Wind Power FAQ

Small Wind and You

Q1: How do residential wind turbines work?

A wind turbine, which is installed on top of a tall tower, collects kinetic energy from the wind and converts it to electricity that is compatible with a home's electrical system. In a residential application with net metering, a home is served simultaneously by the wind turbine and a local utility. If the wind speeds are below cut-in speed (usually a minimum of 2 or 3 metres per second is required) there will be no output from the turbine and all of the needed power is purchased from the utility. As wind speeds increase, turbine output increases and the amount of power purchased from the utility is proportionately decreased. When the turbine produces more power than the house needs, the extra electricity can be sold to the utility if such arrangements are available. All of this is done automatically.

Q2: Don't I have to take wind measurements for a year or more?

For many residential systems the cost of taking wind measurements is not justified. Wind resource data provided by Environment Canada is often sufficient for an experienced evaluator to predict wind turbine performance.

Q3: What about towers?

A rule of thumb for proper and efficient operation of a wind turbine is that the tower height (turbine hub height) should be at least 10 meters above anything within 100 meters of the tower. Typically, 25 to 37 meter towers may be supplied along with the wind turbine, which usually avoids turbulence from buildings and trees on most sites. Wind speed increases the higher you go above ground, and it also becomes less turbulent. In addition, electricity generation from a turbine increases exponentially with wind speed. Thus, relatively small investments in increased tower height can yield very high rates of return in electricity generation. For instance, installing a 10 kW generator on a 30 meter tower rather than an 18 meter tower involves a 10% increase in overall system cost but can result in ~30% more power. Several different types of towers are available, depending upon which manufacturer you select. Each type has its advantages; the most economical tower is the ‘guyed lattice’ tower, but a hinged tower may be easier for you to install yourself and provides easier access for maintenance.

Q4:How reliable are wind turbines? Much maintenance?

Most small turbines have very few moving parts and do not require any regular maintenance. They are designed for a long life (up to 20 years) and operate completely automatically.

Q5: How would I have a wind turbine installed at my home?

Most dealers offer either complete turnkey (ready-to-operate) installations or the option to purchase direct from the factory and install the system yourself. The first option offers more customer support from the company. Self-installation offers significant savings and a hands-on understanding of the turbine. Prospective owners can discuss the options available with manufacturers to decide which method best suits their budget and technical skills.
Approach buying the equipment as you would any major purchase. You will need to weigh costs and various degrees of rugged/durable designs. Obtain and review the product literature from several manufacturers, and research those you want to pursue to ensure they are recognized businesses and their parts and service will be available when you need them. Find out how long the warranty lasts and what it includes, and ask for references of customers with installations similar to the one you are considering. Ask system owners about performance, reliability, maintenance and repair requirements, and whether the system is meeting their expectations.

Q6: How many turbines to power a household or farm?

For a home or farm, one turbine is normally installed. The turbine's size is chosen to meet the energy requirements given the available wind resource.

Q7: What about new small wind turbines that run at very low wind speeds?

Many companies have developed turbines that run at low wind speeds. But because the energy available in the wind is a function of the cube of the wind speed, there is very little energy available to be harvested at wind speeds less than 3 or 4 m/s (10 or 14 kilometres per hour). If you are considering the purchase of a small wind turbine for use in a low wind speed location, shop for turbines with good low wind speed performance; this may mean turbines with larger-than-average rotor diameters for their rated power.

Q8: Is a windmill or an electrical wind turbine better for pumping water?

To pump water using wind energy, you need to place a windmill directly above your pumping site since windmills pump water through mechanical motion rather than using electricity. While this may be appropriate for some users, the wind speed at their desired pumping site may not be strong enough or may be obstructed by trees, embankments, etc. or the foundation at the pumping site may not be stable enough to install a windmill. Therefore, for some users, it may be more desirable to erect an electricity-generating wind turbine where the wind is favourable and run electrical cable to the pumping location, where you use an electrical water pump. Which is more practical and economically feasible for you depends on your property and wind regime.

Small Wind Economics

Q1: Will a small wind turbine save me money?

Since energy conservation is usually less expensive than energy production, making your house or farm more energy-efficient first will likely reduce the amount of investment in a wind system to meet your needs. Most wind system purchasers have done all the reasonable efficiency measures first.
A wind turbine typically lowers a household electricity bill by 50% to 90%. It is not uncommon for wind turbine owners with total-electric homes to have monthly utility bills of only $8 US to $15 US for nine months of the year in the US. In northern parts of the U.S. where less air conditioning is used the bills can be very low year-round. The amount of money a small wind turbine saves you in the long run will depend upon your electricity costs, the amount of electricity you use, the average wind speed at your site, and other factors.

Q2: How much does a wind system cost?

The cost of a wind system varies. The price is dependant on size, on-grid or off-grid application, installation (do it yourself or professional install).

Q3: What size turbine do I need for my home?

Again this varies from location to location, application size, and application.

Q4: What should I watch out for in buying a small wind turbine?

"If it seems too good to be true, it probably is" are words to keep in mind when shopping for a small wind turbine. Over the years, a steady stream of "breakthrough" wind turbines has promised exceptional performance at an incredibly low price. Sometimes the claimed performance violates the laws of physics, promising more power than the total kinetic energy available in the windstream that is intercepted by the rotor's swept area. Most of the popular models of small wind turbines operate at about the same efficiency. The energy production you should expect will be closely related to the swept area of the rotor blades, which is based on the diameter of the rotor. If you are offered a product that promises to run your whole house with a turbine that is much smaller than conventional products, it's time to start asking hard questions.

Q5: How do small turbine costs compare to other alternatives?

Small wind turbines (ranging in size from 250 watts to 50 kW) are often the least expensive source of power for remote sites that are not connected to the utility system. Hybrid systems -- wind/photovoltaic, wind/diesel, and other combinations -- can often provide the most efficient and cost-effective option for rural electrification. Photovoltaics (PV) -- the direct conversion of sunlight into electricity -- is often used to supplement wind power since PV tends to operate best in low wind months. Diesel generators or batteries can be used for backup power and to maintain power production during low wind seasons.
One study of an Arctic community with annual average wind speeds of 15 mph (24 kilometers per hour) compared the cost of a 500-kW diesel system to that of a 200-kW diesel generator and four mid-sized wind turbines. It found that the wind/diesel combination cost considerably more to install ($378,000 US versus $125,000 US), but would deliver fuel savings of $90,000 US per year, paying for itself in less than three years.

Small Wind and Your Environment

Q1: Do wind turbines make noise or interfere with TV reception?

Small wind turbines do make some noise, but this is not a problem as long as the turbine is well-sited and located at least 200 metres from occupied buildings. Small wind turbines do not interfere with TV reception.

Q2: Do small wind turbines kill birds?

Anecdotal evidence indicates that birds occasionally collide with small wind turbines, as they do with any other type of structure. However, such events are rare and very unlikely to have any impact on bird populations. House cats in the U.S., by contrast, are estimated to kill roughly one billion birds each year. Statistically, a single house cat is a much greater threat to birds than a small wind turbine.

Q3: Are small wind turbines safe?

Yes. However, neighbors who are uneasy about a nearby homeowner installing a small wind turbine may raise all sorts of questions about safety. Brief answers to some of these concerns:

• Falling tower: Thousands of wind turbines are installed in the U.S., and their safety track record is excellent. Trees are much more likely to fall than a properly installed wind turbine, but no setbacks or minimum property sizes are required for trees.
• Safety of utility repair personnel during a power outage: Small wind systems shut down automatically in the event of a power outage, and will not energize a dead power line.
• Ice throw from rotor blades: Ice buildup makes wind turbine blades less aerodynamic, so that they turn more slowly. Typically, ice will drop to the base of the turbine tower instead of being thrown.
• Children climbing the tower and falling: Possible, but wind turbines should be treated no differently than other climbable structures such as water towers or amateur radio antennas.