One of the less appreciated privileges of becoming a tenured professor at Harvard University is that most people consider even your wildest ideas seriously.
Federico Capasso, the Robert L. Wallace Professor of Applied Physics at Harvard University’s School of Engineering and Applied Sciences (SEAS), is likely testing the limits of this privilege with a proposal to power the planet with electricity harvested from infrared light emitted from Earth into outer space
If Capasso taught introductory physics at a two-year community college, it seems unlikely that most people would bother writing about his wild-eyed proposal.
But Capasso teaches a genre of science at Harvard University so spectacularly complex that it might as well be magic as far as the lay person is concerned.
In other words, no matter how wild-eyed his ideas may seem, people tend to take them seriously.
And for good reason. Capasso, an Italian-born expert in quantum optics and photonics, pioneered the field of band-gap engineering and co-invented the infrared quantum-cascade laser in 1994.
By most measures, Capasso’s most recent proposal to construct devices that generate electricity by releasing infrared light certainly seems to qualify as wild eyed.
Rather than capturing incoming visible light like a conventional solar photovoltaic panel, Capasso wants to generate direct current electric power by emitting infrared light.
“It’s not at all obvious, at first . . . To generate power by emitting, not by absorbing light, that’s weird. It makes sense physically once you think about it, but it’s highly counterintuitive,” said Capasso. “We’re talking about the use of physics at the nanoscale for a completely new application.”
The proposal appears in this week’s issue of the Proceedings of the National Academy of Sciences.
The paper describes two types of emissive energy harvesters. The first type of harvester is analogous to a solar thermal power generator while the second is similar to a solar photovoltaic cell. The abstract is illuminating:
Renewable energy can be generated whenever heat flows from a hotter to a colder body. One such flow is from the warm surface of Earth to cold outer space, via infrared thermal radiation. An emissive energy harvester (EEH) is a device that can generate energy from emitting thermal radiation into the clear sky. We calculate how much power is thermodynamically available, using a location in Oklahoma as a case study. We discuss two possible ways to make such a device: A thermal EEH (analogous to solar thermal power generation) and an optoelectronic EEH (analogous to photovoltaic power generation). For the latter, we propose using a rectifying antenna, and we discuss its operating principles, efficiency limits, system design considerations, and possible technological implementations.