Renewables Series: Home Wind Turbines
Renewable energy sources are an important part of the UK’s ‘green’ future. Indeed, if the government wants to reach its renewables target by 2020, investment in renewable technologies is only likely to increase. However, some technologies are not as straight forward as they may seem. Take, for example, home wind turbines, the benefits of which are frequently contested.
What is a home wind turbine?
A home wind turbine is a small-scale wind turbine that can be installed at a residential property to generate electricity via wind power. Turbines are usually either pole-mounted or building-mounted, and produce no harmful emissions.
Unlike photovoltaic systems which rely on the sure fact that the sun will rise every day, wind power (also a type of solar energy) carries with it no such guarantee. The efficiency of a wind turbine will depend on a number of factors including wind speeds and the location of the turbine (both on the property, and the property’s whereabouts in the UK). On the one hand, the UK is known to be one of the most blustery countries in Europe, so wind turbines seem like a sensible option. On the other hand, wind speeds in the UK are variable and this often means that the energy output is as erratic as the weather itself, which can make it difficult for some homeowners to justify the purchase of home wind turbines.
This is not to say that wind turbines are ineffective. In the correct location they can generate substantial amounts of energy, but research should be carried out before investing. Wind turbines use energy to generate energy, which isn’t uncommon in renewable systems, but it can be difficult to ensure the energy output exceeds the amount of energy used by the system’s inverter.
So how do home wind turbines work?
There are several stages to generating useable electrical energy from wind power.
1. The blades of the turbine catch the wind
2. The blades begin turning which, in turn, rotates the rotor and shaft
3. The shaft spins the generator to create a DC output
4. An inverter then converts the DC output to AC for use in the home/to be sent back to the national grid.
According to YouGen – a champion of renewable energy in the home – the success of wind power depends largely on the suitability of the site. YouGen describes the key factors for a successful site as having:
- An average wind speed of at least 5 or 6 m/s
- No obstacles nearby which might reduce the wind speed or create turbulence. These include buildings, trees or hills. An ideal site is a smooth hill top with a clear, open stretch to the prevailing wind.
- You are able to connect the turbine to your property and to the national grid.1
This in mind, home wind turbines can be particularly beneficial to properties on the coast where it is often breezy. A town house in London, however, would not be a prime candidate for a home wind turbine (unless it is caught in a wind trap), particularly if it is shielded by surrounding buildings.
The National Energy Centre:
We used YouGen’s handy Wind Speed Lookup tool to look at the average wind speed around the National Energy Centre, our headquarters, to see if our building could benefit from a wind turbine. Although not a residential property, the graph below shows that if we had a wind turbine installed at 25 metres or higher we could expect a good yield due to the higher wind speeds at this altitude. The same is true for a turbine installed at a height of 10 metres, but – as you would expect – with an average wind speed of just 5m/s a wind turbine installed on a taller pole would produce a better output.
As mentioned previously, the efficiency of a home wind turbine will depend on the conditions surrounding the site, but it is also important to understand the efficiency of different types of wind turbine. For instance, it is a given that a small roof-mounted wind turbine (usually under 2kW) is likely to produce a smaller energy output than a larger pole-mounted installation; however, the rate at which electrical energy is generated by a roof-mounted installation is slower than that of a pole-mounted turbine – smaller turbines are therefore more inefficient.
It should also be mentioned that, to work to their fullest potential, wind turbines require smooth airflow and shouldn’t be installed in locations where they experience too much turbulence, for example near busy roads or in built up areas.
To ensure the best possible energy output, many homeowners are doubling up on their renewable systems. According to figures taken from EPCs lodged by NHER members, almost 20% of EPCs with a wind turbine recorded also show that solar PV is installed at the property.
Cost and payback
The Energy Saving Trust (EST) estimates that home wind turbines (including installation) cost:
- up to £3,000 for a roof-mounted 1 kW micro wind turbine
- between £9,900 and £19,000 for a 2.5 kW pole-mounted wind turbine
- between £21,000 and £30,000 for a 6kW pole-mounted wind turbine2
As with solar PV, homeowners can access the feed-in tariff for wind power installations and effectively receive payment for the energy they generate and export back to the grid. As the payback period is affected by the suitability of the site (e.g. wind speed, type of installation, energy consumption etc.) there is no average payback period – this would have to be considered when assessing the property’s suitability.
Noise is another factor to consider when committing to having a wind turbine installed. Whilst some homeowners experience no problems in this area, others have complained of a constant droning noise coming from their turbines when wind speeds are high. Before choosing your turbine and installer, it is best to read consumer testimonials to see how other homeowners have fared.
The pros of home wind turbines:
- Reduce your carbon footprint: wind power produces no harmful emissions
- Feed-in tariffs: the government’s feed-in tariff scheme means that you can earn money for the energy generated by your wind turbine (which helps when paying off the installation) by effectively selling it back to the national grid
- Cut your electricity bills: by using the power generated by your wind turbine you are reducing the amount of electricity you take directly from the grid, thus cutting your electricity bill
- Unobtrusive: unlike PV panels which some consider to be unsightly, a small wind turbine can often go unnoticed
The cons of home wind turbines:
- Expensive to install
- Energy output is hard to predict
- Only suitable to be installed in certain conditions
- Some homeowners report that they are noisy
- Require smooth airflow
Whilst there is a degree of uncertainty in the renewables market following the Brexit vote, it is important to remember that the UK Government is still bound by the Climate Change Act 2008. It is also worth remembering that incentive schemes such as Feed-In Tariffs were devised by the UK and not the EU, which should offer some reassurance to consumers.
For more information on installing home wind turbines, consumer watchdog, Which?, has published an interesting article here.