Integration of Renewable Energy Technologies With Desalination
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ENERGY-WATER NEXUS (AS STILLWELL, SECTION EDITOR)
Integration of Renewable Energy TechnologiesWith Desalination
Ange Abena Mbarga & Lianfa Song & W. Ross Williams &Ken Rainwater
Published online: 9 January 2014# Springer International Publishing AG 2014
Abstract Remote communities in many countries are in needof dependable and affordable fresh water that must be derivedfrom local brackish water or seawater. Thermal and membranedesalination technologies are available, with significant elec-trical or thermal energy requirements. Renewable energy fromwind, solar, geothermal, or other sources may be necessarywhen access to grid electricity is limited. This literature reviewsummarizes the research reported in the last three years (mid-2010 to mid-2013) by teams of experts in water treatment,renewable energy generation, variable-power system controls,system optimization, and economic analyses.
Keywords Desalination . Renewable energy .Wind energy .
Solarenergy .Photovoltaic .Reverseosmosis .Electrodialysis .
Membrane . Hybrid energy . Distillation .Multi-effectdistillation . Economic analysis . Seawater . Brackishwater .
Off-grid . Optimization . Control . Intermittency . Geothermalenergy
AbbreviationsAD Adsorption desalinationBWRO Brackish water reverse osmosisCDP Combined desalination and powerCSP Concentrating solar power
DPG Diesel power generation or diesel power generatorED ElectrodialysisEDR Electrodialysis reversalESS Energy storage systemETC Evacuated tube thermal collectorFC Fixed capacityFPSC Flat-plate solar collectorGC Gradual capacityHOMER Hybrid Optimization Model for Electric
RenewablesMD Membrane distillationMDC Microbial desalination cellMED Multi-effect distillationMEE-FF Multi-effect evaporation forward-feedMSF Multi-stage flashNF NanofiltrationPRO Pressure-retarded osmosisPTC Parabolic trough collectorRE Renewable energyRO Reverse osmosisSEC Specific energy consumptionSGP Salinity gradient powerSWRO Seawater reverse osmosisTDS Total dissolved solidsUF UltrafiltrationWEC Wave energy converterWT Wind turbine
Many communities around the world have limited or no localaccess to fresh drinking water sources, leading to dependenceon BW or SW for potable water supplies. Thermal, such asMSF and MED, and membrane, such as RO and ED, desali-nation processes can effectively lower the TDS concentrations
A. A. Mbarga : L. Song :K. Rainwater (*)Department of Civil and Environmental Engineering, Texas TechUniversity, Box 41023, Lubbock, TX 79423, USAe-mail: firstname.lastname@example.org
A. A. Mbargae-mail: email@example.com
L. Songe-mail: firstname.lastname@example.org
W. Ross WilliamsAltresco Companies, 10940 Parker Road, Parker, CO 80134, USAe-mail: email@example.com
Curr Sustainable Renewable Energy Rep (2014) 1:1118DOI 10.1007/s40518-013-0002-1
to acceptable levels, but with significant energy requirements.Remote locations in developing countries or small islandsmay lack access to dependable electrical grid power. LocalRE from WTs, PV, CSP, and other sources provides potentialalternatives that can either reduce electrical demand from thegrid or allow standalone operation. Most RE sources can beintermittent, so the application of RE to produce a targetvolume of reliable drinking water must address variations inboth the water demands and RE supply. During 20102013,many researchers published their findings related to concep-tual descriptions and designs of potential technology combi-nations, observations of laboratory, pilot, and full-scale appli-cations, as well as simulations of projected operational andeconomic conditions. This review provides brief summariesof the major reported findings as well as citations for theinterested reader to gather additional details.
Three significant concepts emerge from the recent literatureon combinations of RE and desalination, as noted in multiplereferences.
& Power experts can use smart grid concepts to improveRE and desalination combinations through control sys-tems that adjust for variable RE supply or by consideringdesalination systems as controllable loads.
& Energy storage systems (ESSs), such as batteries or ther-mal storage, and planned treated water storage volumescan mitigate the intermittency of wind and solar powersources for continuous water production in standaloneapplications.
& Hybrid energy combinations of solar, wind, geothermal,and fossil fuel generators can be evaluated for both costefficiency and freshwater demand satisfaction.
Al-Qaraghuli and Kazmerski  assembled an excellentand succinct overview of the capabilities of conventionalthermal and membrane desalination processes and their inte-gration with renewable energy. Their article included compar-ison of technical aspects, such as process description andenergy consumption, and economic aspects, such as estimatedcost of water, for various combinations of desalination withRE. In the brief summaries that follow, we have attempted togroup the articles based on certain common themes, althoughthere were often multiple overlapping topics shared acrosstheir objectives and findings.
Reverse Osmosis Desalination Systems With VariousRenewable Energy Sources
RO Powered by Wind
Peate et al.  compared the energy requirements and waterproduction from two hypothetical off-grid SWRO systems.
The first, a FC system, was sized at 1000 m3/d, while thesecond, a GC system, included one 200 m3/d and two 400 m3/d racks that could be turned on as needed. The GC system isable to adapt energy consumption to available WT power.Operational parameters relative to water quality and RO de-tails were simulated with electrical demands of 15124 kWfor different water production rates. Simulations of RE gener-ation were based on 100, 225, and 300 kWWTs assisted by abattery ESS and flywheel energy recovery devices. Wind datafrom the Gran Canaria island in the Spanish archipelagoprovided the input for the energy generation simulations.Overall, the GC system produced less water than the FCsystem, with almost 7 % higher SEC in kWh/m3 of waterproduced. The GC system had less excess energy production,requiring less energy storage capacity. The authors also rec-ommended consideration of treated water storage capacity asanother buffer for system security.
Direct impact of variable electrical supply from WTs onoff-grid RO systems has received some attention. Park et al.[3, 4, 5] investigated the impact of wind speed fluctuationson the performance of a BWRO system. In the first twostudies, a portable small-scale trailer-mounted 300 L/hrBWRO system and 1 kW (at 12.5 m/s) WT were placed in awind tunnel for controllable wind speed ranges and turbulencefluctuations. Park et al.  observed permeate flux and NaClconcentration with changing wind speed for 10 min experi-ments with 30 sec oscillations. The BWRO system perfor-mance was unaffected by the wind speed variations from 3.710 m/s. Next, Park et al.  investigated the impact of inter-mittency on the performance of the BWRO system or no-power intervals of 0.53 min in the wind tunnel. Observedpermeate TDS concentrations increased most for the shorter0.5 min and 1.0 min no-power intervals, indicating the poten-tial need for ESS or water storage for dilution. Finally, Parket al.  used simulations of their small-scale system toinvestigate the potential use of supercapacitors to absorb theimpacts of both wind speed fluctuations (oscillations of 15 secto 20 min) and intermittency (no-power intervals of 0.55 min). Dahioui and Loudiyi  simulated a hypotheticalwind RO system typical of Morocco and found that reducingmaximum capacity of the WT could reduce power fluctua-tions, as would the use of solenoid valves to manage pressurein the RO system.
Xenarios et al.  presented design considerations forselection of a WT for an existing 4500 m3/d SWRO plant onthe island of Mykonos, Greece. The SWRO plant electricaldemand was estimated at 614 kW. Several commerciallyavailable WTs were considered, using one year of local winddata, and a 1.5 MWor 1.65 MWWTwas sufficient.
Rainwater et al.  described a pilot-scale BWRO instal-lation powered by grid-assisted wind energy at Seminole,Texas. An on-site 50 kWWT provides intermittent electricityfor a deep well that taps a brackish aquifer, as well as the
12 Curr Sustainable Renewable Energy Rep (2014) 1:1118
BWRO system designed to produce 220 m3/d (40 gpm) ofpermeate. The system will be monitored for one year todemonstrate the value of the WTs electrical generation andthe production capacity of the deep well.
RO Powered by PV
Bilton et al.  performed theoretical simulations for technicaland economic feasibility of PV for remote small-scale off-gridSWRO and BWRO applications. The BWRO sites includedNew Mexico, Jordan, Australia, and Tunisia. The SWROlocations were Boston, Los Angeles, Cyprus, Jordan, Haiti,and Saudi Arabia. The cost ranges of treated water were 2.172.41$/m3 and 4.967.01$/m3 for BWRO and SWRO, respec-tively. The remote PV/BWRO costs were more than 50 %lower than those with DPG, while the PV/SWRO costs weresimilar or higher than the DPG equivalent.
Qiblawey et al.  described the performance of a small500 L/d BWRO system in northern Jordan powered by PVwith battery storage. The systems actual production averaged267 L/d for raw water with 1700 mg/LTDS, and SEC rangedfrom 2631 kWh/m3. Poovanaesvaran et al.  presented aconceptual discussion of BWRO with PV supplemented withbattery ESS, with a brief review of several installations aroundthe world, as well as comparison of PVand DPG.
Clarke et al. [12, 13] observed the performance of a smalllab-scale BWRO systemwith a capacity of 15 L/hr of permeate,and then used those data in simulation of PV power utiliz