One of the best pieces of scientific news the last decades has been the spectacular improvements in solar energy generation. The current world price was set in 2017 when the Dubai government bought a large future solar contract for 7.3 US cents per Kilowatt Hour, a mere 1/6th of the price in 2010. Compared to the 1970s, solar cells now cost less than 1% of what they were then. Unless you own a coal mine, that counts as great news!
Let’s dream out loud a little as to what this revolution in solar might lead to this century. I expect solar to transform the deserts around the world, and I like the fantasy that solar power will be used to green Australia’s deserts by pumping desalinated water up to the top of the Dividing Range.
Before sharing such dreams, let us first discuss a few technological bottlenecks to wider-scale adoption. A continuing problem for solar is that it is intermittent, meaning that large-scale usage depends on technology to store surplus energy and transport it to and from the areas of generation to where it is used. Both long-distance electricity transport and large-scale storage remain very expensive and very limited in scope at the moment, despite technological advances in both.
As a rule of thumb, you lose 5% of the electricity for every 1,000 kilometres of electricity transport, and even that requires prohibitively expensive electricity lines. That rules out any fantasy wherein Australian solar farms supply New York!
Battery storage has come a long way since the 70s, with of course the big Tesla battery in South Australia showing that you can have large batteries that can turn on and off very quickly, which is important for solar applications because solar is very variable. Yet, even that battery is relatively small and not capable of storing whole days worth of population consumption, and it’s way too expensive as a storage device to allow solar to compete with fossil at the moment for large-scale supply to the grid. It’s current function is to smooth intermittent supply from fossil-fuel power stations, making fossil fuel more attractive!
In case you’re wondering: batteries in the form of ipads or electric cars are basically too small fry to make much of an impact on this equation.
You might think there is some clever combination that solves all problems. For instance, you might fantasise about storing surplus electricity by pumping up water to some high-mountain lake from which you later on draw electricity by having it fall down again. Think carefully about the main issues involved: you lose something like 20% of the energy pumping the water up at the mountain; you need very unusual mountainous terrain that allows you to have two large lakes from which the water tumbles and gets pumped up without much leakage at either end; and if the population is 2,000 kilometres away, you lose another 20% getting the electricity to and fro. All this is quite apart from the installation and running costs of the lakes, the pumps, the solar panels, and the electricity lines. From my reading, such a package is a long way off being commercially viable, and really only a longer-term dream for countries like China that have the requisite mountainous terrain. Continue reading