For some time I have been exploring ways to produce energy without the aid of my trawler's generator. It does not take very long to use 100 hours of genset time, enough for another oil change. First it was a solar panel, and then came an inverter, and now, the latest is a wind turbine.
Wind has been used for producing energy for centuries; first in Persia (present-day Iran) as early as 200 B.C. However, the first known functional windmills were developed by the Dutch in 1300, by means of cloth sails stretched across wooden frames. In some designs these sails could be trimmed to take advantage of unpredictable wind speed conditions. The large windmills of the Dutch design remained in use all across Europe until the introduction of the steam engine in the 1800s.
Wind is in reality a form of solar energy. Winds are caused by the irregular heating of the atmosphere by the sun, the irregularities of the earth's surface, and revolving of the earth. Wind flow patterns are created by the earth's terrain, bodies of water, manmade structures and vegetation. We humans can use this wind flow for many purposes: sailing a boat, flying a kite, flying an airplane and even generating electricity. The term "wind power" describes the method by which the wind is used to produce mechanical power. This mechanical power can then be used for specific mechanical tasks such as grinding grain or pumping water. Or as used on a boat, an alternator in a wind turbine can convert this mechanical power into electrical energy.
So how do they make electricity? Simply stated, a wind generator works the reverse of a fan. As an alternative to using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind spins the blades, which turn a shaft. The shaft connects to an alternator and produces electricity. In our boat's turbine, the alternator produces 220 volt 3-phase AC current. The controller, converter, then converts the AC power to 12 volt DC power to charge the battery bank.
Wind Availability
When evaluating whether a wind turbine is economically realistic for your boat depends on the quality of your wind resources. Usually, average wind speeds of at least 10 mph are required for a small unit to generate enough electricity to be cost-effective. Being on the Atlantic coast, we have afternoon sea breezes in the summer which routinely produce 10-15 mph winds. If your boat is inland, your winds will likely be different.
The most significant component of evaluating your wind resource is an anemometer. Anemometers are wind measuring devices, typically designed with rotating cups mounted on a vertical shaft. The anemometer will allow you to "read" the wind speeds.
If there is another boat owner with a wind generator system in your area, you may be able to obtain useful information from its owners about the electrical output of the system and wind speed data. Such information could be tremendously valuable as an option to installing an anemometer.
Turbine Mounting
Determining the location to mount your wind turbine takes a bit of planning. It must be high enough to capture the wind, preferably away from arches, sails or masts that will block or alter wind flow. There is also the issue of rotating blades. We want to make sure that they do not strike anything while turning, especially someone's head while moving about the boat.
I chose to use the factory designed pole kit that was built for our turbine. It provides a 3-point connection which also allows us to lay it down for servicing. It is powder coated anodized aluminum, with stainless steel, brackets, designed to withstand the harsh marine environment.
My turbine is actually a hybrid system I designed using both wind power and solar power.
Being Neighborly
Many people feel strongly about the need to preserve the views and peace and quiet of their marinas. Expect some questions from your dockmates. Understand your neighbors' natural fear of the unknown and be prepared to respond to their concerns. Some of the concerns raised about wind turbines are not true. They are not, as many people think, hazardous to birds. A shiny reflective window is more dangerous to birds than a small wind turbine. They also have no potential to interfere with radio and television reception.
Wind Turbine Noise
Your neighbors' concerns involving wind turbine noise are important. Regardless of the size of the unit, the possibility for turbine noise to bother other people always exists. Even if a turbine does not emit enough sound to break any noise regulations, the noise it produces may still be offensive to other people. Older turbines were indeed noisy, but modern day engineering has developed turbine blades that are virtually silent. Our turbine is about 3 feet in diameter and at 4 mph winds; the unit produces a light flutter. At 10 mph the unit produces no sound at all.
Wind Turbine Advantages
-- Wind is free
-- Produces no waste or greenhouse gases
-- Does not usually get in the way of other boating activities
Wind Turbine Disadvantages
-- The wind is not always predictable - some days we have no wind at all
-- Some people feel that wind turbines ruin the lines of a boat; I thought that way too in the beginning but have since changed my opinion
-- Some units can be noisy. The small modern wind generators used on boats hardly produce any sound at all
How Much Power Do They Produce
Turbines can be purchased that produce different power outputs. The turbine that I chose is a Sunforce 450 watt turbine. It has a cut-in speed of 4 mph and has a survival wind speed capacity of 157 mph.
The amps (power) produced is:
-- 6 mph winds - 8.3 amps
-- 10 mp winds - 25 amps
-- 14 mph winds - 58.3 amps
The unit has a built in brake that will engage automatically when the batteries are at full charge, or it can be manually set if so desired.
