Fossil fuels have ushered in the modern industrial age, but carbon-neutral methods of electricity production are needed for the future. Salinity gradient energy (SGE) is one approach that is based on using two solutions with large differences in salt concentration to produce electricity. These include naturally occurring water sources with different salinities, such as river water and seawater, and salt brines and seawater or river water, or treated used waters and seawater prior to discharge into the ocean. Many large cities are located in coastal areas. Solutions with different salinities can also be produced for this purpose, for example by thermolytic salt solutions produced using waste heat. Several methods have been proposed to do this so-called “blue” energy source, such as reverse electrodialysis (RED), among others listed on the Technologies link.
At Penn State, our focus is primarily on using waste heat or natural heating/cooling sources (“red energy”) to produce solutions that can be used to make electricity. Ammonia bicarbonate (AmB) is a salt that can be distilled from water at low temperatures (45 degrees Celcius or higher) to make high saline solutions and low saline solutions. These can then be used in SGE technologies to make electricity. Another approach recently invented by the Logan group was a thermally regenerative ammonia flow battery (TRAB). Waste heat is used in this process to produce highly concentrated ammonia solutions that can be stored for use when needed to make electricity, making it both an energy conversion process (heat to electricity) and an energy storage device.
Through links on this website you can learn more about the SGE and TRAB technologies through links to descriptions and photographs of systems used for each technology, power point presentations and videos. For researchers interested in using these systems, we also provide a “make one” page for three of these technologies: RED, HEx and TRAB.
Other renewable energy approaches are also being developed at Penn State based on harvesting organic matter in wastewaters and waste cellulose sources to make electricity or biofuels using microbial fuel cell (MFC) technologies. To find out more about these “green” technologies, visit the Bioenergy or the MFC pages on the Logan homepage.
Prof. Bruce Logan homepage: research areas of bioenergy production using microbial electrochemical technologies, wastewater treatment and bioremediation.
Prof. Chris Gorski: Environmental chemistry, with emphasis on mineral formation and transformation reactions that affect environmental pollutant fate, and applications in energy production, storage, and recovery.