W21: E-Waste Conversion, Bitmain S21 Pro Chassis → Gravity-Fed Organic Worm-Casting Miner
W21 is true e-waste upcycling. We repurpose the empty Bitmain S21 Pro chassis as a durable, stackable shell for a gravity-fed vermicomposting system. The design is open-source, and every 3D-printable part is in the HeatHarvest GitHub repo The result is simple and powerful: kitchen scraps and crop trimmings go in; microbially rich worm castings come out, and those castings feed our HeatHarvest purple sweet potatoes in the heat-capture greenhouse.
Why an e-waste conversion?
Obsolete mining hardware is both a problem and an opportunity. The S21 chassis gives you precision metalwork and mounting points that would be costly to fabricate from scratch. Converting that shell into a worm-casting miner keeps material out of landfills and turns an old form factor into a tool for organic #Bitcoin mining heat food production.
What worm castings are and why they matter?
Worm castings are the end-product of vermicomposting: a stable, humus-rich material loaded with beneficial microbes, plant-available nutrients in gentle concentrations, and a high cation-exchange capacity that buffers fertility. In soil, castings improve structure aggregation, water infiltration and holding, and nutrient cycling at the root interface. They’re forgiving low-salt, low burn risk, and effective in small, regular doses. Castings provide the biological side of fertility: resilient, living nutrition that scales with your grow.
The species that makes the magic happen and its life cycle: red wigglers Eisenia fetida
E. fetida is a surface-dwelling compost worm adapted to rich organic matter. It thrives in loose, moist, well-aerated bedding and responds quickly to steady conditions. Cocoons typically hatch in 2–3 weeks temperature-dependent; juveniles reach maturity in 6–8 weeks; adults lay cocoons regularly when moisture, temperature, and food are good. Feed a thin, weekly top layer of chopped vegetable scraps, coffee grounds are fine. Avoid fats, oils, meat, and salty foods that sour the w21 Maintain moisture with light misting if dry, and add dry coconut coir if it’s too wet. Worms migrate upward to fresh feed, while finished castings consolidate below by gravity.
Design logic: gravity in, gravity out
The W21 uses a vertical drop-through stack inside the S21 shell. New feed is always added at the top; as worms move up, the lower material matures and drops into a sealed harvest drawer for easy collection. Gravity is AWESOME 😎
Using castings in the heat-capture greenhouse
Purple sweet potatoes respond beautifully to castings, tuber quality depends on even moisture, steady micronutrients, and a cooperative microbiome. Castings help deliver all three.
Circular systems and why composting matters
The goal is sovereignty through cycles you control. Scraps feed worms; worms make castings; castings feed the next crop; the crop becomes the next scraps. ♻️ Castings reduce dependence on synthetic fertilizers, build soil structure that buffers stress, and equip roots with microbial allies that supply nutrients when plants signal for them. Because the W21 is built from an otherwise obsolete chassis, the loop begins before the biology: first you recycle a device, then you recycle nutrients. That’s sustainability in practice, local inputs, local processing, local food + Bitcoin heat = 😎
W21 proves that an obsolete miner chassis can become a living machine for Bitcoin heat capture, food production and a champion of sustainability. The design is open, the parts are printable, and the process is teachable. Build one. keep it steady, feed it thoughtfully, and put the castings to work where they matter most in your Bitcoin mining heat-capture greenhouse.
This project is part of our 2025 Bitcoin Mining Heat-Capture Season—HeatHarvest: Proof of Growth.
2025 HeatHarvest Sponsors:
Bitsbetrippin: https://bitsbetrippin.ioBitcoin
Bitcoin Mining World: https://bitcoinminingworld.com
MegaMiner: https://megaminer.market
Ungonverable Misfits
https://blossom.primal.net/4486c39ab88b6bc36f95f7350c97c0de7f3e7b9ffd71ccfeffc5b8f63114f178.mov