It was an example, since obviously different uses of energy will have different improvement factors - but major uses of energy have considerable improvement factors. In case of heating, for example, the factor is theoretically infinite because it's possible to build net-zero-energy buildings. And specifically in case of Germany, a very large portion of natural gas consumption goes into heating, so this is quite relevant here.

> if you point is that it would be cheaper to duplicate a significant portion of our energy generation, one based on renewables and one based on fossil fuels for safety...

I didn't say a word about basing something on fossil fuels.

> that is perhaps true, but that only proves the original point, so I'm a bit confused why you phrase your replies in an antagonistic tone of voice when we seem to agree

I don't see how we "seem to agree". The comment I initially responded to was proposing storing a WEEK's worth of PRIMARY energy in TODAY'S amounts in BATTERIES. Nobody would seriously consider such a contrived scenario; it would be completely pointless. So I can't possibly agree with those numbers.