Friday 15 July 2016

Or maybe we should not be worrying about storing solar energy

There's a conventional wisdom on solar power in particular, and renewables in general, that we need storage to make it work properly. According to brave new climate that will probably stop them from being effective. 

They look at the energy return on energy investment (EROEI) and cite the low score for solar. In other words, the amount of energy that will come out of solar panels is not really enough to make solar panels. This means they are not sustainable and rather than contributing energy, they are using up energy created elsewhere. He suggests we should not just talk about the actual energy used in the process of manufacturing the solar panels, but also things like food and education for the people who are making them. 

Anyway, an energy source with an EROEI of one would just produce enough energy to support itself, and would be of no use to the society. The threshold for useful energy sources is something like 7. 

I have sometimes watched fish jumping out of the river to catch a fly, and wondered whether they were using more energy to catch the fly than they got out of eating it. EROEI is a bit like that. 

He quotes an EROEI of 3.5 for solar panels in Germany. This is already marginal, and if we have to store energy from renewables, then we also need to add the battery infrastructure into considerations of the EROEI, which could make solar a net user of energy rather than supplier. 

There are two other considerations. First is that solar production costs are falling all the time, and this includes embodied energy. The other is that we may soon have batteries parked outside each house in the car.