The encyclopedia · Product & Design · Product decision · 2005–2013
True Energy's Sure Chill fridge holds vaccines at 4°C for ten days without power
Sure Chill uses an ice mass so a vaccine fridge holds 4°C for over 10 days without power; WHO-approved units run across Africa and Haiti.
True Energy
The solution
In hot countries with unreliable electricity, a vaccine refrigerator is a life-support machine: if power fails for hours, the vaccine can heat past its limit and become useless. Solar and mains fridges only work while the power is on, so clinics in remote areas faced a chronic cold-chain gap.
True Energy's Sure Chill design stores cold itself. The vaccine compartment is surrounded by an ice mass, and the physics of water — densest at about 4°C — keeps the cold water exactly where the vaccines are. Because the unit carries its own reservoir of cold, it holds about 4°C for more than 10 days with no power, then recharges when power returns.
By 2013 the large WHO-approved Sure Chill refrigerators were in widespread use in Haiti, South Sudan, Niger and Sierra Leone. The Gates Foundation gave True Energy $100,000 to shrink the technology into portable coolers, and the firm reported about $1 million in orders from UNICEF and other agencies for clinics in Zimbabwe, Chad and Ethiopia.
Why it worked
- The ice mass buffers days of power failure passively
- It works off-grid with no fuel or moving parts to maintain
- WHO approval made it procurable for immunization programs
- UNICEF and agency orders scaled it across hot countries
What can be applied
In unreliable environments, store the energy carrier — cold, not electricity: a passive phase-change reservoir outlasts any machine that depends on the grid.
Aftermath
True Energy continued scaling Sure Chill from large refrigerators toward portable coolers, and the technology became part of the global immunization cold chain, holding vaccines at safe temperatures through power outages in some of the world's hottest regions.
Sources
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