Running computers 24/7
The consensus mechanism (proof-of-work a.k.a. mining) behind the blockchain requires alot of energy. A network of computers that’s constantly trying to solve complex mathmatical formulas to get a reward in Bitcoin and hold up the blockchain. This asks alot of electricity. Not only to solve the complex formulas, but also to keep the hardware cooled. You can imagine that the mining computers can get really hot after calculating formulas the entire day.
Fun fact
An estimate for the bitoin blockchain is that a transaction consumes as much energy as one and a half household in the US per day. If the Bitcoin blockchain continues its current growth, it will consume as much energy in 2020 as denmark.
Can you call this energy, wasted energy? The energy is the price you pay for creating and maintaining a decentralized system that can be trusted. It is an essential component for the economy to work around public blockchain applications.
Alternatives
Many other blockchains try to work on a more sustainable blockchain that doesn’t require as much energy as bitcoin does today. And not only that, many alternative consensus algorithms have been created eversince bitcoin came to our sence.
Here is a great article about a variety of consensus algorithms!
link: https://medium.com/the-daily-bit/9-types-of-consensus-mechanisms-that-you-didnt-know-about-49ec365179da
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Sem