No, that number sounds like a marginal number to me. Someone else commented that miners pay an average of like 4 cents per kWh, which works out to about $30 of electricity costs to miners per transaction. Recent per-transaction miner fees are currently in the $10-20 range, but don't forget the winning miner gets a reward that's currently ~$330,475 per block.

That's terrifying if true. 741 kWh per transaction seems absurd.

> The difference is important because as Bitcoin adoption increases the number of transactions will increase

No, the maximum number of transactions per block is fixed (actually, the maximum size of a block is fixed, but there's a limit to how small each transaction can be).

> and the cost-per-transaction will fall dramatically.

No, because of the limit on the number of transactions, the cost per transaction will increase (users have to pay a higher per-transaction fee to increase the chance of it being included in a block, and miners are incentivized to use the extra income from transaction fees to buy more power).

> No, the maximum number of transactions per block is fixed (actually, the maximum size of a block is fixed, but there's a limit to how small each transaction can be).

This has nothing to do with whether the number of transactions will increase.

>No, because of the limit on the number of transactions, the cost per transaction will increase (users have to pay a higher per-transaction fee to increase the chance of it being included in a block, and miners are incentivized to use the extra income from transaction fees to buy more power).

My point was that they seem to be counting overhead beyond the marginal transaction cost, and if they are, then the number they report will fall as the transactions increase. You seem to be talking about how the marginal cost per transaction will increase.