Volcanic ash, often associated with environmental upheaval, has emerged as a surprising candidate for energy storage, thanks to its unique properties, according to a study conducted by researchers at the University of Barcelona.
In the realm of energy storage, various technologies have been explored, ranging from cost-effective thermal storage to highly efficient heat batteries capable of withstanding extreme temperatures. While some systems utilize abundant materials for affordability, others employ advanced materials such as liquid tin and carbon for enhanced efficiency. However, volcanic ash presents a middle-ground solution with promising attributes for specific applications.
The focal point of a recent study published in the Journal of Energy Storage revolves around concentrated solar power. Unlike photovoltaic panels, concentrated solar power systems involve vast arrays of parabolic mirrors meticulously positioned to concentrate sunlight onto a central point, generating intense heat exceeding 1,000°C (1,832°F).
Traditionally, the generated heat can either be directly converted into electricity through steam turbines or stored for future use using thermal batteries. Many existing installations rely on molten salts for thermal energy storage due to their efficient heat retention capabilities at high temperatures. Yet, molten salts pose challenges, being corrosive and sometimes problematic to handle.
The discovery of volcanic ash’s potential as an alternative heat storage medium stemmed from a volcanic eruption on La Palma Island in the Canary Islands in 2021, which blanketed the surrounding area with an immense volume of igneous rock and ash debris. Utilized extensively in civil engineering projects for its cost-effectiveness, volcanic ash piqued the interest of researchers seeking to explore its viability for thermal energy storage.
In laboratory experiments, researchers compressed volcanic ash into pellets and subjected them to cycles of heating and cooling between 250 and 750°C (480-1,380°F) over 1,000 repetitions. The results revealed exceptional thermal conductivity and heat capacity in the ash, coupled with sustained physical and chemical stability, with minimal oxidation-related mass gain observed.
Furthermore, volcanic ash demonstrated compatibility with molten salts, mitigating their corrosive tendencies and preventing solidification when mixed. This dual functionality offers a cost-effective solution for heat storage, whether used in tandem with molten salts or independently in open receiver systems, where concentrated solar beams are directed onto structures made from volcanic ash, enabling high-efficiency heat-to-electricity conversion.
The researchers underscored the significant potential of La Palma Island’s volcanic ash as a sustainable alternative in the thermal energy storage field, offering cost-effective solutions and potential savings in energy storage.