ComEd Joins Chicago Plug-in Hybrid Conversion Project Targeting 2x Fuel Economy for Escape Hybrid
8 September 2006
ComEd, one of the largest US electric utilities with approximately 5.2 million customers and more than $15 billion in annual revenues, is joining the Illinois Institute of Technology (IIT) Plug-In Hybrid Electric Vehicle (PHEV) Project.
The project, announced in January in collaboration with Chicago-based All Cell Technologies, the City of Chicago and other industrial and government partners, is an effort to convert a Ford Escape hybrid SUV in the city fleet into a plug-in hybrid (PHEV) using a lithium-ion battery pack from All Cell.
All Cell is an Illinois Institute of Technology-based technology transfer company formed in 2001 by Professors Said Al-Hallaj and J. Robert Selman to commercialize lithium-ion batteries in military, medical, portable, and transportation applications using IIT’s patented passive thermal management technology with phase change material (PCM).
In June, All Cell Technologies received $1.25 million in financing from Heartland Angels to support the PHEV project.
Phase change materials are substances that change from solid to liquid and back again when heat is absorbed and expelled, respectively. In this process, PCMs maintain a nearly constant temperature, and thus are employed for thermal engineering in a number of fields.
According to All Cell, suitable phase change materials for use in Li-ion battery applications will have a melting point in the range of between about 30° C and 60° C; a high latent heat per unit mass ratio; and a narrow melting temperature range.
|An earlier schematic of a PHEV battery module using All Cell’s PCM thermal management. Click to enlarge.|
All Cell is assembling the battery pack from commercially available 18650 cells integrated with the company’s PCM technology and control systems into 8-amp, 14.4-volt modules, according to Dr. Al-Hallaj.
The project is envisioned in two phases. The first—which has the targeted outcome of doubling to fuel economy of the Escape hybrid—involves bypassing the OEM battery pack (not removing it) with an All Cell pack of approximately 10 kWh.
The PHEV battery will be working with the constraints of the original controller, thus limiting all-electric speeds to the original lower-speed range. Part of the first phase will be benchmarking the Escape hybrid to determine the required Wh per mile. Depending on the result of the benchmarking, All Cell believes that it might be able to reduce the size of the battery pack a bit and still meet the 2x target for fuel economy.
The second phase will entail replacing the OEM battery and original operating strategy of the controller to support a more robust all-electric range (AER).
The City is supporting the project with a vehicle and with technical collaboration. If the All Cell team meets its fuel economy target, the City will consider converting more vehicles, depending upon price.
ComEd will provide expertise by sharing its best practices from operating its hybrid vehicles. The utility owns 64 hybrid Ford Escapes and its SUV fleet will expand to 114 hybrid vehicles by the end of 2007. ComEd also will provide expertise in technical and regulatory matters related to charging the plug-in hybrid vehicles’ electric drive systems from the utility’s electrical power distribution system.
ComEd is also interested in studying the implications of the potential of vehicle-to-grid charging (V2G) that would emerge with the presence of a large PHEV fleet.
There are few better validations for an emerging technology enterprise than partnership with one of the largest utility providers in the nation. ComEd’s involvement promises significant capacity to realize our vision and provide relief to consumers for the high economic and environmental cost of gasoline.—Bob Anderson, president of All Cell
All Cell already has li-ion batteries based on its PCM technology in the field in medical and portable applications through a licensing deal with MicroSun Technologies.
Thermal management. High-power applications of lithium-ion battery systems require comprehensive thermal management solutions. Operation outside of the optimum temperature range can degrade the performance and safety of the battery.
Active cooling solutions use a manifold, fans or pumps for liquid or air, but also add complexity, size, weight, cost and points of failure.
The All Cell passive thermal management approach integrates a PCM impregnated in a graphite matrix in between the cells of the battery module. The graphite leads to higher thermal conductivity, and the PCM acts as a heat sink, absorbing the heat generated by the battery. The passive system also reduces battery pack volume and weight compared to systems that use active thermal management.
The All Cell batteries have operated safely at temperatures ranging up to 45° C, and have proven operational in the desert in applications served by MicroSun Technologies. All Cell has also determined that its thermal management method can in some cases double the cycle life of the battery system compared to those using conventional thermal management.
US Patent #6,468,689: Thermal management of battery systems
US Patent Application #20060073377: Battery system thermal management
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