A practical demonstration of long-term renewable energy storage

CYTOK’s reference plant at the Bernsteinsee holiday and leisure resort in Lower Saxony, Germany, demonstrates how surplus solar power can be stored in the form of synthetic natural gas (SNG) and used flexibly whenever electricity or heat is required.

The plant has been in continuous customer operation since the end of 2020. Solar power generated by the photovoltaic systems on site is used directly or converted into SNG instead of being fed into the public grid as surplus electricity. This enables the Bernsteinsee site to use 100% of its self-generated solar power.

The stored SNG is used in commercially available combined heat and power units and condensing boilers. Electricity and heat are supplied to the hotel buildings, guest rooms, catering facilities and kitchen, the water-ski facility, apartments at the riding stables, administrative buildings and other infrastructure at the resort. Existing oil and gas heating systems have been replaced as part of the site’s transition towards an independent renewable energy supply.

Long-term storage for electricity and heat

At Bernsteinsee, the produced SNG is compressed and stored in a gas tank with a volume of 13 m³ at 25 bar. The tank stores approximately 3.25 MWh of energy in the form of green methane. Including the complete system configuration, the reference project provides a storage capacity of up to approximately 4 MWh. This allows renewable energy generated during sunny periods to remain available over longer periods and to be converted back into electricity and heat according to demand.

The plant combines electrolysis, catalytic methanation, gas storage, combined heat and power generation and CYTOK’s modified OxyFuel process in one integrated energy system. The CO₂ generated during the closed combustion of SNG remains within the system and is reused for the production of new SNG. Intelligent energy management automatically coordinates the individual processes and the use of the available solar power.

The result is a reliable renewable energy supply that is independent of current solar generation and reduces the site’s dependence on fossil fuels.

From an individually engineered reference plant to a scalable product platform

The Bernsteinsee plant was designed specifically around the existing buildings, photovoltaic systems, heating infrastructure and energy requirements of the holiday and leisure resort. Comparable projects can still be individually planned and configured according to the technical conditions and energy demand of a particular site.

For new projects, CYTOK now also offers its technology as a scalable Power-to-Gas Container Platform. The CYTOK Container Platform transfers the proven processes of the Bernsteinsee reference plant into a standardised and modular product platform.

The main technical components are pre-assembled in dedicated containers and can be adapted to the required production capacity, storage volume, electricity demand and heat demand. This reduces on-site installation work, provides greater planning certainty and enables projects to be implemented and expanded in clearly defined stages.

Depending on the project, several container modules can be combined to create a larger integrated energy system. The container platform is therefore suitable for applications ranging from individual commercial properties and research facilities to industrial sites, residential districts, hotels, utilities and larger Power-to-Gas energy projects.