I was sad to hear of the recent death of Professor Sir David MacKay. I had met him at a few events over the years, but his real impact on me was through his book Sustainable Energy: without the hot air.
Hopefully everyone who reads this blog has also had the opportunity to read David’s book, if not I can highly recommend it. It is free to download here. The book is a wonderful tour of energy use, written in a language that everyone can understand. Most importantly, it seeks to challenge and correct the many assertions made about how quickly and easily we can change the energy system or how easy it would be to power everything from a particular source. Professor MacKay took exception to the loose talk and poor reporting around energy issues and sought to rectify it. In the opening lines of his book he notes;
Perhaps the worst offenders in the kingdom of codswallop are the people who really should know better – the media publishers who promote the codswallop – for example, New Scientist with their article about the “water-powered car.”
That single sentence sets the tone for a very entertaining and thoroughly informative deep dive into all things energy related, with the maths to back it up. He even delves into climate science and offers a wonderful analogy for why atmospheric carbon dioxide is rising when anthropogenic flows of the gas are so much smaller than natural flows (trees etc.). He compares the atmosphere to passport control at an airport!!
But the calculation that has stuck in my head over several years relates to hydroelectricity in the United Kingdom. I don’t know why I remember this story in particular, I am no more a hydroelectricity enthusiast than I am a nuclear enthusiast, but his explanation was just so elegant. Many people imagine that because it rains quite a bit in the UK that we ought to be able to power much of the country with hydro, particularly in Scotland where it is also quite hilly. Professor MacKay’s simple calculation involved the land area of the UK, the average rainfall, the average elevation and the wildly optimistic assumption (just to silence the optimists) that we would catch every drop of rain and then all the potential energy within that water as it drops from the point at which it initially hits the ground until it gets to sea level. The absolute upper limit for hydro comes out at less than 10 kWh/person/day, but the more realistic figure is <2 kWh/person/day. This is against energy demand of around 200 kWh/person/day. Actual hydro in the UK is just 0.2 kWh/person/day.
Sadly we have lost an inspiring energy enthusiast and an entertaining writer and speaker. RIP Professor.