While crypto moves so quickly that it may feel like forever ago, Ethereum’s transition from proof-of-stake to proof-of-work is still spawning fresh research on the energy consumption of blockchain networks—most recently from the University of Cambridge.

The Cambridge Centre for Alternative Finance (CCAF), best known for its Bitcoin energy consumption dashboards and research at the Cambridge Judge Business School, unveiled its Cambridge Blockchain Network Sustainability Index (CBNSI) on Wednesday.

The tool explores the environmental implications of the merge while comparing Bitcoin to Ethereum—the two largest cryptocurrencies by market cap. It also represents the organization’s foray into publishing dashboards for proof-of-stake networks.

Bitcoin and Ethereum once relied on a proof-of-work mechanism for validating transactions, where computers continuously crunch complex calculations in hopes of winning tokens as a reward. But last summer, Ethereum finally transitioned to proof-of-stake, where transactions are verified by actors that have pledged tokens to a network, often in the form of staking.

While the Ethereum Foundation was quick to say the transition made Ethereum 99.95% more energy-efficient, according to CCAF research, the energy consumption of Ethereum plummeted by 99.99% after the merge.


Using height as an analogy, the research compares the current energy use of Bitcoin to Ethereum, both before and after the merge. 

If Bitcoin’s energy use was represented by Malaysia’s Merdeka 118, the second-tallest building in the world at 679 meters, Ethereum’s pre-merge energy usage would have been the London Eye at 135 meters—around five times smaller. To continue the analogy, CCAF writes the post-merge Ethereum network could be represented by a raspberry, or 1.5 centimeters.

However, researchers noted that electricity consumption doesn’t completely describe the network’s carbon footprint. It fails to capture the greenhouse gas emissions linked to its computing power, the researchers wrote.

The tool marks the latest research produced under the Cambridge Digital Assets Programme (CDAP), a research initiative hosted by the CCAF in collaboration with organizations such as the International Monetary Fund (IMF), according to a blog post. The initiative is also being conducted in collaboration with a few staid financial institutions, such as Fidelity, Goldman Sachs, Invesco, Mastercard, and Visa.


The tool also provides energy estimates for Bitcoin and Ethereum that are updated daily. At each network’s current rate, the index estimates Ethereum’s annualized power consumption as 5.8 gigawatt-hours compared to around 132.2 terawatt-hours for Bitcoin.

The energy consumption of blockchain networks has been a contentious topic for years. And the conversation surrounding Bitcoin’s carbon footprint has heated over the last month, following an expose on Bitcoin mining by the New York Times and an art piece backed by Greenpeace titled “Skull of Satoshi.”

When Cambridge’s electricity index for Bitcoin was released in 2019, Cambridge researchers acknowledged that the measure of Bitcoin’s energy use was a “best guess,” explaining it’s hard to measure reliably due to constant fluctuations.

Similarly, the artist behind the “Skull of Satoshi” said the energy consumption conversation surrounding Bitcoin isn’t black-and-white, having engaged in conversations with people who believe Bitcoin mining supports the demand for greener power sources and helps give a purpose to what would be wasted energy.

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