The buzz around the cryptocurrency grows after Elon Musk’s Tesla reveals it has bought $1.5bn worth of Bitcoin. But what’s its impact on global energy use? Plus how people in China have been using the Clubhouse audio social app to discuss usually banned topics. And new figures on the performance of the Covid-19 contact tracing app used in England and Wales. Presented by Rory Cellan-Jones, with BBC senior tech reporter Jane Wakefield. Produced by Jat Gill. (Image: Representation of a Bitcoin plugged into a power outlet. Credit: Getty Images).