SOFC systems are key elements of integrated energy management
The SOFC fuel cell systems we have developed offer many benefits, including their high electrical efficiency of around 60 percent. What’s more, the process heat that is generated when the gaseous fuels are converted into electricity can also be extracted and used – doing so opens up the possibility of achieving overall efficiency of up to 90 percent. A pilot project that is being conducted in the energy facility of our Research and Development Center in Schwieberdingen is also testing how efficiently these systems work in part-load operation when they are used as elements of integrated energy management.
In Schwieberdingen, more than 6,000 research and development associates are shaping the mobility of the future, focusing particularly on the advanced development of vehicle drives and fuels, electromobility, and the associated supply infrastructure. They are also developing control units and software platforms. Powerful IT infrastructure requiring commensurately high levels of energy is installed at the site.
The biggest pilot project for Bosch SOFC systems so far
The plan is that our Bosch solid oxide fuel cell (SOFC) systems will become permanent elements of the energy supply system at our Research and Development Center, converting gaseous fuels into electricity and heat. The first SOFC units have been operating reliably in the pilot project in Schwieberdingen since 2020. 20 extra units were added in 2023. The development goal is for the fuel cell system to generate around 200 kW of electrical power. There are also plans for a further expansion. In the pilot project, the SOFC units cover part of the baseload power requirements at the site and represent the biggest SOFC field trial so far. During the pilot phase, the SOFC systems are working in conjunction with an existing co-generation plant and are similarly fueled by natural gas. As soon as appropriate infrastructure has been built, the aim is to run a further developed version of the fuel cell systems on green hydrogen that is produced using renewable energy.
A number of goals are being pursued in the pilot project.
- One of these is to demonstrate how it will be possible to use the technology to generate energy in a highly efficient and decentralized process.
- Another goal is to show how fuel cell systems fit into an integrated energy system that combines electricity generated from a variety of renewable sources.
- What’s more, the pilot project is being used to trial the extraction of the process heat that is generated. The fuel cell units emit thermal energy. If this energy is utilized for heating or air conditioning purposes, for example, the overall efficiency of an SOFC system increases to up to 90 percent of the energy used.
Test site for part-load operation
“SOFC systems are designed for continuous operation – but that doesn’t necessarily mean that they need to operate at full capacity all the time,” says Michael Hausleitner, Technical Project Manager in the SOFC project at Bosch. “In the pilot project, we are therefore testing the ability of fuel cell systems to supply energy in a highly efficient manner in part-load operation scenarios, too.” When the system’s controls adapt the electricity output to match the demand for energy, this is called “modulation” in engineering jargon. “A typical use case might involve SOFC part-load operation during the day, when our photovoltaic systems are producing a lot of electricity and directly converting solar energy into electrical energy is the most efficient method. In the evenings and overnight, we then increase the SOFC output to keep the energy system balanced,” Hausleitner explains.
Our fuel cell systems don’t just work efficiently in full-load operation. During the pilot phase, we’re trying out all the power ranges in which the SOFC technology delivers the benefits of the system.
In terms of practical applications, there are many scenarios that call for this level of flexibility. For example, a supermarket that gets its energy from an SOFC system will need less electricity and air conditioning during the night, so the energy supply can be powered down overnight accordingly. The pilot project in Schwieberdingen is reflecting these sorts of situations in which the production of electricity follows the load curve of the connected consumers. It is identifying the power ranges in which SOFC systems work with high levels of efficiency and conducting tests to work out the speed at which the power output can be altered. When it comes to the market launch of the SOFC systems, the potential for modulation will be a key functional element of the technology.
Elements of an integrated energy system
At the Schwieberdingen site, an integrated energy management system is being put in place and expanded, and the SOFC systems are integrated into it. “We are using photovoltaic systems on roofs and facades as well as solar car ports to produce more and more electricity from renewable sources to cover our own power needs. We also have plans for two wind power plants,” says Ulrich Schneider, who is an associate in the Research and Development Center’s Facility Management department. In this role, he is responsible for the electrical infrastructure and the SOFC pilot project on site. “The amount of available electricity generated from renewable sources varies according to the season and the time of day. When you have a complex system like this, obtaining its energy from a variety of sources, the SOFC systems can help balance out the electricity supply.” At times when the solar systems or wind power plants are producing less electricity, the output of the fuel cell systems can be increased accordingly.
“Another important benefit of the SOFC system in an energy network is that heat can be extracted,” Schneider adds. The process heat that is generated when gaseous fuels are converted into electricity makes high-temperature fuel cell systems particularly efficient – it can either be used directly as heating energy or be converted in an absorption chiller to provide cooling for air conditioning systems. SOFC systems in data centers are a prime example of an application scenario. They generate electricity on site for the servers in a decentralized process that ensures a reliable supply. At the same time, the thermal energy that is produced during the process can be used to cool the server rooms.
Since the SOFC systems are being developed with the aim of using green hydrogen as the energy source, one of the future scenarios for the integrated energy system in Schwieberdingen involves the in-house production of this hydrogen. “We can take the green electricity that we generate ourselves but don’t use directly and convert it into hydrogen by means of electrolysis. We can then store that hydrogen and use it to run our fuel cell systems,” explains Hausleitner. Hydrogen that is produced using electricity from renewable sources is completely CO₂-neutral. What’s more, we can use technology we have developed ourselves for this purpose. Not only is Bosch pressing ahead with fuel cell technology for converting hydrogen into electricity and heat, but it is also driving forward the development of key components for electrolyzers that produce hydrogen.
An overview of SOFCs in the Bosch Research and Development Center in Schwieberdingen
An SOFC fuel cell system that could yield an electrical output of around 200 kW is in operation at the site. In the field trial, the SOFC system is part of an integrated energy concept that combines electricity from a variety of renewable sources. The pilot project is being used to test various aspects, including performance range and heat extraction.
Goal
To test the performance range of SOFC systems
Area of application
Incorporation into an integrated energy system in an industrial environment
Location of use
Bosch Research and Development Center in Schwieberdingen
SOFC systems are the perfect elements for integrated energy management. They can balance out fluctuations in the available electricity generated from renewable sources and are particularly efficient in terms of combined heat energy and electrical energy.
- SOFC units installed in the energy facility
- percent electrical efficiency
- percent overall efficiency when heat is extracted
- kW (nominal) of electrical energy
- Operational start of the SOFC system
The Bosch SOFC system is currently in the pilot phase. All technical specifications given are development objectives and refer to the beginning of life.
