Professor Frank Lipnizki and Professor Ann-Sofi Jönsson at the Department of Chemical Engineering at Lund University
Thermodynamic calculation (using Gibbs free energy of mixing) indicates that 0.8 kWh of energy is obtained when 1 m3 of freshwater flow into the sea. Globally, mixing river water and seawater has a potential of 2.6 TW, which is the second-largest marine-based renewable energy source next to ocean waves. The extractable potential is around 2 TW that is more than 10 percent of the total global potential of renewable energy sources.
However, this number for Salinity Gradient Power (SGP) can be increased significantly by considering other sources of SGP. For instance, the SGP potential from wastewater discharge into the ocean is estimated to be 18 GW, and the novel SGP application based on a closed-loop system using excess waste heat could also potentially enable the production of more than 120 000 GWh/year.
Salinity gradient power, which is so-called Blue Energy, is a completely clean and sustainable energy source with no toxic gas emissions. Unlike intermittent wind and solar energy sources, Blue Energy can be exploited continuously 24h per day and 365 days a year. It can be obtained from natural or artificial resources. Naturally, SGP can be harvested in river mouths, where two solutions with different salinity meet, from saline groundwater, saltworks, salt lakes, natural brine. An artificial source of SGP include but are not limited to oil-gas fields and brine from desalination units.
The theoretical investigation disclosed the power production by SGP can be potentially competitive against other alternative energy sources. However, harvesting Blue Energy was not practically feasible on a large scale due to the low performance of the technologies.
The outcome of this research could have a considerable impact on the renewable energy industry in Sweden. Two key objectives of this proposal are to assess the potential of blue energy as a sustainable renewable energy source in Sweden and to adapt a RED system based on Swedish water resources. The outcome of this research provides crucial information regarding the harvesting of Blue Energy. For instance, the natural and artificial hot spots for harvesting, the theoretical and experimental extractable energy, and the cost of energy production will be presented. This information will be very useful for a possible startup company in Blue Energy harvesting in Sweden.