Deep Fission Wants To Put Nuclear Reactors Deep Underground

November 23, 2025 by Maya Posch 76 Comments

Today’s pressurized water reactors (PWRs) are marvels of nuclear fission technology that enable gigawatt-scale power stations in a very compact space. Though they are extremely safe, with only the TMI-2 accident releasing a negligible amount of radioactive isotopes into the environment per the NRC, the company Deep Fission reckons that they can make PWRs even safer by stuffing them into a 1 mile (1.6 km) deep borehole.

Their proposed DB-PWR design is currently in pre-application review at the NRC where their whitepaper and 2025-era regulatory engagement plan can be found as well. It appears that this year they renamed the reactor to Deep Fission Borehole Reactor 1 (DFBR-1). In each 30″ (76.2 cm) borehole a single 45 MWt DFBR-1 microreactor will be installed, with most of the primary loop contained within the reactor module.

As for the rationale for all of this, at the suggested depth the pressure would be equivalent to that inside the PWR, with in addition a column of water between it and the surface, which is claimed to provide a lot of safety and also negates the need for a concrete containment structure and similar PWR safety features. Of course, with the steam generator located at the bottom of the borehole, said steam has to be brought up all the way to the surface to generate a projected 15 MWe via the steam turbine, and there are also sampling tubes travelling all the way down to the primary loop in addition to ropes to haul the thing back up for replacing the standard LEU PWR fuel rods.

Whether this level of outside-the-box-thinking is a genius or absolutely daft idea remains to be seen, with it so far making inroads in the DoE’s advanced reactor program. The company targets having its first reactor online by 2026. Among its competition are projects like TerraPower’s Natrium which are already under construction and offer much more power per reactor, along with Natrium in particular also providing built-in grid-level storage.

One thing is definitely for certain, and that is that the commercial power sector in the US has stopped being mind-numbingly boring.

Damn Fine (Solar Powered) Coffee

November 19, 2025 by Jenny List 30 Comments

The folks at Low Tech Magazine are here again, this time with a solar powered coffee maker. Lest you think of a large parabolic mirror with a pot at its focus, in this case the device is much more friendly. It’s a table-top appliance that relies upon a 100 W, 12 V panel for its operation.

They make the point that an electric coffee pot requires at least 300 W to work, so what’s the secret? In this case, insulation, as a standard moka pot is placed within a nichrome heating element set in mortar and surrounded by cork. On the outside are tiles, though they appear largely ornamental and the write-up suggests you could experiment with other materials to serve as an enclosure.

It appears to be an effective coffee maker, with the significant caveat that it’s hardly fast. In full sunlight the first pot takes over an hour to brew, with subsequent ones once it’s up to temperature being somewhat faster. But you can’t argue with the idea of free power, even if your favourite caffeinated beverage may now take a while to appear.

We like this idea, despite its slow brewing. We’ve featured Low Tech Magazine before, not least in their solar powered oven.

Artsy And Durable Recycling From A Heat Press

November 7, 2025 by Ian Bos 9 Comments

Plastic recycling is something that many of us strive to accomplish, but we often get caught up in the many hurdles along the way. [Brothers Make] are experienced in the world of plastic recycling and graced us with a look into a simple and reliable way to get consistent thin sheets of durable plastic. Using a common T-shirt press and a mixture of plastic scraps, you can get the process down quickly.

Summarizing the process is pretty easy due to its simplicity. You take a T-shirt press, put some Teflon baking sheets on both sides of some plastic scraps, and then press. Repeating this a couple of times with different colored plastic will get you a nice looking sheet of usable sheets for any purpose you could dream of. Thicker pieces can have some life changing applications, or as simple as guitar picks, as shown by [Brothers Make].

Make sure to try out this technique yourself if you have access to a press! Overuse of plastic is a widely known issue, and yet it feels like almost no one attempts to solve it. If you want a different kind of application, try making your own 3D printing filament out of recycled plastic!

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DIY Powerwall Blows Clouds, Competition Out Of The Water

November 6, 2025 by Tyler August 34 Comments

Economists have this idea that we live in an efficient market, but it’s hard to fathom that when disposable vapes are equipped with rechargeable lithium cells. Still, just as market economists point out that if you leave a dollar on the sidewalk someone will pick it up, if you leave dollars worth of lithium batteries on the sidewalk, [Chris Doel] will pick them up and build a DIY home battery bank that we really hope won’t burn down his shop.

The Powerwall-like arrangement uses 500 batteries salvaged from disposable vapes. His personal quality control measure while pulling the cells from the vapes was to skip any that had been discharged past 3 V. On the other hand, we’d be conservative too if we had to live with this thing, solid brick construction or not.

That quality control was accomplished by a clever hack in and of itself: he built a device to blow through the found vapes and see if they lit up. (That starts at 3:20 in the vid.) No light? Not enough voltage. Easy. Even if you’re not building a hoe powerbank, you might take note of that hack if you’re interested in harvesting other people’s deathsticks for lithium cells. The secret ingredient was the pump from a CPAP machine. Actually, it was the only ingredient.)

In another nod to safety, he fuses every battery and the links between the 3D printed OSHA unapproved packs. The juxtoposition between janky build and careful design nods makes this hack delightful, and we really hope [Chris] doesn’t burn down his shed, because like the cut of his jib and hope to see more hacks from this lad. They likely won’t involve nicotine-soaked lithium, however, as the UK is finally banning disposable vapes.

In some ways, that’s a pity, since they’re apparently good for more than just batteries — you can host a website on some of these things. How’s that for market efficiency?

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Building A PV Solar-Powered Quadcopter

November 1, 2025 by Maya Posch 71 Comments

The solar-powered quadcopter from below. (Credit: Luke Maximo Bell)

One of the most frustrating parts about flying a quadcopter is having to regularly swap battery packs, as this massively limits what you can do with said quadcopter, never mind its effective range. Obviously, having the sun power said quadcopter during a nice sunny day would be a much better experience, but how workable is this really? While airplanes have used solar power to stay aloft practically indefinitely, a quadcopter needs significantly more power, so is it even possible? Recently, [Luke Maximo Bell] set out to give it a whirl.

His quadcopter build uses a large but very lightweight carbon fiber frame, with large 18″ propellers. This provides the required space and lift for the solar panel array, which uses 27 razor-thin panels in a 9×3 grid configuration supported by a lightweight support frame.

Due to the lightweight construction, the resulting quadcopter actually managed to fly using just the direct power from the panels. It should be noted however that it is an exceedingly fragile design, to the point that [Luke]’s cat broke a panel in the array when walking over it while it was lying upside-down on a table.

After this proof of concept, [Luke] intends to add more panels, as well as a battery to provide some buffer and autonomous flying hardware, with the goal of challenging the world record for the longest flying drone. For the rest of us, this might make for a pretty cool idea for a LoRaWAN mesh node or similar, where altitude and endurance would make for a great combo.

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HRV Gets Home Automation Upgrades

October 26, 2025 by Bryan Cockfield 5 Comments

In our modern semi-dystopia, it seems like most companies add automation features to their products to lock them down and get consumers to buy even more proprietary, locked-down components. The few things that are still user-upgradable are getting fewer and farther between, but there are still a few things that can be modified and improved to our own liking like this control panel for a heat recovery ventilator (HRV).

HRVs are systems that exchange fresh, outside air with stale, inside air while passing them both through a heat exchanger to keep from wasting energy. Many systems run continuously but they aren’t always needed, so some automation is beneficial. This upgrade from [vincentmakes] improves the default display for a Zehnder Comfoair Q350 HRV with a color display as well as adding it in to a home automation system, letting a user control fan speeds remotely as well as alerting the user when it’s time for filter replacements and providing up-to-date information from all the sensors in the HRV.

The project builds on a previous project which adapted an ESP32 to interact with the CAN bus used on these devices. With these upgrades the user can forgo the $300 proprietary upgrade that would be needed to get the same functionality otherwise. It’s also fully open-source so all that’s needed is to flash the firmware, replace the display, and enjoy the fresh air. There’s other modern HVAC equipment that can benefit from new controllers and a bit of automation as well.

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A Solar Oven For Cloudy Days

October 18, 2025 by Tyler August 19 Comments

Every Boy Scout or Girl Guide probably had the experience of building a simple solar oven: an insulated box, some aluminum foil, and plastic wrap, and voila! On warm, sunny, summer days, you can bake. On cloudy days, well, you need another plan. The redoubtable [Kris De Decker] and [Marie Verdeil] provide one, with this solar-electric oven over on LowTechMagazine.

Now, you might be wondering: what’s special here? Can’t I just plug a full electric range-oven into the inverter hooked to my Powerwall? Well, yes, Moneybags, you could — if you had a large enough solar setup to offset the storage and inverter losses, that is. But if you only have a few panels, you need to make every watt count. Indeed, this build was inspired by [Kris]’ earlier attempt to power his apartment with solar panels on his balcony. His electric oven is one of the things that stymied him at that time. (Not because cooking took too much energy, but because it took too much power for his tiny battery to supply at once.)

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