Could Solar-Powered Airships Offer Cleaner Travel?

The blimp, the airship, the dirigible. Whatever you call them, you probably don’t find yourself thinking about them too often. They were an easy way to get airborne, predating the invention of the airplane by decades. And yet, they suffered—they were too slow, too cumbersome, and often too dangerous to compete once conventional planes hit the scene.

And yet! Here you are reading about airships once more, because some people aren’t giving up on this most hilarious manner of air travel. Yes, it’s 2024, and airship projects continue apace even in the face of the overwhelming superiority of the airplane.

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Dry Ice From Seashells, The Hard (But Cheap) Way

[Hyperspace Pirate] wants to make his own dry ice, but he wants it to be really, really cheap. So naturally, his first stop is… the beach?

That’s right, the beach, because that’s where to find the buckets of free seashells that he turned into dry ice. Readers may recall previous efforts at DIY dry ice, which used baking soda and vinegar as a feedstock. We’d have thought those were pretty cheap materials for making carbon dioxide gas, but not cheap enough for [Hyperspace Pirate], as the dry ice he succeeded in making from them came out to almost ten bucks a pound. The low yield of the process probably had more to do with the high unit cost, in truth, so cheaper feedstocks and improved yield would attack the problem from both ends.

With a supply of zero-cost calcium carbonate from the beach and a homemade ZVS-powered induction heater tube furnace at the ready, [Hyperspace Pirate] was ready to make quicklime and capture the CO2 liberated in the process. That proved to be a little more difficult than planned since the reaction needed not just heat but a partial vacuum to drive the CO2 off. An oil-free vacuum pump helped, yielding a little CO2, but eventually he knuckled under and just doused the shells in vinegar. This had the fun side effect of creating calcium acetate, which when distilled not only corrodes the copper still plumbing but also makes a lousy but still flammable grade of acetone. Once enough CO2 was stored in a couple of beach balls, the process of cooling and condensing it into dry ice was pretty much the same as the previous method, except for taking advantage of the Joule-Thomson cryocooler he built a while back.

The result is a hundred or so grams of dry ice snow, which isn’t great but still shows promise. [Hyperspace Pirate] feels like the key to improving this process is more heat to really drive the calcination reaction. Might we suggest a DIY tube furnace for that job?

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These 3D Printed Biocatalytic Fibers Scrub Carbon Dioxide

On today’s episode of “What If?” — what if the Apollo 13 astronauts had a 3D printer? Well, for one thing, they may have been able to avoid all the futzing with duct tape and procedure list covers to jury rig the lithium hydroxide filters, at least if they’d known about these 3D printed enzymatic CO2 filters. And time travel…they probably would have needed that too.

A bit of a stretch, yes, but environmental CO2 scrubbing is at least one use case for what [Jialong Shen] et al from the Textile Engineering Department at North Carolina State University have developed here. The star of the show isn’t so much the 3D printing — although squirting out a bio-compatible aerogel and cross-linking it with UV light on the fly is pretty cool. Rather, the key to developing a CO2-scrubbing textile is carbonic anhydrase, or CA, a ubiquitous enzyme that’s central to maintaining acid-base homeostasis. CA is a neat little enzyme that coordinates a zinc ion in its active site and efficiently catalyzes the addition of water to carbon dioxide to produce bicarbonate and hydrogen ions. A single CA molecule can catalyze the conversion of up to a million CO2 molecules per second, making it very attractive as a CO2 filter.

In the current work, an aerogel of poly(ethylene glycol) diacrylate/poly(ethylene oxide) (PEG-DA/EO) was used to entrap CA molecules, holding them in place in a polymer matrix to protect them from denaturation while still allowing access to gaseous CO2. The un-linked polymers were mixed with photoinitiators and a solution of carbonic anhydrase and extruded through a fine nozzle with a syringe pump. The resulting thread was blasted with 280–450 nm UV light, curing the thread instantly. The thread is either wound up as a mono-filament for later weaving or printed directly into a 2D grid.

The filament proved to be quite good at CO2 capture, managing to scavenge 24% of the gas from a mixture passed over it. What’s more, the entrapped enzyme appears to be quite stable, surviving washes with various solvents and physical disruptions like twisting and bending. It’s an exciting development in catalytic textiles, and besides its obvious environmental uses, something like this could make cheap, industrial-scale bioreactors easier to build and run.

Photo credits: [Sen Zhang] and [Jialong Shen], NC State; [Rachel Boyd], Spectrum News 1

[via Phys.org]

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Hackaday Links: December 25, 2022

Looks like it’s lights out on Mars for the InSight lander. The solar-powered lander’s last selfie, sent back in April, showed a thick layer of dust covering everything, including the large circular solar panels needed to power the craft. At the time, NASA warned that InSight would probably give up the ghost sometime before the end of the year, and it looks like InSight is sticking to that schedule. InSight sent back what might be its last picture recently, showing the SEIS seismic package deployed on the regolith alongside the failed HP3 “mole” experiment, which failed to burrow into the soil as planned. But one bad experiment does not a failed mission make — it was wildly successful at most everything it was sent there to do, including documenting the largest marsquake ever recorded. As it usually does, NASA has anthropomorphized InSight with bittersweet sentiments like “Don’t cry, I had a good life,” and we’re not quite sure how we feel about that. On the one hand, it kind of trivializes the engineering and scientific accomplishments of the mission, but then again, it seems to engage the public, so in the final rinse, it’s probably mostly harmless.

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Better Air Quality Sensing With CO2

Measuring air quality, as anyone who has tried to tackle this problem can attest, is not as straightforward as it might seem. Even once the nebulous term “quality” is defined, most sensors use something as a proxy for overall air health. One common method is to use volatile organic compounds (VOCs) as this proxy but as [Larry Bank] found out, using these inside a home with a functional kitchen leads to a lot of inaccurate readings. In the search for a more reliable sensor, he built this project which uses CO2 to help gauge air quality.

Most of the reason that CO2 sensors aren’t used as air quality sensors is cost. They are much more expensive than VOC sensors, but [Larry] recently found one that was more affordable and decided to build this project around it. The prototype used an Arduino communicating over I2C to the sensor and an OLED screen, which he eventually put in a 3D printed case to carry around to sample CO2 concentration in various real-world locations. The final project uses a clever way of interfacing with the e-paper display that we featured earlier.

While CO2 concentration doesn’t tell the full story of air quality in a specific place, it does play a major role. [Larry] found concentrations as high as 3000 ppm in his home, which can cause a drop in cognitive function. He’s made some lifestyle changes as a result which he reports has had a beneficial impact. For human-occupied indoor spaces, CO2 can easily be the main contributor to poor air quality, and we’ve seen at least one other project to address this concern directly.

Ceiling Fan Adds CO2 Sensor

Ceiling fans seem to be an oft-misunderstood or overlooked household appliance. As such, they seem to have missed a lot of the IoT wave. Sure, you can get smart controllers for them to plug into your home automation system of choice, but these mostly rely on temperature sensors, simple timers, or voice commands. There’s a lot more to a ceiling fan than maintaining a comfortable temperature, as [EJ] demonstrates with this smarter ceiling fan build.

A big part of the job of a ceiling fan is to improve air circulation, which can help a room from feeling “stuffy”. This feeling is usually caused by excess CO2 as a result of respiration in an area where the air is not moving enough to exhaust this gas. Not only does [EJ]’s controller make use of a temperature monitor for controlling the fan automatically, but there is also a CO2 sensor integrated to improve this aspect of air quality when needed.

The entire build is based on a Raspberry Pi Zero, and nothing needed to be changed about the ceiling fan itself for this added functionality because it already included a radio-based remote control. With some monitoring of the signals produced by the remote, the Raspberry Pi was programmed to mimic these commands when the surrounding sensors captured a condition where [EJ] would want the fan on. There’s also a manual control button as well, so the fan control is not entirely in the hands of the computer.

For a little more detailed information about this build, there’s a separate project page which details a lot of the information about the RF waveform capturing and recreation. And, if you want to take your fan to the next level, take a look at this one which focuses on building a smartphone app to control the fan instead.

Engineers: Be Subversive To Be Green

The caterers for the volunteer workforce behind the summer’s MCH hacker camp in the Netherlands served all-vegan food. This wasn’t the bean sprouts and lentils that maybe some of the more meat-eating readers might imagine when confronted with vegan food, nor was it a half-as-good array of substitutes with leathery soy hamburgers and rubbery fake cheese smelling suspiciously of feet.

Instead it was a well-crafted, interesting, and tasty menu that was something to look forward to after several hours driving a vanload of handwashing sinks. It was in one of their meals that I found food for thought when driving a week later past the huge Garzweiler open-cast lignite mine on my way through Germany to Luxembourg’s Haxogreen as part of my European hacker camp summer tour.

The meal was deep-fried soy protein strips and the mine is probably one of Western Europe’s dirtiest and most problematic CO2 sources in a country that likes to imagine itself as environmentally friendly, so where in this unlikely connection did I find a pairing? Continue reading “Engineers: Be Subversive To Be Green”