@laufi @michiel

So at the end of the day it's never choice between "clean" and "dirty" but between "more and less dirty". Therefore the only objective comparison is between specific engineering metrics, which are well described for all energy sources:

* lifecycle greenhouse gas emissions (how much CO2 per kWh)
* surface power density (how much area taken per kWh)
* capacity factor (how much time it works)

And then eventually you can look at price (LCOE).