In the CleanCoin project, South Pole examined the climate impacts of cryptocurrencies and developed a

live emissions calculator of the Bitcoin and Ethereum blockchain networks. We did this to raise awareness

and provide opportunities for wallet holders to take action, and to further define the key attributes of a

sustainable digital currency.

southpole.com 1523EN, 11.2017

THE CLEANCOIN PROJECT

CO2 for Bitcoin and Ethereum vs equivalent banknote

Bitcoin Ethereum0

2

4

6

8

10

12

1 Ethereum = $2980.31 tCO

2

$5,506 in £10 banknotes0.02 tCO

2

$298 in £10 banknotes0.001 tCO

2

1 Bitcoin = $5,50611.2 tCO

2

Co2 emissions of one Bitcoin and Ethereum versus an equivalent value in banknotes

The challenge

The ‘Proof of Work’ system that both Bitcoin and Ethereum are

currently based on means their energy use and thus greenhouse

gas emissions are higher than other forms of currency.

Each time currency is bought or sold it is transferred in a network.

This is called a transaction. With more transactions per block,

Ethereum has a lower carbon footprint per transaction than the

Bitcoin blockchain. However, no cryptocurrency can yet handle

as many transactions per second as the Visa network does.

Ethereum aspires to this level but needs to become more than

30,000 times more efficient to do so. Bitcoin is further behind -

180,000 times less efficient than Visa.

These cryptocurrencies’ current carbon footprints are significant.

With over 7.7 million tonnes of CO2 Bitcoin’s footprint is roughly

equivalent to the total carbon emissions of Costa Rica for one

year. While Ethereum’s is almost 60% lower at around 3.1 million

tonnes of CO2, it is still roughly equivalent to the total carbon

emissions of Namibia over the same time period.

The solution

If cryptocurrency and other Blockchain technology developers

and users become aware of the problem, changes can be made:

• Proof of Stake could be a much more energy efficient

alternative to the Proof of Work system now used to verify

and validate a transaction or block.

• Green labels can be developed for cryptocurrency miners

and Blockchain technologies that are driven by renewables

or use more energy efficient systems.

• Carbon offsetting options for cryptocurrencies can be

developed – the cost of offsetting would be much lower

than the value of the coins.

• More efficient hardware is available. If Ethereum mining

hardware were as energy efficient as the specialised

hardware used for Bitcoin mining, its overall emissions per

coin and per transaction would be even lower when

compared to Bitcoin.

Bitcoin vs. Ethereum hashrate

9,935,312 Th/s 115 Th/s

10,000,0001,000

100,0001,000,00010,000

10,000,0001,000

100,0001,000,00010,000

© 2017 South Pole Group. The information contained herein is subject to change without notice. South Pole Group shall not be liable for technical or editorial errors or omissions contained herein.

0

1

2

3

4

5

6

CO2 per transaction Hardware efficiency

0.06 tCO2

0.01 tCO2

0.00000033 tCO2 Bitcoin Ethereum

J/Mh

0.00017 J/Mh

5.4 J/Mh

Bitcoin vs. Ethereum hashrate

CO2 emissions per transaction Hardware efficiency

Disclaimer: The findings in this factsheet are from analysis of data collected on October 24th, 2017. They will not therefore match the current numbers for greenhouse gas emissions for Bitcoin and Ethereum displayed on the live greenhouse gas calculator at: www.cleancoins.io