Experimental Development of a Zero Carbon Boiler to a stage where it can deployed in real homes with beta customers


Caldera is a heat storage company looking to decarbonise the economy by solving grid scale problems. The UK government is looking to tackle the economic impact of Covid-19 by 'building back better' a green economy that will deliver directly on the government's Clean Growth Strategy and net zero carbon ambition.

Caldera has developed a Zero Carbon Boiler which takes renewable electricity from the grid and converts it into heat which is stored within the unit until the consumer wants heating or hot water. The Warmstone technology will increase the amount of renewable energy that can be productively used, which in turn keeps down the cost of renewable energy. To bring this technology a step closer to reality, the unit needs to be developed to a point where it is safe to deploy and test in a domestic home.

The Zero Carbon Boiler has an innovative core inside that is trademarked as "Warmstone" Technology. The Warmstone technology is a low cost storage media that is able to absorb renewable electricity and store the equivalent energy for a 4 bedroom home to cover a 24 hour period on the coldest winter day or seven days of hot water in the summer. The energy is retained with 5-10% losses per day with an efficient insulation strategy.

The Zero Carbon Boiler is cylindrical in shape, weighs 1.5 tonnes and is 1m in diameter by 1.6m tall. The unit will be located externally to the property or in a garage or plant room. The existing boiler is removed and replaced with a Heat Interface Unit. Heat Interface Units are mass produced as they are used in district heating networks to transfer heat from the network to individual homes. The use of a standard Heat Interface Unit means that this technology is a straight forward retrofit and can be carried out by a plumber without additional training or modification to the property. The Heat Interface Unit is connected to the Zero Carbon Boiler via two insulated pipes. The Zero Carbon Boiler is also connected to the main electricity supply to the home.

To date a half size unit has been built and tested in Cadera's production facility in Fareham, with a full size unit in manufacture ready for deployment to a test house in September this year (2020). When the new unit has been installed and is functioning in the test house it will be at Technology Readiness Level 5 (September 2020).

This project will develop the Technology Readiness Level 5 unit to a Technology Readiness Level 6 status so that it can be safely fitted in real homes in summer 2021 for trials over the following winter. The project will include the manufacture of two units with one being used for certification testing and the other installed for trials at the Caldera facility in Fareham.

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