Historic and suppressed technologies for energetics

An overview of techniques and methods used in energy generation and storage, which is based on materials in present days environmentally problematic, is given. Sometimes advances in certain area, using materials in new ways may have unintended or unrealized negative consequences elsewhere. This is often true for consequences that become obvious only after an extended period of time. This article is taking look at the use of several metals (mercury, lead, cadmium and nickel) in technologies related to applications in energy generation and storage. As the poisonous nature of these elements and their compounds and their impact on environment became more and more apparent, the use of these metals in many technological processes was curtailed or pushed into background, still perhaps used for a niche application only, if not entirely eliminated. As a result, properties and use of these metals are downplayed in present curricula and awareness of their historical utility is disappearing. The purpose of this perspective article is to give an overview of some obsolete applications of these metals related to energy storage with the goal to highlight ingenuity of prior generation of engineers and scientists.