Article Review · Science · 2017

Water from Desert Air: The 2017 Demonstration

PaperWater harvesting from air with metal-organic frameworks powered by natural sunlight
AuthorsH. Kim, S. Yang, S. R. Rao, S. Narayanan, E. A. Kapustin, H. Furukawa, A. S. Umans, O. M. Yaghi, E. N. Wang
PublishedScience, 2017
DOI10.1126/science.aam8743
Read the Original Paper ↗

Chemistry papers rarely produce photographs a policymaker understands. This one did: droplets condensing inside a sunlight-driven device containing MOF-801, operating at 20 to 30 percent relative humidity where conventional dew harvesting is thermodynamically hopeless. The MIT-Berkeley collaboration, Wang's device engineering wrapped around Yaghi's sorbent, demonstrated roughly 2.8 liters of water per kilogram of MOF per day under laboratory conditions of one sun and desert-grade dryness.

The mechanism is a heat pump run by sunlight and patience. Overnight, the MOF's sub-hydrophilic pores fill from dry air thanks to that steep low-humidity uptake step characterized in the 2014 isotherm study; by day, mild solar heating releases the water into a condenser at ambient temperature. No compressor, no membrane, no electricity, only an isotherm with the right shape.

Honest calibration matters, because press coverage inflated this into solved-water-scarcity. The demonstrated quantities are grams per device-cycle, one cycle per day, with the headline liters-per-kilogram figure an extrapolation from a proof-of-concept containing about 1.3 grams of MOF. Zirconium sorbent cost, multi-cycle-per-day engineering and scaling all remained future work, some of it since delivered by follow-up field trials in Arizona and beyond.

Judged as what it is, a feasibility landmark coupling twenty years of framework chemistry to a working device, it is close to flawless, and it gave the field its single most persuasive answer to the perennial question of what MOFs are actually for.

Reviewer's VerdictThe field's best public argument for itself. Read the supplementary numbers, not just the headline.

This review reflects the independent opinion of Team LR at MOFsResearch.com. It is an educational commentary on the cited publication and is not affiliated with or endorsed by the original authors or publisher. Verify all figures against the original paper before use.