By Danny Vincent
BBC News, Hong Kong
Chandler Guo was a pioneer in cryptocurrency, the digital currencies that can be created and used independently of national central banks and governments.
In 2014 he set up an operation to produce one of those currencies, Bitcoin, in a secret location in western China.
“Mining” Bitcoin is a power hungry enterprise involving dozens of computers so he used power from a hydroelectric station, in partnership with a local Chinese government official.
At its peak his machines were capable of mining 30% of the world’s Bitcoin. He believed Bitcoin would one day change the world and replace the dollar.
But now he sees a new force emerging – a payment system created by the Chinese state and known as Digital Currency Electronic Payment (DCEP).