New storage technology for “green” energy


Bosch and Fraunhofer ISE conduct research into decentralized energy supply using fuel cells

  • Target of 80 percent of electricity from renewable sources by 2050
  • Hydrogen as a cost-effective, commercially viable storage medium
  • Cross-sector supply of households and vehicles
  • Project funded by the German Federal Ministry for Economic Affairs and Energy

Bosch logoEnsuring energy supplies are reliable, commercially viable, and ecologically sustainable while also putting the emphasis on protecting the environment is one of the biggest tasks of the 21st century. Renewables have a particularly important role to play in this endeavor, though finding a way to store that energy in a commercially viable way remains a challenge. This is precisely what the DESS2020+ (District Energy Storage and Supply System 2020+) research project seeks to address, with the primary objective of eliminating the need to transport “green” power over long distances. This is to be achieved by developing decentralized storage solutions for power from renewable sources. The project is sponsored by the German Federal Ministry for Economic Affairs and Energy (BMWi), and is coordinated by Robert Bosch GmbH working alongside the Fraunhofer Institute for Solar Energy Systems ISE.

In its 2010 Energy Concept, the German federal government set out its plan to thoroughly overhaul Germany’s energy supply by 2050. Its main goals are to re-duce primary energy consumption by 50 percent as well as increase the share of renewables to 80 percent of electricity demand and 60 percent of the gross final consumption of energy (across all energy sources including heat and fuel). Storing energy from renewable sources such as the sun or wind poses a particular challenge, since the amount of energy obtained is heavily dependent on the weather.

Potential storage solution in the spotlight
“We are looking into a largely closed system for residential areas, in which power is generated from renewables and then stored and consumed on location. The hope is that this will work not only in the connected households, but also for hydrogenpowered vehicles,” says Annika Utz, the engineer who is head of the DESS2020+ project at the Bosch research campus in Renningen. Researchers there have opted for a system with three core components: a proton exchange membrane (PEM) electrolyzer; a solid oxide fuel cell (SOFC); and multiple hydrogen storage tanks. It is hoped that this combination will solve the problem of energy storage and thereby provide a reliable supply of energy from renewable sources.

Hydrogen energy storage
Researchers assume that in a given residential area there will be around 100 households in which power is obtained from a renewable source such as solar panels. A PEM electrolyzer uses this power to break water down into its component parts of oxygen and hydrogen. The hydrogen is stored in tanks and used to power the fuel cell regardless of when the energy was initially obtained. This fuel cell then supplies electricity on demand, as well as energy to arm up water and heat the connected buildings. “The solid oxide fuel cell is particularly suited to this task, since it can run on both hydrogen and natural gas – making it perfect for the transition from fossil fuels to renewable sources of energy. This is critical in establishing a reliable supply of energy. If at any time not enough hydrogen is available, the system can briefly switch over to natural gas,” explains Utz. There is another advantage to this storage system, too: while with conventional batteries greater capacity translates into higher costs, in the case of hydrogen large quantities can be stored relatively cost effectively – making it a more commercially attractive storage medium.

Fuel for vehicles, too 
As well as supplying households with energy, the system is also designed to play its part in ecofriendly mobility. Homes could be fitted with a hydrogen fuel pump for the efficient refueling of fuel-cell powered vehicles in just a few minutes. However, this requires the pressure of the hydrogen to be increased to around 800 bar – as against a pressure of 50 bar to supply buildings with energy. To achieve this greater compression, researchers at Bosch and Fraunhofer ISE are examining the potential of a low-maintenance, highly efficient electrochemical compressor
for the transport sector.


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Three years of research
The DESS2020+ research project will run for three years until October 2018. It forms part of the German Federal Ministry for Economic Affairs and Energy’s sixth energy research program, entitled “Research for an environmentally friendly, reliable, and affordable energy supply.”

Project participants:
Robert Bosch GmbH
Fraunhofer Institute for Solar Energy Systems ISE
German Federal Ministry for Economic Affairs and Energy


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