Saline groundwater, which underlies 60% of India, can negatively impact health as well as cause a water source to be discarded because of its taste.
A quarter of India's population live in villages of 2000–5000 people, many of which do not have reliable access to electricity. Most village-scale, on-grid desalination plants use reverse osmosis (RO), which is economically unviable in off-grid locations.
Here researchers at the Massachusetts Institute of Technology justify photovoltaic-powered electrodialysis (PV-ED) as an energy- and cost-effective means of desalinating groundwater for inland villages in rural India. They also present the design requirements for a village-level system.
Technical and ethnographic factors are used to develop an argument for PV-ED for rural locations, including:
- system capacity
- biological and chemical contaminant removal
- water aesthetics
- recovery ratio
- energy source
- economics of water provision
- maintenance, and the
- energetic and cost considerations of available technologies.
Within the salinity range of groundwater in India, ED requires less specific energy than RO (75% less at 1000 mg/L, and 30% less at 3000 mg/L). At 2000 mg/L, this energetic scaling translates to a 50% lower PV power system cost for ED versus RO.
Thus PV-ED has the potential to greatly expand the reach of desalination units for rural India.
Desalination, Volume 352, 3 November 2014, Pages 82–91.