Using Home Windmills for Power
Operation and Installation of a Windmill for Home Power
The media and Government Environmental Agencies are always encouraging us to think green and lower our carbon footprint.
Well, the installation of a home windmill for power can generate electricity to subsidise your power consumption. But before you rush out and orrder one, there are a few pertinent questions to consider,
- Where and how do I install the windmill?
- Do I have enough wind to run a windmill?
- What will be the payback period?
- How much power will it produce?
- How much CO2 will I save by using the windmill?
- Do I need planning permission?
These are some of the questions I hope to answer in this article. I will also examine how to carry out a wind survey, and their installation to the best operating location for an optimum regular power output.
We shall discuss the outcomes of this in a summary at the end of the article where we can decide if the wind power is a suitable form of renewable energy for your particular home
The Windmill Location
This is a major factor, so be sure that there are no high buildings, trees or hills nearby which will create turbulence – not a good thing for a home power windmill.
This is easily checked with the local authority, but in most cases, planning permission is a requirement in the UK and Europe under the PPS22 Planning Policy Statement 22: Renewable Energy(see below for policy information).
The Initial Wind Survey.
Most government environmental departments have a section on renewable energy for the domestic market. Their website normally contains a section on wind turbines. In this section, there will be an average wind speed calculator. The postal code is inserted and the average wind speed for your location is shown and should be above 5m/s to make the project viable.
If the location has a good average wind speed and planning permission isn’t going to be a problem, then an in-depth survey should be taken by a reputable wind survey company. This entails the setting up of wind monitors at different heights and locations around your intended plot, and can take anything up to two or three months, costing you around £350($566), but well worth every penny as this is the most relevant part of installing the windmill. The report will give wind speed, sustainability, direction and will recommend the size of generator to install.
So now we have decided to go ahead with the project, we can have a wee look at how the windmill works.
A windmill for home power of 2 kW size consists of a hub containing a set of rotor blades, a nacelle and a support mast, the components operating as follows.
The Rotor Blades
The windmill can be multi bladed depending on the manufacturer, but three or four blades are the norm. They can be made from wood, Glass Reinforced Fiber (GRP), or aluminium and should be well balanced, non-corrosive and light.
The blades are fitted into the hub and drive the turbine shaft through the nacelle into the gearbox and driving the power generator.
This is the watertight GRP oblong streamlined container with a tail fin to hold the blades into the prevailing wind. The nacelle contains the rest of the working components which are bolted to support pads inside the nacelle using anti-vibration bolts to limit noise during operation. These include:
The Drive Shaft.
The shaft is driven by the blades and supported the full length of the nacelle by sealed-for-life bearings. The shaft enters the nacelle into the gearbox which controls the revolutions to the power generator.
The Power Generator
This usually produces a DC current which is inverted to AC suitable for the house electric main supply. However some modern generators supply AC power so an inverter is not required.
In each case the supply cable from the generator is routed down through the hollow mast, exiting at the bottom and run underground to the gable end of the house. From here it is connected to the main isolation box in the normal manner.
The Support Mast
This is usually in the form of a hollow pipe manufactured from GRP, steel or aluminium. It is flanged at each end to facilitate mounting to the nacelle swivel coupling at the top, and for bolting onto the concrete foundations at the bottom.
The mast can also be in the form of a free standing steel latticed tower, with the same fitting arrangements as the conventional mast.
The Windmill Installation
The foundations are excavated and concrete poured, incorporating rebar if required and left to set. The mast is then lifted onto the concrete founds, leveled and secured to the concrete using long, high tension steel foundation bolts.
The nacelle, complete with the rotor blades and swivel flange is then lifted into position and fitted to the mast top flange using high tension steel bolts.
A windmill for home power is a great method of lowering your carbon footprint and saving you cash, once it has paid for itself.
However, there are certain procedures to be followed to ensure your house is in a viable windy location, without high obstructions nearby. Planning permission is usually required and a reputable firm should be selected to carry out a wind survey and subsequent windmill installation.
A ball park figure for the cost of supply and installation of a windmill for home power is around £11000, ( $17794), but once installed and operating a government grant may be available of up to £2500, ($4044) provided the windmill is supplied and installed by a listed approved renewable energy company.
A 2kW windmill described in the article can save up to £380 ($615) a year on electricity use from the grid.
Calculating the Payback Period
With a government grant, the payback period, provided it is producing the rated power will be
11000-2500/380 = 20 years. This is much the same as double glazing payback period and the anticipated life of the equipment.
However, prices of windmills are falling as energy prices rise and a windmill installation project can save 2.6 tons of CO2 per year. You also will have the satisfaction of sitting, having a drink in your garden, watching the blades whirring round, producing your electricity.
There are cheaper, smaller wind turbines known as micro wind turbines which bolt onto the gable end of the house. These are rated at up to 1kW, but so far, field trials have not been promising, the output being nowhere near the manufacturers’ claims. This is mainly due to wind turbulence or from the turbine being sheltered from the wind by neighboring high buildings.
They are also reported to be noisy; vibration being prevalent and structural damage to the house a possibility.
Notwithstanding this, some people in the right location using the most modern micro-power models have had good, sustained power outputs.
So we are left with my 2kW windmill, sited in the garden, well away from any high protuberances, do you think you can benefit from installing a home windmill for power?
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