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Energy isn't actually produced as amount of energy in the universe is constant... It's just form of the energy that is converted back and forth.

This is also the core reason for avalanche effect in required hashing power for most proof-of-work coins... It's essentially self-feeding loop. Because it takes longer to unlock the mining rewards than to unlock normal transfers, people need to constantly mine more blocks to get rewards of previous blocks.

Like I've written before, only way to solve the issue is to avoid accepting blocks with too small amount of transactions. When the actual time between subsequent blocks increases too much compared to expected time, it will drive the difficulty down and that makes mining blocks easier, thus less profitable with powerful hardware.

If difficulty drops too much, it causes the network to generate more potential blocks and that causes more competition between miners and mining pools and that drives the difficulty back higher...