Sunday, May 4, 2008

OTEC and Wave Energy Technologies in Hawaii

The primary purpose of my paper was to describe select wave energy and ocean thermal energy conversion (OTEC) technologies from technical, policy oriented, economic, and environment standpoints. Furthermore, my paper discussed and analyzed why these technologies are inherently suited for applications around the Hawaiian Islands. Since 33% of electricity comes from petroleum in Hawaii, raising cost of crude oil has brought light to various renewable energies within the past few years, including ocean energy sources. Therefore, my report demonstrates that Hawaii can meet its goal of 20% renewable by 2020 and 70% renewable by 2030 if the state incorporates select ocean energy technologies into their renewable energy portfolio while still allowing other alternative energies to grow alongside.

Ocean thermal energy conversion (OTEC) is a process which makes use of the oceans’ natural thermal temperature gradients in order to produce power via Rankine cycle power generation. On an average day, 23 million square miles of ocean seawater absorb the equivalent energy of 250 billion barrels of oil. If 10% of this energy were extracted, that would be equivalent to nearly 5 times the amount of energy the world consumes per day [8]. My findings were that OTEC could prove cost-effective in Hawaii within the next five years. This is so because the cost of petroleum, which accounts for 33% of Hawaii's fuel for electricity generation, will drive diesel power stations to the point where they will be less cost-effective than other renewable technologies like OTEC. Even though the efficiencies of OTEC systems are low, the energy is free, and extremely abundant.

In my paper I discussed two types of wave energy technologies, oscillating water column devices and point absorbers. The oscillating water column (OWC) is a device mounted onshore or as an offshore floating device that produces electricity by the movement of air across a turbine. When a wave approaches on shore, the wave displaces air within the OWC, turning a turbine. When a wave retreats back, air is sucked into the OWC and the turbine spins in the same direction as before. This continuous process produces electricity by converting the mechanical work of the turbine into electricity via a generator. Point absorbers are wave energy devices that take advantage of the elliptical motion of particles resting on ocean surface waves. When any object sits on a surface wave, it moves in the lateral direction as well as in an up and down motion, resulting in an overall elliptical motion. Point absorbers utilize this energy by transfer the up and down motion into a hydraulic piston which pumps water. This pumped water can be utilized to turn a small turbine within the point absorber or to spin a turbine offshore.

Considering the extremely high wave heights around the Hawaiian Islands, wave energy technologies are very suitable. Since the state of Hawaii is an island, it has large coastline perimeter, allowing for vast wave energy technology potential. The following is are the concluding remarks from my paper:

From environmental and economically standpoints, the feasibility of OTEC systems and wave energy technologies is still unclear. As with any new technology that must be implemented on a large scale, this is to be expected. Producing tens or hundreds of megawatts of power in the oceans is a daunting task that requires years of experimentation and cost-benefit analysis. Yet, from a technical standpoint, OTEC systems and the discussed wave energy technologies present themselves as technically feasible alternatives for applications in the state of Hawaii. Hawaii’s large wave heights and underwater temperature differences allow the state of Hawaii to utilize OTEC and wave energies at their advantage, if state government so chooses.

As large and overwhelming as the ocean is, so too is the economic and engineering task of designing large offshore and onshore ocean energy power plants. In order for Hawaii to meet its goals of 20% renewable fuels by 2020 and 70% of its energy mix from renewable by 2030, the state government should first provide for access to federal waters where companies like Finavera Renewables and CETO can test their products year round. This is the first and most crucial step towards launching any large scale ocean energy system within the Hawaiian Islands.

Secondly, a cap and trade system or carbon tax would not be suitable for Hawaii because its electricity mix is far different from the rest of the U.S. Given that 33% of Hawaii’s electricity comes from petroleum, rising crude oil prices is in itself a wakeup call for the alternative energy capabilities that Hawaii possesses. The money spent on a cap and trade system or carbon tax could more aptly be spent on grants for testing on federal lands or offshore. Money spent increasing the efficiencies of these ocean technologies will pay for itself, given that ocean energy power plants rely on large scale production in order to be cost-effective.

Finally, the state of Hawaii should cut down, not punish its producers, on its electricity generation from petroleum in order to create market incentives for other alternative technologies. The truth of the matter is that ocean energy technologies are at least five to ten years away from being cost effective, therefore, it is imperative to allow these technologies to mature and then blossom when the time is apt. In the meantime, more cost-effective technologies like solar and geothermal should be given incentives to grow. Heavy incentives and tax rebates should be given for installed solar capacity on homes and buildings so that Hawaii can reduce its dependency on fossil fuels. By allowing different parts of the alternative energy industry to grow with the newly revived OTEC and wave industries, the state of Hawaii can economically make its way towards 70% renewable energy by 2030 and 100% renewable in the future.

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