They've just unveiled the world's largest air purifier in Iceland. Christened "Mammoth" the machine can filter up to 36,000 tons of CO2 from the atmosphere every year. It's the biggest carbon capture device ever built – but is it mammoth enough? And do the economics stack up? Other scientists are using microbes to speed the process of mineralisation, the turning of CO2 into rock. And all the while the search for alternative energy sources continues with an Icelandic company even getting ready to drill down into an underground magma chamber to try and tap its thermal potential. Dr Rudy Kahsar – Manager, Carbon Dioxide Removal Team, Rocky Mountain Institute (RMI) Dr Gokce Ustunisik – Associate Professor of Petrology, South Dakota School of Mines and Technology Bjorn por Gudmundsson – Chief Executive Officer, Krafla Magma Testbed Dr Jess Adkins – Professor of Geochemistry and Global Environmental Science, California Institute of Technology