World Electr. Veh. J., Volume 2, Issue 3 (September 2008) – 6 articles , Pages 181-235

Controls of a PEM fuel cell stack are one of the crucial issues for securing efficient and durable operations of the stack. When the air is excessively supplied, the efficiency of the system drops. Conversely, insufficient supply of the air causes oxygen starvation at a dynamically varying load. In particular, proper cooling strategy ensures rejecting heat produced and prevents any thermal stress on thin layers of cells. Excessive cooling decreases the working temperature and consequently drops efficiency of the stack. In contrast, the thermal stress imposed by insufficient cooling may reduce the lifespan of the layers.
Design of controls needs a model for the plant that sufficiently represents its dynamics. Current models available are either empirical or computationally intensive, which do not allow for analysis of a stack behavior and associated controls. The paper addresses development of a high dynamic model for a stack that is based on transport of charges, flow of fuels and byproducts taken into temperature effects. The stack is constructed with single cells composed of sandwiched multiple layers that are thermally and electrically coupled. Air is supplied by a blower, which voltage is regulated. Two representing control strategies for the air supply system are designed and compared. Heat is rejected by a thermal circuit that consists of a pump, a three-way valve, and a radiator with a fan and a reservoir. In order to control the coolant flow rate, a linear cascade and a state feedback control are designed and compared, which includes a feed-forward function that is derived from load profile. In addition, the temperature effect on air flow rate is compensated, so that a deviation of the oxygen excess ratio can be suppressed.
The dynamics and performance of the designed controllers are evaluated and analyzed by simulations using dynamic fuel cell system models at a multi-step current and a current profile measured at the Federal Urban Driving Schedule. The results show that the control strategy proposed reduces not only temperature rise in the catalyst layer but also the parasitic power needed for operation of the air and coolant pumps maintaining the oxygen excess ratio set. Full article

A great deal of research funding is being devoted to the use of hydrogen for transportation fuel, particularly in the development of fuel cell vehicles. When this research bears fruit in the form of consumer-ready vehicles, will the fueling infrastructure be ready? Will the required fueling systems work in cold climates as well as they do in warm areas? Will we be sure that production of hydrogen as the energy carrier of choice for our transit system is the most energy efficient and environmentally friendly option? Will consumers understand this fuel and how to handle it?
Those are questions addressed by the EVermont Wind to Wheels Hydrogen Project: Sustainable Transportation. The hydrogen fueling infrastructure consists of three primary subcomponents: a hydrogen generator (electrolyzer), a compression and storage system, and a dispenser. The generated fuel is then used to provide transportation as a motor fuel.
EVermont Inc., started in 1993 by then-governor Howard Dean, is a public-private partnership of entities interested in documenting and advancing the performance of advanced technology vehicles that are sustainable and less burdensome on the environment, especially in areas of cold climates, hilly terrain and with rural settlement patterns.
EVermont has developed a demonstration wind powered hydrogen fuel producing filling system that uses electrolysis, compression to 5000 psi and a hydrogen burning vehicle that functions reliably in cold climates. And that fuel is then used to meet transportation needs in a hybrid electric vehicle whose internal combustion engine has been converted to operate on hydrogen Sponsored by the DOE EERE Hydrogen, Fuel Cells & Infrastructure Technologies (HFC&IT) Program, the purpose of the project is to test the viability of sustainably produced hydrogen for use as a transportation fuel in a cold climate with hilly terrain and rural settlement patterns. Specifically, the project addresses the challenge of building a renewable transportation energy capable system. The prime energy for this project comes from an agreement with a wind turbine operator. Full article

Transportation accounts for almost one third of the total final energy consumption of Spain. This energy demand is almost completely met by oil, which in the case of this country, with almost no oil sources, must be imported. Meanwhile, wind energy is becoming an important component in the country’s electricity generation portfolio, with a four fold increase in the last 5 years, going up to 8 GW installed power in 2004 and a planned upgrading to 20 MW predicted for 2010. So in a medium term scenario, this wind energy will become an important component, bigger than 30%, in the country’s electricity power generation system. Therefore, full exploitation of wind energy for transportation should be, from an economical point of view, a must. The two above-mentioned problems: coverage of transportation energy needs and full use of wind park capabilities, together with a third one related to the environmental impact of the use of oil in such a big quantity, could be solved if a hydrogen economy is successfully applied in the transportation sector. The critical questions are: (1) how much electricity would be required to make this solution possible and (2) by what scenario can surplus wind energy be best used to meet transportation energy needs, at least partly. In this paper, different scenarios for the use of the electricity generated in the wind parks for hydrogen production are proposed, deducing for each one the fraction on oil requirements that can be removed and the technical and economical viability of such scenarios in order to reach a sustainable transport in Spain. Full article

Honda has been researching and developing fuel cells to resolve issues we face such as air pollution and energy conservation. In September 1999, Honda installed its internally developed fuel cell stacks on its fuel cell test vehicle for the first time. Since then, we have made efforts to increase the commercial value of our fuel cell vehicles by setting the aim of our fuel cell development to attain a more compact design with higher output, and to be more adaptable to wider areas. In October 2003, Honda announced the new-generation fuel cell stack, and delivered the Honda FCX to New York State in November 2004. We test-ran the FCX in wider areas and a great deal of information was obtained regarding the FCX’s environmental adaptability and durability.
This paper describes the current and future work on the Honda FCX fuel cell vehicle and fuel cell stack. Full article

The “Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” also known as the Fuel Cell Vehicle and Infrastructure Learning Demonstration, is a 5-year U.S. Department of Energy (DOE) project started in 2004. The purpose of this project is to conduct an integrated field validation that simultaneously examines the performance of fuel cell vehicles and the supporting hydrogen infrastructure. Four industry teams are currently operating more than 77 vehicles and 14 refueling stations, with plans to add over 50 additional vehicles and several additional refueling stations during the remainder of the project duration. This paper covers the progress accomplished by the demonstration and validation project since inception, including results from analysis of six months of new data.
With three sets of public results having been presented previously, this paper comes at roughly the midpoint of the project, just as second-generation fuel cell stacks and vehicles are being introduced and some early vehicles are being retired. With many fuel cell stacks having accumulated well over 500 hours of real-world operation, there is now a higher level of confidence in the trends and projections relating to the durability and voltage degradation of these first-generation fuel cell stacks.
Public results for this project are in the form of composite data products, which aggregate individual performance into a range that protects the intellectual property and the identity of each company, while still publishing overall status and progress. In addition to generating composite data products, NREL is performing additional analyses to provide detailed recommendations back to the R&D program. This includes analysis to identify sensitivities of fuel cell durability to factors such as vehicle duty cycle, number of on/off cycles, time at idle, and ambient temperature. An overview of this multivariate analysis and preliminary findings will be shared, with future project activities discussed. Full article