It’s not necessary to be a nerd to understand how wind power works

Wind is caused by the uneven heating of the Earth by the sun and the fact that temperatures are invariably attempting to reach an equilibrium (heat is obviously moving to a cooler area). With the rising expense of energy and the destruction of the environment from non-renewable fuels, it is more and more equitable to harvest this renewable resource.

The benefits of wind energy are that it is virtually free (after you buy the equipment) and there’s no pollution. The disadvantages include the fact it’s not a continuing source (the velocity varies and many times it is insufficient to make electricity) and it typically requires about one acre of land.

How Wind Energy Works

The volume of power that’s available varies by wind speed. The amount available is called it’s power density and it is measured in watts per square meter. Due to this, the U.S. Department of Energy has separated wind energy into classes from 1 to 7. The common wind speed for class 1 is 9.8 mph or less while the average for a class 7 is 21.1 or more. For effective power production, class 2 winds (11.5 mph average speed) are often required.

Normally, wind speeds increase as you get higher above the Earth. This is why, the typical wind mill is installed on a tower at least 30 feet above obstructions. There are 2 basic kinds of towers useful for residential wind power systems (free standing and guyed). Free standing towers are self supporting and are usually heavier which means they take special equipment (cranes) to set them up. Guyed towers are supported on a concrete base and anchored by wires for support. They typically are not as heavy and most manufacturer’s produce tilt down models which may be easily raised and lowered for maintenance.

The kinetic (moving energy) from the winds is harnessed by a device known as the turbine. This turbine consists of airfoils (blades) that capture the energy of the wind and use it to turn the shaft of an alternator (like you have on a car only bigger).

That there are two basic types of blades (drag style and lifting style). We all have seen pictures of old-fashioned windmills with the large flat blades which are an example of the drag style of airfoil. Lifting style blades are twisted rather than flat and resemble the propellor of a small airplane.

A turbine is classified as to whether it is made to be installed with the rotor in a vertical or horizontal position and whether the wind strikes the blades or the tower first. A vertical turbine typically requires less land for it’s installation and is an improved option for the more urban areas around the globe. An upwind turbine is designed for the wind to impact the airfoils before it does the tower.

These units normally have a tail on the turbine which is required to maintain the unit pointed into the wind. A downwind turbine doesn’t need a tail as the wind acting on the blades tends to maintain it oriented properly.

These turbine systems would be damaged if they were to be allowed to turn at excessive speeds. Therefore, units should have automatic over-speed governing systems. Some systems use electrical braking systems although some use mechanical type brakes.

The output electricity from the alternator is sent to a controller which conditions it for use in the home. The usage of residential wind power systems requires the home to either remain tied to the utility grid or store electricity in a battery for use when the wind doesn’t blow sufficiently.

When the home is tied to the grid, the excess electricity that is created by the residential wind power system can be sold to the utility company to reduce or even eliminate your utility bill. During periods with not enough wind, the home is supplied power from the utility company.

The price of Wind Energy

Small residential wind power turbines can be an attractive alternative, or addition, to those people needing more than 100-200 watts of power for their home, business, or remote facility. Unlike PV’s, which remain at basically a similar cost per watt independent of array size, wind generators get less expensive with increasing system size. At the 50 watt size level, for instance, a small residential power windmill would cost about $8.00/watt compared to approximately $6.00/watt for a PV module.

That’s why, all things being equal, Photovoltaic is cheaper for very small loads. As the system size gets larger, however, this “rule-of-thumb” reverses itself.

At 300 watts the wind mill costs are down to $2.50/watt, while the PV costs are still at $6.00/watt. For a 1,500 watt wind system the cost is down to $2.00/watt and at 10,000 watts the price of a wind generator (excluding electronics) is down to $1.50/watt.

The author

Mary Jones writes for the residential wind energy systems website, her personal hobby blog centered on suggestions to reduce CO2 and lower energy costs using alternative power sources. My complete Bio

Thursday, 29 April, 2010
15:00 PM

Ken Brock outside his photo-voltaic equipped home in Kesgrave. Picture Sarah Lucy Brown myphotos24 ref – slb 010 ken brock 4

WHILE many people think the future of the global environment is in the hands of the younger generations, a new breed of “pensioner greens” are demonstrating that all ages can play a part – especially if it makes good financial sense.

Ken and May Brock are among those who are taking advantage of a new Government scheme which provides a long-term, guaranteed income for all the small-scale renewable energy they can generate – regardless of whether it is fed into the grid or used in their own home

The scheme is aimed at helping to achieve a target of the UK producing 15% of its electricity from renewable sources by the year 2020.

It pays homeowners for each kilowatt–hour of electricity produced from renewable sources – about four times the market cost..

Ken Brock with his home-generated power apparatus

The new “feed-in” tariff became effective from April 1 and makes a great deal of economic sense for those willing and able to make the investment in technology such as solar panels, photo-voltaic cells or small wind turbines.

The Clean Energy Cash-back scheme is open householders, businesses, communities, farmers, schools and hospitals – anyone who want to generate “green” electricity from renewable installations up to five mega-watts in size (equivalent to two large commercial wind turbines) although the payments vary by technology and size

Pensioners on a fixed income but with savings are among those who are often in a position to introduce green technology – not only to save money but to play their part in reducing the national reliance on power stations which burn fossil fuels, producing global warming gases.

Mr and Mrs Brock, of Kesgrave, already had solar panels on their bungalow, producing hot water. Now they have had photovoltaic (PV) cells – to convert the sun’s energy into electricity – installed and the investment is expected to save about £900 a year on their electricity bill..

The power is measured through a metering system

The couple, who have three children and four grand-children, were rubbing their hands with glee during the spell of sunny weather earlier this month.

For they are earning up to 41.3p for every kilowatt hour of electricity the cells produce. And if they produce so much energy they feed some back into the grid they will receive a 3p a kilowatt hour bonus. All the income is tax-free.

(continued below)

According to East Green Energy, Kelsale, the firm which installed the PVs for the Brocks, the cells should generate about 1,750 kilowatt hours a year.

Ken Brock is a member of a new order of pensioner greens who are fitting renewable energy into their homes.He has installed photo voltaic cells to generate electricity. Picture Sarah Lucy Brown myphotos24 ref – slb 010 ken brock 1

The firm estimates the system could generate a profit of more than £19,000 over the next 25 years if electricity prices continue to rise at five percent a year.

This figure may even prove an under-estimate, given the recent warnings from Ofgem, the industry regulator, of a looming energy crisis

Mr Brock, a retired building surveyor, said he hoped the PV cells would generate about half the electricity used in his home:

“The overall cost of the installation was £11,000 for which I received a £2,500 grant from the Government as well as an interest-free loan for £4,000 from Suffolk Costal District Council.”

Mr Brock, who was born in Ipswich, went to the town’s Civic College and worked for many years for Tolly Cobbold, said: “I thought it would be mostly young people taking advantage of this scheme but it seems to be mainly people in my age group – people who haven’t got a mortgage and have the opportunity to do things like this.

His interest in renewable technology goes back a long way. In the 1950s and 60s, while studying building construction, he learned about ground and air-sourced heat pumps. In the late 1960s he seriously thought about installing a heat pump for domestic use but never went ahead.

“When I first looked into installing PV panels, the maths didn’t add up. But now, with the technical improvements in renewable energy and the feed-in tariffs, it means mean we will recoup expenditure within ten years,” Mr Brock said.

He expects the PVs to generate about half of the electricity he and his wife use in their home.

Mr Brock would like to see renewable energy installations included in all new buildings – preventing the need for at least some new power stations.

Linda Grave, East Green Energy spokeswoman, said: “We are seeing a real increase in interest in renewable energy from the over 60s. On a fixed income it really makes sense.”

She added: “Going green is no longer just about the environment. This legislation means you can make money by becoming a mini generator. Rising oil prices means people are more concerned about their carbon footprint for the sake of their bank balance, rather than the environment.

“With bank interest rates at an all-time low, people can make a very healthy return of seven to ten percent by investing in a suitable form of renewable energy in their home.”

Friends of the Earth, which led the campaign for a micro-generation payment scheme, believes it will make small-scale green electricity technologies an attractive investment for home-owners, housing associations and some businesses, cutting energy bills and creating new jobs in the clean energy sector.

A YouGov survey for Friends of the Earth, the Renewable Energy Association and the Co-operative Group, published in January, revealed that 71 per cent of homeowners said they would consider installing green energy systems if the feed- in tariff scheme was generous enough.

Friends of the Earth’s Executive Director, Andy Atkins said: “This new scheme is a tremendous opportunity for people across the UK to play their part in the green energy revolution – and earn tax-free money too.

“The Clean Energy cash-back scheme will allow householders to earn tax-free cash by turning their homes into mini green power stations, cut fuel bills and play their part in tackling climate change.

“UK homes are responsible for over a fifth of UK emissions, but by slashing energy waste, and fitting renewable electricity systems such as solar panels on our roofs and wind turbines in our gardens, they can be part of the solution to climate change.

The scheme also covers other green technologies such as water turbines (in rivers or old water mills) and anaerobic digesters, which make electricity and heat from burning the gas produced by degrading organic waste.

Friends of the Earth is calling on which ever party wins the General Election to be more ambitious and increase the support to all small scale renewable electricity technologies and larger community owned schemes.

“The scheme launched today means small-scale renewable technologies are predicted to provide just two per cent of the UK’s electricity by 2020. While this is welcome, it is inadequate. Friends of the Earth has shown that a stronger scheme could see six per cent of UK electricity generated by these technologies by 2020 or two and half times the output of Sizewell B nuclear power station,” Mr Atkins added.

By April 2011 solar thermal and heat pumps will also be eligible for payment under another scheme announced by the Government.

Home owners must use an MCS (Micro generation certification scheme) accredited company to be eligible for “feed in” payments.

You can find small wind turbines and grid-tie hardware in the Residential Energy Kit Store