Harvester pulls 1.5 gallons of drinking water from arid air per day
Researchers at MIT have demonstrated a material-based “water harvester” that can pull around 1.5 gallons of drinking water per day from arid air, but only by heating the device to about 184 °C multiple times daily. Commenters question its practicality, noting very high energy requirements (11–23 kWh per liter) compared with conventional dehumidifier-style condensers, and debate whether waste heat or concentrated solar could realistically supply that energy. The thread also examines how much water people actually need in hot, dry climates and whether such systems meaningfully help compared with simpler options like standard dehumidifiers, rainwater storage, or existing desalination and purification methods.
Device concept and operation
- Device absorbs water vapor from arid air using a special material, then requires heating to ~184 °C (363 °F) to release it.
- Lab prototype reportedly yields ~5.8 L (1.5 gal) per kg of material per day at 30% relative humidity.
- Some commenters reference other passive or low-power devices based on molecular sieves/nanotubes, but details are sparse and often patented.
Energy use and efficiency
- Original paper (linked in thread) reports about 11–23 kWh per liter of water for this class of systems.
- Multiple commenters note this is far worse than conventional cooling-condensation units (roughly 0.3–3 kWh/L cited in discussion).
- Debate over whether using “waste heat” or concentrated solar could make the high temperature requirement practical.
Comparison to existing tech / DIY
- Several people point out that dehumidifiers and air conditioners already produce water as a byproduct, often more efficiently.
- Suggestions include pairing heat pumps, or using simple dehumidifiers with surplus solar for small-scale water production.
- Some ask for DIY plans, but others note the core material is heavily patented and the device is not truly “passive.”
Use cases, scalability, and practicality
- Prototype is benchtop only; no field-scale deployments yet.
- 1.5 gal/day is seen by some as “enough for several people,” others argue it barely covers drinking needs, especially in hot, arid conditions.
- Some see niche value where high-quality drinking water is scarce but low-grade heat is abundant.
Water needs and hydration digression
- Long subthread debates recommended daily fluid intake, the “8 cups” rule, over- vs under-hydration, and how much people actually drink.
- No consensus; participants stress wide individual and climatic variation.
Environmental and water-cycle impacts
- One concern: large-scale atmospheric harvesting might impact local ecosystems.
- Counterargument: even scaled deployment would likely be negligible compared to total atmospheric water, and most water re-enters the cycle via breath and waste.
Tone and meta
- Mix of enthusiasm for novel materials/geometry (e.g., copper foam, desiccant concepts) and strong skepticism about feasibility vs basic physics and existing dehumidifiers.
- Thread includes some humor and pop-culture references, but core discussion centers on energy efficiency and real-world usefulness.