Issue of February, 09, 2004
  de uso

The ocean's waves transformed into electricit
Credit: Mauricio Ramos
Brazil's Clean Energy Effort Rides Ocean Waves
By Mario Osava

Surfers are not the only ones who will be enjoying the massive power of the Atlantic Ocean's waves on the Brazilian coast. For the first time in the Americas, ocean waves are to be used to generate electricity -- enough for 200 families in Ceará state.

RIO DE JANEIRO, (Tierramérica).- If all goes as planned, by the end of 2006 Brazil will debut the first electricity-generating plant in the Americas that uses the power of ocean waves, churning out a potential of 500 kilowatts on the Atlantic coast of the northeastern state of Ceará.

The project, which could generate enough energy to supply 200 households, is being developed by the COPPE engineering graduate program at Rio de Janeiro Federal University, which has already built a small-scale demonstration model at its Submarine Technology Laboratory (LTS).

Construction of the full-size plant became feasible with an agreement signed Feb. 2 by the Ceará state government and Electrobrás, the national electric company.

"Ceará has the ideal conditions because the Trade Winds blow there, generating good, regular wave action, " explained Segen Estefen, coordinator of the project and head of LTS.

With some innovative technology, unlike what is being developed in other countries, this alternative and renewable source of energy will be competitive, with a cost equivalent to the energy generated by the hydroelectric dams already built in Brazil and 30 percent cheaper than wind energy, Estefen told Tierramérica.

The new project is to be built on Brazil's Atlantic coast, near 70 percent of the 174 million people in the country, saving costs of transmission lines, which is what drives up rates for electricity coming from hydroelectric dams located far from consumers.

With 8,500 km of coastline, Brazil has enormous wave-power potential. Estefen estimates that it could contribute 15 percent of the electricity consumed in the country "within 10 to 15 years if the government decides to promote programs" in that direction.

The energy potential of all of the world's oceans is estimated at one or two terawatts, enough to cover the energy demands of the global population, but most of that potential is not economically feasible to tap into.

Using 10 to 20 percent of it "would be colossal," commented Estefen, adding that alternative sources "will always be complementary."

The wave-powered plant designed by his team uses floats that, with the movement of the waves, activate a hydraulic pump that injects water into a hyperbaric chamber, originally developed to test equipment for undersea exploration and deep-water oil drilling, and withstands extremely high pressure -- as in conditions at depths of 5,000 meters.

The hyperbaric chamber releases high-pressure jets of water that move the turbines that convert their energy into electricity.

This invention takes advantage of existing technologies, especially those developed for ocean-bottom oil extraction, an area where Brazil has made major advances.

The equipment is available and all of it can be produced in this country, keeping the project's costs down, says Estefen.

Other countries farther along in wave energy, like Britain, which has two plants in operation and five in development, utilize oscillating columns of water to generate electricity.

In this case, a giant tube is inverted into the wave, and the rising water level pushes up the air inside the tube, moving a turbine. And the reverse occurs when the water level decreases, as the wave diminishes, also generating electricity, explained Eliab Ricarte, whose doctorate research contributed to the Brazilian wave energy project.

But the British technology involves great variations, with the rotation of the turbine doubling from one moment to the next, depending on the size of the wave and its movement. The Brazilian model, meanwhile, has the advantage of regularity, said Estefen.

In Denmark, experts are developing what has been dubbed the "Wave Dragon", technology for a larger energy generating plant, capable of putting out four megawatts. It requires high waves, out at sea, in order to move the turbines with the same force. Estefen noted that it would not be operable in summer because of the lack of large waves.

Australia and Japan are also developing technologies to take advantage of wave energy, and in the developing world, Brazil is joined by India and China. But for now, the norm is small prototypes, with a capacity of up to one megawatt. An effective contribution to commercial energy production remains a goal for the future.

Interest in this alternative source has intensified in the past five years due to the priority given to climate change issues on the international agenda, according to the World Energy Council.

Other factors include the debate surrounding the Kyoto Protocol, which has not entered into force but sets goals for reducing greenhouse gas emissions, as well as the rise in petroleum prices.

Britain also set an example with its 1999 decision to invest in ocean wave energy.

The Japanese model is known as "Mighty Whale" and entails a column of oscillating water in a ship, taking advantage of the greater energy potential of waves in the open sea. It was watching a video about that experiment that Ricarte decided to dedicate his doctoral thesis to ocean wave energy.

The Brazilian approach is to build relatively small installations, with a capacity of one to 30 megawatts, keeping the already low environmental impact to a minimum.

There is also the possibility of "shared use", such as utilizing the energy plants to protect the coast, reducing erosion. And in some cases the ocean bottom could be altered to obtain larger waves, and that could benefit surfers, says Ricarte.

* Mario Osava is an IPS correspondent.

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