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Responding to Climate Change 2011

Home | Spotlight on Energy | Forschungszentrum Jülich Fuel cells: a technical assessment
 

Fuel cells: a technical assessment of impact

Forschungszentrum Jülich

Implementation of the DMFC stack into a four wheel scooter
Implementation of the DMFC stack
into a four wheel scooter

Fuel cells operate on a principle established in the first half of the seventeenth century. This is based on the direct electrochemical conversion of a fuel’s chemical energy into electricity. Depending on the gas and the cell used, higher efficiencies are achieved than in conventional power generation where generators are driven by internal combustion engines or turbines.

Clean fuel gases from a variety of energy carriers are used in fuel cells; this reduces CO2 and atmospheric pollutant emissions considerably. Moreover, the widespread use of fuel cells improves supply security and industrial competitiveness. They are used in stationary, portable and mobile applications with a power range between a few watts and several megawatts.

IEF-3, one of nine sub-institutes within the Jülich Institute of Energy Research, provides research results and system solutions for small drives, on-board and stationary power supply, as well as cogeneration with fuel cells.

Covering rising demand efficiently

Today’s mobile electric drives are limited by their integrated accumulators because of range, recharging time and weight. A direct methanol fuel cell (DMFC) supply module can replace an accumulator, especially for small vehicle drives. A IEF-3 market study showed forklift trucks can be driven by the DMFC system developed by IEF-3, if the design is adapted and production costs cut, thus increasing power density, efficiency and lifetime.

HT-PEFC Stack
HT-PEFC Stack

An optimised supply unit with DMFC makes vehicle operation cheaper and can be used for three shifts before being recharged for only a few minutes. Methanol, as a biogenic fuel, ensures a CO2-neutral energy supply. Results of characterisation measurements at an operating temperature of 70°C were 26% for cell efficiency and 67mW/cm² for power density.

These systems for on-board power supply in vehicles improve energy efficiency and cover rising demand for electrical energy. Operating fuel cells, with the middle distillates available on aircraft, ships and trucks, must use fuel converted to a hydrogen-rich gas by an autothermal reformer (ATR) and then turned into electricity by a high-temperature polymer electrolyte fuel cell (HT-PEFC).

Fuel cell heaters are used for converting the oil, EL, in stationary decentralised cogeneration applications (CHP) in the home. IEF-3 has a reactor for autothermal reforming of diesel and kerosene with a lifetime of 2,000 hours at a kerosene conversion rate of 99%. The aim is a lifetime of at least 5,000 hours, at a conversion rate over 99.7%. Currently, HT-PEFC development at IEF-3 is a 5-kW stack undergoing extensive operating tests, with objectives to reach ATR lifetimes, a power density of 250mW/cm² and a 50% efficiency.

Tailor-made for a decentralised power supply

High-temperature fuel cells with ceramic electrolytes (SOFCs) convert natural gas into electricity and heat. SOFCs can thus be used for all natural-gas applications which require both process heat and electricity, particularly in decentralised power supply in industry and households. This efficient conversion means the generated process heat is used without costly infrastructure, increasing efficiency considerably.

The fuel cells are built in the form of stacks, enabling tailor-made implementation of any power requirements and segmentation of modules. This facilitates section-wise expansion and maintenance processes. Jülich SOFC research encompasses the complete scientific and technical process, from functional materials and resolution of structure-activity relationships to component and system verification. In different operation analyses, power densities of 1.38W/cm² at 700°C and degradation rates of 0.4% per 1,000 hours for 18,000 hours have already been demonstrated.

Forschungszentrum Jülich pursues cutting-edge interdisciplinary research in health, information technology and energy and the environment. The two key competencies of physics and supercomputing concentrate on long-term, fundamental and multidisciplinary contributions to science and technology, and on specific technological applications. With over 4,400 staff, Jülich is one of the largest European research centres.

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Forschungszentrum Julich
www.fz-juelich.de/ief

 
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