Assalamualaikum,

Dear friend you mentioned the best issues raising in existing Blockchain and I'm fully agreed with your statement that Blockchain needed much power to run the system and consuming a large quantity of electricity.

The blockchain always requires space to store the blocks that are produced and could reach a saturation point. Even if you use nodes, they may require more space in the future.

Storage is also a problem but it can be solved when the issue become severe but it still a problem.

You mentioned the good features of Blockchain and Blockchain is immutable that is a impressive features of it.

Blockchain has advantages and disadvantages but we need to work to convert the disadvantages into advantages. Very amazing and informative entry.

Good luck in this contest. My best wishes are with you.

Regards: @cryptobitcoins