Hydro power has been used as a stick to beat the left for years, fairly ignorantly it turns out. As recently as last week, luminaries such as Piers Akerman, renowned hydrogeologist and power-systems engineer have been hoping to wedge the left by pointing out their perceived hypocrisy. The old adage goes: If the left were really serious about addressing climate change, they would dam the country to capacity, and power our economy to hydroelectric, zero emissions victory!
There are three major errors bundled into this statement, all easily disproved. I’m surprised Piers’ engineering training hadn’t led him to these conclusions himself, given how confidently hydro is supported, calling it “the only real alternate source of renewable energy”.
For starters, the renewable and sustainable credentials of large-scale hydro-electric power are very much in dispute. From a sustainability point of view, the problem is methane. Dams require large areas of land to be flooded, usually containing plant material. The water excludes oxygen, and causes the plant material to anaerobically decompose. Anaerobic digestion leads to methane emissions and methane is a powerful greenhouse gas. The maths of the comparison are complicated, but lowering CO2 emissions by emitting more methane, which is 20 times more potent as a greenhouse gas, is a pretty risky strategy.
The argument over whether damming a river is a renewable energy source is debatable too. I assume in this case Piers is referring to how wonderfully dispatchable hydro power is. One literally just turns on the tap and electricity comes out. But, obviously, rain is required for there to be any water to let out. Even really wet places run out of water and therefore run out of electricity. The Basslink DC cable from Tasmania to the mainland was built to transfer the abundant hydro power they had and make some money in the NEM. However, it stopped raining, and rather than exporting, Tasmania imported 70% of their electricity in 2007. For the same reasons that “more dams” is not a suitable potable water supply policy option, more dams will not guarantee our electricity supply.
How much capacity are we talking about anyway? If we built every single dam available to us in Australia, how much electricity could we produce? The current best estimate for “technically feasible” (at any cost) hydroelectric power in Australia is 60TWh annually. In 2009-10, we used closer to 240TWh, about four times the total hydro power available.
So can hydro-electricity power Australia? Not really. Is it renewable anyway? Almost certainly not. Are there actually low carbon alternatives? Absolutely. And I’ll get to them in future posts.