As a civilization, we are proficient with the “boil water, make steam” method of turning various heat sources into power we feed our infrastructure. Away from that, we can use solar panels. But what if direct sunlight is not available either? A team at MIT demonstrated how to extract power from daily temperature swings.
Running on temperature difference between day and night is arguably a very indirect form of solar energy. It could work in shaded areas where solar panels would not. But lacking a time machine, or an equally improbable portal to the other side of the planet, how did they bring thermal gradient between day and night together?
This team called their invention a “thermal resonator”: an assembly of materials tuned to work over a specific range of time and temperature. When successful, the device output temperature is out-of-phase with its input: cold in one section while the other is hot, and vice versa. Energy can then be harvested from the temperature differential via “conventional thermoelectrics”.
Power output of the initial prototype is modest. Given a 10 degree Celsius daily swing in temperature, it could produce 1.3 milliwatt at maximum potential of 350 millivolt. While the Hackaday coin-cell challenge participants and other pioneers of low-power electronics could probably do something interesting, the rest of us will have to wait for thermal resonator designs to evolve and improve on its way out of the lab.
Early on in the year, Hackaday published one of its short daily pieces about plans from the people behind altpwr.net for a low voltage DC power grid slated for the summer’s SHACamp 2017 hacker camp in the Netherlands. At the time when it was being written in the chill of a Northern Hemisphere January the event seemed so far away, but as the summer fades away along with the deep tan many SHACamp attendees gained in the Dutch sunlight it’s worth going back and revisiting the project. Did they manage it, and how did they do? This isn’t really part of our coverage of SHACamp itself, merely an incidental story that happens to have the hacker camp as its theatre. Continue reading “That Decentralised Low Voltage Local DC Power Grid, How Did It Do?”
January, for many of us in the Northern Hemisphere, can be a depressing month. It’s cold or wet depending where you live, the days are still a bit short, and the summer still seems an awfully long way away. You console yourself by booking a ticket to a hacker camp, but the seven months or so you’ll have to wait seems interminable.
If you want an interesting project to look forward to, take a look at [Benadski]’s idea for a decentralised low voltage local DC power grid for the upcoming SHA 2017 hacker camp in the Netherlands. The idea is to create a network that is both safe and open for hacking, allowing those with an interest in personal power generation to both have an available low-voltage power source and share their surplus power with other attendees.
The voltage is quoted as being 42V DC +/- 15%, which keeps it safely under the 50V limit set by the European Low Voltage Directive. Individuals can request a single 4A connection to the system, and villages can have a pair of 16A connections, which should supply enough for most needs. Users will need to provide their own inverters to connect their 5V or 12V appliances, fortunately a market served by numerous modules from your favourite Far Eastern sales portal.
This project will never be the solution to all power distribution needs, but to be fair that is probably not the intention. It does however provide a platform for experimentation, collaboration, and data gathering for those interested in the field, and since it is intended to make an appearance at future hacker camps there should be the opportunity for all that built up expertise to make it better over time.
We’ve touched on this subject before here at Hackaday, with our look at the availability of standard low voltage DC domestic connectors.
Wind turbine image: Glogger (CC BY-SA 3.0) via Wikimedia Commons.