Wow! The solution to our energy needs....

Gah. "Thermal resonator", forsooth. BITD even MIT engineers knew that you can't get a resonance out of the heat equation because it has a real-valued, first-order time dependence.

Cheers

Phil Hobbs

NT

Cursitor Doom also reads - and believes - the Daily Mail. What's being talked about is one more micro-energy harvester that collects enough power to keep some micro-powered sensor/monitor going indefinitely.

The Linear Technology application notes is dated 2010 so the idea has been around for a while.

I doubt if MIT reported their development as anything else, but English science reporters don't know anything about science, and the Daily Mail is into writing "news" which titillates readers who don't known any better.

That's about 50x the energy budget of a pacemaker.

If you can harness thermal swings in a pacemaker, your patient might just have bigger problems.

Tim

They are engineers not mathematicians so I would bet on "NOT". For process engineers PID process controllers work by Magyck.

I rather liked the thin film passive device that cools itself in direct sunlight and there is now a derivative of that work that might even be viable. Selective absorbtion of thermal IR and reflection of most near IR and visible light to lose more by radiation than it gains from solar flux.

(the original was epitaxial growth bandpass filter technology)

I do wonder how well it works when it gets mucky though.

You can do a lot with that kind of power. But practical usage also requires small size and low cost. Otherwise you are better off just using a mid-sized battery.

A lot? No. Over 99% of apps are going nowhere on 1.3mW. Even a small coincell can outwit that.

NT

It sounds like they are storing energy (in some wax?) and then releasing it later. ~1mW for a few hours a day is hardly going to set the world on fire.

George H.

Thanks, GH

A CR2032 coin cell (quite a big one) has a standard discharge current of about 0.2 mA at 3 V - that is 0.6 mW. It has a capacity of perhaps 200 mAH. So two /large/ coin cell batteries are needed for 1.3 mW, and will last about a week at that power usage.

You can do lots with power budgets far lower than 1.3mW - as demonstrated by the number of gadgets that last for months or years on coin cell batteries.

Fick's law isn't compatible with special relativity, the elliptic heat equation is a non-relativistic approximation to a hyperbolic equation

Cool facts: the physics of heat and heat transfer is not completely understood by science. The undergraduate textbook version of "The Heat Equation" is wrong, it admits information propagation faster than light. Modifications of that equation to "correct" that problem upgrade it to a second order dependence in time, but formulations of equations like that then sometimes appear to violate the laws of thermodynamics.

Your average coin cell can put out waaay more than 0.2mA. 0.2 might be a self discharge figure, don't know, but nothing like their ability to supply.

NT

You can run a string of about a dozen LEDs for a couple hours off a CR2016; they bin them to have similar forward voltages and then run them in parallel off a single current-limiting resistor for the set

knew that

I'm not sure what you are on about? Is this in the article or something you have looked at? Heat is energy and that's pretty well understood, unless you are talking about theoretical temperatures during the big bang.

To understand metals/electrons you need some QM. The Sommerfeld theory of metals does a decent job. I went looking... this might be OK.

George H.

bitrex is an uneducated twit... at best spouting stuff from high school science classes.

Do us all a favor and stop responding to him. ...Jim Thompson