Case Study: Installation of Renewable Energy System to Matiu-Somes Island
Matiu–Somes Island is a nature and scientific reserve in Wellington Harbour. There are resident wardens on the island and up to 65 overnight visitors and around 22,000 day visitors per year. The island has a rich history as both a quarantine and internment camp. The island was powered by diesel generators giving only 10 hours power per day and with the cost of getting diesel to the island this was a very expensive option.
Developments in optics and lamp technology made it possible to reduce power consumption to levels where solarisation became feasible. A 50w lamp was capable of achieving almost the same range as the old 1000W incandescent lamps. In addition the old rotating Fresnel lenses were removed.
A combined solar and wind installation with battery back up was designed to make the optimum use of both the wind and solar profiles throughout the year along with developing energy efficiency initiatives. With an annual consumption of about 25,000 kWhrs per year a system using a 6 kW Kingspan Wind Turbine and 4 kW peak of solar was installed. Wellington gets some very high winds and the Kingspan turbine was chosen for its reliability and ability to keep generating in these high winds. A research project generating and storing hydrogen from surplus energy has also been installed. The site is fully monitored and can be view at: logicenergy.com
The system is proving to be highly reliable. There is now a 24 hour power supply to the whole island giving much more comfortable living conditions. There is often a surplus of power which when the batteries are full has to be wasted. Electric appliances are now being used when there is surplus energy further reducing the requirement for bottled gas.
The installation has reduced the diesel generator usage to the minimum required for monthly maintenance with the generator often not being required for months. Thus the running and maintenance costs for the diesel generators have been slashed. There is a decrease in the amount of gas being burnt thus significantly reducing the cost to ship hydrocarbons on to the island. The CO2 emissions have been reduced to a minimum which is especially good for a scientific and nature reserve. The combined wind and solar system is keeping the batteries well over 70% even though they were sized to a minimum thus extending the life of the batteries considerably and further reducing costs.
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