We're going to need a lot of solar panels

There are many chemical plants synthesizing chemicals in large quantities: ammonia, ethanol, etc.

Until 10 years ago, the cheapest primary fuel was all fossil fuel based, so making synthetic fuels from fossil fuels is simply a loss in efficiency.

Only in the last decade, for the first time, renewables are a cheaper form of primary energy, creating motivation for a fuel producing energy plant R&D.

BTW: instead of raging at people with your own definition of "real" and "not real" it may help to talk in terms of Technology Readiness Level as used by eg NASA. I can see why you say electricity to synthetic fuel "isn't real" but its not "not real" in the same way perpetual motion is not real.

Here is a similar project that generates kerosene and diesel from water and carbon dioxide by using a ceria-based redox reaction to convert them into hydrogen and carbon monoxide (syngas):

https://newatlas.com/energy/solar-jet-fuel-tower/

The plant created 5191 liters (1371 gallons) of syngas in 9 days, whereas a Boeing 787 Dreamliner carries 126,372 liters (36,384 gallons). The conversions are not linear, but that is something like a refueled plane every 219 days, give or take an order of magnitude. Looks like the conversion efficiency is 4% but 20% is expected after recycling heat and catalyst improvements.

I find stuff like this simultaneously inspiring and devastating. The technology has arrived to easily create our own electricity and fuel without having to deal with supply chain issues around centralized photovoltaic manufacturers, yet the size of the challenge is insurmountable. There is simply no way to scale this big enough to save the natural world before global warming destroys it at the end of the century.

So, that leaves us with nuclear power (fission). I appreciate that a lot of people have worked very hard on it and have humanity's best interests at heart. But they don't understand human psychology. We all know that we've been lied to about the safety of nuclear power, but they pretend that it can be made safe. While simultaneously avoiding discussion about the externalities like nuclear waste storage, nuclear proliferation, even the inherent security issues around large centralized power generation or what will happen after wars or other emergencies force workers to abandon nuclear facilities. So I don't trust them, and that's why I don't consider nuclear to be a viable alternative, and I have an unlimited list of evidence against it so I don't bother debating it anymore.

Which leaves us with what I feel is the actual solution. Yet again, as in most things, we have to pull ourselves up by our bootstraps. I think that we'll solve it through cultural evolution. Each of us has to get to sustainability on an individual level, then lift at least one other person (preferably someone we don't know) out of dependence. Which is still a big problem, but it's smaller than paying off a mortgage.

So everyone's gotta wake up, forget they got hoodwinked, stop listening to the wealthy and powerful people talking us out of this, and just start doing it. Be a real conservative, lead by example. Be a real liberal, pay it forward. Mourn the breakdown of our institutions that set this back 40 years. Then do something about it by evangelizing sustainability and stop voting for people who pass the buck. Help people who don't get it find their way out of cognitive dissonance.

Solarpunk is a great place to start.

Look at how well Europe's dependence on Russian gas is going.

Please don't forget that my claim is in the context of somebody else claiming that insulating all housing in Europe would at least take 100 years.

Now you are literally redefining the terms I use and then quoting them back to me to argue your new semantics, are you serious?

On average, a house is considered to last 100 years in Germany. Call it economic lifetime or whatever else you want. I still stand by that claim, as it is common knowledge. I quoted specific numbers on the housing stock which are consistent with that claim (though no proof of causation, as there are plenty of reasons why we have a lot of new stock, for example in general rising number of buildings.)

And of course the insulation is not "for free", but the additional costs are usually worth it. I also mentioned that many people decide irrationally because they do not want the work associated with planning and ordering the maintenance to be performed.

None of this matters to show that the above mentioned claim how long renovation of the current housing stock will take is completely out of the world.

Note that I am by no means a civil engineer or architect, but following the discussion and researching the topics associated with the Energiewende in the different sectors for over a decade now. I may still well be wrong in this instance. But you won't convince me of that if you try to prove me wrong on semantics and just asserting that I were intellectually unable to understand your arguments. So please also state some relevant facts and sources to support your claims if you want to try further to convince me, otherwise continuing this discussion is probably a waste of time for me as we both will probably not learn anything new. Thanks.

From what I've seen with old country side houses in France just insulating the roof and the windows can already bring very good results (heat lost through walls is usually only around 25% of all the losses). A quick and cheap solution for the roof is to lose the attic and blow the isolating material directly on it.