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Fuel cell heating units
Projektinfo 05/2012
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New approaches to supplying domestic energy

Fuel cells have unique abilities: in contrast to other co-generation (CHP) plants, they directly convert the chemically bound energy of fuel sources such as hydrogen or natural gas without using a flame. If they are deployed in heating devices, they generate electricity and heat efficiently. Indeed, they are considerably more efficient than combining conventional electricity generation and condensing boilers.

The new fuel cell heating units supply the entire heating in residential buildings. They consist of a fuel cell that co-generates electricity and heat in combination with an integrated boiler. A heat storage tank stores hot water and heating energy. The units can be deployed both in new buildings as well as in the modernisation of central heating systems.

Compared with the separate generation of electricity in power plants and heat in condensing boilers, the new systems enable CO2 savings of between 25 and 35%. They have an overall efficiency of more than 96%. Their particular advantage is that the electrical efficiency is more than 33%.

For an average single-family home, a manufacturer calculates that the costs for electricity and heating are reduced by several hundred euros per year. However, the fuel cell heating units, which are currently only produced in small numbers, are still considerably more expensive than comparable conventional technology.

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New technology is ready for the market

The successful market introduction of fuel cell heating units now depends on optimising the service life, efficiency and costs. The progress made until now by the researchers and developers is nevertheless impressive: the lifetime of the fuel cell stacks has doubled to 20,000 hours and continues to increase, and thanks to initial small-scale production runs it is becoming cheaper to manufacture components and peripheral devices. Still existing challenges identified by the manufacturers include reducing the investment and operating costs, further increasing the stack service life, simplifying the systems and reducing servicing and maintenance requirements. The developers estimate that the fuel cell heating technology will be ready for the marketplace by 2014.

Field tests now need to establish the long-term suitability of the tested systems in practice. This energy-saving, future-oriented technology will then be ready to conquer the boiler rooms. However, they first of all need start-up funding from energy supply companies and the government to enable larger production runs to compete with other CHP plant systems in the medium term. Various cell types are being tested for the fuel cell heating units.

Low-temperature polymer electrolyte (PEM) fuel cells work in a temperature range from around 80°C and can be started up and shut down in a short period of time without the material being damaged by heating or cooling. Because they cannot be operated directly with natural gas but only with hydrogen, a reformer is connected upstream of the fuel cell stack to treat the gas.

Solid-oxide fuel cells (SOFCs) work with temperatures above 600°C. This technology has the advantage that the pre-treatment of the natural gas is substantially simplified.

Using funding from the German government, the manufacturers developed optimised fuel cell heating units based on laboratory models and several prototype generations. Complete systems are now being field-tested that compactly combine all components in a functional as well as user- and service-friendly manner. A typical system consists of the following components: gas treatment (reformer, desulphurisation), fuel cell system as well as additionally required components for the system integration (pumps and blowers, valves, connection technology, sensors, condensate separator, water treatment, air filter). In addition there is also the electrical system with the control and management system as well as an auxiliary boiler, heating manager and the heat storage tank.

The researchers and developers have conducted a comprehensive package of development work and tests to complete the system: materials and core components had to be adapted to the special requirements and correspondingly more precise specifications drawn up, while processing and production procedures also had to be optimised and suppliers obligated to meet the high quality requirements. 

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Addresses

Device development
BAXI INNOTECH GmbH

Project coordination Callux
ZSW Baden-Württemberg

Service

BINE-Projektinfo 05/2012
(PDF, 4 pages, 1.1 MB)

Links

Practical test Callux
www.callux.net

Developer and manufacturer Ceramic Fuel Cells
www.cfcl.com.au

Developer and manufacturer Hexis AG
www.hexis.com

National Organisation Hydrogen and Fuel Cell Technology
www.now-gmbh.de