Ethereum’s energy consumption from the blockchain's inception in 2015 until it moved to a proof-of-stake (PoS) consensus mechanism late last year is about equal to that used by all of Switzerland in just a year, according to the University of Cambridge’s Centre for Alternative Finance (CCAF).
The CCAF, known for estimating the Bitcoin network’s energy consumption over the past several years, says Ethereum’s consumption totaled 58.26 Terawatt hours (TWh) between 2015 and the so-called Merge. Switzerland’s annual electricity consumption is 54.88 TWh, while Bitcoin’s is 143.9 TWh, according to the CCAF.
It’s not just Bitcoin network's energy consumption that’s a worry for the environmentally conscious. For example, artists exploring the craze for non-fungible token (NFT)-based collectibles have expressed their concern over the amount of power needed to mint works on Ethereum.
To this end, CCAF has cast its net wider and released the Cambridge Blockchain Network Sustainability Index (CBNSI), and with it an in-depth study of Ethereum’s electricity use from a contemporary and historical perspective.
The move to PoS reduced Ethereum’s consumption by over 99%. To illustrate the impact of the change, CCAF provided a comparison with the height of some well-known edifices.
If, for example, Bitcoin’s energy use is represented by Kuala Lumpur's Merdeka building, the second-highest in the world at some 678.9 meters (2230 feet), Ethereum’s previous proof-of-work (PoW) mining consensus system would stand at the comparable height of the London Eye, a 135 meter-high observation wheel. As a PoS power consumer, Ethereum has shrunk to the size of a raspberry, according to CCAF.
Being a not-for-profit institute, the CCAF aims to provide public value, hence the creative approach to illustrating energy use, explained Alexander Neumüller, CCAF research lead for digital assets and energy consumption.
“If I go out on the street now and ask, 'Hey, what is 100 terawatt hours? What is six gigawatt hours?' people don't know,” said Neumüller in an interview with CoinDesk. “So we have tried to contextualized it in the form of pictures, specifically with the buildings and, of course, the raspberry. This makes these magnitudes very clear without an understanding of energy notations.”
While Ethereum’s energy consumption is now orders of magnitude smaller than Bitcoin’s, CCAF is careful not to take a view on which algorithm might be better or worse, said Neumüller. He told CoinDesk that, in his opinion, proof-of-stake is not a perfect substitute for proof-of-work, and that a lot of additional factors come into play.
“When you talk about PoW, for instance, it is very hard to attack the network, even if you have extensive financial resources, because you actually need to buy and employ hardware as well as get access to energy,” he said. “PoS is really more financial based. So if your main objective was to disrupt the network, it would just be a case of acquiring the native tokens.”
CCAF estimates Ethereum will consume 6.56 GWh of electricity annually. To put that into perspective, the annual electricity consumption of the Eiffel Tower is 6.70 GWh, while keeping the lights on for a year at the British Museum requires 14.48 GWh.
Providing an estimate of Ethereum’s historical energy footprint is useful for projects that may want to start offsetting that debt, which happens to be a post-Merge project underway at ConsenSys. This offsetting process is being addressed by a group of Web3 firms now called the Ethereum Climate Platform.
“We decided to look back at the seven years of proof of work Ethereum,” said ConsenSys head of partnerships Steven Haft in an interview. “We looked at our so-called historic carbon debt to see what we could do to clean up our record of emissions over these over these past years.”
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