Sometime, I think that "Proof of Work" is very similar to "Proof of Burn".
Usually in "Proof of Burn" you "burn" some cryptocoin sending it to an invalid address, and the blockchain has a proof that they are unrecoverable. (It was popular before someone notice that with an ICO you can have your cake and eat it too.)
In "Proof of Work" you "burn" a few barrels or petrol to produce electricity and then make some hash with the electricity, so if you find the correct hash it is a probabilistic proof that you burned the petrol. (You can cheat with other source of energy, like solar or wind, but they also have a cost.)
Usually in "Proof of Burn" you "burn" some cryptocoin sending it to an invalid address, and the blockchain has a proof that they are unrecoverable. (It was popular before someone notice that with an ICO you can have your cake and eat it too.)
In "Proof of Work" you "burn" a few barrels or petrol to produce electricity and then make some hash with the electricity, so if you find the correct hash it is a probabilistic proof that you burned the petrol. (You can cheat with other source of energy, like solar or wind, but they also have a cost.)