Although Proof-of-Work (PoW) has proven through Bitcoin to be the most secure mechanism for securing a blockchain, this past year has shown that mining as we know it is not secure. As PoW problems be continuously revealed and amplified over the course of 2018, the value and success of mining has been increasingly contended.
When the price of Bitcoin exploded in 2017, so did the amount of work miners contributed while competing to mine blocks and accumulate BTC. Environmentalists were increasingly concerned as energy consumption by the blockchain continued to grow, eclipsing that of many entire nations. At current rates, the energy consumption of Bitcoin is comparable to that of Hong Kong.