Introduction

The innovative system for the production of electricity is based on the use of fuel cells within a high cycle efficiency that converts the thermal energy dissipated by heat sources at “low” temperature (e.g. ~ 80 ° C) and low enthalpy, such as solar thermal energy and/or waste heat from industrial processes (e.g. from thermal power plants), thanks to a molecular dissociation chemical reaction characteristic of the cycle. The proposed electrochemical cycle is a closed thermal regenerative cycle.

 

Technical features

The cycle is based on the chemical and electrochemical transformation of hydrogen iodide HI. It is a thermal regenerative cycle applied to a H₂/I₂ fuel cell.

In the chemical semi-cycle, the thermal energy, supplied at a low temperature (≥ 80°C), increases the enthalpy of the system by evaporating the hydrogen iodide in an aqueous solution at low pressure/temperature; subsequently, the HI can be thermally decomposed into its oxidizing and reducing agent. This releases electricity from the cell, bringing the mixture to high temperature by “Joule” effect. Subsequently, the mixture is brought back to a low pressure/temperature, causing all the substances except for the hydrogen to condense. The hydrogen will then be separated from the mixture. In the electrochemical semi-cycle, the chemical energy (enthalpy) is transformed into electrical energy through a fuel cell (flow battery), recombining the substance and then “closing the cycle” which is characterized by an efficiency of up to 55% and a useful energy density of >18kW per mole of dissociated HI. 

Possible Applications

• Production of electricity from renewable energy sources;
• Production of electricity from solar thermal systems at low/null concentration;
• Recovery of waste heat (at medium-low temperature) from industrial processes or thermoelectric power plants, avoiding energy waste;
• Production of Hydrogen H₂ and Oxygen O₂ with high efficiency.

Advantages

• Electrochemical chemical cycle closed;
• Thermal regenerative cycle;
• Highly efficient conversion of solar thermal energy or energy generated in thermal power plants;
• Fuel cell cooled by the operating fluid itself.