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Green power

Wind farms

Wind farms - a form of green power.

Credit: iStockphoto

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Where does it come from?

There are many forms of green electricity, ranging from the emission-free solar and wind alternatives through to burning the by-products of sewage treatment. Unfortunately, no single power technology is adequate to replace coal as our primary source of electricity, but each has its particular role to play.

One of the purest forms of electricity generation is solar. According to the National GreenPower Accreditation Steering Group, the average amount of solar energy that lands on Australia each day is enough to handle our energy needs 15,000 times over.

Photovoltaic cells are used to convert a small proportion of that solar energy directly into electricity. Several energy companies are now using solar power as a form of green energy, much of which comes from the largest solar farm in the southern hemisphere, based in Singleton in NSW. This solar farm, partially funded by the NSW government, has an impressive 480 kW capacity, and it alone reduces carbon dioxide emissions by 550 tonnes a year.

Backed by BHP Billiton and Rio Tinto, engineering firm, Worley Parsons recently announced they intend to build the world's largest solar power plant in Australia, operational in three years. It could power 300,000 homes.

Solar power is clean and emits no greenhouse gases during generation, but it’s currently limited in its application due to the expense of photovoltaic cells and the fact that the sun stops shining at night-time. With projects the scale of the solar power plant, the cost is expected to come down. But we will always have night-time. Proponents of solar point out that energy demand is reduced while everyone is sleeping, and suggest that combining solar with wind can address the issue.

Wind is another popular form of green electricity generation, and is rising in popularity worldwide, especially in Europe. All you need to generate power using wind is a big windmill and a consistent breeze – something in the region of 20 km/h to 30 km/h.

However, like solar, wind is unreliable (no wind = no power). Furthermore, there are limited locations where wind power can be used – although Australia is blessed with some ideal locations, especially in the south of the mainland as well as Tasmania. In fact, around 10 per cent of South Australia’s electricity is already generated by wind power – in 2002, they had no wind farms.

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