For this reason, approaches to geo-engineering that merely reflect heat back into space need to be viewed cautiously.

ECONOMIST: Global warming

The witnesses include experts from the Institution of Engineering and Technology, the UK Energy Research Centre, and the Combined Heat and Power Association.

BBC: Week ahead

At Virginia Polytechnic Institute and State University, electrical engineering professor Dong Ha and his team are in the early stages of studying how to employ body heat to power a circuit.

WSJ: Harnessing Energy From the Body to Power Devices

Thousands of centrifuges are needed and the engineering is tricky, but the process is more easily hidden, with reasonable electrical requirements and no heat or gas that can be detected by sensors.

ECONOMIST: Asia.view