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This section is only concerned with wind turbines that can be sensibly added to a residential home...

economics of a domestic windmill
  Cost:  High
  ROI:  13 to 27 Years (No FIT)
  Skill:  Specialist
  Energy Saving:  Medium
  CO2e Saving:  Medium
 How much this measure costs to install: Low : Medium : High
 ROI is the time it takes to return the investment in fuel savings for an average gas heated 3 bed semi-detached house and assumes no government incentive schemes are used: Years
 How easy this is to do: DIY-Easy : DIY-Skilled : Specialist
 How much energy will be saved with this measure: Low : Medium : High
 How much Carbon Dioxide emission will be saved with this measure: Low : Medium : High

Unlike other forms of renewable energy, wind power requires very little explanation. Most of us will understand that the wind rotates a wind turbine generating electricity.

NB Please note this article only relates to wind systems installed and operated without the Feed-in Tariff government incentive scheme and only looks at the true economies of the technology. Please refer to the energy saving trust for the latest on The FITs scheme as they do make a significant difference making wind power economically viable.

The question addressed here is how effective are they and are they worth the investment. To work out how much energy you may generate you need to know how windy it is in your area, and there are several resource on the internet to do this, just do a Google search, The UK Government has various resources but they insist on arching them or moving them around in line with political change, rather dumb. In a very urban area wind may be totally impractical for so many reasons, not least of all how much wind there is with buildings disturbing the wind flow, so do you your homework for your specific location.

For those interested, wind turbines come in two main types; horizontal axis (HAWT) and vertical axis (VAWT) (see diagram ). Horizontal axis turbines are the more familiar ‘windmill’ type where the blades rotate in a vertical plane about a horizontal axis and the turbine is dynamically rotated on its tower to face the wind. Vertical axis turbines do not need orientation into the wind. Vertical axis turbines are particularly suited to small wind power applications because they have a small environmental impact and no noise, the technology

The wind databases give you wind speeds at 45m, 25m and 10m above ground level, to give you and idea of placement. Wind speed also vary with time, from nothing on calm days to occasional violent gusts. If the wind speed at a site is recorded over a year, it will be seen to vary about a mean wind speed value. This is the annual mean wind speed (AMWS) and is an indication of how much wind energy is available. In the UK, AMWS could be as low as 4 m/s (9.0 mph) for an inland site to around 8 m/s (13 mph) or higher on the most exposed sites.

various wind turbines

The general consensus is that you will need at least 5m/s to make it worthwhile and this seems to be the number most suppliers use when they quote the generating capacity of their systems. It is also apparently the average wind speed in the UK. The table below shows a few systems with a range of typical manufacturer quoted generating capacity and estimates of payback periods. The total cost for the installation of a larger domestic installation is around the £15,000 mark +/- £5000. Accuracy is very tricky here because it depends on the foundations required, the battery storage system used (or grid connection) and the windmill chosen, so the table includes a range of data so you can see what install cost you should aim for. The smallest installation we have found is a 1.75 turbine it costs between £2500 and £5000 installed and ready to use, and "with a fair wind" could produce about 1000kWh each year.

System 1 System 2 System 3 System 4
Annual energy generation 1000 kWh 2500 kWh 3750 kWh 5000 kWh
Equivalent standard rate mains electric price of this energy and potential CO2 emission reduction. £187
(367kg)
£467.5
(917.5kg)
£701.25
(1376.3kg)
£935
(1835kg)
Payback period with and installation cost of £ 2500 13 years 5 years
Payback period with and installation cost of £ 5000 27 years 11 years 7 years
Payback period with and installation cost of £ 10000 21 years 14 years 11 years
Payback period with and installation cost of £ 15000 32 years 21 years 16 years
Payback period with and installation cost of £ 20000 29 years 21 years

System 4 is at the high end of what is possible with a 5m/s wind speed and the numbers in the table for this system probably reflects what would happen with an average annual wind speed closer to 7m/s, So to get a payback period for your investment below twenty years you probably need to be in a very windy area and have paid as little as possible for your system.

Comments and Questions

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Church - JOHN LEESE  2016-01-12 15:59:22
Our church is on a hill in an isolated position ,would a wind power system be suitable,would the government feed in tariff be available for any surplus electricity produced.Are you aware of any churches that have used this.The heating bill is a major expense and of course is only needed occasionally.

Thanks,

John.

Thank you,