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Published on March 22nd, 2013 | by Jo

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# When will the greenhouse power a green house?

According to the Quarterly Update of Australia’s National Greenhouse Inventory, over the year to September 2012, greenhouse gas emissions from Australian sources totaled 546.1 Megatonnes of CO2 equivalent (Mt CO2-e).

Of this, 190.7 Mt CO2-e was emitted from electricity production — which was a decrease of 2.4% from the previous year. Emissions from electricity decreased partly because Australia used less electricity, and partly because renewable sources were used more while sources such as coal were used less.

Specifically, electricity generation from:

* black coal decreased by 3.7% (from 107.4 to 103.4 Terawatt hours)
* brown coal decreased by 2.4% (from 54.3 to 52.9 Terawatt hours)
* natural gas increased by 3.0% (from 23.2 to 23.9 Terawatt hours)
* hydroelectric stations decreased by 1.1% (from 14.7 to 14.6  Terawatt hours)
* renewable sources (other than hydroelectric) increased by 10.1%, from 6.4  to 7.1 Terawatt hours.

Assume, rather unrealistically, that these percentage increases and decreases continued from year to year. In such a scenario, when would electricity production from renewable sources (hydroelectric and others) overtake production from coal (black and brown)?

Question created by Chaitanya Rao, Daniel Mathews and Norman Do

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