Salinity gradient energy: a new source of renewable energy for Australia

Abstract

Energy production in Australia depends heavily on fossil fuel combustion, which has adverse effects on our environment, including climate change. To reduce its reliance on this perilous source of energy, the country has been giving significant financial incentives to promote renewable energy. Today, renewable energy accounts for less than 5% of the energy consumption, but this share is estimated to reach 8% by 2030. Australia also expects 20% of the electricity generation to be provided by renewable sources by 2020, representing a significant increase compared to the current share of only 7%. This predicted growth in renewables is a response to government targets set to reduce gas emissions and financial incentives for research and development on renewables. In this study, we present salinity energy as an alternative of renewable energy source for Australia. Salinity energy occurs in nature during the mixing of waters with different salt concentrations (e.g. where rivers meet the oceans). When efficiently harnessed, this energy can be turned into power. This article analyses Pressure-Retarded Osmosis, a technology available to harness salinity energy and discusses possibilities for the exploitation of salinity energy in Australia. This research found that the country has a significant potential for osmotic power production. Some favourable factors are: 1) The proximity of the major energy consumption centres to the ocean; 2) The high evaporation rates that could be used to generate more concentrated solutions with higher power production potential; 3) The existence of vast areas of salt beds that could be used to generate brine; 4) The projected desalination plants that could be coupled to osmotic power plants and 5) Government incentives for research on renewable energy.