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The development and exploitation of sustainable and environmentally friendly energy sources are required in order to resolve global energy shortages and to reduce the reliance of many countries on fossil fuel combustion. Salinity gradient energy has been considered a potential candidate for renewable energy due to the abundance of saline waters that could be combined with less saline solutions across the globe. Pressure Retarded Osmosis (PRO) is one of the technologies to harness salinity gradient energy. Apart from zero carbon dioxide emission, PRO is capable of producing power with less periodicity, abundance and low environmental impacts. One of the preconditions for the technical and financial feasibility of PRO, however, is the development of a PRO-specific membrane—one that meets the conditions that none of the current commercially-available membranes have met so far. The current paper discusses the progress made in PRO membrane development, particularly during the past decade, and analyses the challenges that are still hindering the implementation of PRO at large scales. Also, this paper explores possibilities for the implementation of PRO by analysing various combinations of existent solutions of various salt concentrations. Australia has been chosen to demonstrate some potential applications of PRO. This vast country has extensive reserves of saline waters that could be paired with less concentrated solutions to generate power. For each combination of solutions, a conceptual idea is presented, and an estimate of power production is given. Also, advantages and disadvantages of each scheme are discussed. The ideas and estimates can be easily extrapolated, with minor adjustments, to other countries with similar conditions. It is hoped that this publication will be valuable to those nations that have similar policies as Australia’s, with government incentives for the development and implementation of new technologies to explore new renewable energy sources. [ABSTRACT FROM AUTHOR]

Abstract: A great quantity of renewable energy can be potentially generated when waters of different salinities are mixed together. The harnessing of this energy for conversion into power can be accomplished by means of the Pressure Retarded Osmosis (PRO). This technique uses a semipermeable membrane to separate a less concentrated solution, or solvent, (for example, fresh water) from a more concentrated and pressurized solution (for example sea water), allowing the solvent to pass to the concentrated solution side. The additional volume increases the pressure on this side, which can be depressurized by a hydroturbine to produce power – thus the term ‘osmotic power’. This paper reviews technical, economical, environmental and other aspects of osmotic power. The latest available research findings are compiled with the objective of demonstrating the rapid advancement in PRO in the last few years – particularly concerning membrane development – and encouraging continued research in this field. Also, the hurdles involved in the effectuation of PRO plants and the research gaps that need to be filled are analyzed in this article. Additionally, osmotic power production using configurations other than the traditional pairing of river water and sea water are discussed. It is hoped that this review will promote further research and development in this new and promising source of renewable energy. [Copyright &y& Elsevier]

Yu, Y., Zhang, H. and Lemckert, C., 2013. Seasonal variations of the salinity and turbidity in the Brisbane River estuary, Queensland, Australia. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.) The Brisbane River estuary, Queensland, Australia, is a vital ecological region and of importance for people who live nearby. The estuarine health status has been influenced by both marine and riverine conditions. The estuary experiences high turbidity and salinity throughout most of the year, however, little is known about the actual turbidity and salinity structures within it. This study examined ten-years of field data to investigate the seasonal variations in salinity and turbidity. The results revealed that the salinity at the Brisbane River mouth was estimated to be 31.7 and 32.8 ppt during wet and dry seasons, respectively. The surface longitudinal salinity then decreased along the estuary, with the highest decreasing rates of 0.7 and 0.6 ppt/km occurring within the mid-estuary. The average salinity flux was 8.19×104 and 8.25×104 ppt m3/s during the wet and dry seasons, respectively. The slight discrepancy of salinity fluxes between two seasons may be attributed to the lack of consideration of the other freshwater inflows to the estuary. The actual salinity flux through the estuary will therefore fall within the two estimated flux values. It was also found that the length of the turbidity maximum was approximately 35 km during wet season, which was three times as long as it is during the dry seasons. The values indicate the perceived, and actual, health of the estuary changes with season and location and thus care must be taken when interpreting ad-hoc measurements. [ABSTRACT FROM AUTHOR]

Abstract: Runoff from the urban environment is a major contributor of non-point source contamination for many estuaries, yet the ultimate fate of this stormwater within the estuary is frequently unknown in detail. The relationship between catchment rainfall and estuarine response within the Sydney Estuary (Australia) was investigated in the present study. A verified hydrodynamic model (Environmental Fluid Dynamics Computer Code) was utilised in concert with measured salinity data and rainfall measurements to determine the relationship between rainfall and discharge to the estuary, with particular attention being paid to a significant high-precipitation event. A simplified rational method for calculating runoff based upon daily rainfall, subcatchment area and runoff coefficients was found to replicate discharge into the estuary associated with the monitored event. Determining fresh-water supply based upon estuary conditions is a novel technique which may assist those researching systems where field-measured runoff data are not available and where minor field-measured information on catchment characteristics are obtainable. The study concluded that since the monitored fresh-water plume broke down within the estuary, contaminants associated with stormwater runoff due to high-precipitation events (daily rainfall>50mm) were retained within the system for a longer period than was previously recognised. [Copyright &y& Elsevier]