LAUSR

Ever increasing energy demand and environmental concerns requires new and clean energy supplies, many of which are intermittent and non-correlating with demand. In order to balance supply with demand a universal energy vector can be employed such that intermittent renewable energy can be stored and transported and then used when needed. Hydrogen is the perfect universal energy vector and one of the possible solutions that ensures environmental cleanness and maximum utilisation of renewable energy sources and high efficiency where the combustion of this fuel yields only water. One abundant and freely available energy source both anthropogenic and natural is heat. Heat can be obtained from industrial processes and is indeed often seen as a waste product with a premium to remove but is notoriously difficult to capture store and indeed transport. Capturing and storing low grade heat is therefore a significant opportunity and can be achieved via the coupling of thermoelectric generators and water electrolysers. A thermoelectric generator is placed within a thermal energy gradient and produces a flow of current which is fed to the electrolysis unit with which it produces hydrogen and oxygen as the final products. The hydrogen can be stored for long periods and transported for "On demand" use in fuel cells for electricity of hydrogen burners for a return to thermal energy. This review summarizes the current state-of-the-art from researchers to implement thermoelectric generators and utilize heat as a primary energy source to produce hydrogen which could replace the need for extra electric power to run hydrogen production units. Further, discussion is made on suitable requirements, modifications and other related aspects associated with such a new and novel method of hydrogen generation. Hydrogen produced from otherwise wasted energy sources can be considered to be green.