions of his original design running off the coast of Northern Ireland.

He states, "In the 1970s, the big snag was the market for that technology consisted of people with no money.  Now it’s clear governments are gagging for new renewable energy technology."

The turbines at one of his company's projects, the SeaGen project, produce 1.2 MW per year, enough to power 1,140 households and costs $3.6M USD to build.

Worldwide, there are many similar stories to Mr. Fraenkel's.  The young tidal power industry is filled with very old ideas which are only now coming to light.  Two key technologies dominate the field:  tidal range power, produced from the up and down bobbing of the sea, and tidal flow power, produced by the flow of the tides parallel to the ocean floor.  For both of these industry fields, the key challenges are the same -- getting enough funding to prove the technology and figuring out how to get costs down and create long lasting plants.

By 2020, up to $3.6B USD is expected to be pumped into the tidal power industry, which has over 30 firms competing to produce the best solutions.  The drive is fueled by investors attracted to the financial perk of tax breaks in the U.S. and Europe.  Hugo Chandler, renewable energy analyst at the Paris-based International Energy Agency, states, "Tidal energy has an enormous future, and the U.K. has a great resource (if construction costs come down).  Its time may be just around the corner."

However, one key roadblock to tidal power continues to be its high cost.  In Britain, wind power has been efficiently implemented, cutting costs to 7 pence (approximately 10 cents) per kWh. This is very competitive with the cost of coal power, which is 5 pence/kWh (7 cents/kWh).  However, tidal currently costs 15 pence/kWh (21 cents/kWh).

The main reason for the high cost is the elaborate work needed to build plants capable of surviving the salty seas and to install the plants in the often turbulent waters offshore.  Unlike wind generators, tidal turbines' gearboxes and generators must be watertight.  The turbine machinery also has to withstand a flow of 9.3 knots (10.7 MPH), delivering three times the force that wind delivers to land turbines.  Angela Robotham, MCT’s 54-year-old engineering chief, explains, "The forces you’re trying to tap into are your enemy when it comes to engineering the structure."

With an estimated 15 percent of the world's useable tidal resources, Britain is a prime target for those looking to harvest the tides, and a key proving ground for many firms.  In addition to MCT's SeaGen tidal tower/turbine setup, OpenHydro has deployed a 250 kW design offshore (2007), and Hammerfest Strom AS has deployed its first 300 kWh turbine farm off the coast of neighboring Norway (2003).

The Carbon Trust, a key tidal investment group, states that 2,500 megawatts of tidal may be installed by 2020 at the aforementioned $3.6B USD cost.  These figures don't seem overreaching given the many big announcements.  OpenHydro announced that it will be installing three one-megawatt turbines off the U.K.’s Channel Islands and another in Canada’s Bay of Fundy. 

Iberdrola SA, a Spanish utility, has also announced plans to install 20 one-megawatt Hammerfest Strom turbines off the Spanish coast at three sites by 2011.  MCT is working on a 10.5 MW farm in Anglesey, Wales to be complete in 2012.  Scottish Power recently announced a 60 MW project is in development off the coast of England.  Russia claims to be working a 10 GW tidal farm, which will dwarf the current largest -- a 240 MW farm in France.

MCT's Fraenkel is convinced that all the new efforts will bring costs down.  He adds, "It’s as expensive as it could possibly be at the moment because we’re at the earliest stage.  Once we’re able to go for bigger projects, the cost will come down."

MCT Managing Director Martin Wright continues, "Fossil fuel represents burning off the Earth’s capital, and now we’re going back to the energy that’s available to the planet in the course of the day.  Tidal stream energy is no longer a nice-to-have. It is a must-have."

However, despite the rhetoric, the cost hurdle remains significant.  Currently tidal is so far from cost competitive that it loses much investment and R&D money to wind and solar.  Still, the sheer amount of energy that is in the tides makes it equally hard to resist.

Furthermore, one great mystery is how long the new plants will last.  Given the fact that most designs have only been deployed in the past 10 years, there's a lack of solid numbers for plant lifespans and maintenance costs.  How these factors play out will only become known with time and may have a major negative or positive impact on the push to adopt tidal. 

In short, as tidal power efforts surge ahead, the destination is still a bit of a mystery and few can say quite what the future holds.





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