This happens already!! As the other commenter mentioned you need transmission lines between the countries, but in more developed parts of the world this is the norm.

One of my favourite websites shows current generation as well as the interconnects between grids: https://app.electricitymaps.com/map/72h/hourly

To clarify, it is a significant stretch that under British law Palestine Action committed any acts of terrorism.

It is mostly an authoritarian overreach.

And the reason that people are protesting so vehemently is two-fold:

Firstly, it is critical for the functioning of our society, that the government is not able to freely carry out gross abuses of power such as the designation of Palestine Action as a terrorist group.

Secondly, it is relatively trivial for the government to use their proscription of Palestine Action as a basis for the proscription of subsequent protest groups, and they have also already used it to arrest people simply for signs which say things like “free Palestine”.

In other words, protestors are able to make twice the impact with a single protest.

You are correct that the protests are specifically about the group Palestine Action. Which while they have committed crimes within the UK haven’t committed any acts of terror. And therefore should not be classified as terrorist.

The terror act was extremely controversial when it was enacted because it grants the government far reaching authoritarian abilities which are fundamentally against our standard of human rights.

It is only acceptable for extreme cases of groups which are in fact committing acts of terror against civilian population.

Therefore, it is protesting against the decision to designated a group which is not terrorist as terrorist