Drought has always been a problem but is increasing. Shortages of potable water worldwide are expected to rise to 50 percent by 2025, potentially spurring political instability and international conflict. Desalination of seawater can help coastal communities with local shortfalls but the process today is costly and not particularly efficient. But a new system developed by New Jersey Institute of Technology (NJIT) chemical engineering professor Kamalesh Sirkar offers hope for a significant leap forward. 

In 10 Innovations in Water Purification, Patrick J. Kiger writes:

In Sirkar’s direct-contact membrane distillation (DCMD) system, heated seawater flows across a plastic membrane containing a series of hollow tubes filled with cold distilled water. The DCMD’s tubes have tiny pores, which are designed so that they can be penetrated by the water vapor which collects on them, but not by salt. The vapor diffuses through the pores and is drawn off, to be condensed again into liquid water.

According to Sirkar, his system is extremely efficient — it can produce 80 liters (21 gallons) of drinking water per 100 liters (26 gallons) of seawater, about twice what existing desalination technology can produce. One potential downside of DCMD is that it requires a steady, inexpensive source of heat in order to prevent the water temperature on either side of the membrane from equalizing. But there’s the possibility that DCMD systems could someday recycle waste heat from shore-based factories and offshore oil drilling operations, making it a win-win for everybody

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