Archive for the ‘base load’ tag
Geothermal as base load
Australia’s left-leaning New Matilda yesterday published a piece asking, Is Geothermal The Baseload Alternative? It reminds me that I want to get around to publishing my own calculations of price per megawatt for various energy sources in both Australia and the US. Geothermal could be crucial to the energy mix over the next few years but there are too many figures floating around out there. So more on that soon.
The author, David Hollier, provides a neat summary of how geothermal works:
To harvest geothermal energy, you need to drill four to five kilometres below the surface, where the rock temperatures are 200 degrees or more, hot enough for the liquid they heat to drive turbines. The first challenge is to get wells down into this layer to check that the rocks are hot enough. If they are, you can pump water into the rock at a pressure high enough to fracture the rock, and to allow the water to move through the fractures, forming a reservoir. Then other wells are drilled, and the hot water is pumped back up to surface where it drives the turbines.
Once the system is up and running, this hot water can be constantly recycled. There are no other inputs into the process. Unlike wind and solar, it does not rely on specific weather conditions. And apart from the wells, there is no “mine” as such: minimal demands are made of the land. Geothermal is a renewable energy source that taps the ceaseless heat production at the earth’s core as it radiates towards the surface.
He raises an issue that I’ve mentioned a few times recently here:
So if all this is true, why have we heard so little about geothermal? If it’s a solution to the clean energy crisis, why hasn’t industry development been accelerated before now? Is it a victim of coal industry resistance — or a PR failure? Or might it have something to do with the fact that there are now more lobbyists than credible climate change scientists doing the rounds in Canberra?
Too bloody right. As Al Gore has noted many times, the lack of political will is the chief obstacle to action on global warming:
A couple of minor points. First, geothermal is not totally GHG-neutral. There are some emissions, primarily associated with the construction of the plant. Also, I take issue with David’s point here: “Solar and wind. Wind, tidal and solar. We all know that these can’t yet deliver baseload.” This is not true and I’ve written about it before.