One day everyone will use China's digital currency'

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).

It's really a digital version of China's official currency, the yuan, and Mr Guo feels DCEP will become the dominant global currency. "One day everyone in the world will be using DCEP," he says.

"DCEP will be successful because there are a lot of Chinese people living outside of China - there are 39 million Chinese living outside of the country.

"If they have a connection with China they will use the DCEP. They can make DCEP become an international currency."

But many question whether it will succeed and there are concerns that it will be used by Beijing to spy on citizens.