I don't have a source, but the current block reward is $275,000 plus another 20% or so in transaction fees, and it stands to reason the energy cost of mining a

I don't have a source, but the current block reward is $275,000 plus another 20% or so in transaction fees, and it stands to reason the energy cost of mining a block should converge to the block reward plus transaction fees. You get about one block and 2000 transactions every ten minutes.