Wind Turbines

Morri Consult are aware of the increasing fuel costs that have resulted in higher gas, electricity and oil bills for consumers and businesses alike. This together with the increasing effect on the environment of the burning of fossil fuels has led us to focus on renewable energy sources. Our particular expertise is in providing cost-effective solutions for customers.

In terms of harnessing wind energy, Britain is uniquely placed in Europe as we receive about 40 percent of all Europe's wind! So we ought to be able to exploit this to our advantage.

Unfortunately, nothing is a straightforward as it first appears and there are many factors to be considered before selecting wind energy as a viable alternative energy source for the domestic user. This information sheet attempts to explain in layman's terms some of the pros and cons of wind generation. If you want more information or just a chat about some of these issues don't hesitate to give us a call.

New government legislation is in place already for new build property but come 2010 every householder will be responsible for the level of CO₂ (carbon dioxide) they produce, known as their carbon footprint. This will result in increased taxes for heavy producers so now is an opportune time to consider how you will meet these challenges in a way that will save you money over your existing energy arrangements.

Wind Turbine

Renewable Energy – Harnessing Wind Power

New technologies mean that energy can be extract using wind generation can be installed easily and cost-effectively than ever before. In fact, DIY stores have offered wind turbines as 'off-the-shelf' products. However, before rushing out and buying one, it is wise to stop and consider whether such a system is right for you and your circumstances.

Even though wind energy is free, the installation cost is still significant and the 'payback time' depends on the amount of energy you will be able to extract and offset against the installation cost. It may be that other forms of alternative energy (e.g. Solar Power) represent a better investment. Some of the factors to consider are discussed below.

Quality of Wind

Wind is plentiful in the U.K. but it is a variable commodity. The electricity generated at any given time is directly dependent on wind strength. So it can be seen straightaway that the level of available power is constantly varying as the wind gusts and the wind speed ebbs and flows.

Also turbulence causes problems and loss of efficiency. It is unfortunately a fact that obstacles such buildings, trees, hills and valleys cause the wind to be deflected and to 'swirl'. This swirling considerably reduces the amount of energy we can extract. So to get the best out of a wind turbine it should be sited in an open area with as little obstruction as possible. This is why the best sites are on the coast or on the tops of hills.

Wind Power

The power that is available from wind is proportional to the cube of the wind speed. This means that if the wind speed doubles, the potential power goes up by a factor of 8.

However, it also means that if the wind speed halves, only an eighth of the previous power is now available.

The diagram above shows a typical power curve. As you can see there is not much power available until a reasonable wind speed is reached (say around 10 mph) but at 25 mph it really starts to deliver some power. Of course at higher speeds even more power is available but it there is a danger that if we try to extract the power we risk damaging the wind turbine. So wind turbines have a designed maximum operational limit.

As we mentioned above, wind speed is constantly varying and so the available power also varies.

However, because of the cube relationship between wind speed and power, the power fluctuates far more. For example an increase in wind speed from 4 m/s to 5 m/s results in almost a doubling of power.

Wind Turbines

Wind turbines come in a variety of sizes and designs. However, they all basically consist of the same elements:

  • Rotor Blades (usually 2 or 3 blades), which is attached to…..
  • A gearbox (necessary to 'gear up' and turn a generator at a speed which will produce electricity, which is attached to…..
  • A generator to produce the electricity.

There is also usually some form of 'yaw' control which keeps the rotor blades facing the wind. Very simply the wind turns the rotor, which turns the generator to produce electricity. The question is; how do we use this electricity given that it is;

  • Constantly varying and even dropping to zero when the wind speed is low
  • Incompatible with your normal domestic supply in terms of voltage and frequency
  • Of relatively low power (in home applications)

To use the energy we need to store it to smooth out the 'lumps' and then draw the energy off at a constant rate in a form we can use. To do this we have a couple of options, we can use the energy to charge batteries and so store the electricity until we want to use it.

This is ideal where the installation is remote and there is no mains electricity. Or, we can 'sell' our 'lumps' of energy to the National Grid and 'buy' it back at a constant rate. So we are effectively using the Grid as our storage medium. However, to do this we need to convert our electricity into a form that the grid will accept. We do this using an electrical device called an Inverter.

This is an additional cost and we need to be generating sufficient energy to make it worthwhile (i.e. averaging more than 1 kW).

This brings us to the subject of how much power a wind turbine can extract. This is primarily a function of the 'swept area' of the blades. If we double the length of the blade, we can extract four times the power. So we begin to see why wind energy really starts to work for large installations that can generate upwards of 10 kW at modest wind speeds.

So the message should be clear, for wind generation size matters, the bigger the installation the more sense it makes. However, don't be put off by the above, once the installation is paid for, the energy is truly for nothing and you are genuinely doing your bit to conserve energy and reduce carbon emissions. You do need to consider the pros and cons before deciding if it is right for you.

Our Policy

At Morri Consult we are happy to discuss all forms of alternative energy sources with you to allow you to make the right decision. We won't try to sell you anything that is not economically right for you. We believe in giving it straight in terms of the facts and figures and what you can expect from an alternative energy source.

We do not supply equipment from a single supplier, we will advise and help you select the product that best meets your needs. Above all we are always around to answer your questions and deal with any issues that may arise.

We are professionally qualified engineers and technicians with teams of trained staff and we never 'hard sell'.