Mon, 20 June, 2022
With the increasing demand for geothermal energy comes the need to overcome the intermittent, unstable performance of power generation associated with current geothermal energy technologies. Phase change materials (PCM) are one of the potential solutions to guarantee the normal functionality of geothermal power generation systems. Finding a stable heat storage medium with excellent heat transfer properties at high temperatures has been a hot spot for many researchers in the scientific community, in particular, the corrosion behaviour of potential metal/metal-alloy materials applied in thermal energy transfer and storage systems. Whilst there are many versatile media options, high temperature molten salts have become the industry choice for PCMs due to their significant merits - low vapour pressure, low reactivity in air and high operating temperature. Carbon steels in combination with aluminium are commonly considered for potential metal/metal-alloy materials for service in the low temperature sections of geothermal power plants. Nevertheless, the development of PCMs still encounters the inherent disadvantage attributed to the severe corrosion of pipes and vessels at high operating temperatures.
As part of the GEOSMART project, TWI is currently focussing on assessing the corrosion behaviour of potential metal/metal-alloy materials by exposure to nitrate-nitrite PCMs at elevated temperatures. Various electrochemical techniques are employed during the exposure tests with the aim of ranking the materials suitability for PCM applications. The aggressiveness of the PCM in relation to the metal/metal-alloy material stability and performance will not only address the major limitations associated with higher operating temperatures, but also provide a detailed understanding on the corrosivity of the PCMs and the corrosion resistance of the metal/metal-alloy materials.
The GeoSmart project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 818576.