Overview
High-temperature thermal energy storage (TES) is expected to be a critical component in low-cost decarbonisation technology pathways for heavy industries. The key driver is that where heat is required from renewable sources, it is significantly cheaper to store energy as heat than as electricity in pumped hydro or batteries. This study will benefit HILT CRC industry partners, particularly those in alumina, cement and lime, and iron ore fields by informing how high-temperature TES may (or may not) be suited to providing heat to these processes, through up-to-date information about the various TES options, and assessment of how these technologies match to the needs of specific use-cases.
In 2024, this project was extended for a further 2 years – see RP2.017.
Project Details
This project aims to better understand the requirements and needs of users of high-temperature heat within HILT CRC, and to provide these stakeholders clear, contemporary information about options for high-temperature thermal energy storage integration into their processes.
This will be done via a Scoping Study that focusses first on particular use-cases – fluidised bed H2-DRI, and alumina and lime calcination to identify needs, requirements and value proposition as they relate to high-temperature TES. The Scoping Study will examine the high-temperature TES technology options themselves, with the aim of providing a preliminary assessment of which technologies are best suited to each use-case.
The expected outcomes from this project included:
- Better understanding of the needs for thermal storage pertaining to each use-case, including technical requirements, key performance criteria, site specific factors, integration requirements/challenges, value proposition.
- A clear technology landscape for high-temperature TES options, and an evaluation (via SWOT analysis) of how they fit with the needs of HILT CRC end users.
- Flow sheets modelling integration of hot stored iron ore into a fluidised bed H2-DRI process.
- Simplified system performance model of PB-TES systems for integration to alumina/lime calcination processes.
- Techno-economic assessment of the storage and integration options.
- Evaluation of the technical challenges and risks.
- Recommendations for any future HILT CRC investment in research and/or demonstration of high-temperature TES, on the basis of the findings of the Scoping Study and Case Studies.
Phase 1 of RP2.009 was completed in September 2024, and phase 2 (RP2.017) is underway.
Research Areas
New technology to accommodate multiple energy sources and offer flexibility in switching between them
Outcomes
RP2.009 examined two case studies for thermal energy storage integration to HILT processes in depth:
- retrofit of high-temperature thermal storage to a calciner in an alumina refinery
- supply of heat to a hydrogen fluidised bed direct reduction process, for iron making.
For alumina, heat is required at a temperature around 1000°C. Hot blast stoves are regenerative heating systems used for heating air that is fed into blast furnaces in steelmaking, and an example of a fully commercial system designed for heating air at the temperatures required.
This project investigated the feasibility of repurposing hot blast stoves for longer-term storage, and electrical heating. The encouraging results indicated that the concept could potentially displace about one-third of energy normally provided by natural gas. Phase 2 is investigating further options for deeper levels of gas replacement, in both retrofit and new build cases.
For iron ore, the research team developed an initial flow sheet integrating thermal storage. The cost of heat supply from this route was about 23% cheaper compared to a reference case in which heat was provided by burning hydrogen. There are opportunities to further increase this benefit, and these are being further developed in phase 2.
Published Scientific Papers
- Lee L, Ingenhoven P, Saw WL, Nathan GJ. The techno-economics of transmitting heat at high temperatures in insulated pipes over large distances. Applied Energy. 2024; Vol. 358, 122634.