Hi, this is KJ. I am a Ph.D. candidate from the University of Liverpool.

I am proposing a useful PoW without replacing Nakamoto Consensus. I named it Economic Proof of Work (EcoPoW).
I have talked about this algorithm to several experts in Blockchain,
including Dr. Jiaping Wang, Dr. Qi Chen from MSRA, Dr. XiaoKang Mo, Prof. Xi Chen from NYU, and received positive feedback.
It is relatively simple to understand if you are familiar with PoW and Proof of Replication (PoRep).

EcoPoW uses PoW as an encoding algorithm during the PoW outputs consensus.
As the consensus uses the left bits of the hash output binary (the more 0s, the more difficulty), the encoding algorithm uses the right N bits.
When N=8, we encode 1 byte at a time (around 256 sha2 hashes to encode 8 bits).
Since N is adjustable, we can change the difficulty of encoding, such as 2 bytes a time (around 65536 hashes to encode 16 bits ).
The encoding is expensive as designed, and decoding is cheap as it only takes one hash operation.

The reason we need to use PoW as an encoding algorithm is that the computation can be used for Proof of Replication.
It is the key algorithm for blockchain storage, such as Filecoin.
Filecoin uses PoRep for user data security against Outsourcing Attacks.
The core idea of PoRep is to encode the user file's original content into a unique replication with their unique name as a key (a public key can be used as the key).

When verifying, the prover needs to compute the proof from the replication instead of the original content.
Even the prover can perform an Outsourcing Attack by fetching the replication from others and decoding in seconds,
and he still needs a lot of computation and time to encode the decoded content with his name into his unique replication.
This prevents the Outsourcing Attacks as it is cheaper to keep the replication honestly on his storage device.

After diving into the research, once the PoW is useful, there are some important impacts:
1. The miners are making money by selling their computation and storage resources.
The coins are not the only revenue source for the miners.
2. Once the computation is consumed locally, miners will no longer sell the computation to the mining pool to exchange the coins.
It will bring true decentralization to the blockchain world.
3. The PoW computation is task-based.
If there is no demand, the computer will go to sleep mode to save energy.

We propose to build a blockchain with storage and EcoPoW.