# DIY absorption refrigerator runs on fire, salt and minimal solar power

> **Key takeaway:** A home-built absorption cooling system achieved 5°C using only a fire-heated saltwater solution, a small solar panel for pumps, and no conventional refrigerants.

**Published:** 2026-10-18T23:00:48+00:00 
**Source:** Hackaday Hardware 
**Category:** open-hardware 
**Canonical URL:** https://fosswire.org/news/diy-absorption-refrigerator-runs-on-fire-salt-and-minimal-so.html 

## Summary
Greenhill Forge has built a heat-driven absorption refrigerator that uses water and road salt as its working fluids instead of conventional refrigerants. The system boils a saltwater solution with fire, condenses the vapor, then evaporates it under low pressure to absorb heat from the cooled space. A small solar panel or battery powers only the pumps and fans. In initial tests, the unit reached approximately 5°C with 16°C ambient temperature—below typical refrigerator targets but demonstrating the concept with minimal infrastructure.

## How the salt-and-fire cooling loop works
- **Generator loop**: Fire heats a tank of water mixed with road salt; boiled water travels up a tube to the condenser
- **Condenser to absorber**: A partially opened valve allows water to drip into the low-pressure absorber section, where it boils rapidly at reduced pressure and absorbs heat
- **Vapor removal loop**: A shower of salt solution captures the water vapor and moves it away from the cooled area
- **Electrical demand**: Small solar panel or battery sufficient for pumps and fans only; bulk energy input is thermal from the fire
- **Performance**: ~5°C achieved at ~16°C ambient in first tests; short of standard refrigerator temperatures but functional proof-of-concept
- **Monitoring**: Temperature and pressure sensors added for system control and observation

## Why it matters
The design offers a path to refrigeration without dependence on compressed gases or significant electrical infrastructure, potentially relevant for off-grid and resource-constrained settings. The use of common materials (road salt, water) and low-tech fabrication may make replication more accessible than conventional absorption systems requiring ammonia or lithium bromide.