When the wind blows, wind energy is a great idea. But when it stops, you need another power source. Solar equipment is expensive, and so is diesel fuel, which supplies three-fourths of the island of Dominica’s power generation needs. But Dominica Electricity Services Ltd. plans to take advantage of its volcanic origins as it anxiously awaits the government’s drilling for geothermal energy this summer.
“The cost is less than solar, we think, but there is risk, as they have to drill exploratory wells to hit the resources, and after that, they will drill production wells,” General Manager Collin Cover says of the geothermal consultants. “In the exploratory wells, they look at the quality of the steam, temperature and pressure, and the chemical content of the steam, and then from that, they’ll determine what type of plant they should build. They’re confident it can produce all the requirements for the island. There’s even confident hope of selling electricity to Martinique and Guadalupe by submarine cable.”
Dominica has never explored for geothermal energy before. Wind and solar energy also are being considered by Dominica Electricity Services. One of the hotels on the island with which Dominica Electricity Services has an interconnection agreement has a wind generator. Because of this wind generator, the hotel produces some of its electrical power requirements, and so buys less from Dominica Electricity Services. When there is sufficient wind and the turbine is producing more than the hotel needs, the utility purchases the excess power. “On a given day, we can sell to them and buy from them at different times of day,” Cover points out. The hotel has no means of storing the electricity generated by wind energy.
Unfortunately, installing a wind farm is hampered on Dominica by the country’s mountainous terrain. The entire population of approximately 67,000 island residents only uses 16.5 megawatts of electricity – “as much as a mid-sized Walmart,” Cover jokes.
Hydropower Generation
Dominica Electricity Services uses hydropower from three run-of-the-river plants on the banks of the Roseau River, which flows through Roseau, the capital of Dominica. “As the Roseau River comes down the Roseau Valley, we have three different points on the river where we have three small hydrostations – Laudat, Trafalgar and Padu,” Cover explains.
The three stations together provide 6.6 megawatts of power. “When it is dry season, we typically get about 3 to 3.5 megawatts or less,” he estimates. “We’re doing a little bit of storage in the fresh water lake above the first power station [Laudat], but only for about a day’s supply. So it’s not dammed like a typical big hydroelectric project, which has several weeks or months of storage.”
Cover estimates the hydrostations provide from 20 percent of the island’s annual electricity generation in a dry year to up to 28 percent in a year with good rainfall. The majority of the island’s electricity is generated by two power stations at Fond Cole and Sugar Loaf that both use diesel fuel, which through August 2011 was averaging US $4.16 a gallon.
Advanced Metering
Another project of Dominica Electricity Services Ltd. is converting the island’s electric meters to new advanced models. “We’ll be more than 75 percent of the way by the end of the year,” Cover declares. “We will be able to read all meters from the main office. Estimated bills will be a thing of the past. The meters will alert the main office of outages, tampering or volage excursions and provide usage profiles and history.
“Under certain conditions, these meters can sense when they have been bypassed or tampered with,” Cover reports. “If they detect suspicious activity, they send out alerts.” They also can sense problems like low voltage – which may be caused by loose connections or poor transformer operation – before the problem is evident to the consumer.
Individual meters communicate with each other wirelessly. A collector meter in each area is hard-wired back to the utility’s meter-reading server in the home office. It collects data from its peers and transmits it to the server. The pattern of outages and voltage deviations reported by the advanced meters and upfront diagnostics can help technicians determine the cause before they go out and investigate it.
