Hey mate. Chains are secured in different ways. The big one is Proof of Work (PoW), that's how bitcoin and ethereum work. It uses computer processing cycles to secure the network. That uses a lot of energy.
Chains like Hive use a different method. Proof of Stake/Delegated proof of stake.
PoS/DPos doesn't use energy intensive computer cycles to secure the network; so uses dramatically less power. Somewhere around 1-3%.
Considering crypto is at this point inevitable, supporting chains which use Dpos is arguably more environmentally friendly than not using chains at all. (and letting PoW become the default standard.
Hope that helps. Happy to clarify if need be.
RE: What is the environmental impact of Hive? [I'm asking, I don't have the answer]