RadCasts

Nuclear power should be a powerful ally in the fight against climate change but cost and safety issues hold it back. Could a new generation be safer and cheaper? Tom Heap meets the team behind the molten salt reactor that can use nuclear waste as fuel and is claimed to be significantly cheaper and safer than current reactors.

Ian Scott was a senior scientist at Unilever, pioneering research into skin-ageing, but when he retired from the field of biological sciences he became fascinated by the costs of nuclear power. Why had nuclear electricity- which we'd once been promised would be 'too cheap to meter'- become one of the most expensive forms of energy generation. The answer lay with the safety mechanisms that have to be built-in to reduce the risk of another Chernobyl or Fukushima. If he could develop a system that would be much safer then it would, almost certainly, be much cheaper.

Scott's central idea- to use molten salt as a coolant rather than water- caught the eye of energy authorities in Canada and Ian's company, Moltex, has plans to build its first reactor in New Brunswick. Significant safety concerns remain, with some in Canada concerned about Moltex plans to use spent fuel from conventional reactors and others raising fundamental issues about the corrosive qualities of molten salt and the generation of radioactive tritium

Tom visits the Moltex laboratories and climate scientist, Tamsin Edwards, gauges the potential impact on greenhouse gas emissions.

Producer: Alasdair Cross Researcher: Sarah Goodman

Produced in association with the Royal Geographical Society. Special thanks for this episode to Professor Ian Farnan and Dr Eugene Shwageraus from the University of Cambridge.

Biochar is an idea thousands of years old but one that seemed to have been (foolishly) lost by many along the way.

Like charcoal, biochar is made by baking wood in the absence of oxygen and then quenched. It can then be ground down and worked into the soil to improve fertility and crop yields. It's believed to have been applied thousands of years ago in the Amazon, to generate the Terra Preta.

The biochar locks in much of the carbon captured by the trees and stabilises it. Tom meets Forester Dave Faulkner and his team at Whittlewood to see the productions process in Northamptonshire.

Meanwhile, Josiah Hunt experimented with the process in Hawaii and now supplies across California. As well as capturing carbon and improving the soils, he says they're removing liability wood to reduce forest fires and are helping to produce green electricity.

Can this ancient process help bring new hope?

Producer Anne-Marie Bullock Researcher Sarah Goodman

Produced in association with the Royal Geographical Society. Special thanks for this episode to Professor Stuart Haszeldine and Dr Ondřej Mašek from the University of Edinburgh and the UK Biochar Research Centre.

Concrete blocks are the foundations of the modern world but they could be greener. Tom Heap meets Colin Hills and his team turning waste dust and carbon dioxide into building materials.

Professor Hills of the University of Greenwich has developed a technique that mimics natural processes, using carbon dioxide as a glue to form stone aggregates from waste dust left behind by heavy industry. The spin-off company, Carbon 8 Systems, has compressed the process into a shipping container and now makes building materials in the UK and France with this clever carbon-munching technique. Colin's colleague, Nimisha Tripathi wants to adapt the system for the developing world, choosing waste from her native India- things like pistachio shells and banana skin- to make a tailored range of building products relevant to the region in which they're made.

Tamsin Edwards of King's College London joins Tom to consider just how much carbon dioxide we can remove from the atmosphere by developing this new generation of bricks and mortar. Producer: Alasdair Cross Series Researcher: Sarah Goodman

Produced in association with the Royal Geographical Society. Special thanks for this episode to Professor Paul Fennell and Dr Rupert Myers of Imperial College London and to Professor Karen Scrivener of École Polytechnique Fédérale de Lausanne.

How to improve mass catering for the planet. Tom Heap considers how changing the menus in schools, hospitals and the armed forces could help in the fight against climate change.

Andy Jones, chair of the Public Sector Catering 100 Group, explains how his own farming family background informs his drive to reduce the amount of meat served in canteens and increase the choice of vegan and vegetarian options. Tom visits hospitals in Nottingham to see the drive in action and joins climate scientist, Dr Tamsin Edwards to consider the carbon impact of a broader shift from beef to beans.

Producer: Anne-Marie Bullock Researcher: Sarah Goodman

Produced in association with the Royal Geographical Society. Special thanks for this episode to Dr Rosie Robison from Anglia Ruskin University and to Dr Tara Garnett and Dr Peter Scarborough from the University of Oxford.