The sunfire solution, which it believes is the world’s largest commercial reversible electrolysis module, enables the efficient, long-term storage of large amounts of energy. The fully integrated system, based on the company’s RSOC (reversible solid oxide cell) technology, converts surplus renewable energy – e.g. from wind power or solar photovoltaic arrays – into hydrogen, which can then be stored at high pressure.
When electric power is required, it is generated in a highly environmentally friendly way, using hydrogen taken out of storage (i.e. in fuel cell mode). It only takes a few minutes to switch the system from energy input to energy output mode.
In electrolysis mode the system yields 42 m3/h of hydrogen at up to 85% efficiency. When switched to fuel cell mode, it delivers 50 kW of electric power at up to 60% efficiency. These values provide a basis for the realisation of other customer applications in the field of industrial-scale hydrogen production and energy storage.
In addition to hydrogen, the system can also be operated in fuel cell mode utilising cheap natural gas or biogas taken from the grid.
sunfire partnership with Boeing
The RSOC system represents an important milestone in the partnership between sunfire and Boeing, who began working together in November 2014. sunfire developed the RSOC system at its headquarters in Dresden in collaboration with Boeing engineers, who brought their experience with energy systems for unmanned undersea vehicles.
‘The cooperation with Boeing has been fantastic, and they’ve made a huge contribution in terms of finalising the systems integration concept,’ says Nils Aldag, Chief Financial Officer of sunfire GmbH.
Testing at Boeing and US Navy
The high-performance RSOC module was delivered to Boeing Network & Space Systems in California last September, and consists of a hot box, cold box, control unit, and steam generator. This first unit – with enhanced cybersecurity features – was commissioned on the Southern California Edison power grid at Boeing’s Huntington Beach facility.
It was subsequently installed for further testing on the Navy’s microgrid at the Naval Facilities Engineering Command, Engineering and Expeditionary Warfare Center in Port Hueneme, California.
Hydrogen for energy storage
Highly compressed hydrogen can be stored in almost unlimited volumes, and so offers significant advantages over battery-based or pumped-storage hydroelectricity options for energy storage, which are characterised by restricted capacity. It also solves the long-term storage problem with batteries, which naturally self-discharge over time.
The use of electrolysis to convert renewable energy delivers high-purity, ‘green’ hydrogen, which can also be sold as a stand-alone product to consumers such as industrial companies and refineries. The storage function also enables RSOC systems to make a significant contribution to grid stabilisation, generate environmentally friendly power and heat, and improve power station efficiency by enhancing capacity utilisation.
sunfire hot on solid oxide cells
sunfire is developing solid oxide electrolysis cells (SOECs) and solid oxide fuel cells (SOFCs). High-temperature electrolysis is used to efficiently split steam into hydrogen and oxygen. The hydrogen produced can either be converted into fuels using the company’s Power-to-Liquids process, or used in the hydrogen mobility or industrial sectors.
Last autumn sunfire delivered an SOFC for the Ship-Integrated Fuel Cell (SchiBZ) project in Germany, to demonstrate the reliability of fuel cells for onboard power on ships.