You can save % energy per transaction by using Bitcoin Cash (BCH) instead of Bitcoin (BTC)
If the Bitcoin Cash (BCH) blocks is fully used for payments, the energy cost per transaction gets as low² as $ 
If the Bitcoin (BTC) blocks get filled¹ with payments, the transactional energy cost alone will still be $ 
A typical payment takes up  bytes .
The average miner uses  joule per TH .
Miners pay an energy costs of  ¢ per kWh .
Nonmining energy costs is insignificant .
Energy statistics
BTC
BCH
Total energy consumption (kilowatthours / day)
Estimate based on last 24 hours
 Wh
 Wh
Energy consumption per transaction (kilowatthours / transaction)
Estimate based on last 24 hours
 Wh
 Wh
Optimal based on full blocks¹
 Wh
 Wh
Fee market statistics
BTC
BCH
Cost per transactions (US cent / transaction)
Energy cost
 ¢
 ¢
Paid fee
 ¢
 ¢
Optimal cost based on full blocks¹
 ¢
 ¢
Network statistics
BTC
BCH
Hashrate (Terahashes / second)
Estimated² based on last 24 hours
 Th
 Th
Transactions (transactions / day)
Measured³ from the last 24 hours


Optimal based on full blocks¹


Measured³ from the last 24 hours


Optimal based on full blocks¹
 b
 b
¹ Bitcoin (BTC) is calculated with a 2mb blocksize to accomodate the space from segwit .
² Optimal energy efficiency is still far from ideal, and needs to be improved significantly.
³ Measured statistics was fetched with the Blockchair API.