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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Analysis of a Wave-Powered, Reverse-Osmosis System and Its Economic Availability in the United States: Preprint

A wave energy converter (WEC) system has the potential to convert the wave energy resource directly into the high-pressure flow that is needed by the desalination system to permeate saltwater through the reverse-osmosis membrane to generate clean water. In this study, a wave-to-water numerical model was developed to investigate the potential use of a wave-powered desalination system (WPDS) for water production in the United States. The model was developed by coupling a time-domain radiation-and-diffraction-method-based numerical tool (WEC-Sim) for predicting the hydrodynamic performance of WECs with a solution-diffusion model that was used to simulate the reverse-osmosis process. To evaluate the feasibility of the WPDS, the wave-to-water numerical model was applied to simulate a desalination system that used an oscillating surge WEC device to pump seawater through the system. The annual water production was estimated based on the wave resource at a reference site on the coast of northern California to investigate the potential cost of water in that area, where the cost of water and electricity is high compared to other regions. In the scenario evaluated, for a 100-unit utility-scale electricity-producing array, the estimated levelized cost of energy for these WECs is about 3-6 times the U.S.'s current, unsubsidized electricity rates. However, with clean water as an end product and by directly producing pressurized water with WECs, rather than electricity as an intermediary, it is presently only 12 percent greater than typical water cost in California. This study suggests that a WEC array that produces water may be a viable, near-term solution to the nation's water supply, and the niche application of the WPDS may also provide developers with new opportunities to further develop technologies that benefit both the electric and drinking water markets.

16 TIDAL AND WAVE POWER↗
DOE OSTI2016

Chaotic micromixer utilizing electro-osmosis and induced charge electro-osmosis in eccentric annulus

Efficient mixing is of significant importance in numerous chemical and biomedical applications but difficult to realize rapidly in microgeometries due to the lack of turbulence. We propose to enhance mixing by introducing Lagrangian chaos through electro-osmosis (EO) or induced charge electro-osmosis (ICEO) in an eccentric annulus. The analysis reveals that the created Lagrangian chaos can achieve a homogeneous mixing much more rapidly than either the pure EO or the pure ICEO. Our systematic investigations on the key parameters, ranging from the eccentricity, the alternating time period, the number of flow patterns in one time period, to the specific flow patterns utilized for the Lagrangian chaos creation, present that the Lagrangian chaos is considerably robust. The system can obtain a good mixing effect with wide ranges of eccentricity, alternating time period, and specific flow patterns utilized for the Lagrangian chaos creation as long as the number of flow patterns in one time period is two. As the electric field increases, the time consumption for homogenous mixing is reduced more remarkably for the Lagrangian chaos of the ICEO than that of the EO.

42 ENGINEERING↗
DOE OSTI2025

Self-regulating behavior of hybrid membrane systems as demonstrated in an element-scale forward osmosis-reverse osmosis hybrid system

Hybrid membrane systems can be difficult to design due to the requisite flow rate matching between up- and downstream unit operations. In this work, we use a forward osmosis-reverse osmosis (FO-RO) hybrid system to demonstrate how some membrane systems can exhibit self-regulating behavior due to osmotic coupling. This can reduce the need for complex control systems for flow balancing. We show this behavior using a module-scale test bed that can mimic the behavior of larger scale operations. The system shows permeate flow rate near-convergence between the FO and RO modules after startup or when perturbed by a change in RO module pressure. The behavior of this hybrid system demonstrates that some membrane operations can exploit osmotic interdependence, rather than expensive control systems, to achieve steady state operation.

Debottlenecking↗
DOE OSTI2025

Mineral Scale Formation during Crossflow Reverse Osmosis at Constant Flux and Constant Transmembrane Pressure Conditions

Mineral scale formation on membrane surfaces is a significant challenge in reverse osmosis water purification. Laboratory fouling experiments are typically run such that the transmembrane pressure (TMP) is fixed, and the permeate flux decreases over time as scales accumulate on the membrane surface. However, this change in flux means that the hydrodynamic conditions at the membrane surface are continuously changing, which could affect crystallization and foulant deposition processes. Operating under constant permeate flux conditions, in contrast, is advantageous because it keeps the hydrodynamic conditions relatively consistent, making it possible to compare how membrane properties (e.g., surface chemistry) affect fouling propensity. Industrial reverse osmosis operations are not run strictly in either constant TMP or constant flux mode; while they may start at a constant TMP, feed pressure may be periodically adjusted to maintain permeate water production within a specified range. Here, the scarcity of constant permeate flux reverse osmosis scaling experiments reported in the literature frustrates efforts to compare membrane fouling processes under constant TMP and constant flux conditions. For the first time, the evolution of the fouling layer resistance was compared as a function of cumulative permeate volume per membrane area during constant TMP and constant flux reverse osmosis filtrations. Scaling experiments were conducted by challenging commercial reverse osmosis membranes with a model feed solution nearly saturated with calcium sulfate dihydrate (gypsum). At low fluxes, the increase in fouling layer resistance was quantitatively similar for the two operational modes. In contrast, at high fluxes, the fouling layer resistance increased more rapidly in constant flux filtration than in constant TMP filtration. The mechanism of scale formation in constant TMP and constant flux operation was self-limiting and self-reinforcing, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Technoeconomic Optimization of Waste Heat Driven Forward Osmosis for Flue Gas Desulfurization Wastewater Treatment

With the Environmental Protection Agency’s recent Effluent Limitation Guidelines for Steam Electric Generators, power plants are having to install and operate new wastewater technologies. Many plants are evaluating desalination technologies as possible compliance options. However, the desalination technologies under review that can reduce wastewater volume or treat to a zero-liquid discharges standard have a significant energy penalty to the plant. Waste heat, available from the exhaust gas or cooling water from coal-fired power plants, offers an opportunity to drive wastewater treatment using thermal desalination technologies. One such technology is forward osmosis (FO). Forward osmosis utilizes an osmotic pressure gradient to passively pull water from a saline or wastewater stream across a semi-permeable membrane and into a more concentrated draw solution. This diluted draw solution is then fed into a distillation column, where the addition of low temperature waste heat can drive the separation to produce a reconcentrated draw solution and treated water for internal plant reuse. The use of low-temperature waste heat decouples water treatment from electricity production and eliminates the link between reducing water pollution and increasing air emissions from auxiliary electricity generation. In order to evaluate the feasibility of waste heat driven FO, we first build a model of an FO system for flue gas desulfurization (FGD) wastewater treatment at coal-fired power plants. This model includes the FO membrane module, the distillation column for draw solution recovery, and waste heat recovery from the exhaust gas. We then add a costing model to account for capital and operating costs of the forward osmosis system. We use this techno-economic model to optimize waste heat driven FO for the treatment of FGD wastewater. We apply this model to three case studies: the National Energy Technology Laboratory (NETL) 550 MW model coal fired power plant without carbon capture and sequestration, the NETL 550 MW model coal fired power plant with carbon capture and sequestration, and Plant Bowen in Eularhee, Georgia. For each case, we identify the design that minimizes the cost of wastewater treatment given the safely recoverable waste heat. We benchmark the cost minimum waste-heat forward osmosis solutions to two conventional options that rely on electricity, reverse osmosis and mechanical vapor recompression. Furthermore, we quantify the environmental damages from the emissions of carbon dioxide and criteria air pollutants for each treatment option. With this information we can assess the trade-offs between treatment costs, energy consumption, and air emissions between the treatment options.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2015

Compatibility Study of Nanofiltration and Reverse Osmosis Membranes with 1 Cyclohexylpiperidenium Bicarbonate Solutions

The switchable polarity solvent forward osmosis (SPS FO) desalination process requires use of a polishing filtration step to remove trace quantities of draw solution from the product water stream. Selected nanofiltration (NF) and reverse osmosis (RO) membranes were tested for their ability to recover water from 1-cyclohexylpiperidenium bicarbonate solutions in this application. This submission includes the experimental data used to calculate NF and RO membrane flux-normalized net driving pressure (FNNDP) and flux-normalized rejection (FNR) performance in recovering water from 1-cyclohexylpiperidenium bicarbonate solutions. This data is further described and visualized in the manuscript entitled "Compatibility study of nanofiltration and reverse osmosis membranes with 1 cyclohexylpiperidenium bicarbonate solutions" (see attached Compatibility Study Manuscript).

15 GEOTHERMAL ENERGY↗
DOE OSTI2025

Solvent Transport in Disordered and Dynamic Membrane Pores: Implications for Reverse Osmosis and Nanofiltration Membranes

Pressure-driven separations with nanoporous membranes, such as reverse osmosis and nanofiltration, play a vital role in addressing water scarcity and enabling resource recovery. Understanding water or solvent transport in membrane pores is essential for advancing membrane separation technologies. A key question in transport modeling is to establish a relationship between solvent permeability and membrane porous structure properties, such as porosity or pore size. The nano- and subnanometer pores in polymeric membranes such as reverse osmosis and nanofiltration membranes are highly tortuous and dynamically connected, which challenges the conventional methods of transport modeling. This study addresses this challenge by developing a theoretical framework to describe solvent transport through membranes with dynamic and disordered porous structure. Specifically, we propose a lattice model to describe the pore network, while preserving the viscous nature of solvent permeation. We further establish a relationship between solvent permeability and membrane porosity or pore size, which is validated by molecular dynamics simulations and experimental data. By integrating this relationship into the solution-friction model, we define pore connectivity and local friction coefficient to quantify the impact of pore structure on solvent permeability. Our analysis highlights the dominant influence of pore connectivity on the permeability of reverse osmosis and nanofiltration membranes, particularly when the pore size approaches the dimensions of solvent molecules. Overall, this study provides critical insights into water and solvent transport mechanisms in nanoporous membranes, opening the door for strategies to substantially enhance membrane performance.

membranes↗
DOE OSTI2018

Numerical Modeling and Dynamic Analysis of a Wave-Powered Reverse-Osmosis System

A wave energy converter (WEC) system has the potential to convert the wave energy resource directly into the high-pressure flow that is needed by the desalination system to pump saltwater to the reverse-osmosis membrane and provide the required pressure level to generate freshwater. In this study, a wave-to-water numerical model was developed to investigate the potential use of a wave-powered desalination system (WPDS) for water production. The model was developed by coupling a time-domain radiation-and-diffraction method-based numerical tool (WEC-Sim) for predicting the hydrodynamic performance of WECs with a solution-diffusion model that was used to simulate the reverse-osmosis (RO) process. The objective of this research is to evaluate the WPDS dynamics and the overall efficiency of the system. To evaluate the feasibility of the WPDS, the wave-to-water numerical model was applied to simulate a desalination system that used an oscillating surge WEC device to pump seawater through the system. The hydrodynamics WEC-Sim simulation results for the oscillating surge WEC device were validated against existing experimental data. The RO simulation was verified by comparing the results to those from the Dow Chemical Company’s reverse osmosis system analysis (ROSA) model, which has been widely used to design and simulate RO systems. The wave-to-water model was then used to analyze the WPDS under a range of wave conditions and for a two-WECs-coupled RO system to evaluate the influence of pressure and flow rate fluctuation on the WPDS performance. The results show that the instantaneous energy fluctuation from waves has a significant influence on the responding hydraulic pressure and flow rate, as well as the recovery ratio and, ultimately, the water-production quality. Nevertheless, it is possible to reduce the hydraulic fluctuation for different sea states while maintaining a certain level of freshwater production, and a WEC array that produces water can be a viable, near-term solution to the nation’s water supply. A discussion on the dynamic impact of hydraulic fluctuation on the WPDS performance and potential options to reduce the fluctuation and their trade-offs is also presented.

16 TIDAL AND WAVE POWER↗
DOE OSTI2017

Osmotically assisted reverse osmosis for high salinity brine treatment

Here, this work evaluates a novel osmotically assisted reverse osmosis (OARO) process for dewatering high salinity brines using readily available membranes and equipment. While traditional reverse osmosis processes are limited to treating brines with osmotic pressures below the membrane burst pressure, in OARO, the osmotic pressure difference across a membrane is reduced with a permeate side saline sweep. A series of OARO stages can be used to sequentially reduce the concentration of the feed until a traditional RO process can obtain fully desalinated water. This paper develops an OARO model to identify feasible operating conditions for this process and to estimate the water recovery and energy consumption across a range of brine feed concentrations. For a feed of 100–140 g/L sodium chloride, we estimate that the OARO process is capable of a 35–50% water recovery with an energy consumption of 6–19 kWh per m 3 of product water. Finally, the results suggest that an OARO dewatering process improves upon the recovery of reverse osmosis for high salinity brines and has a comparable or lower energy consumption than mechanical vapor compression.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Experimental investigation of a reverse osmosis desalination system directly powered by wave energy

Powering desalination processes with renewable energy is a promising solution to address the global issue of water shortage with minimum carbon footprint and environmental impact. Here, we experimentally investigate a sustainable reverse osmosis (RO) desalination system directly powered by wave energy. In this system, seawater is pressurized and pumped to a RO desalination module via a piston pump directly driven by an oscillating surge wave energy converter (OSWEC). An accumulator is adopted on the feed inlet to mitigate the pressure fluctuations under time-varying ocean conditions. Meanwhile, a needle valve on the brine outlet is used to adjust the system pressure and water recovery. A 1:10 scaled model was designed, fabricated, and tested in a wave tank based on the Froude scaling law. Further, the optimal specific water productivity (SWP) obtained in the tank tests with 3.5 g/L feed salinity was 2.23m 3 /kWh, indicating a full-scale specific water productivity of 0.22m 3 /kWh for 35g/L seawater salinity. The influence of needle valve tuning on the specific water productivity was experimentally investigated and analyzed. Under a specific operational condition, tuning this valve improved specific water productivity by about 17% and reduced the system pressure by 24%, thereby avoiding extreme pressure and improving the system’s capability. This pilot study demonstrates that ocean wave energy is a promising source to sustainably power reverse osmosis desalination and provide freshwater water for coastal regions.

16 TIDAL AND WAVE POWER↗