title_body: How does Cardano compare with other blockchains in terms of being eco-friendly? It is pretty common knowledge now that Bitcoin is extremely energy intensive to mine, and that Cardano is several orders of magnitude less intensive. However, there are other cryptocurrencies that are marketed as eco-friendly, like Nano, but they are not necessarily blockchains. How does Cardano compare to other blockchains and cryptocurrencies in terms of being eco-friendly?
  Also, how will this change in the future if Cardano gains the same popularity as Ethereum or Bitcoin? Will this cause Cardano to become more energy intensive to mine, thus making it less eco-friendly?
upvoted_answer: The rate of transactions per second does not affect Cardano's power consumption significantly, but implementation of smart contracts, scaling mechanisms, etc. may have a measurable impact in the future.
  Cardano is largely as eco-friendly as all proof-of-stake blockchains.  Its actual energy consumption is roughly the power consumption of a typical staking pool node times the number of staking pool nodes.  The power consumption per transaction is millions of times more energy efficient than Bitcoin.
  In general
  
  Proof-of-work (PoW) blockchains rely on the miner's ability to produce the answer to a question whose answer must be guessed, then proven to be correct.  The more guesses and proofs that the miner can make per second, the higher their odds of winning the next reward.
  Proof of stake (PoS) blockchains rely on the quantity of a cryptocurrency owned or delegated to the miner to raise their odds in a fair lottery to win the next reward
  
  PoW blockchains favor miners with the most computing power and PoS blockchains favor miners with the most coins (owned or delegated).
  Over time this has led to the two largest PoW cryptocurrencies (Bitcoin and Ethereum) using millions of times more power than PoS blockchains.
  Cambridge Bitcoin Electricity Consumption Index