Case study: Mana and Kapiti Islands sustainability
Mana Island
In May 2009 a 2.9-kW photovoltaic (PV) solar electricity generation system was installed on Mana Island. This included solar panels, a cluster of batteries, and inverters. It is estimated that the system will generate 3,434 kWh per year.
Note: A KWh (kilowatt-hour) is the amount of power consumed or generated over a period of one hour.
PV system, Mana Island
Why change?
- Diesel delivery and use on Mana Island cost DOC over $12,000 per year.
- The diesel generators are amongst DOC's least efficient.
- The generators ran approximately 12 hours per day in two shifts limiting the times work could be done.
Mana Island Energy Efficiency and Renewable Energy Programme
Together, solar water heating and PV electricity generation have resulted in a 55% reduction in the amount of electricity that needs to be generated by the diesel generators.
The installation of the battery bank also allows electricity to be used at any time.
Solar PV system, Mana Island
Kapiti Island
In 2009 the house on Kapiti Island needed to be replaced. This allowed a number of sustainability features to be incorporated into the new house, including:
- Thick insulation.
- Double-glazed windows.
- Lined curtains.
- Thicker carpet underlay.
- 100% wool carpet.
New sustainable house on Kapiti
Island
The house was designed to have as much solar energy collection as the site would allow, as well as taking advantage of natural light to reduce energy requirements.
Solar hot water heating, an efficient woodburner and energy efficient lightbulbs have been installed.
What next?
DOC will be installing PV solar panels, batteries, an upgraded mini hydro system and heat pumps on Kapiti Island, which will:
Solar water heater on roof of new house on
Kapiti Island
- Reduce DOC's carbon footprint.
- Produce 7,058 kWh of electricity (by solar panels and mini hydro system).
- Reduce energy usage by 1,414 kWh through energy efficiency measures.
- Insulate island activities from fluctuations in fossil fuel costs.
- Increase operational independence of the island staff.
- Improve productivity of the staff through less time spent on maintenance.
Energy efficiency measures will include:
- Installing insulation and heat pumps.
- Draught proofing windows and doors.
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