Domestic Wind Power

There are two primary types of domestic wind turbines.  Large mounted turbines that are typically 9 – 11 meters in height and roof mounted turbines. Both have positive and negative aspects.  Mounted, stand alone Turbines are large sometimes unsightly structures. They are expensive and very much site dependent. They are however, cost effective and energy efficient. Payback period is typically 10 – 15 years at current energy prices (which we expect to increase). Owners can at this point can begin to either sell energy back to the grid or offset their standard energy consumption with freely generated wind power.

Wall mounted wind turbines are substantially cheaper, tidier and more dynamic. Unfortunately there are substantial problems associated with the installation. Wind, as you might expect, moves the turbine and can cause substantial vibrations which can effect the structural integrity of your roof. The output of the small turbines is considerably less as well, usually in the region of 600-800 KWH per year. Cost effectiveness is substantially less than that off larger turbines. Without significant grant funding the payback period could be over 15 years.

FAQ

Will a wind turbine save me money?
Yes. The wind turbine typically lowers your electricity bill by 20 to 90 percent per annum (depending on the size). It is not uncommon for wind turbine owners with total-electric homes to have monthly bills eliminated. The amount of money a small wind turbine will save you over the course of its lifetime will depend upon its cost, the amount of electricity you use, the average wind speed at your site, and the sizing of the turbine.

What size turbine would I need for my home?
Homes use approximately 6,400 kilowatt-hours (kWh) of electricity per year (about 780 kWh per month). Depending upon the average wind speed in the area, a wind turbine rated in the range of 2 to 5 kilowatts would be required to make a significant contribution to meet this demand.

Who should consider buying a wind turbine?
A residential wind turbine can be a relatively large device and is not suitable for urban or small-lot suburban homes. Except for very small wind turbines (i.e., with rotors one meter or less in diameter) on very small towers, a property size of 1/3 acre or more is desirable.
The economics of a wind system are very sensitive to the average wind speed in the area, and to a lesser extent, the cost of purchasing electricity. As a general rule of thumb, if economics are a concern, a turbine owner should have at least a 10 mph average wind speed and be paying at least 12 cents/kWh for electricity.

Will it help the environment if I install a wind turbine at my home?
Yes. Wind turbines produce no pollution (after construction, sale and transport) and by using wind power you will be offsetting pollution that would have been generated by your electricity supply company. Over its life span, a small residential wind turbine can offset approximately 1.2 tons of air pollutants and 200 tons of greenhouse gases (carbon dioxide and other gases which cause climate change).

Don’t I have to take wind measurements for a year or more?
For most residential systems the cost of taking wind measurements is not justified. Wind maps is sufficient for an experienced evaluator to predict wind turbine performance. In very hilly or mountainous areas, however, it may be best to collect wind data before purchasing a system to ensure that your site is not in a sheltered area.

Do wind turbines make noise or interfere with TV reception?
Small wind turbines do make some noise, but not enough to be found objectionable by most people. A typical residential wind system makes less noise than the average washing machine. Wind turbines do not interfere with TV reception.

Will I have to change any of the wiring in my house?
No. A wind turbine is easily retrofitted to virtually any home without the need to change any wiring or appliances.

What about towers?
A tower is usually supplied along with the wind turbine. Tall towers are necessary to raise the wind turbine above turbulence generated by obstacles on the ground and trees. Wind velocity and, therefore wind turbine performance, increases with tower height. Several different types of towers are available, depending upon which manufacturer you select. Each type has its advantages; the most economical type of tower is the guyed lattice tower, but a hinged tower can be easier for you to install and provides easier access for maintenance.

How much does a wind system cost?
A small turbine can cost anywhere from €2,000 to €30,000 installed, depending upon size, application and manufacturer.

How reliable are wind turbines? Will I have to perform 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.

How do wind turbines perform as an investment?
The wind system will usually recoup its investment through utility savings within 8 to 20 years and after that the electricity it produces will be virtually free. Over the long term, a wind turbine is a good investment because a well-sited wind system increases property value, similar to any other home improvement. Many people buy wind systems in preparation for their retirement because they don’t want to be subject to unpredictable increases in utility rates.

Selling Energy back to the Grid

Wind turbines can be connected to the ESB network using a Grid Tie inverter. In this case the grid acts as a battery, absorbing any excess energy not used in the home. This exported power is credited to your ESB account at the rate of 19c per Unit for the first 3,000 units each year and 9c per Unit for the remainder.
Alternatively, wind turbines can be used for heating only, in which case, no batteries are required. A 2.5kW machine in a well exposed site will produce roughly 8,600kWh per annum which is enough to supply the average house with all its electricity needs and a certain amount of heat. The 6kW machine in the same site will deliver roughly 22,000kWh, and the 15kW will deliver roughly 55,000kWh

The benefits of wind electricity

• Harness a plentiful energy source: in Ireland we have an ideal environment, topography and wind supply to make it an effective form of both domestic and national energy generation
• Cut your carbon footprint: wind electricity is green, renewable energy and doesn’t release any harmful carbon dioxide or other pollutants.
• Cut your electricity bills: wind is free, so once you’ve paid for the initial installation your electricity costs will be reduced.
• Store electricity for a calm day: if your home isn’t connected to the National Grid you can store excess electricity in batteries and use it when there is no wind.
• Sell electricity back to the grid: if your system is producing more electricity than you need, or when you can’t use it, someone else can use it – and you could make a bit of money.

Is wind electricity suitable for my home?

To tell if a small scale domestic wind turbine is right for you, there are a few key questions to consider:

• Are there any large obstacles like buildings, trees or hills near your home? Small domestic wind turbines work best in exposed locations, without turbulence caused by these type of obstacles
• Is your home is a windy area? To be effective you need an average windspeed of no less than 5m/s.
• Is your home located away from the National Grid? Small domestic wind systems are particularly suitable for use in remote locations where mains electricity is unavailable.
• Do you need planning permission? Small domestic wind systems normally do require permission from your local authority, so check before you install a system.

Choosing your Site

The following are some basic points that you should consider first:

1. Is your proposed location reasonably free of obstructions 1-2 km towards the South West? (i.e. hills or trees in the direction where the sun sets in the summer)
2. Is your location completely free of any obstruction 14 metres from tower in any direction? The windmill should be 14 metres minimum away from the border of your land as well.
3. Is this location behind your main building?
4. Is the distance behind the windmill relatively free of obstruction? i.e. does the land rise quickly behind the site meaning that wind may bypass the proposed location?

Financial and environmental considerations

Financial

Generally, payback on your wind turbine investment depends on the following;

1. Your total ESB bill
2. What size windmill you would like to consider
3. The efficiency of the location for wind generation

Example Payback period

A detached house would generally look at between a 3-6Kw wind turbine to meet their demands.

The payback for this would be approx 8 -12 years with the windmill lifetime estimated around 25 years

Environmental

Each year, for every megawatt of Irish wind energy that displaces fossil fuel power production, environmental, economic and social benefits include:

• Clean electricity to meet the electricity needs of 650 homes
• Removes the need to import 6,450 barrels of oil
• The avoidance of 2700 tonnes of CO2
• The avoidance of 49 tonnes of SO2
• The avoidance of 5.5 tonnes of NOx
• The avoidance of 175 tonnes of slag and ash for landfill