Three projects from one pile of hardware

In July I laid everything out on the table and asked what it could become. Three directions came out of it.

The pile wasn’t anything special: a retired office desktop, a couple of single-board computers, a microcontroller or two, two ESP32 boards, and a stack of cables. Most households and workshops have something like it in a closet. That’s the point of starting here. The greenest hardware is almost always the hardware that already exists, because most of a computer’s environmental cost is spent before it’s ever switched on, in the mining, refining and manufacturing. Finding a second job for a machine stretches that cost over more years of use.

The inventory

1. A community environmental mesh

A solar-powered, offline-first sensor network:

• ESP32 boards as sensor nodes
• A Raspberry Pi Pico as a rain and wind gauge
• The Le Potato as the mesh gateway
• The OptiPlex 5070 as the data hub that keeps the history

The idea is local weather and soil data that belongs to the people who live there. Commercial weather services report from an airport or a regional model. A garden two miles away can be a few degrees colder on a clear night or get twice the rain from a summer storm. A handful of cheap sensors, reporting over a radio mesh to a box that keeps the history, turns guesswork about frost and watering into real numbers, and the data can be shared freely with neighbours, schools and anyone else who wants it.

2. A local-first knowledge hub

Offline file sharing, mesh messaging and local maps, so a neighborhood can keep sharing what it knows when the internet is down.

There are mature open-source projects that do most of the heavy lifting here. Kiwix packages Wikipedia and other reference sites to read fully offline. Internet-in-a-Box bundles that kind of content into a local “digital library” served over Wi-Fi from something as small as a Raspberry Pi, so any phone or laptop nearby can browse it. Organic Maps is a free, open-source navigation app that works entirely offline. Pair those with a mesh for messages and you have most of what a community needs in a long outage: reference, maps and a way to talk.

3. A solar protocol server

The OptiPlex on solar power, serving community information over Wi-Fi. The power budget is worked out.

The budget made one thing clear: the OptiPlex uses about ten times more power than everything else on the table combined. It may be better as the occasional heavy lifter than the always-on server, with a small board doing the everyday serving. That decision can wait until the panels are tested and the real numbers are in.

The buddy system

Each device has a partner that can cover for it. If the gateway goes down, another board can take over its job; if the hub is off to save power, the sensor readings queue up until it wakes. Resilience doesn’t come from any single machine being reliable. It comes from no single machine being essential.

Where it stands

The brainstorm, the hardware inventory and the buddy-system map (which devices pair up and cover for each other) are done. No code yet. The next purchase is LoRa radios, which turns the first two directions into something real. See planning a LoRa mesh.

Further reading

• Kiwix. Wikipedia and other reference sites, fully offline.
• Internet-in-a-Box. A free, open-source offline library you can serve from a Raspberry Pi.
• Organic Maps. Open-source, fully offline maps and navigation.
• Automated mini greenhouse with ESP32 for Home Assistant, Open Electronics, 2026. A worked example of ESP32 sensors and relays on local, open-source software.
• Appropedia. A long-running wiki of appropriate technology and sustainability projects.