MIT Extracts Power from Temperature Fluctuations

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.

[via Engadget]

Harvesting Energy from the Earth with Quantum Tunneling

More energy hits the earth in sunlight every day than humanity could use in about 16,000 years or so, but that hasn’t stopped us from trying to tap into other sources of energy too. One source that shows promise is geothermal, but these methods have been hindered by large startup costs and other engineering challenges. A new way to tap into this energy source has been found however, which relies on capturing the infrared radiation that the Earth continuously gives off rather than digging large holes and using heat exchangers.

This energy is the thermal radiation that virtually everything gives off in some form or another. The challenge in harvesting this energy is that since the energy is in the infrared range, exceptionally tiny antennas are needed which will resonate at that frequency. It isn’t just fancy antennas, either; a new type of diode had to be manufactured which uses quantum tunneling to convert the energy into DC electricity.

While the scientists involved in this new concept point out that this is just a prototype at this point, it shows promise and could be a game-changer since it would allow clean energy to be harvested whenever needed, and wouldn’t rely on the prevailing weather. While many clean-energy-promising projects often seem like pipe dreams, we can’t say it’s the most unlikely candidate for future widespread adoption we’ve ever seen.

Injection Molding iPhone Cases from Trash

We imagine you’ve heard this already, but waste plastic is a problem for the environment. We wrap nearly everything we buy, eat, or drink in plastic packaging, and yet very little of it ends up getting recycled. Worse, it doesn’t take a huge industrial process to melt down a lot of this plastic and reuse it, you can do it at home if you were so inclined. So why aren’t there more localized projects to turn all this plastic trash into usable items?

That the question that [Precious Plastic] asks, and by providing a centralized resource for individuals and communities looking to get into the plastic recycling game, they hope to put a dent in the worldwide plastic crisis. One of their latest projects is showing how plastic trash can be turned into functional iPhone cases with small-scale injection molding.

Pushing plastic into the mold

The video after the break goes into intricate detail about the process involved in creating the 3D CAD files necessary to make the injection molds. Even if you don’t plan on recycling milk jugs at home, the information and tips covered in the video are extremely helpful if you’ve ever contemplated having something injection molded. The video even demonstrates a neat feature in SolidWorks that lets you simulate how molten plastic will move through your mold to help check for problem areas.

Once you’ve designed your mold on the computer, you need to turn it into a physical object. If you’ve got a CNC capable of milling aluminum then you’re all set, but if not, you’ll need to outsource it. [Precious Plastic] found somebody to mill the molds through 3DHubs, though they mention in the video that asking around at local machine shops isn’t a bad idea either.

With the mold completed, all that’s left is to bolt the two sides together and inject the liquid plastic. Here [Precious Plastic] shows off a rather interesting approach where they attach the mold to a contraption that allows them to inject plastic with human power. Probably not something you’d want to do if you’re trying to make thousands of these cases, but it does show that you don’t necessarily need a high tech production facility to make good-looking injection molded parts.

This project reminds us of the tiles made of HDPE plastic with nothing more exotic than what you’d find in the average kitchen. Projects like these really drive home the idea that with the right hardware individuals can turn trash into usable products.

[via 3DHubs]

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Biologic Additive May Lead to Self-Healing Concrete

If you get a cut or break a bone, your body heals itself. This everyday miracle is what inspired [Congrui Jin] to try to find a way to make concrete self-healing. The answer she and her colleagues are working on might surprise you. They are adding fungus to concrete to enable self-repair.

It isn’t just any fungus. The conditions in concrete are very harsh, and after testing twenty different kinds, they found that one kind — trichoderma reesei — could survive inside concrete as spores. This fungus is widespread in tropical soil and doesn’t pose any threat to humans or the ecology. Mixing nutrients and spores into concrete is easy enough. When cracks form in the concrete, water and oxygen get in and the spores grow. The spores act as a catalyst for calcium carbonate crystals which fill the cracks. When the water is gone, the fungi go back to spores, ready to repair future cracking.

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An Indoor Garden? That’s Arduino-licious

Gardening is a rewarding endeavour, and easily automated for the maker with a green thumb. With simplicity at its focus,  Hackaday.io user [MEGA DAS] has whipped up a automated planter to provide the things plants crave: water, air, and light.

[MEGA DAS] is using a TE215 moisture sensor to keep an eye on how thirsty the plant may be, a DHT11 temperature and humidity sensor to check the airflow around the plant, and a BH1750FVI light sensor for its obvious purpose. To deliver on these needs, a 12V DC water pump and a small reservoir will keep things right as rain, a pair of 12V DC fans mimic a gentle breeze, and a row of white LEDs supplement natural light when required.

The custom board is an Arduino Nano platform, with an ESP01 to enable WiFi capacity and a Bluetooth module to monitor the plant’s status while at home or away. Voltage regulators, MOSFETs, resistors, capacitors, fuses — can’t be too careful — screw header connectors, and a few other assorted parts round out the circuit. The planter is made of laser cut pieces with plenty of space to mount the various components and hide away the rest. You can check out [MEGA DAS]’ tutorial video after the break!

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Shah Selbe: Science in the World’s Wildest Places

When we think of building research hardware, lab coats and pristine workbenches come to mind. Shah Selbe used to do something kind of like that when he was engineering satellite propulsion systems. But after putting twelve of them into space, he ditched the office gig and took his gear to some of the wildest places on earth. He’s an explorer and fellow with the National Geographic Society, and at the Hackaday Superconference he shared his experiences building research hardware that gathers data in incredibly remote places.

Shah makes a really good point about two very different trends in our world over the past several decades. While we’ve had unparalleled technological growth, we’ve also seen horrifying wildlife trends to the point that some scientists believe we’re currently in a sixth mass extinction event. But to know that for sure, and look for ways to prevent and reverse it, we need reliable data. This is a fascinating problem because the world is huge, and we simply can’t monitor everything.

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Less Dear Heating For The Deer

Keeping animals from tropical regions of the world in a cold climate is an expensive business, they need a warm environment in their pens and sleeping areas. Marwell Zoo was spending a small fortune keeping its herd of nyalas (an antelope, not as the title suggests a deer, native to Southern Africa) warm with electric heating, so they went looking for a technology that could reduce their costs by only heating while an animal was in its pen.

One might expect that a passive IR sensor would solve the problem, but a sleeping nyala too soon becomes part of the background heat for these devices, and as a result, the heaters would not operate for long enough to keep the animals warm. The solution came from an unlikely source, a coffee queue monitoring project at the IBM Watson headquarters in Munich, that used an array of infra-red sensors to monitor the changing heat patterns and thus gauge the likelihood of a lengthy wait for a beverage.

In the zoo application, an array of thermal sensors hooked up to ESP8266 boards talk back to a Raspberry Pi that aggregates the readings and sends them to the IBM Watson cloud where they are analyzed by a neural net. The decision is then made whether or not a nyala is in the field of view, and the animal is toasted accordingly.

This project has some similarities with a Hackaday Prize entry, automated wildlife recognition, in its use of Watson.

Nyala image: Charlesjsharp [CC BY-SA 4.0 ].