[91] No efficiency without flexibility

Those values are useful to compare the energy efficiency of a cogeneration system with that of separate generation. But seen from a distance, aren’t they relics from another era? If you exchange an electricity grid connection and a natural gas boiler for a solar PV panel generating the electricity for both your house and your heat pump, isn’t that also a cogeneration system? Moreover, one with infinite efficiency? That is, if you are going off-grid, which is unlikely, because you will have difficulty to match supply and demand.

This brings us to another weakness of those efficiency calculations: they don’t take the time of electricity and heat production into account, while in fact both vary considerably in value over time.

[60] Is using the internet efficient?

What is the carbon footprint of the internet? The ‘immateriality’ of the internet may be an illusion. Search robots and social media sites are big users of server energy. In 2007, ‘Greening the media’ reported that the energy use of information technology is close to 3% of all energy use, similar to aviation. But how to get away from this? Should we introduce a concept like “internet use efficiency”?

At least, contrary to aviation, computer servers use electricity, an energy carrier that is well on its way to decarbonisation.