Low Head Turbine Generates Plenty Of Power

May 22, 2026 by Bryan Cockfield 30 Comments

Engineering design makes all kinds of tradeoffs. Power trades off with torque, strength trades off with weight, and cost can trade off with quality. For designing a hydroelectric turbine, one of the main tradeoffs is hydraulic head with flow rate. Many large dams meant for bulk power generation will go with high head (or medium) designs, and for small dams with low head it’s usually not cost effective to build any generation. But if you’re really determined, you’ll want to build a low head water turbine like this one.

The build aims to use easy-to-find materials and simple tools. It uses 110mm and 160mm PVC pipe to not only siphon water up and over a dam, but to house the turbine as well. The turbine is built from a computer fan and sits inside the pipe with a shaft running through a Y-type fitting to the generator. The generator is built from a scavenged hoverboard wheel, and outputs a reported 3.3A DC at 60V for around 200 watts of power with only around 3m of head. The design allows the turbine to be placed at the point in the pipe that best suits the environment.

[OpenSourceLowTech], the creators of this project, make a compelling case that this build is cheaper than a 150W solar panel and it might even be able to produce more energy as well over certain timeframes, provided there’s a reliable source of water available and the owners of the dam don’t mind someone siphoning water over it continuously. The build video is worth a watch as well if for nothing else than the animation, which documents the build in excellent detail. Generating usable energy from hydropower doesn’t even need this big of a dam; if all you need is to charge your phone this tiny waterwheel will get the job done.

Thanks to [Keith] for the tip!

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Improving An Aquarium Chiller With An Industrial Controller Transplant

May 22, 2026 by Maya Posch 7 Comments

A healthy aquarium ecosystem requires very specific conditions, with factors like the salinity and temperature having to be just right to keep said ecosystem happy. As some species are adapted to fairly cold water, this requires the use a water chiller. Recently [The Blunt Oracle] modified one of these aquarium-focused chillers with a much better controller to make it both more accurate and potentially more efficient as well.

The target for the surgery was a generic Shanhuchong Y-160 chiller that after a brief teardown turned out to use an STC-1000 style controller. The biggest disadvantage with this unit is probably that it just has one temperature probe, which monitored the temperature of the heat exchanger rather than that of the chilled water tank.

This controller was replaced with a Wi-Fi-equipped Elitech ECS-974T sourced for $50 off AliExpress that uses the same 71 x 29 mm form factor. Following that it was just a matter of some creative rewiring – as shown in the top image – and installing the twin temperature probes of the new controller.

Being able to monitor also the temperature of the chilled water adds a layer of redundancy that’s very welcome after splurging thousands of clams on a fancy aquarium and its inhabitants. As a bonus the Wi-Fi interface allows for it to be monitored and controlled remotely, with [The Blunt Oracle] pushing the Home Assistant configuration in a PR as well that recently got merged. They’d also like to extend their thanks to Elitech for having pretty good documentation that really helped with creating the HA configuration file, which is a rarity with many of such controllers.

University Of Utah’s TRIGA Research Reactor Set To Produce Electricity

May 7, 2026 by Maya Posch 27 Comments

Research reactors come in many forms and sizes, with the TRIGA class being commonly found at universities. The TRIGA reactor at the University of Utah was installed in 1975, and for the past half century the thermal energy it produced was bled off into cooling systems. Now for a world’s first, the reactor will be used to generate electricity instead.

A TRIGA reactor core, with the blue glow from Cherenkov radiation. (Source: DoE, Wikimedia)

What makes the TRIGA design so practical for small research reactors is its inherent safety due to the use of uranium zirconium hydride (UZrH) fuel, which imposes a strong negative thermal coefficient on the reactivity. Along with no need for any kind of containment, these pool-type, water-cooled reactors thus allow for a pretty good look at the literal internals of the reactor core.

Their thermal power outputs range from 0.1 – 16 MW_th, with the University of Utah reactor generating on the low end of the scale here, at 50 kW_th. This energy will be partially used by a generator that has been developed by Elemental Nuclear, a startup company who looks to be trying to commercialize TRIGA fuel for microreactors with sodium coolant.

The installation at this TRIGA reactor should thus be seen as a proof-of-concept for Elemental Nuclear’s generator design, which uses a closed Brayton cycle with helium gas to generate an output of about 2-3 kW_e from the ~13 kW generated by the turbine. This generated power will – of course – be used to power some racks with GPUs for ‘AI’ tasks. If successful, it could show the way for TRIGA-based microreactors to power datacenters.

Top image: the TRIGA reactor during a tour. (Credit: University of Utah)

Using Hamster Power To Charge A Phone

May 5, 2026 by Maya Posch 24 Comments

It seems fair to say that hamsters are a somewhat divisive pet, between their fluffiness, high-strung nature, short lifespan and incessant squeaking that sounds like some electronic device is trying to tell you something. With that in mind, maybe that having these fuzzy little critter take up some of the daily slack will help endear them to more people. Something like helping to charge mobile devices by converting their frantic exercise wheel time into electrical power. Cue [Flamethrower]’s hamster wheel-powered generator.

Due to the irregular pacing of the hamster on its wheel it makes sense to treat it as an energy harvesting problem, for which the common CJMCU-2557 module – featuring the TI BQ25770 – is a pretty good option. It covers a voltage input from 0.1 – 5.1 V after a cold start minimum of 0.6 V, with a maximum current of 0.1 A.

The modules come with a super capacitor to store collected energy, but you can further charge a connected battery, for which [Flamethrower] used salvaged 18650 Li-ion cells. After letting the hamster do its thing for a night in the – admittedly far too small wheel – there’s enough power in the cell to at least start charging a smartphone, though sadly it’s not mentioned how much power was harvested.

Hopefully the hamster in question will be overclocked with a larger wheel, along with detailed measurements of how many hamsters it takes to charge the average phone.

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Magnetic Induction Heats Water

May 1, 2026 by Bryan Cockfield 49 Comments

Producing hot water off-grid is a surprisingly energy-intensive activity, and although it looks simple on its surface it can get quite complicated especially when used in large scale for something like providing hot water for an entire home. When using combustion to heat the water there needs to be proper venting as well as control of the fuel, and even storage of the hot water needs to be meticulous to avoid certain pathogens. [Greenhill Forge] has built an off-grid solution for heating hot water that doesn’t necessarily rely on any combustion, though, provided he can find something to spin his custom electric machine.

The machine in question is, of course, an induction heater. It works similar to any simple electric motor, generator, or transformer except in this case the eddy currents generated are exploited rather than minimized. Normally these currents, generated when a magnet passes by a metal, are wasted heat in other machines but in this induction heater it’s the goal. The machine’s stator is built from copper tube wound in a spiral which allows water to flow through and absorb heat. The tube is soldered into one electrically solid mass to maximize the eddy currents. The rotor is taken from a previous generator built by [Greenhill Forge] which holds the permanent magnets.

During the initial tests using a power drill to drive the generator, he was able to heat 1.5 liters of water from 7.9C to about 24.4 C in three minutes. The math works out to providing 575 watts of power to the heater, and with something that could spin the generator faster it might have the potential to provide around 14.5 kW. Provided that there’s a source of energy around, such as a wind or water turbine, this could be a fairly sustainable way of generating hot water in off-grid situations. Some of [Greenhill Forge]’s other projects are centered around this idea as well, like one of his builds which uses waste sawdust to heat his workshop with a custom-built stove.

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2026 Green Powered Challenge: Supercapacitor Enables High-Power IoT

April 28, 2026 by Bryan Cockfield 3 Comments

With all the battery technologies and modern low-current sleep modes in most microcontrollers, running a sensor and microcontroller combo off-grid and far away from any infrastructure is usually not too difficult a task. Often these sorts of systems can go years without maintenance or interaction. But for something that still has to be off-grid but needs to do some amount of work every now and then like actuating a solenoid or quickly turning a servo, these battery-based systems can quickly run out of juice. To solve that problem, [Nelectra] has come up with this high-power capacitor-based IoT system.

Although supercapacitors don’t tend to have the energy density of batteries, they’re perfectly capable of powering short tasks in off-grid situations like this. They’re also typically able to tolerate lower voltages, extreme temperatures, and shock better than most batteries as well. A small solar cell on the top of this device keeps it topped up, and when running in deep sleep mode can hold a charge for up to six days. In more real-world applications supporting sensors, relays, or other actuators, [Nelectra] has found that it can hold a charge for around three days. When a quick burst of power is needed, it can deliver 1.5 A at 9 V or 500 mA at 24 V.

[Nelectra]’s stated goal for this build is to bridge low-power energy harvesting and practical field actuation, enabling maintenance-free systems such as irrigation control and remote switching without batteries, going beyond simple sensor applications while not relying on always-on power from somewhere else. Something like this would work really well in applications like this automated farm, which has already provided some unique solutions to intermittent power and microcontroller applications that need very high reliability.

2026 Green Powered Challenge: Adding Low-Power Sleep To Microcontrollers

April 27, 2026 by Bryan Cockfield 19 Comments

When building a project to operate on battery power for long periods of time, having a microcontroller with a reliable and extremely low-power sleep mode is critical. When processing power isn’t needed, it should be able to wait around using almost no energy until an interrupt triggers it. Once triggered, the CPU performs its tasks and then puts itself right back to sleep, making sure the battery lasts as long as possible. Unfortunately, not every microcontroller has sleep capabilities or has an acceptably low level of power use for maximizing battery life. For these systems, a tool like this power manager might come in handy.

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