LIVIN’ LARGER WITH SMALL WIND

Like all other wind energy projects, the key to success with small wind turbines is location.

Generally, the more interference there is to wind flow, the less electricity a small turbine generates. That’s why authorities discourage installing small turbines (100-to-500 watt capacities to 2.5-to-50 kilowatt capacities) in urban environments. But there are exceptions.

Alex Murley, Small Systems Manager, British Wind Energy Association (BWEA): "We need to be wary of generalizations…If you put a turbine on a high-rise building above all the wind turbulence it will perform very well."

Small turbine energy return is primarily proportional to size: A 1-kW turbine will generate 10-to-20% of annual energy use. At average wind speed (6.5 meters/second), an average UK house using 3300 kW-hrs/year (a utility bill of £500), a 1-kW turbine earns £50-to-£100/year and at a cost of £1500 pays itself off in 15-to-30 years.

A larger, £22,000 Proven Energy 6-kW turbine generates 12,500 kW-hrs/year and earns better returns so has a shorter pay off.

Returns from selling unused electricity to the grid via a feed-in tariff or from selling Renewable Energy Credits (RECs) for cutting emissions earns more money and can shorten the pay off period to 10 years.

A still-larger Gaia-Wind 11-kW turbine costs £35,000 ($65,000), produces 40,000 kW-hrs/year and, with the feed-in and RECs, can pay off in 5 years.

BWEA: "At the right locations…small wind systems can produce electricity cheaper than the grid and payback their embedded carbon within months."

Remember: Wind speeds vary, thereby varying pay offs. And it is not only the speed of the wind that matters.

Lynda Garman, technical sales executive, small turbine supplier Proven Energy: "The swept area [the area through which the blades turn] is very important to the function of a wind turbine. If you put a small turbine in a turbulent area it will not work efficiently."

These variations make picking the right location challenging. There has been some adverse publicity for small wind turbines recently, based on the hard numbers from the smaller, urban projects. It is true the numbers are not readily favorable at present, but that will not likely be true for much longer.

Alex Murley, BWEA:"As the cost of energy goes up and up and technology costs come down, even the smaller micro turbines will be very interesting opportunities to save money and carbon…"

One of the first important changes in the cost-benefit analysis for small wind in the UK is the pending feed-in tariff. Anticipating that the government will follow other European governments and institute a guaranteed rate of return over a long period of time, small wind installation jumped 80% from 2006 to 2007 and will likely double from 2007 to 2008.

BWEA Small Wind Systems – UK Market Report 2008

American Wind Energy Association: Small Wind

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Can ‘small wind’ reap big rewards?
Matthew Knight, September 19, 2008 (CNN)
and
U.K. Small-Scale Wind-Power Turbine Installs May Double in 2008
Nicholas Larkin, September 20, 2008 (Bloomberg News)

WHO
British Wind Energy Association (BWEA) (Alex Murley, Small Systems Manager); The UK Low Carbon Buildings Program; Lynda Garman, technical sales executive, small turbine supplier Proven Energy

WHAT
With predictions from BWEA that the installation of “small” wind turbines could double this year, CNN surveyed the facts and issues on turbines ranging from 100-to-500 watt capacities to those with 2.5-to-50 kilowatts capacities.

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WHEN
2007: 3,459 private turbine installs (80% over 2006)
2008 (estimate): 7,844 private turbine installs
2009 (hypothetical): 2008 (estimate): 13,000+ private turbine installs
2020: 35% of power from New Energy sources (Government goal)
Normal turbine life-span: 20 years

WHERE
- Rural locations are 4 times as efficient at urban locations.
- Urban problems: (1) Structures break up the wind. (2) Populated areas require smaller turbines which are less efficient.

WHY
- Cost: $1500-to-$3000 (1 kW), $45,000 (6 kW), $70,000 (15 kW). Installation included. Battery and inverter extra. Batteries wear out and require replacement.
- Subsidies are available. (Ex: UK Low Carbon Buildings Program gives £2,500 for New Energy projects.
- The Warwick Microwind Trial project discourages small wind for urban locations.
- There are about 100,000 small wind turbines in the UK now but it is estimated there will be 3 million by 2020.
- Energy savings vary by location and turbine size, making pay off periods vary from 5-to-30 years.
- Emissions from production are zeroed in 6 months to 2 years.
- Installations must be permitted and can be resisted, especially in urban areas, due to aesthetics or noise.

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QUOTES
- Alex Murley, Small Systems Manager, BWEA: "The domestic wind turbine market in the UK grew by 80 percent from 2006 to 2007".
- Warkwick Trial, interim report: "Great care should be taken in selecting suitable sites for building-mounted turbines…more work is required to create a robust method for predicting average wind speeds in urban locations."
- Stephen Andrews, Senior Technical Project worker, Center for Sustainable Energy: "For urban areas there is still a large question mark. The wind resource is less than expected. But as soon as you move into a rural area, and as long as you have a good resource then small-scale wind turbines -- up to 15 kilowatts -- are very good. They can have a payback of much less than 10 years."
- Alex Murley, Small Systems Manager, BWEA: "In the UK market, 172 grams of carbon is saved for every kilowatt hour produced by a wind turbine."