Too bad this twitter thread is completely free of sources. It made looking up the real numbers way more difficult than it needed to be. I was also entirely unsurprised to see a push for nuclear at the end, because the pro-nuclear camp shares with the green NGO's a visceral dislike of proper sourcing of facts.

But, ok, let's check just the first tweet that makes factual claims:

"Nearly 40% of Europe’s so-called renewable energy is currently obtained by combusting wood, much of it coming from forests in the US."

40%! Wow, that's crazy! If it were true of course.

So here's the EC brief on biomass energy in the EU, with data as of 2018 (pre-brexit):
https://publications.jrc.ec.europa.eu/repository/handle/JRC1...

"Biomass for energy (bioenergy) continues to be the main source of renewable energy in the EU, with a share of almost 60%. The heating and cooling sector is the largest end- user, using about 75% of all bioenergy (see section 1)."

So, 60% of renewable energy comes from biomass, but what is biomass?

"Forestry accounts for more than 60% of all EU domestic biomass supplied for energy purposes: in 2016, direct supply of woody biomass from forests and other wooded land contributed 32.5% (44 Mtoe), and indirect supply of wood contributed another 28.2% (38 Mtoe). Almost 27% (36 Mtoe) originated from agricultural biomass (equally from agricultural crops and agricultural by-products), with waste (municipal, industrial, etc.) making up the remaining 12.4% (17 Mtoe)."

So, that's 60% of wood that is part of the 60% that is biomass, which comes to around 36%. Not quite 40%, but still bad if all of it is unsustainable. And you can clearly see that rounding this number up is where the 40% comes from. Greenpeace by the way uses 35% in their materials, also opposing wood pellets but for different reasons, so you can tell they're drawing from the same source but rounding down instead of up.

But, is it unsustainable? What do direct and indirect mean?

- "Direct supply of woody biomass from forests and other wooded land for energy generation includes: fellings, residues from fellings (tops, branches, bark, stumps) or landscape management residues (woody biomass from parks, gardens, tree rows, bushes)."

- "Indirect supply of woody biomass includes: residues from sawmilling, woodworking, furniture industry (bark, sawdust), by-products of the pulp and paper industry (black liquor, tall oil) or processed fuelwood, post-consumer recycled wood (recycled wood for energy generation, household waste wood)."

I would say that the indirect wood does look like it's a sustainable practice, reusing material that otherwise is wasted. And the direct wood includes landscape management residues, which also are clearly material that otherwise would go to waste. So, I would say that if we look at actual felled trees that are used directly for burning, that comes to less than 30% of 60%, or less than 20% of renewable energy that comes from burning actual felled trees. That's already quit a step down from 40%.

Alright, but where do those trees come from, and are they unsustainable? Are there really vast amounts of wood pellets being transported from the U.S.?

"Biomass supply for bioenergy (i.e. primary energy) in the EU reached 140 Mtoe in 2016. Of this, 96% was sourced from within the EU and the remaining 4% was imported from non-EU countries."

"Wood is the most important single source of energy from renewables in many Member States."

"Wood pellets have become an important energy carrier traded on a large scale and over long distances, due to their high energy density and stable characteristics. Global production reached 29 million tonnes in 2016, of which more than 50% was produced in the EU. The EU is also the main consumer globally (23 million tonnes, of which 32.6% is consumed in the UK, 9.1% in Italy, 8.7% in Germany, 8.7% in Denmark and 7.4% in Sweden). In some Member States, the consumption of wood pellets relies mostly on imports, e.g. the UK (94.7%) and Italy (81%). Wood pellets are mostly used in the residential sector for heating (in Italy, Austria, etc.) or for electricity production (in the UK, Austria, etc.)."

So, not that much is actually imported, and the EU is actually the largest wood pellet producer in the world, and fully a third of the consumption of wood pellets was done by the UK. So, that means that the EU numbers will look better post-brexit. Amusingly, the UK is a nuclear energy proponent.

So, that's just the first tweet that makes a factual claim. There are a bunch of others which with a cursory glance look equally dubious. I'll leave it to others to fact check those.

So, in conclusion, I would say make of this what you will, but I think it's safe to say that this twitter thread is mostly nonsense.