Producing off grid energy from the wind can be an ideal source in a rural location for caravan camping, glamping or at an outdoor event as a power supply.
To produce a decent amount of power you need a good wind site. The best starting point is to access a wind speed database such as https://www.rensmart.com/Maps Enter the postcode of the location you wish to site a wind turbine. The wind data base will advise you the average wind speed in metres/second (m/s) at various heights. Ideally anything above 5.5m/s at 10 metres, otherwise a wind turbine may not be a viable option for you. Variations can occur depending on the elevation of the land.
At 5.5 m/s with a clean air site the FuturEnergy Airforce1 wind turbine could produce an estimated 1100kw per year, so if the average wind speed is more than 5.5m/s this is all the better.
A good wind site location for a horizontal wind turbine needs to be in a rural location in clean air area away from trees, hedges, walls, and buildings which may cause turbulence. Therefore, do you have the correct conditions to produce the power you require? By comparing how much power you potentially need (to run appliances) to the wind speed in your area and how much power you can potentially produce is a good indicator to see if this energy source will work for you.
Example: Average Wind Speed 5.5m/s = estimated 1100kwh = 1100kwh of electricity over 12 months or more if the wind speed is higher. At 6.5m/s this would increase to an estimated 1800kwh and at 7.5m/s an estimated 2,500kwh increasing exponentially.
Wind is best shared with solar as a hybrid system gaining the best of both worlds taking advantage of the sun in the summer and the wind in the winter.
Storing the power created by both sources in a lithium battery enables the use of the energy created when required. The battery energy may be used off-grid or on grid with the correct equipment.
Not just any wind will do. For a wind turbine to operate efficiently it needs air that moves uniformly in the same direction and is strong enough to provide sufficient energy to turn the turbine. In general, the higher the turbine is above the local environment, the stronger and more stable the wind will be.
Go fly a kite
An inexpensive and visually productive way to find out at what height turbulent air ends, and smooth, laminar airflow begins, is to fly a kite at the proposed wind turbine location on a windy day, preferably when the wind is coming from the prevailing direction. To visualize airflow, use tape-streamers tied to the kite’s string every 5metres or so. Wildly fluttering tape indicates turbulence, smoothly extended tape means smooth air. Be sure to take the angle of the kite’s string into account when calculating height.
The energy in the wind increases with the cube of the wind speed (P x V³), and wind speed increases with height. An increase of just 26% in wind speed means twice as much power is available in the wind, and the wind turbine will produce almost twice as much. Double the wind speed and there is almost eight times as much power available. A small additional investment in tower height may therefore be well worth the cost due to the increased energy production.
Multiple wind turbines can also be utilised thereby increasing the power produced but these need to be spaced so not to cause turbulence from each unit.
The bottom of a hill, valley, or ravine makes for a poor place to site a wind turbine. The wind tends to drop in speed at the bottom of a smooth hill, then speed up as it goes up the hill, reaching around twice the wind speed at the top of the hill.
For obstructions that are not smooth, such as a cliff (i.e., a sudden rise in the landscape), it gets much more difficult. Sharp edges create turbulence. The airflow at the top of the cliff can be stronger than the average wind speed in the area, but close to the cliff’s edge it will also be very turbulent, making it a poor site for a turbine. It may be possible to use a higher tower or set it far enough back from the cliff edge to get above the inevitably turbulent air.
The lee side, (downwind of the prevailing winds), of a prominent object makes for a very poor wind turbine site. The object will create large turbulence on its downwind side, and the average wind speed will drop off dramatically. This leaves no energy for the wind turbine to harvest.
The effect of airflow over any obstruction, including trees and shrubs, tends to create a “bubble” of turbulent air around twice the height of the obstacle that extends 20 times the height of the obstacle downwind from it.
FuturEnergy has been manufacturing the Made in Britain, Airforce1 1kw micro wind turbine for over 15 years now at their premises just outside Stratford-upon-Avon in Warwickshire. The vision was to manufacture a robust small wind turbine that would generate enough power to make a difference. This has culminated recently with the Airforce Controller that is supplied with a 24v or 48v wind turbine systems ready to be mounted on a standard sized scaffold pole. The Airforce Control automatically protects the turbine in strong wind conditions, providing battery charging control, whilst monitoring wind speeds and power generation. Customers are now able to connect to their wind turbine from anywhere in the world using the free iPhone/Android app and check on the turbines power output, even allowing them to start and stop the turbine. The kit includes: The FuturEnergy wind turbine body AC (incorporating their 1kw permanent magnet generator), tail assembly, 3 bladed rotor set, manual AC stop switch, Airforce1 Controller and anemometer complete with 12m of anemometer cable. Price: £2,250.00 (inc.VAT) www.futurenergy.co.uk
Will the Airforce be with you!