ARC E-Newsletter 1/30/26: The Icy-Ball - A Heat Driven Refrigerator
Aprovecho Research Center
The Icy-Ball : A Heat Driven Refrigerator
That’s an Icy-Ball (and a younger Dean) in a photo from ARC in 1994. Dr. Larry Winiarski and I built 18 somewhat scary prototypes and eventually made ice. We had replicated a pre-rural-electrification 1920s ammonia/water absorption refrigerator.
A fire heats the water/ammonia mixture and separates the ammonia out of the water (it turns into gas at a lower temperature). Then the pressure in the sealed system rises until the ammonia gas becomes a liquid. The Icy-Ball is taken off the fire and the small ball (full of liquid ammonia) is placed in an insulated box that has water (we made ice cubes) in it. The pressure in the system goes down and the liquid ammonia turns into gas robbing heat from the insulated box which freezes the water. The ice in the box cools food in the non-electric refrigerator.
The basic absorption cycle function of this 1920s appropriate technology is still in use today in RV and Camper fridges, and in developing countries.
How amazing to make ice from fire!
Read more about it here: en.wikipedia.org/wiki/Icyball
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The annual ETHOS Conference is set for Feb. 5-7, 2026. Join us at OSU Portland Center in Portland, Oregon (or online) for ETHOS 2026, the clean cooking conference. Leaders and advocates from the household energy sector come together to share research, explore solutions, and build lasting partnerships.
Discover the latest in technology, business innovation, and carbon markets. Sessions include:
- Electric induction stove adoption
- New stove designs
- fNRB and carbon methodology updates
- Carbon and finance innovations
Hear from experts at Gold Standard, Verra, KOKO Networks, East Africa Power, CCS, Biomassters, Berkeley Air, and more.
This in-person gathering fosters meaningful networking and ends with the beloved lighting of the stoves—a celebration of stove designs from around the world. Virtual attendees can join live presentations, share their work virtually, and engage in interactive discussions.
Don’t miss this chance to connect, learn, and lead in the clean cookstoves space. Visit ethosconference.org/ethos2026 for details and to register to attend in person or online. *Students and international collaborators can attend online for no cost, if need be.*
Hope to see you there!
Find the new book "Improving Biomass Stoves 2025," resources, publications and information about our work at www.aprovecho.org
Find archived newsletters online at aprovecho.org/newsletters
© 2026 Aprovecho Research Center/Advanced Studies in Appropriate Technology
76132 Blue Mountain School Road, PO Box 1175, Cottage Grove, Oregon, 97424 - USA
(541) 767-0287 • www.aprovecho.org