Renewable harvesting

Sustainable Energy – without the hot air - 10 pages - David J.C. MacKay

PC/laptop consumes about 0.2 kWh/day, which is 200W during 1 hour (or 2 lightbulbs for an hour, or roughly 20W during 24 hours).
iPhone consumes about 0.005 kWh/day (2 kW/year which is to power ten 100-watt incandescent lightbulbs for an hour)
A human consumes about 125 kWh/day

average energy measured in kWh, meaning averaged use during a day
How Much Electricity Do Your Gadgets Really Use?

Harvesting the Earth’s infrared energy

Year-round, the devices would produce an average of 2.7 W/m2, or 0.06 kWh/m2 per day, the researchers calculated.

Harvesting renewable energy from Earth’s mid-infrared emissions- Steven J. Byrnes, Romain Blanchard, and Federico Capasso

https://en.m.wikipedia.org/wiki/Electromagnetic_spectrum

technical papers

• Harvesting renewable energy from Earth’s mid-infrared emissions

A Shockley-Queisser analysis of an ideal optimized diode, taking into consideration the realistic transmissivity spectrum of the atmosphere, indicates the theoretical maximum power density of 3.99 W/m2 with the diode temperature at 293 K. The results here point to a pathway towards night-time power generation.

• Radio-Frequency Rectifier for Electromagnetic Energy Harvesting: Development Path and Future Outlook By Simon Hemour, Member IEEE, and Ke Wu, Fellow IEEE

This paper reviews the evolution and the historical milestones/breakthroughs of
electromagnetic energy conversion techniques over the years with an emphasis on
low-density energy-harvesting technologies.