How much energy per transaction?

Assuming a fee of .033usd per transaction and an average energy cost of .141usd per kwh, it takes `.033 / .141 = ` .234kwh for one transaction.

Another way to calculate it is if there are 17921 transactions in 679 blocks in the last 24 hours, that's 26.4 transactions per block. The difficulty at time of writing is 223130858736, which means that it takes 22kwh for one transaction assuming a Ryzen 5950x at 21000 hashes per second drawing 200 watts `.2*223130858736/26.4/21000/3600`

That's a pretty big discrepancy...

Looking at the block reward, 198.92usd / 26.4 transactions / .141usd per kwh = 53 kwh

Are there any other ways to calculate the energy cost? Am I forgetting to factor something? Which method is most accurate? Will the energy cost change? If so, how and why?

The difficulty number isn't helpful to your calculation. Let's try this way:

The total network hash rate is 1.78GH according to https://monerohash.com/# on Jan 14th 2021. Let's say your Ryzen is getting 21,000 hashes per second at 200 watts. The network runs on a much more diverse set of CPUs than this fancy chip, but just to arrive at a number... that's 1,780,000,000 hashes/sec / 21,000 = 84,761 Ryzens. At 200 watts each, that's 16,952,200 watts. At 0.10 USD per kWh, the network burns \$1,695.22 per hour just to secure itself. With blocks at the regular 2 minute frequency, 30 blocks per hour, that's 1,695.22/30 = \$56.50 per block in electricity.

At our current transaction rate of about 900 transactions per hour, that's a nice round 30 transactions per block, so about \$56.50/30 or \$1.88 in electricity to do a single transaction. Of course, blocks can get much bigger, and we could scale up to many more transactions for the same amount of energy. It's probably best to just stick with the high level total hash rate divided by hashes per second of a reasonably efficient chip.

This estimate is probably low because the network is surely not using Ryzen 5950x's by and large.

• Is the discrepancy between the electricity cost per transaction and the actual fee because of Monero's inflation via mining? Mar 31, 2021 at 23:17
• Miners aren't aware of how much energy is being consumed at any given time, so there's no tie between fees and electricity cost. Miners consider the size of your transaction and the current median block size. See the pull request here: github.com/monero-project/monero/pull/1276/files. I'm just pulling this out of the air. Current code may differ. Yes, inflation/addition to supply with coinbase transactions are helping to pay for all that electricity. Depending on the price of Monero, the network should be more or less willing to mine it. Apr 2, 2021 at 5:19