MIX-MOXes - Mixed Metal Oxides Energy Stations for zero-carbon thermal energy generation with integrated heat storage

The provision of heat is a vital foundation of modern society; however, its decarbonization remains largely unaddressed. Three key fundamental challenges remain to be addressed: 1) traditional fossil-fuels need to be replaced with zero-carbon energy carriers with substantial energy and power density for efficient generation of heat; 2) efficient and cost-effective thermal energy storage capacity needs to be deployed and 3) zero-carbon technologies for generation and storage of heat need to be developed in a circular economy context. Despite significant efforts, none of the solutions so far proposed fully replace the essential functions that fossil fuels provide in generation and storage of heat.

Recent studies theoretically predicted that fast oxidation - i.e. combustion - of micro-scale powders of abundantly available metals such as iron and aluminium could release a theoretical energy storage density 10x of traditional fuels (~8400 MJ/m3), at comparable temperature and reaction rates, but without CO2 emissions. This is a remarkable but largely unproven potential; so far proposed zero-carbon heat generation and heat storage technologies only reach ~15-20% storage density and conversion reaction rate of traditional fossil fuels. Furthermore, metal oxide particles are the only expected product of the fast oxidation reaction. Once collected it is believed that oxide particles could be regenerated back to metal powder via renewable-energy driven processes, closing the energy and resources cycles and thus providing Power-to-Metal-to-X paths within a circular economy.

However, new radical technologies and processes are needed to combust and regenerate metal powders in a controllable and efficient manner. Whether this is possible remains unclear due to the absence of fundamental understanding and application of the mechanisms controlling reactive flows of metal powders. Here therefore lies a field of high-risk discovery research with huge application potential.

This project sets the ambitious goal to establish the technological potential - through a proof-of-concept study - of an entirely new family of integrated systems for thermal energy generation and heat storage that harness the fundamental phenomenon of zero-emission combustion and regeneration of all-recyclable metal powders. At its centre is a combined experimental & numerical/theoretical approach. The project will unveil the influence of particle-level interactions on ignition and regeneration processes; at component level proof-of-concept experiments will demonstrate at lab-scale continuous combustion of metal powder aerosol with concurrent capture of oxide products for subsequent regeneration. Finally, at the whole process level, a roadmap will be developed to set future research needs for upscaling of the technology and manage associated upscaling risks.

If proven successful, Mix-MOXes project could therefore provide the foundations for a disruptive zero-carbon technology for heat generation and storage in the future UK circular economy context. As such, it has the potential to replace or retrofit UK fossil-fuel based assets, particularly where combined heat and storage is delivered at large scale: i) centralized energy generation and storage in district heating systems, ii) industrial process heat for hard to decarbonize UK energy-intensive industries, iii) Retrofit or replacement of power stations to exploit existing infrastructure to provide combined zero-carbon generation and storage at grid scale. Our preliminary conservative estimation reveals that Mix-MOXes could provide the UK with CO2 savings in excess of 40MtCO2/year alongside new circular routes for material resources.