Off-grid coastal and island communities cannot sustain conventional desalination for safe drinking water
#00052
Coastal, island, and remote communities sit beside seawater but lack safe drinking water. Conventional desalination (RO, thermal) requires reliable power, capital, trained technicians, and supply chains they don't have — and discharges brine that harms local ecosystems.
#00056Passive solar-thermal interfacial crystallizer using laser-textured superwicking black metal
A femtosecond-laser-textured aluminium panel wicks seawater uphill across its face, absorbs ~92% of sunlight to evaporate it, and uses the coffee-ring effect plus salt creeping to push crystallised salt to the panel edges — self-cleaning, no membranes, no chemicals, no electricit
#00057Containerized solar-PV reverse osmosis operated by the local community
A shipping-container RO plant powered by solar PV and battery storage, producing ~75,000 L/day for ~25,000–35,000 people, operated by trained local staff and partly funded through water sales. Capital cost ~US$0.5–0.57M; ~20-year service life.
#00059Passive solar still (basin distillation) — the simplest, most durable, most area-hungry option
A black-lined basin of saltwater under a sloped glass cover: sun evaporates the water, it condenses on the glass and runs off as distillate. No moving parts, no consumables, repairable with local materials — but output is ~4–6 L/m²/day, so area demand is the binding constraint.
#00058Coastal fog harvesting with mesh collectors where advection fog is reliable
Where coastal advection fog is dependable, vertical mesh nets passively strain water droplets from wind-driven fog into reservoirs — no energy, no membranes, no seawater intake. Cheap and low-tech, but geographically constrained and historically prone to social/ownership collapse