Pilot demonstration of concentrated solar-powered desalination of subsurface agricultural drainage water and other brackish groundwater sources

The energy–water nexus is addressed with the experimental demonstration of a solar-powered desalination process system. This system was designed for high-recovery treatment of subsurface agricultural drainage water as a reuse strategy as well as other brackish groundwater sources. These water sources may exhibit wide fluctuations in salinity and makeup and pose a high risk for operational troubles due to high scaling potential. A first-of-itskind open-cycle vapor-absorption heat pump is coupled with a multiple-effect distillation train and a large parabolic trough solar thermal concentrator. Without the heat pump, the distillation operation showed a minimum thermal energy consumption of 261.87 kWhth/m3. With the heat pump, the thermal energy consumption was reduced by more than 49% to 133.2 kWhth/m3. This reduction in thermal energy requirement directly translates into a 49% reduction in solar array area required to power a process with the same freshwater production rate as a system without an integrated heat pump. An optimized design was modeled and the thermal energy performance of a commercial system is projected at 34.9 kWhth/m3 using a 10-effect MED operating at 85% recovery. © 2014 Elsevier B.V. All rights reserved.

A first-of-its-kind solar-powered desalination process system was demonstrated for high recovery of high scaling propensity agricultural drainage water as a water reuse strategy at the Panoche Water & Drainage District in California's Central Valley. The system was designed with the energy–water nexus in mind in order to decouple water production from energy production as well as limit the use of fossil fuels by turning to renewables in the form of solar-thermal power. The system was operated both with and without the AHP in order to demonstrate its effectiveness at reducing the overall energy requirement of the process. The experimental and simulation results showed fairly good agreement. The AHP–MED system performed very favorably from both an energy consumption viewpoint as well as a robustness viewpoint. The final results are summarized below. • MED-only operated at a maximum PR of 2.522 and a minimum SC of 261.87 kWhth/m3. • AHP–MED operated at a maximum PR of 5.269 and a minimum SC of 133.2 kWhth/m3. • Design and simulation of an optimal AHP–MED utilizing ten distillation effects showed a PR of 18.4 and an SC of 34.9 kWhth/m3.