Build to Zero and the EIC Accelerator: Storing Solar Power as Steam

Build to Zero, incorporated in 2022 and based in Seville, develops ThermalBox, an electro-thermal energy storage system that uses renewable electricity to heat molten salts, stores the heat, and delivers process steam to factories around the clock, replacing gas boilers. Its EIC Accelerator project receives an EU contribution of €2,491,249 and runs from December 2024 to November 2026, according to CORDIS. It targets small and medium industrial users in chemicals, food and drink, paper and textiles that need steam below 400 °C, and aims to validate the system in an industrially relevant environment.

In the first year, the report says, Build to Zero standardised and validated all core components: a redesigned molten-salt electric heater, a once-through steam generator in a vertical helical-coil design, and a modular, transportable storage tank. Industrial manufacturing and pre-testing of all major components were completed, "with factory acceptance tests confirming compliance with design specifications", giving a "FOAK-ready design", according to CORDIS. The steam generator was built with Alfa Laval, which said in October 2024 that the first unit would be deployed at Dekitra, a chemicals maker, according to Alfa Laval.

Where Build to Zero Stands Now

The Spanish register lists sales in the €500,000 to €1 million bracket, share capital of €866,410 and a board that includes the venture firm Axon Partners Group, according to Empresia. No equity round, EIC Fund investment or commissioning of the Dekitra installation has been announced. The company's website news section has not been updated since 2024.

The Technology: Solar-Plant Storage in a Box

Sensible heat storage in molten salts is a proven technology, the EIC report says, previously limited to large power plants. Build to Zero's contribution is making it compact, factory-built and transportable for individual factories. Electricity heats the salt when power is cheap or abundant; the stored heat later boils water into steam on demand. The EIC report says this also gives the grid flexibility by shifting industrial demand.

What the EIC Award Promised, and What the Record Shows

The project runs until November 2026, so it is too early to judge it. The first year delivered a validated design and tested components, which is real engineering progress. The decisive step, a unit supplying steam in a working factory, was described as the next stage and has not been reported.

1. Components validatedDeliveredFactory acceptance tests.
2. Standardised MVP designDeliveredFOAK-ready.
3. Industrial installationNot reportedDekitra planned.
4. Market deploymentPendingNo orders public.

The Money

The award was blended finance; no EIC Fund investment has been announced. Build to Zero's financing beyond the EIC grant and its board investor is not public.

What Cannot Be Checked

Why Europe Should Care

Industrial heat below 400 °C is still mostly supplied by natural gas, while renewable power is increasingly curtailed, the EIC report says. A heat battery that turns surplus electricity into round-the-clock steam addresses both.

The Verdict

Build to Zero and the EIC have not been asked for comment for this article. It is based entirely on public records and published statements, linked throughout.