Michael Papapetrou

REAPower: use of desalination brine for power production through reverse electrodialysis

AbstractSalinity gradient power (SGP) represents a viable renewable energy source associated with the mixing of two solutions of different salinities. Reverse electrodialysis (SGP-RE or RED) is a promising technology to exploit this energy source and directly generate electricity. However, although the principle of this technology is well known since several years, further R&D efforts are still necessary in order to explore the real potential of the SGP-RE process. With this regard, the aim of the REAPower project (www.reapower.eu) is the development of an innovative system for power production by SGP-RE process, using sea (or brackish) water as a diluted solution and brine as a concentrate. The use of sea or brackish water (instead of fresh water) as diluate allows reducing the electrical resistance of the diluate compartment and increasing the achievable output power. This work presents the R&D activities carried out so far within the REAPower project, particularly focusing on the relevant progresses in...

Analysis and simulation of scale-up potentials in reverse electrodialysis

AbstractThe reverse electrodialysis (RED) process has been widely accepted as a viable and promising technology to produce electric energy from salinity difference (salinity gradient power e.g. using river water/seawater or seawater and concentrated brines). Recent R&D efforts demonstrated how an appropriate design of the RED unit and a suitable selection of process conditions may crucially enhance the process performance. With this regard, a process simulator was developed and validated with experimental data collected on a laboratory-scale unit, providing a new modelling tool for process optimisation. In this work, performed within the REAPower project (www.reapower.eu), a process simulator previously proposed by the same authors has been modified in order to predict the behaviour of a cross-flow RED unit. The model was then adopted to investigate the influence of the most important variables (i.e. solution properties and stack geometry) on the overall process performance. In particular, the use of diff...

AUTONOMOUS DESALINATION UNITS BASED ON RENEWABLE ENERGY SYSTEMS - A REVIEW OF REPRESENTATIVE INSTALLATIONS WORLDWIDE

The ADU-RES co-ordination action is an EC funded project that aims to bridge the gap between successful R&D work and commercial applications of small desalination systems powered by renewable energy. This paper reviews installed units in order to define the state of the technology. Ninety-one plants were identified and sixteen of them were reviewed for their technical and economical performance. The examined units desalinate brackish or sea water and employ different technologies including: solar thermal distillation, wind energy or photovoltaic panels (PV) combined with revere osmosis (RO) as well as mechanical vapour compression driven by wind turbines. It was found that the technology has made significant progress over the past years. Still, cost-effective solutions have to be developed especially for the scaling of the membranes caused by the intermittent operation or the corrosion because of the high-temperatures. Also the energy efficiency and the controlling of the systems have to be further developed. The first products are in the market and will improve through competition and experiences resulting from implementation in real conditions for long periods.

Salinity gradient engines

Abstract This chapter is devoted to the description of a new class of heat engines based on salinity gradient technology and able to convert low-grade heat into power. The salinity gradient power (SGP) process is employed within a closed loop composed of two different sections: (i) the SGP unit devoted to the energy production, and (ii) a regeneration unit fed by the solutions exiting from the SGP unit and able to restore the initial concentration, thus regenerating the salinity gradient. The main features, limits and perspectives of this novel heat engine are described along with an overview of the state of the art presented in the literature and an example of exergetic analysis of the cycle. Also, additional information on the availability of the low-grade heat and on the economic evaluation of the produced energy is presented..