DIY Float Valve For Passive Hydroponics Leverages 3D Printing

February 19, 2022 by Donald Papp 10 Comments

[Billy] has a special interest in passive hydroponics (also known as the Kratky method), which is a way of growing plants in nutrient-rich water that does not circulate. As the plant grows and liquid level drops, only the tips of the roots remain submerged while more and more of the root surface is exposed to oxygen in a harmonious balance. However, “thirsty” plant types (tomatoes, for example) throw off this balance, and the system needs to be modified. To address this, [Billy] designed and printed a passive float valve system that takes care of topping up the reservoir only when needed, without using pumps or any other electrical equipment.

Commercial or industrial float valves are too big to use in his small tanks, which led [Billy] to test dozens of DIY designs. He used everything from plastic water bottles to pipe ends, but nothing quite measured up. With 3D printing, [Billy] was able to create a sealed, lightweight float that exactly matched the housing and tube locations.

A strip of silicone works as a sealing agent.

The way [Billy]’s float valve works is by using a hollow object as a kind of buoyant plug inside a housing. When the water level is high, the buoyant object rises up and presses a strip of silicone against an outlet, preventing water from flowing. If the water level is low, the buoyant plug drops and water is free to flow. With a reservoir of fresh nutrient-rich water placed above the grow tank, gravity takes care of pushing a fresh supply down a tube, so no active pump is needed. Combined with a passive float valve, the system pretty much runs itself.

Watch [Billy] give a tour of his system and valve design in the video embedded below. He’s got a lot of experience when it comes to working with projects involving liquids. Only someone as comfortable as he is would make his own DIY dishwasher.

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Spin Some Spudgers From Secondhand Silverware

February 12, 2022 by Kristina Panos 20 Comments

Even though it’s not the right tool for the job, we’ve all used a flat head screwdriver for other purposes. Admit it — you’ve pried open a thing or two with that one in the toolbox that’s all dirty and dinged up anyway. But oftentimes, screwdrivers just aren’t thin enough. What you need is a spudger, which for some reason, seem to only come in plastic. Blame our disposable times.

In a relevant break from building electronics, [lonesoulsurfer] took the time to craft a set of spudgers and such from secondhand silverware. These are all made from spoons and butter knives sourced from a thrift store. For the spoons, [lonesoulsurfer] removed the heads with an angle grinder, shaped them on a belt sander, and thinned them out until they were spudger-slim. After doing the same with the handle end, [lonesoulsurfer] polished up the new tools on the wheel with some compound.

Not all of these are spudgers — some are destined to scrape, and others for lifting badges and decals. But they all live in harmony in a handy carrying case. Check out the build video after the break.

On the other hand, sometimes a disposable tool is all you really need.

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Mining And Refining: Lithium, Powering The Future With Brine

February 9, 2022 by Dan Maloney 28 Comments

Many years ago, I read an article about the new hotness: lithium batteries. The author opened with what he no doubt thought was a clever pop culture reference by saying that the mere mention of lithium would “strike fear in the hearts of Klingons.” It was a weak reference to the fictional “dilithium crystals” of Star Trek fame, and even then I found it a bit cheesy, but I guess he had to lead with something.

Decades later, a deeper understanding of the lore makes it clear that a Klingon’s only fear is death with dishonor, but there is a species here on earth that lives in dread of lithium: CEOs of electric vehicle manufacturing concerns. For them, it’s not the presence of lithium that strikes fear, but the relative absence of it; while it’s the 25th most abundant element in the Earth’s crust, and gigatons are dissolved into the oceans of the world, lithium is very reactive and thus tends to be diffuse, making it difficult to obtain concentrated in the quantities their businesses depend on.

As the electric vehicle and renewable energy markets continue to grow, the need for lithium to manufacture batteries will grow with it, potentially to the point where demand outstrips the mining industry’s production capability. To understand how that imbalance may be possible, we’ll take a look at how lithium is currently mined, as well as examine some new mining techniques that may help fill the coming lithium gap.

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Move Aside Solar, We’re Installing An Algae Panel

February 7, 2022 by Matthew Carlson 58 Comments

[Cody] of Cody’sLab has been bit by what he describes as the algae growing bug. We at Hackaday didn’t know that was a disease floating around, but we’ll admit that we’re not surprised after the last few years. So not content to stick to the small-time algae farms, [Cody] decided to scale up and build a whole algae panel.

Now, why would you want to grow algae? There are edible varieties of algae, you can extract oils from it, and most importantly, it can be pumped around in liquid form. To top it off, all it needs is just sunlight, carbon dioxide, and a few minerals to grow. Unlike those other complicated land-based organisms that use photosynthesis, algae don’t need to build any structure to hold themselves up or collect sunlight; it floats.

The real goal of the algae is to build a system known as “Chicken Hole.” The basic idea is to have a self-sufficient system. The algae feed the insects, the insects feed the chickens, and so on up the chain until it reaches [Cody]. While glass would make an ideal material for the algae tubes, plastic soda bottles seem like a decent proxy for a prototype and are much cheaper. He connected around 100 half-liter bottles to form long tubes and a PVC distribution system. The algae needs to be pumped into an insulated container to prevent it from freezing at night. At first, a simple timer outlet controlled the pump to only run during the day, draining it via gravity at night. However, the algae can’t heat up enough when running on cloudy, cold winter days, and it cools off. A solar panel and a temperature sensor form the logic for the pump, with a minimum temperature and sunlight needed to run.

[Cody] mentions that he can expect around 10 grams of algae per day on a panel this size in the winter. He’s going to need quite a few more if he’s going to scale up properly. Perhaps in the future, we’ll see panels growing algae robots? Video after the break.

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Supersized Power Bank Built From An EV Battery

February 3, 2022 by Jenny List 25 Comments

Perhaps one day in the future when our portable electronics are powered by inexhaustible dilithium crystals, we’ll look back fondly on the 2020s when we carried around power banks to revive our flagging tech. Oh how we laughed as we reached for those handy plastic bricks only to find them drained already of juice, we’ll say. [Handy Geng] won’t be joining us though, because he’s made the ultimate power bank, a 27,000 AH leviathan that uses an electric car battery for storage and supplies mains power through a brace of sockets on its end.

The vehicle battery is mounted on a wheeled trolley along with what appears to be either the in-car charging unit or a mains inverter. The whole thing is styled to look like a huge version of a pocket power bank, with a curved sheet metal shell and white hardboard end panels. The demonstration pushes the comedy further, as after charging a huge pile of phones he replenishes an electric scooter before settling sown by a chilly-looking river for a spot of fishing — along with his washing machine, TV, and electric hotpot for a spot of cooking. We appreciate the joke, and as we know him of old we’re looking forward to more.

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Underwater Tanks Turn Energy Storage Upside-Down

February 2, 2022 by Lewin Day 129 Comments

Pumped hydro storage is one of the oldest grid storage technologies, and one of the most widely deployed, too. The concept is simple – use excess energy to pump a lot of water up high, then run it back through a turbine when you want to get the energy back later.

With the rise in renewable energy deployments around the world, there is much interest in finding ways to store energy from these often-intermittent sources. Traditional pumped hydro can help, but there is only so much suitable land to work with.

However, there could be a solution, and it lurks deep under the waves. Yes, we’re talking about underwater pumped hydro storage!

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Power For Nothing And Your Kicks For Free

January 30, 2022 by Al Williams 68 Comments

We all know that you can convert heat into electricity. Usually, you do that with some form of steam, but there are other methods, too, including thermocouples. If you’ve ever seen something producing waste heat, you’ll appreciate Penn State’s work to harvest power from hot pipes. The idea is simple in theory: create a flexible thermoelectric generator that can wrap around hot pipes or other surfaces to gather otherwise lost heat. The full (paywalled) paper is also available.

The devices can produce up to 150% more power per unit area compared to other thermoelectric generators. A three-square-inch test device produced over 50 watts. Scale that up to an industrial pipe hundreds of feet long, and you could create some serious power. To accomplish this, the scientists used strips of six thermocouples and connected them for a total of 72 thermocouples. Liquid metal between layers improved the device’s performance.

This isn’t a totally new idea. Russia was famous for making radios in the 1950s that operated using a generator that went around the flue of a kerosene lamp. Since the Russians were pulling this off in the 1950s, converting heat into electricity is obviously nothing new. Of course, your body creates heat, too, so why not use that?