You can do a bed & ISA the same day within an hour or two but you would have to pay CGT on any gains over £12,300 less any expenses less any other asset losses. This is on the gain in your ordinary share account.
The problem with green tech is that it relies on rare earth minerals for batteries, wind turbines, etc. So in 20 years time these minerals are going to be non existent on this planet. Long before oil runs out.
It will stay as "unknown" forever. All buys and sells are guesses anyway by the system. The only people who know for sure are the buyer, the seller and the MM.