The critisized article uses 550g/kWh for the German grid mix, but in 2018 it already was down to about 480g/kWh and is on track to be lower in 2019 as reneweabl

The critisized article uses 550g/kWh for the German grid mix, but in 2018 it already was down to about 480g/kWh and is on track to be lower in 2019 as reneweables are expanded. So that number is quite off already. H.W. Sinn has made a range of presentations (you can find them on youtube if you understand German) where he tries to show how reneweables are infeasible. Also there, he has the pattern to use slightly out of date numbers as basis of his calculations. I actually have met C. Buchal at university, but that is quite some time ago. He is a really nice guy and as a physicist he should have spotted the shortcomings of this publication. But from what I have read, he is working on synthetic fuels, so that might explain the angle.