How does wind energy work?

Wind is a clean and infinite energy source, which can be a big piece of the energy puzzle. Here we'll walk through how wind energy works.

A brief history

Although modern wind turbines are new technology, harnessing wind energy is not a new concept.

Throughout history we’ve harnessed the wind’s energy, with sail boats and windmills used to pump water and process grain.

How wind energy works - turbines

Turbines are the most common electricity-generating method. The wind turns large turbine blades, which spins a generator shaft and produces electricity (more about the parts of a wind turbine)

The electricity can then charge batteries, be connected to a building’s mains power, or connected to the power grid.

Wind turbines come in all shapes and sizes, from large scale wind farms to small scale wind turbines used to power a single home or business.

The European Union is leading the way with 48 percent of the world’s installed wind power capacity. In 2009, wind turbines installed in the EU produced 163 TWh of electricity – avoiding 106 million tonnes of carbon emissions [1].

Residential wind options include small wind turbines such as 500w rated turbine generators – enough to run lighting or a few appliances – to larger scale turbines such as a 2kw rated – enough to power an entire house plus sell some to the national grid depending on how much you use.

The most common model is the blade turbine, however a new style of turbine has recently emerged – vertical axis turbines.

Vertical axis turbines are smaller, lower to the ground, and create less noise – so are good for residential areas.

The praticalities of how wind energy works is simple, but socially and economically, not so simple.

How much electricity can a turbine produce?

Electricity output depends on a number of variables including location (how much wind there is), turbine size and style, and rotar diameter.

Wind turbines have a rated capacity - how much electricity they will produce at optimal wind speeds. A 2kW rated wind turbine will produce 2 kWh of electricity for every hour it's exposed to optimal wind.

Generally, residential wind turbines are designed to function with wind speeds between 11 and 15 meters per second [3]. Larger turbines are often positioned in high wind-exposure locations, so are designed to function at higher wind speeds - thus producing more electricity.

Because of the intermittent nature of wind, general guidelines are that wind turbines will output between 10-40% of their rated capacity [3].

A realistic estimate of how much electricity a wind turbine would produce can be calculated using the average wind speed and hours for your location and turbine model specifications.You can calculate this yourself, or a local dealer will have all the measurements.

The debates for and against wind power

The main hindrance to wind power’s proliferation is the capital costs. Wind turbines are large and cost a lot of money to construct. They also require a reasonable amount of land, which is another expense that makes this free energy not so free.

Interfering with the aesthetics of the land is another issue with wind turbines. The ideal location for a wind turbine is often rural and natural landscapes. Just as any issue of social policy, some people don’t mind seeing wind turbines out their front window, and some do.

Another issue with wind power is that wind is intermittent. It’s not windy all the time in every location, so wind power production doesn’t happen around the clock. The true power of wind energy is positioned as a contributing piece to the clean energy puzzle.

A secondary cost consideration is savings on carbon taxes and Emissions Trading Schemes – which are set at a per kg amount. A report on the New Zealand wind energy economy states that increasing wind energy installations to supply 20% of the country’s electricity needs will mean nationwide savings of $390 per person per year – based on production and carbon-tax reductions. [2]

An interesting discussion is the cost of developing clean energy technologies – and the lack of commercial viability compared to conventional energy such as coal or nuclear. An interesting fact to note is that early nuclear development was subsidised by approximately $19/ kilowatt hour. Early wind technology worldwide was subsidised at approximately $0.57 / kilowatt hour.

Unlike conventional energy production, wind is infinite and it doesn’t produce any toxic by-products such as carbon or ethane.

It also doesn’t require any ongoing raw resources, which are expensive in terms of energy used for extraction, pollution from extraction and transportation, as well as financial costs of equipment and ongoing labour hours.

Summary

In summing up, wind is a low cost, low maintenance energy production method.

Wind energy works by harnessing natural wind movements, capturing it as kinetic energy through turbine blades, then converting the kinetic energy into electricity through an electro magnetic generator at the top of the turbine.

References

[1] European Wind Energy Association (EWEA). (2011). Statistics and targets.

[2] Infometrics Ltd. (2011). The potential contribution of wind generation to the economy: Report to New Zealand Wind Energy Association.

[3] Energy Efficiency and Conservation Authority (EECA). (retrieved 2011). Small Wind Turbines. Retrieved from http://www.energywise.govt.nz/how-to-be-energy-efficient/generating-renewable-energy-at-home/small-wind-turbines#the