Salinity Gradient Power: Utilizing Vapor Pressure Differences

Olsson, Mark; Wick, Gerald L.; Isaacs, John D.

doi:10.1126/science.206.4417.452

Cited by 92 publications

(39 citation statements)

References 6 publications

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“…RED is one of the technologies able to retrieve energy from the mixing of two solutions [2]: e.g. pressure retarded osmosis [3], hydrocratic generators [4], and vapor pressure difference utilization [5]. RED processes have been operated up to now by adopting river water as dilute solution and seawater as concentrated solution.…”

Section: Introductionmentioning

confidence: 99%

CFD simulation of channels for direct and reverse electrodialysis

Tamburini

Barbera

Cipollina

et al. 2012

Desalination and Water Treatment

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Flows within very thin channels, typically filled with spacers, can be often encountered in many processes such as electrodialysis (ED) and reverse electrodialysis (RED). Although the ED and the RED processes have been studied for a long time, the optimization of the fluid dynamics within the channels is still an open problem. In the present work, realized within the EU-FP7 funded REAPower project, computational fluid dynamics simulations were carried out in order to predict the fluid flow field inside a single ED/RED channel. Some different configurations were tested which includes: an empty channel, a channel provided with a spacer, and a channel filled with a purposely manufactured fiber porous medium. Two types of spacers were investigated: (1) a commercial type made of woven perpendicular filaments and (2) an overlapped perpendicular filament spacer. A sensitivity analysis concerning computational grid size and topology was performed. For the cases investigated, adopting the hybrid grids mainly composed of hexahedral volumes was found to be more reliable and less computational demanding than tetrahedral grids. As concerns the dependence of the pressure drops on the flow rate, the empty channel was found to guarantee the lowest pressure drops at a given fluid flow rate, as expected. Conversely, the woven spacer filled channel was found to provide larger pumping costs. The pressure drops along the channel filled with a porous medium even at low flow rate were very high thus suggesting that this specific configuration may be unsuitable and that further investigations should be devoted to this topic

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Section: Introductionmentioning

confidence: 99%

CFD simulation of channels for direct and reverse electrodialysis

Tamburini

Barbera

Cipollina

et al. 2012

Desalination and Water Treatment

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“…Electric power production from salinity gradients-by harvesting the free energy lost during the mixing of river with sea water in estuaries-in principle, has the potential of becoming a significant source of electricity on the global scale [1][2][3][4][5]. The main technologies developed for that purpose to date, namely, pressure-retarded osmosis and reverse electrodialysis, exploit the osmotic pressure difference using hydrostatic pressure or electric potential differences applied across membranes [6].…”

Section: Introductionmentioning

confidence: 99%

Blue Energy and Desalination with Nanoporous Carbon Electrodes: Capacitance from Molecular Simulations to Continuous Models

et al. 2018

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Capacitive mixing (CapMix) and capacitive deionization (CDI) are currently developed as alternatives to membrane-based processes to harvest blue energy-from salinity gradients between river and sea waterand to desalinate water-using charge-discharge cycles of capacitors. Nanoporous electrodes increase the contact area with the electrolyte and hence, in principle, also the performance of the process. However, models to design and optimize devices should be used with caution when the size of the pores becomes comparable to that of ions and water molecules. Here, we address this issue by simulating realistic capacitors based on aqueous electrolytes and nanoporous carbide-derived carbon (CDC) electrodes, accounting for both their complex structure and their polarization by the electrolyte under applied voltage. We compute the capacitance for two salt concentrations and validate our simulations by comparison with cyclic voltammetry experiments. We discuss the predictions of Debye-Hückel and Poisson-Boltzmann theories, as well as modified Donnan models, and we show that the latter can be parametrized using the molecular simulation results at high concentration. This then allows us to extrapolate the capacitance and salt adsorption capacity at lower concentrations, which cannot be simulated, finding a reasonable agreement with the experimental capacitance. We analyze the solvation of ions and their confinement within the electrodes-microscopic properties that are much more difficult to obtain experimentally than the electrochemical response but very important to understand the mechanisms at play. We finally discuss the implications of our findings for CapMix and CDI, both from the modeling point of view and from the use of CDCs in these contexts.

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“…The transport of ions through the ionic membranes allows the production of a continuous current (DC) at a given voltage, thus an electrical power. Other technological approaches have been proposed or experimented [15,16], but it is beyond the scope of this paper to present and describe all the technological approaches proposed for the production of energy from salinity gradients.…”

Section: Introductionmentioning

confidence: 99%

Exergy as a Useful Variable for Quickly Assessing the Theoretical Maximum Power of Salinity Gradient Energy Systems

Labrecque

2009

Entropy

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It is known that mechanical work, and in turn electricity, can be produced from a difference in the chemical potential that may result from a salinity gradient. Such a gradient may be found, for instance, in an estuary where a stream of soft water is flooding into a sink of salty water which we may find in an ocean, gulf or salt lake. Various technological approaches are proposed for the production of energy from a salinity gradient between a stream of soft water and a source of salty water. Before considering the implementation of a typical technology, it is of utmost importance to be able to compare various technological approaches, on the same basis, using the appropriate variables and mathematical formulations. In this context, exergy balance can become a very useful tool for an easy and quick evaluation of the maximum thermodynamic work that can be produced from energy systems. In this short paper, we briefly introduce the use of exergy for enabling us to easily and quickly assess the theoretical maximum power or ideal reversible work we may expect from typical salinity gradient energy systems.

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Salinity Gradient Power: Utilizing Vapor Pressure Differences

Cited by 92 publications

References 6 publications

CFD simulation of channels for direct and reverse electrodialysis

CFD simulation of channels for direct and reverse electrodialysis

Blue Energy and Desalination with Nanoporous Carbon Electrodes: Capacitance from Molecular Simulations to Continuous Models

Exergy as a Useful Variable for Quickly Assessing the Theoretical Maximum Power of Salinity Gradient Energy Systems

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