A Power-to-Heat Long Duration Energy Storage for decarbonizing the industrial thermal processes

Project Information

ThermalBox

Grant agreement ID: 101188588

DOI

10.3030/101188588

EC signature date 20 November 2024

Start date 1 December 2024

End date 30 November 2026

Funded under

• The European Innovation Council (EIC)

Total cost

No data

EU contribution

€ 2 491 249,00

Coordinated by

BUILD TO ZERO SL
Spain

Periodic Reporting for period 1 - ThermalBox (A Power-to-Heat Long Duration Energy Storage for decarbonizing the industrial thermal processes)

Reporting period: 2024-12-01 to 2025-11-30

Summary of the context and overall objectives of the project

Industrial heat represents one of the most difficult sectors to decarbonise in Europe. A large share of industrial energy consumption is dedicated to the production of process steam and low-to-medium temperature heat, typically below 400 °C, which is still predominantly supplied by fossil fuels, mainly natural gas. This results in high greenhouse gas emissions, exposure to fuel price volatility and increasing risks related to energy security.

In parallel, Europe is rapidly increasing the penetration of renewable electricity generation. While this transition is essential to achieve climate neutrality, it also creates challenges for the power system, including variability, grid congestion and renewable energy curtailment. Industrial heat demand, which is typically continuous and inflexible, remains largely disconnected from the growing availability of renewable electricity. Bridging this gap is therefore a key challenge to achieve the objectives of the European Green Deal, Fit for 55 and the EU Industrial Strategy.

The ThermalBox project addresses this challenge by developing a modular Power-to-Heat and Thermal Energy Storage solution that enables the decarbonisation of industrial steam production while supporting the integration of renewable electricity into the energy system. ThermalBox converts renewable electricity into high-temperature thermal energy, stores it efficiently using molten salts, and delivers clean process steam on demand, independently of real-time electricity availability.

The overall objective of the project is to develop, validate and prepare for market deployment a cost-effective, scalable and reliable solution capable of supplying continuous decarbonised steam to small-to-medium industrial users, while also providing demand-side flexibility services to the electricity grid. The project targets energy-intensive sectors such as chemicals, food and beverage, paper and textiles, where electrification options are currently limited and the decarbonisation potential is high.

By adapting a proven technology, sensible heat storage in molten salts, to a compact, modular and industrially deployable design, ThermalBox aims to replace fossil-fuel boilers with an electrified thermal storage system powered by renewable electricity. Through validation in an industrially relevant environment and advancement to a high level of technological readiness, the project lays the foundations for market entry, contributing to CO2 emission reductions, improved industrial energy resilience and a more flexible and efficient electricity system.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The main achievement was the standardisation and validation of all core components. The molten-salt electric heater was redesigned to ensure uniform heat transfer, controlled salt temperatures and full turndown capability under dynamic operation. Material selection and corrosion testing confirmed long-term compatibility with nitrate/nitrite molten salts.

In parallel, the Once-Through Steam Generator (OTSG) was optimised for molten-salt operation. A vertical helical coil configuration was validated as the FOAK reference design, ensuring compactness, thermal efficiency and stable operation across the operating range.

The molten-salt storage system was engineered for modular deployment, with a transport-compatible tank geometry and a standardised insulation and heat-tracing concept defined to ensure safe operation and low thermal losses.

At system level, all subsystems were integrated into a standardised ThermalBox® Minimum Viable Product (MVP). System-level thermal, hydraulic and safety analyses were completed, including hazard identification and operability assessments. Industrial manufacturing and pre-testing of all major components were successfully completed, with factory acceptance tests confirming compliance with design specifications.

As a result, the project significantly increased the technological maturity of the ThermalBox® system and delivered a validated, standardised and FOAK-ready design, establishing a solid technical basis for first-of-a-kind installation and commissioning.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The ThermalBox® project has delivered a Minimum Viable Product (MVP) that advances the state of the art in electrified industrial heat by integrating Power-to-Heat conversion, long-duration thermal energy storage and digital control into a single, modular system for industrial steam generation.

The MVP demonstrates that molten-salt thermal storage, previously limited to large-scale power plants, can be implemented as a compact, factory-assembled and transportable solution suitable for industrial environments. The system enables continuous steam production decoupled from real-time electricity consumption, combining operational robustness with flexibility.

Key advances include a molten-salt electric heater capable of dynamic, high-power operation with full turndown, a compact once-through steam generator designed for flexible operation, and a modular molten-salt storage concept with reduced footprint. The integration of the ETESAI® digital control platform enables coordinated and adaptive operation of all subsystems, going beyond hardware-only thermal storage solutions.