As Bitcoin's price hits a new all-time high, it's now estimated to use as much electricity as the whole of Argentina But is this remotely sustainable? Justin Rowlatt speaks to cryptocurrency expert and University of Chicago economics professor Gina Pieters about why such heavy energy consumption is an intrinsic feature of Bitcoin, and why the higher it's value rises, the more its energy footprint expands. But what about it's carbon footprint? That's a debate we get to hear both sides of, with crypto evangelist Ethan Pierse saying that Bitcoin miners are helping to finance the expansion of renewable energy sources, while the more sceptical data analyst Alex de Vries says they are burning plenty of fossil fuels to compete in an expensive and pointless lottery. Plus Kenneth Rogoff, the former chief economist of the International Monetary Fund, compares Bitcoin to a work of modern art, and wonders whether its future may be as a curiosity at a Star Trek convention in the year 2100. Producer: Laurence Knight (Picture: Blue Neon light, Bitcoin shape; Credit: Getty Images)