Why the new consensus mechanism is needed in blockchain technology?

The Blockchain with PoW consensus was first developed to solve the cryptocurrency double-spending and byzantine fault problem. The PoW consensus solved the problem very effectively. But due to its high computation and specialized hardware need, a lot of questions from society has been raised on the PoW consensus. To solve the limitations of PoW, a lot of other consensuses have been proposed in the literature as an alternative solution of PoW. However, the other consensus has its own benefits and drawbacks. So, to understand the consensus mechanisms our paper first describes the internal architecture of blockchain and then explain five consensuses of the blockchain network with its detailed comparative analysis of internal characteristic. We believe this comparative analysis will be helpful for those researchers who need to understand the major characteristics that a given consensus offer for their work.