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Micro-wind turbine energy guide

Micro-wind turbines convert wind directly into electricity, which can be used within your home or fed back into the electrical grid. This guide contains important information that may be useful if you are considering purchasing a micro-wind turbine for your home or small business.

What is a micro-wind turbine?

A micro-wind turbine uses the wind to turn a small generator, which produces electricity. An inverter conditions this electricity to ensure it is compatible with appliances in your home and can be safely fed into the electricity grid.

Does energy efficiency matter if I plan to get a micro-wind turbine?

Yes. If you use less energy, you will need less energy to be generated by your micro-wind turbine. This means you will need a smaller turbine, which will cost less. Replacing inefficient appliances with efficient ones is nearly always more cost effective than using micro-wind turbine technology. Spending a few thousand dollars on highly efficient appliances could reduce your energy consumption enough to save tens of thousands of dollars you would otherwise need to spend on a larger wind turbine. It is particularly important to use energy-efficient air conditioning, space heating, ventilation, water heating, lighting and refrigeration systems.

How long will a system last?

Turbines can last over 20 years, though lifetime is highly dependent on turbine design, manufacturing quality and how well it is maintained. Once your turbine is installed, plan to schedule a check-up and possible maintenance such as oiling and greasing at least once a year. Inverters must typically be replaced every 5–10 years and this should be accounted for when assessing the cost of a system.

Do micro-wind turbines produce much noise?

Most well designed micro-wind turbines will produce very little noise that can be heard above background noise levels, though some noise will be produced from the bearings inside the turbine and the interaction of the blades with the air as they rotate. Look for a turbine which has been independently tested to IEC standard 61400-11 and the results demonstrate the average sound pressure level created by an operational small scale wind turbine does not exceed 10dB(A) of the average background noise at a distance of one tower height plus half the rotor diameter downwind of the turbine. The Department of Planning is likely to require this as evidence that demonstrates the turbine will not create an audible nuisance to neighbors.

What happens if a micro-wind turbine is hit by lightning?

Like any other electronic item, lightning can damage a micro wind turbine, but lightning protection systems should be fitted, which will reduce the risk of any damage occurring. Failure to do this could lead to a lightning strike destroying your turbine, inverter and even electronics within your home.

What size turbine do I need to provide enough electricity for my home?

Micro-wind turbines are usually sized electrically in terms of ‘kilowatts’ of installed capacity. A 2–3 person home with a good wind resource typically requires between 3 and 5 kilowatts of installed capacity to meet its annual electrical energy requirements, though this will vary depending how much electricity you use.

Where should a micro-wind turbine be located?

The performance of micro-wind turbines is highly sensitive to the turbine’s location, as nearby objects can have a significant impact on the quality of the wind resource. Unlike solar technologies, where shading of sunlight is clearly visible and can be easily avoided, it takes careful and thorough analysis of an individual location to understand the nature of the wind resource. Regardless of the ‘cut-in’ wind speed at which the turbine will start rotating, most small turbines generate less than 10% of their installed capacity below wind speeds of 10 mph. Any objects within a few hundred feet of the turbine, such as trees and buildings, can interfere with the wind flow reducing wind strength and causing turbulence, which can shorten the turbines lifetime due to fatigue stresses. Before investing in a micro-wind turbine, you should ensure an anemometer is installed for at least six months to measure the wind resource as close to the proposed height and location of the turbine as possible. Your installer should use this data, combined with historical wind data from the weather service, to predict the performance of the turbine once installed. Micro-wind turbines should generally be mounted on independent support structures rather than attached to buildings, particularly homes. It may be acceptable to mount turbines on a tower attached to a commercial building of steel frame or reinforced concrete construction, in which case a locally registered structural engineer should approve the design.

How high should a micro-wind turbine be mounted?

The small wind industry generally recommends the lowest point of a wind turbines blade should be at least 30 feet above the height of any obstacles within a 500-foot radius to avoid interference. Where this would result in an excessively high tower, the presence of three trees or less, or similar sized objects, should be acceptable within a 500-foot radius provided they are outside a 300-foot radius and do not reach the elevation of the lowest part of the turbine’s blade path, as shown below.

Will the Department of Planning allow micro-wind turbines?

The Department of Planning’s,  A Guide for the Installation of Renewable Energy Generation and Collection Systems provides all the relevant information you’ll need to apply for the approval of any system.

The Bermuda Plan 2008 Planning Statementfencourages the development of renewable energy sources and permits their installation in any zone at the discretion of the Development Applications Board, or through a Permitted Development Permit where applicable. Delays may be experienced if the application is incomplete or does not include all the relevant information required. For more information contact the Department of Planning directly at (441) 297-7756.

Micro-wind turbines, aircraft and radar

To avoid possible interference with aircraft, turbines are not allowed within the airport control zone as defined in the Bermuda Plan 2008 Planning Statementf. Most micro-wind turbines are not expected to create significant problems for radar systems due to their small size and relatively low height. However, as a precaution, it is recommended that turbines are not installed within the line of sight of the Doppler weather radar on Cooper’s Island. The Department of Energy’s Micro-Wind Turbine Airport Radar Map shows both the airport control zone and parts of the Island where turbines of varying height may be within the line of sight of the Doppler radar.

How much does a micro-wind turbine cost?

A turbine should cost around $7,000–$9,000 per kilowatt of installed capacity, so expect to pay between $21,000–$27,000 for a 3 kilowatt system. Try to obtain several quotations from different installers to get a competitive price.

How long will it take for the turbine to pay for itself?

The length of time it will take for a micro-wind turbine to pay for itself depends on the initial cost of the turbine, the cost of electricity over the lifetime of the turbine, and most importantly the quality of the wind resource where the turbine is installed. Expect a reasonably priced turbine with a good wind resource to pay for itself in around 8–10 years, though this will reduce as the price of fossil fuels increases. Your installer should be able to assist you with estimating how long it will take for your system to pay for itself.

What is the Government doing to reduce the cost of micro-wind turbines?

There is no import duty on wind turbines.

Is financing available for micro-wind turbines?

Your installer may be able to recommend financing options for micro-wind turbines, but make sure you are confident the turbine will produce as much energy as the installer has predicted, otherwise it may not save or produce enough electricity to repay your investment.

How much will I be paid for any extra electricity produced?

BELCO currently offers a ‘net metering’ rate for any electricity fed into the electrical grid from small scale renewable energy systems. A net metering rate means the rate paid to you for any energy you feed into the electric grid will be exactly the same rate you pay for energy you buy from BELCO, including the fuel adjustment surcharge. If you pay $0.34 per kilowatt hour you consume, you will be paid $0.34 per kWh you feed back. A 3 kilowatt turbine with a good wind resource should generate just over $180 worth of electricity a month at current rates ($0.34 per kilowatt hour).

How long will this rate be offered?

The ‘net-metering’ rate is subject to change in the future, but any changes must be approved by the Energy Commission, and the Government is committed to ensuring a fair rate is paid to those producing electricity from renewable energy resources.

Micro-Wind Turbine System Installation Information

What local companies install micro-wind turbines?

Several local companies offer micro-wind turbines, though the Government does not yet certify installers. If you are considering buying a turbine, ensure your installer holds an appropriate qualification. Installers should hold a NABCEP Small Wind Installer Certification, other similar certification, or possess a strong background in engineering.

Can I install my own system?

It is very important for micro-wind turbines to be properly designed and installed if they are to perform in a safe and efficient manner. Due to the cost of micro-wind turbines, the difficulty in assessing the wind resource at any given site and the potential safety hazards of improperly installed turbines, the Department of Energy recommends you use a certified installer who has the necessary knowledge and experience to ensure your system is properly designed and installed. A certified installer should also be able to ensure your system meets BELCO’s qualifying criteria so you can interconnect with their electrical grid.

How do I know if a turbine is good quality?

There are many start-up companies manufacturing turbines that do not have a proven track record of reliable service, so look for a turbine manufacturer with at least 10 years’ experience in producing turbines. Many turbine manufacturers do not provide accurate information on the performance of their products, so ensure turbines have been independently tested. Look for models that have been approved by the US Small Wind Certification Council (SWCC) or have received accreditation from the  Microgeneration Certification Scheme (MCC).

These certification schemes are relatively new so you may have to wait a few months to find a certified turbine. Inverters should comply with IEEE 1547 and UL 1741 so make sure you ask your installer for equipment that meets these standards. These standards are also listed in BELCO’s qualifying criteria and must be adhered to if you wish to interconnect with their electrical grid.

Should I look for a warranty on a system?

Look for a manufacturer’s warranty on the turbine, mounting structure, and inverter of at least five years. Installation warranties vary from company to company, so make sure you ask around and choose carefully.

Will a micro-wind turbine survive a hurricane?

The survivability of a turbine depends on how well it has been designed, built and also upon the particular conditions experienced during a hurricane. If your system is properly designed, installed and maintained using high-quality products it should withstand category 3 hurricane force winds, though the Department of Energy recommends you plan to lower and secure the turbine prior to hurricane force winds. It is best to discuss any concerns directly with your installer, though you may also wish to consider insuring your system. Remember that damage could occur from flying debris such as loose tree branches, so if a hurricane is approaching, make sure you trim any trees and secure any loose objects near the turbine.

Batteries, the electric grid and BELCO

Do I need batteries to store the electricity produced by a micro-wind turbine?

Battery systems increase the cost of a turbine installation substantially and if you are connected to the electric grid, there is probably no need to have any. By entering into an interconnection agreement with BELCO, they will act as your back-up by providing electricity when you need it and accepting excess electricity generated by your turbine back into the grid, for which you will be credited.

Can a micro-wind turbine provide electricity when there is an electricity outage?

Most grid-connected turbines automatically disconnect from the electric grid if there is an outage to prevent electricity flowing back into the electrical grid when it is off. This prevents electrocution of line-workers who may need to repair damaged equipment. Although battery systems can provide backup power in case of an outage, a small generator is usually a more cost effective option for most homes.

What will my legal relationship with BELCO be?

BELCO offers a standardized interconnection agreement for small-scale renewable energy generation systems, which must be signed by both BELCO and the customer before you can connect your turbine to the electric grid. This agreement provides a clear legal framework for your relationship with BELCO, which creates a consistent and safe way for small-scale renewable generators to connect to BELCO’s electric system. The agreement is available from BELCO’s website, www.belco.bm.

How does the billing work?

Once the interconnection agreement is approved by BELCO, a new electric meter will be installed to track both the energy you consume and the energy you export to the electric grid. At the end of each month, all energy produced will be subtracted from the energy you have consumed and your bill adjusted appropriately. If you produce more than you consume over a six month period, you will be given a net bill credit on either 30 June or 31 December.

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