Monday, June 09, 2008

The Answer is Blowing...?

Sweeping across the Caribbean and Africa, the alize trade winds have brought ships to Cape Verde’s shores and dust into newly swept homes each summer for centuries. But today, these winds may prove more useful than ever, fueling a clean, renewable energy that powers homes and businesses, and reduces dependence on foreign oil.
Wind energy has a long history. For centuries peoples have harnessed the wind’s power to sail ships, crush grain, pump water, and cut wood. Fossil fuels virtually replaced it by the 1930’s, but oil shortages in the 70’s forced many countries to revisit it. Today, just over 1% of world energy comes from wind, but wind generates 19% of energy in Denmark, while Germany, the U.S. and Spain each produce more than 15,000 Mega-Watts of wind power.
In sharp contrast, only 3-5% of Cape Verde’s energy comes from wind. But with wind speeds averaging 5-9.7 m/s2, and electricity demand increasing by 8-15% per year, wind has huge potential. Electra built its first wind park on Sao Vicente in 1989, and today there are three functioning wind parks on Sal, Sao Vicente, and Santiago. In concert, they contribute 15,000 kW to the electricity grid.
Each of these wind parks is composed of 2 or 3 wind turbines, each with a rotor, a generator, and a tower. The rotor captures the kinetic energy of the wind through blades designed to be lifted by the wind, similar to airplane wings. The motion then drives the generator to produce electricity.
One major constraint is financing. With each turbine costing many thousands of U.S. dollars, and producing at best 322 kWh per month, each one will pay for itself only after 4.5 years. Fortunately, Infraco, a US company, in collaboration with the Cape Verdean government with invest 40 million euros to build new plants on four islands, increasing the power to 17% -25% of total energy production. Wind power will then total 20-25MW.
Wind is highly erratic--changing direction and intensity---wind energy is difficult to store. That makes wind an “intermittent generator”, meaning its guaranteed output must be valued at zero, and therefore that diesel capacity must be able to meet 100% of demand. Wind’s intermittency is what prevents it from supplying more than 25% of any country’s total energy.
Current efforts aim to address these difficulties. A proposed Thermo-Wind-Solar Power Plant could provide constant, storable energy by generating thermal energy. Wind would be used only as a cold source, while the soil, oceans or warm water sources on Santo Antao would provide the warm source.
Proposals like these are promising, but their implementation is urgent, if Cape Verde is to meet its goal of 50% renewable energy by 2020. If they do, it will be worth catching wind of.


Blogger Joel said...

More questions than comments (and I suppose I could look such things up myself, but I prefer to have you do it and dumb it down for me):
1. What's Infraco's interest in helping out the C.V. gov't?

2. In your research, did you come across any explanation as to why it's difficult to store wind energy?

3. I forgot number three?

sorry to be a pain.


8:11 PM  

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