Practicality

Many homeowners wonder whether putting up a windmill is a smart way to lower their electricity bills, and many manufacturers of windmills are trying to interest homeowners in those products. But small-scale residential wind power is not as easy or as efficient as it may seem, for several reasons.

First, the amount of wind in your area is probably insufficient to meet most of your home's energy needs. A windmill at normal height will probably generate just 30 to 35 percent of its rated power, so one that's rated for 1.5 kilowatts (1500 watts), will probably only produce about 500 watts at most times.

Second, wind speeds tend to be lower during the day, when air conditioning, appliances and similar factors spike demand. Wind speeds are generally higher at night, when most households are asleep and don't need as much power.

In addition, it's very expensive and difficult for the average homeowner to install a windmill higher than 40 or 50 feet, well below the optimum height. Commercial windmills are typically hundreds of feet high, where winds are stronger and steadier.

Windmill salespeople may mention that power companies are required to purchase any power you don't need. That's true - but you'll be responsible for the cost of the extensive engineering required to deliver power to your power supplier's lines safely. Plus, any power you sell will be at a lower wholesale rate, not the higher retail rate you pay for power you use.

If you're giving serious thought to a windmill purchase, talk with both your power supplier and an independent electrical engineer. Be sure to compute how long it will take you to recoup your installation costs in energy savings. For many homeowners, it can take 40 or 50 years before the monthly savings total enough to cover the cost of installing a windmill.