5. Outlook

Thermoelectricity, thermo-acoustic, combined turbo-supercharging, exotic thermodynamic cycles, thermal-electric and thermal-pneumatic co-generators are also now promising ways of harnessing waste energy.

The same is true of geothermal energy, which is booming as a means of harnessing waste and renewable energy, as in the Azores, where it accounts for almost 50% of the archipelago's local production of low-carbon energy, as in many other parts of the world.