There's an interesting paper on an Ambient Temperature Power Harvester, which was presented at The ACM International Joint Conference on Pervasive and Ubiquitous Computing (UbiComp):
...we present a thermal power harvester that utilizes naturally changing ambient temperature in the environment as the power source. In contrast to traditional thermoelectric power harvesters, our approach does not require a spatial temperature gradient; instead it relies on temperature fluctuations over time, enabling it to be used freestanding in any environment in which temperature changes throughout the day.
This design is inspired by the Atmos Clock, a 17th century clock design, which contains a small expansion chamber, and uses the expansion and condensation of a gas to make a small mechanical motion. There are details on How the Atmos Clock works, and the history of the clock. The original clock used the motion for mechanical winding, where this design converts the motion to electrical energy, and provides:
...the ability to power a sensor node, transmit sensor data wirelessly, and update a bistable E-ink display
after as little as a 0.25 °C ambient temperature change.
The paper itself is a available for download as a five page PDF, and there's a simple demonstration video of the device.
Reported at New Scientist, with earlier stories from Nanowerk and The University of Washington.
(Score: 4, Informative) by tonyPick on Friday September 19 2014, @02:02PM
Minor correction: It's the implementations of "atmospheric pressure and temperature" powered clocks that date back to the 17th century. Technically the Atmos is specific to the name of a later design and implementation: From wikipedia
The first Atmos clock was designed by Jean-Léon Reutter, an engineer in Neuchâtel, Switzerland, in 1928.
(But you can't edit submissions once they're in the queue.)
(Score: 2) by tibman on Friday September 19 2014, @03:44PM
It isn't much power at all but it is interesting that it can harvest when both cooling and heating. Even indoor climate controlled areas have temperature swings over 0.25C. Very niche but very cool too.
SN won't survive on lurkers alone. Write comments.
(Score: 2) by bob_super on Friday September 19 2014, @03:48PM
That's the answer to cell battery issues if you're shopping in the Midwest.
Winter: Freezing cold outside, nice temp inside.
Summer: uncomfortably hot outside, freezing cold inside stores (applies to most of the US)
If you're trailing the wife through a shopping spree, at least your toys could remain charged to keep you distracted at each stop.
(Score: 4, Interesting) by Zinho on Friday September 19 2014, @07:25PM
The Long Now foundation commissioned a rather large-scale clock [longnow.org] that runs on a similar principle:
The Clock is designed to run for 10,000 years even if no one ever visits (although it would not display the correct time till someone visited). If there is no attention for long periods of time the Clock uses the energy captured by changes in the temperature between day and night on the mountain top above to power its time-keeping apparatus. In a place like a top of a mountain, this diurnal difference of tens of degrees in temperature is significant and thus powerful. Thermal power has been used for small mantel clocks before, but it has not been done before at this scale.
I assume that the Atmos clock referred to in TFS is the prior art referred to by the Long Now clock's writeup.
I love seeing new uses for old technology! It amazes me that the paper's authors managed to run electronics on the 21mJ harvested in a day/night temperature cycle, kudos for the inventive use of old tech for the power source.
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin