Megawatt a mega climate change buzzword

We are now (Nov 2009) in the countdown to the Copenhagen Conference on Climate Change (COP15). You will need to intimately understand what a megawatt is and how it is used. It may not become the scientific buzz-word that its cousin megabyte did, but if you want to properly participate in the greenhouse debate, you need to throw megawatt into your conversation every now and then and even megawatt hours.

What is a megawatt?

A megawatt (abbreviated to MW) is a metric unit of power. It is made up of mega – the Greek word designated to mean one million – and watt, named after James Watt (1736-1819). Watt was a British engineer who “invented” the modern steam engine and in doing so is credited with creating the industrial revolution.

A watt is the metric measurement of power that replaced horsepower (a much more tangible measure). A horse (we assume a standard working horse of the 18th century) when harnessed to a machine will lift 550 pounds at the rate of 1 foot per second. This is one horsepower, as defined by James Watt.

The watt is the basic metric measure of power and is defined in reference to other metric measures. The watt is equal to a power rate of one joule of work per second of time. In electrical terms, one watt is the power produced by a current of one ampere flowing through an electric potential of one volt. At this point we move on.

So back to the megawatt! It is therefore equal to one million watts, which for reference is equivalent to about 1340 horsepower (if that helps).

In the energy industry the MW is used to describe the capacity of power generating plants or the usage level of the power. One megawatt is enough to power approximately 800 residential homes.

Australia’s power capacity

Australia has a total power capacity of over 53,000 MW.

According to ANSTO (report no longer available) three-quarters of Australia’s electricity (in 2009) came from coal, 14 per cent from natural gas, eight per cent from renewable sources (mainly hydroelectric, wind power and bioenergy) and one per cent from oil.

The Snowy Mountains Hydro-Electric Scheme has a capacity of about 3756 MW.

There were 50 wind farms in Australia at the close of 2008, with a total of 756 operating turbines. The total operating wind capacity was 1,300 MW meeting 1.3% of Australia’s energy demand.

In May of this year (2009), Australia’s Prime Minister, Kevin Rudd, announced plans to build the world’s largest solar power station with a capacity of 1000 MW.

What is a megawatt hour (MWh)?

There is one more thing you need to know: the metric unit of energy, especially electrical energy, is the megawatt hour (MWh). This is a measure of how much energy is produced (or consumed). The megawatt tells you the capacity of a plant and the megawatt hour tells you have how long it was running and therefore how much energy it produced.