Domestic wind power is another renewable energy technology which is gaining popularity. Different systems run in slightly different ways, but the most common systems run like this.
Electricity is generated by the wind turbine. The electricity from it smoothed out by a piece switch gear, and then sent to the main fuse board. The idea behind smaller (and most common) domestic wind turbines is that will displace your “base load” electricity. That is to say the electricity it generates (75-250W) is less than the minimum amount of electricity your house is using. So at all times you will consume all of the electricity it is making, and so none will ever escape out onto the national grid. This is good because the value of the electricity you buy is quite high (probably 16c or so) while the value of electricity supplied to the market is quite low (about 6c).
Some systems use batteries to store electricity for use at peak times, but batteries are expensive and bulky, and adding them to a system adds to inefficiency by a good bit. The bulk of this inefficiency comes from converting the electricity to DC, for storage, and then back to AC, for use in your house (see the inverter bit below).
The 3 blade wind turbine we see most commonly has been chosen due to a bit of physics showing that it takes the most energy out of the wind possible. Older turbines which have more blades have since been proven to be less effective over a range of wind speeds. The essence of the thing is that trying to block the wind is the wrong way to go about it, the best solution is to “catch” the wind, and be dragged along by it. Hence 3 blades, and also the particular pitch (angle) they are set at. In very large turbines the blades can be adjusted to be at the optimal pitch, but that would be overkill for smaller turbines.
Some more expensive turbines use gearboxes to optimise the energy being extracted from the wind, working no different to the gears on your bike. Cheaper and smaller ones often don’t bother with this however as it adds to the cost and provides more things to break.
Generators and alternators produce electricity from the rotation of the turbine motor. A generator produces Direct Current (DC) power while an alternator produces Alternating Current(AC) power.
In systems where batteries are included, inverters are added. Inverters are pieces of equipment that turn electricity from D/C (like in batteries) to A/C (like grid electricity).
Yaw systems are used to align the turbine to the proper angle of the wind. Most domestic wind systems use a simple tail vane to do this.
But do they work
Well first, you must accept a fact about the wind… it is not always there. So once we’re got that out of the way… then yes… they do.
Because wind is an intermittent resource, you can’t expect it to supply all your electricity needs. The idea with wind is that it will generate electricity when it is windy, and when it is calm, you’ll need to use another energy source. So if you buy a wind turbine, and see that it is rated to generate 100W, then you can hope to get an average 33W from it. If it is rated to 750W, then you’ll get an average of 250W. Average does mean average though… So it might be generating 0W, or might be generating 600W, or any variation.