Argonne tests, creates fuel cells to power the future
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Materials
Another critical fuel-cell research area is materials - the devices have to be durable and inexpensive for general use. As one example, materials scientists have designed new metal supports for solid-oxide fuel cells that are stronger, deliver better performance, are easier to make and cost less than current designs.
 POWER TEST – Chemist Laura Miller (foreground) prepares a TuffCell sample for testing its power output at various loads, which is a critical measure of a fuel cell's usefulness. Chemist Cecile Rossignol works in the background. |
Used in Argonne's TuffCell, a new solid-oxide fuel-cell design, the stronger, metallic bi-polar plates replace the traditional, costly and fragile ceramic-cell supports. The metal supports are easier to make. In conventional processing, the ceramic supports are successively sintered - processed at high temperatures - as each of the four layers is added. In the TuffCell, only one high temperature step is used in the cell fabrication.
TuffCell could be used in auxiliary-power units for tractor-trailers. These trucks run their engines overnight to keep refrigeration units cool, or to provide electricity to the cab for lighting and appliances. Some states are banning truck idling, because of the vehicle emissions.
While this application seems small, use of TuffCell or other fuel cell-powered auxiliary-power units could prevent annual emissions of 22 tons of the greenhouse gas carbon dioxide, 1,024 pounds of nitrogen oxides and 390 pounds of carbon monoxide per truck per year; based on an Argonne study, these estimates assume that an average truck idles for 1,830 hours a year. There are about 500,000 such trucks now operating in the country.
Modeling fuel-cell powered cars
Although fuel-cell vehicles are mechanically simpler than cars with conventional internal combustion engines and transmissions, many of their interactive systems still need to work together efficiently. To aid in this effort, Argonne researchers have developed several software tools based on the laboratory's years of experience in fuel-cell and transportation research. These tools are being used in industry, universities and other national laboratories as well.
The laboratory's General Computational toolkit (GCtool) is used for designing, analyzing and comparing different fuel-cell power-plant configurations. GCtool lets engineers try out different system configurations without the expense and delays of actually building prototypes. GCtool was adapted from earlier software that the laboratory created to model nuclear, space and shipboard service power.
Working with staff from the Nuclear Engineering Division, Chemical Engineering Division (CMT) researchers use GCtool to design fuel-cell systems. Their research has shown that more can be less.
"We found," said CMT Associate Director Jim Miller, "that focusing only on increasing the efficiency of the fuel processor - the component that converts hydrocarbon fuel into hydrogen for the fuel cell - may actually lower the overall system efficiency."
Kumar explained that just increasing the fuel-processor efficiency can steal energy from elsewhere in the system. Rather, the complete fuel-cell system must be considered in its entirety to ensure that the most efficient system is implemented.
The software also showed that the compressor/expander and heat and water recovery subsystems that manage water and operating pressure in fuel-cell systems play a more critical role in system efficiency than had been expected.
The whole car
 FUEL PROCESSOR – Argonne's fuel processor turns petroleum-based fuels, such as gasoline, into hydrogen plus carbon monoxide and carbon dioxide. The carbon monoxide is then converted into additional hydrogen plus sulfur and carbon dioxide and the sulfur is removed, leaving only traces of carbon dioxide and hydrogen. The hydrogen powers each of several fuel cells, which make electricity to power the vehicle. The emissions are carbon dioxide and a small amount of water. |
Fuel-cell car designers need to simulate beyond the fuel-cell system to study energy storage requirements and other questions that must be addressed before large-scale commercialization. Engineers in Argonne's Center for Transportation Research have developed software that can be used to simulate and analyze almost all imaginable powertrains. Called Powertrain Systems Analysis Toolkit (PSAT), it was created in conjunction with Ford, General Motors and DaimlerChrysler.
The software analyzes fuel economy, emissions and performance for any driving cycle or profile for a broad range of vehicles from conventional to fuel-cell drivetrains and up to four-wheel-drive configurations.
GCtool and PSAT were modified to work together when DOE requested Argonne researchers to establish energy storage requirements for three vehicles using a projected fuel-cell technology.
GCtool is the benchmark system for evaluating fuel-cell system designs for DOE's Office of Hydrogen, Fuel Cells, and Infrastructure Technologies. The fuel cell modules in Argonne's PSAT software, and also in the National Renewable Energy Laboratory's Advanced Vehicle SimulatOR (ADVISOR) program, were derived from Argonne's GCtool simulations. GCtool has been licensed to more than a dozen organizations; its continued development is supported by DOE's Office of Energy Efficiency and Renewable Energy.
Fuel Cell Test Facility
As fuel-cell technologies emerge, the laboratory's Fuel Cell Test Facility provides independent, standardized testing and evaluation. Argonne's facility is the only such facility in the national laboratory system, and it is one of the few in the nation that can test full, automotive-sized systems.
From specific subsystems to fully integrated systems with their own fuel processing and air supply, a fuel cell's performance, operation and durability can be compared with competing technologies.
The test facility controls the temperature, pressure, humidity and flow rate of both fuel and air supplies. The fuel can be either pure hydrogen or a simulated reformate. Lab equipment can also monitor and evaluate the fuel cell's water management system. The facility will be updated to evaluate integrated fuel-cell systems including fuel reformers and energy storage devices.
Hydrogen highway
Planning for the hydrogen-for-vehicles infrastructure is underway. Argonne's on-board reforming may be a transitional step, but is not considered the final solution. Hydrogen can be produced from a variety of sources including fossil fuels like coal or natural gas, biomass and water using either electricity (electrolysis) or high temperatures.
Because it has a relatively low energy density, hydrogen must be compressed, liquefied or adsorbed onto a highly reactive material before it can be distributed as a vehicular fuel. Each of these production sources and delivery forms has advantages and disadvantages.
Transportation analysts such as Argonne's Marianne Mintz are evaluating alternative combinations of production and delivery systems to determine the best ones in terms of cost, safety and energy efficiency. With so many variables and unknowns, Mintz plans to work with agent-based modelers in Argonne's Decision and Information Sciences Division. Leaders in the emerging field of complex adaptive systems, researchers there will be examining the behaviors and interactions of various agents that could be involved in producing and delivering hydrogen within a larger system. And with its many variables, the future of the hydrogen infrastructure is a complex system.
"Once the hard work of defining agents and modeling their decision processes is complete, agent-based modeling allows researchers to see the whole system with interdependencies previously unimaginable," said Mintz.
Argonne's fuel-cell research is making important contributions to the Freedom-CAR Partnership and the nation's energy security. FreedomCAR's goal is to develop practical and cost effective fuel-cell vehicle, fuel and infrastructure technologies. The plan is for fuel-cell vehicles to be cost-effective alternatives to gasoline-powered vehicles by 2015 and the choice of many consumers by 2020.
For more information, please contact Catherine Foster (630/252-5580 or media@anl.gov) at Argonne.
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