A case study:
- April 1st, 2008
- in Yachting
Planetpower – Two things the BVI has in abundance are sun and sea breezes. In a world where the cost and conservation of energy represents a constant challenge, you may be forgiven for wondering how free energy sources, with which Mother Nature so generously blesses these Islands, can be harnessed by householders in the BVI. Two things the BVI has in abundance are sun and sea breezes. In a world where the cost and conservation of energy represents a constant challenge, you may be forgiven for wondering how these free energy sources can be harnessed by householders in the BVI.
The first thing you need to consider is the law. Total energy self-sufficiency is not an option and the government utility should be your "primary provider" of electricity. So why bother?
Well, one reason is cost. One householder to whom we spoke spent an estimated $6,000 to set up a system to run his lights, entertainment and kitchen appliances, but insisted that the savings he made on his electricity bill would soon recoup the investment.
Another resident suggests, "We're not interested in just cost saving, but in having energy all the time." Conditions are not always normal, and during the hurricane season, Mother Nature can certainly oversupply the Islands with breezes. In these dangerous winds, main electricity may be cut for safety's sake. True, there is no sun for your solar panels either, but if you store the energy you have generated in a bank of batteries, you can be one of the very few to sit in a lighted house with an ice cube floating in your G&T whilst the hurricane blows a Hooley outside.
The two main options for harnessing power are a photovoltaic solar panel and a wind turbine. With the photovoltaic panel, the sun excites silicon wafers in the panel to produce 12v electricity, which is fed into a series of 12v batteries. When siting the panel, install it about 18° from the horizontal and give it as much Southern exposure as possible. This will give the panel the longest window of sun.
Don Mitchell of Alternative Energy Systems recommends 12 panels to be sure of producing enough energy for household needs with 10-15% spare for battery charging. To complement the solar panels, a 7 to 8 foot diameter wind turbine can produce 1,000 watts and can be mounted on a tilt-down tower so that it may be safely lowered during storms. Energy stored in the 12v batteries can be used in two ways. First, you can use it directly to power an energy-efficient 12v lighting system. Second, for conventional lighting circuits and for your other electrical uses, you can feed the power through an inverter to convert your 12v DC into the 120v or 220v AC you need.
The batteries represent an asset in themselves. You can top them up from a generator if the sun isn't shining but they should store enough energy to see you through 2 to 3 days of bad weather. You could keep a 12v lighting circuit running for months, just on stored energy.
Obviously, the bigger your inverter and the more batteries you have, the more you can run off wind and sun energy. The costs of all this do add up, so the initial investment is significant. A realistic system that would cope with the needs of most households might involve a 7 KW inverter, two batteries, up to 12 solar panels and a wind turbine and tower. However, to put this outlay into perspective, your costs going forward are virtually nil, especially if you select DC (direct current) products that derive the maximum advantage from the energy supplied to them.
The alternative way to secure an independent power source is a generator. A 7 KW diesel generator will be about half the cost of the inverter, but you will then need an auto-transfer switch, a dedicated generator house and fuel tank, and you will have the ongoing cost of fuel.
So, whether as part of a suite of energy solutions or as your principal source of power, should there not be a place in your life for alternative energy? One user of alternative energy answered the question quite clearly: "In today's world, I cannot imagine anyone building without making some provision for alternative energy. That would be foolish".