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Living Lightly column

Free, clean and safe energy, anyone?

By Lauriston Muirhead

Coal is mostly carbon (C).  When we burn it for energy, the carbon combines with oxygen (O2) in the air and produces carbon dioxide (CO2).

CO2 is very good at absorbing heat – so more CO2 means more energy from the sun is retained in our atmosphere.  This was clearly demonstrated by Eunice Foote in 1856 and many others since – including “The Mythbusters – Does CO2 warm air?”  Yes, this is what is causing the earth to heat up.

Let’s say we could safely and cheaply capture the CO2.  That would be fine – except for the mercury.

Each tonne of coal contains about 0.1 gram of mercury.  This doesn’t sound like much but, in Australia, we burn about 250,000 tonnes of coal per day.  This equates to about 25,000 grams or 25 kilograms per day of mercury being released into the environment.

The sea now contains so much mercury that pregnant women are advised not to eat too much of certain types of fish as they accumulate mercury and are known to create foetal abnormalities.  Let’s say we could capture all the CO2 and mercury.  That would be fine – except for the methane.

When coal is mined, methane trapped within the coal seams is released into the atmosphere.  Not as much methane is released from mining coal as CO2 is from burning it, but methane is 25 times more “warming” than CO2.  Let’s say we could capture all the CO2, the mercury and the methane.  That would be fine – except for the nitrous and sulphur oxides.

These oxides are released when coal is burnt and produce smog and acid rain.   Let’s say we could capture and store the CO2, the mercury, the methane and the oxides.  That would be fine except for the radioactivity.

Burning coal concentrates the natural radioactivity within the coal resulting in most coal fired power plants being more radioactive than most well run nuclear power plants.

Surely if we could fix all the above, it would be fine.  Except coal, just like oil and gas, will run out.  So why don’t we use forms of energy that will never run out, where the energy source is free and the conversion to electrical energy is clean and safe?

Carbon capture anyone? Or perhaps solar, wind, pumped hydro and storage!