Many island owners use gas generators as a back-up source of energy on their islands. Gas generators are great for temporary usage and supplying energy for essential needs such as heating or electricity. Before purchasing a generator it’s important that you know what your will need to power and for how long you wish to power it. You may also want to consider the ease of transporting the generator to your island and the amount of fuel you will need to transport to the island for the generator. These two factors may influence the type of generator you purchase. Typically a 900 W generator will power a small refrigerator, seven 60W bulbs and a 200 watt fan. This generator will require 2.53 gallons of gasoline every 24 hours and sells for approximately $790. A 4000W generator can power a coffee maker a full size refrigerator (725 watts); lights a fan and a 750 Watt microwave. Alternatively it could power a well pump. This type of generator would require 11.7 gallons of gasoline every 24 hour and costs approximately $1,000 dollars. An 8000W generator can run a well pump, a coffee maker, a refrigerator, lights, a fan, a microwave, a sump pump and heating equipment (up to 1800 watts). Alternatives the system could run a 32,000BTU air conditioning unit. This type of generator requires about 25 gallons of gasoline every 24 hours and costs about $1,250.

Wind power is the conversion of wind energy into more useful forms, usually electricity, using wind turbines. Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator. Wind turbines range from small four hundred watt generators for residential use (Image 1) to several megawatt machines (Image 2) for wind farms. Small scale turbines are available that are approximately 7 feet (2 m) in diameter and produce 900 watts. Units are lightweight, e.g. 16 kilograms (35 lbs), allowing rapid response to wind gusts and are easy to mount, much like a television antenna.

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The average lowest retail cost of a large photovoltaic array is approximately $4 a watt (down from $7.50 in 1990). The most common size module used is about 4′ 5″ x 2′ 2″ and produces 120 Watts. To power a small, occasionally used island cabin (approx. 400 sq. feet) a simple system can cost under $1000. For this price the system would include a 120W PV module and module mount, 2 deep-cycle batteries, a charge controller, a 400W inverter, fuses, and wiring. This type of system could run lights, radio, small TV, etc. but not a typical refrigerator. The module would produce about 0.5 kWh/day (under good solar conditions) and the batteries would store a useful 2 kWh.

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The sun provides an abundant, renewable and efficient source of energy. The amount of solar energy intercepted by the Earth every minute is greater than the amount of energy the world uses in fossil fuels each year. There are two types of “solar panels,” electrical and thermal. The electrical type is generally referred to as a “photovoltaic module” or a “solar module.” It is a solid state device or an assembly of solid state devices and produces electricity only. These devices are usually seen as long flat panels mounted on rooftops perpendicular to the arc of the sun. The electricity created is either used immediately or stored in batteries. The thermal type of panel generally consists of water piping, glass and insulation and is generally much larger in size (often 4′ x 10′) and is used to heat water for the home.

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