System modeling methodology and analyses for materials-based hydrogen storage Jose ´ Miguel Pasini a, *, Bart A. van Hassel a , Daniel A. Mosher a , Michael J. Veenstra b a United Technologies Research Center, 411 Silver Lane, East Hartford, CT 06108, USA b Ford Motor Company, 1201 Village Road, Dearborn, MI 48121, USA article info Article history: Received 19 November 2010 Received in revised form 18 May 2011 Accepted 26 May 2011 Available online 16 August 2011 Keywords: Hydrogen storage Light-duty vehicle System modeling Metal hydride Sodium aluminum hydride Fuel cell abstract In the global efforts to develop advanced materials-based hydrogen storage, the various on- board reversible hydrides, adsorbents and chemical storage candidate materials and systems each have their individual strengths and weaknesses. An overarching challenge in associated research and development is to devise material/system architectures which satisfy all requirements for viability in a particular application area, such as light-duty vehicular transportation. System modeling at the level which encompasses not only the storage material and vessel/reactor, but also integration with a fuel cell and balance-of-plant components, provides a more complete assessment of viability and guides options for improvement. The current work covers the methodology developed for conducting such system modeling consistently across multiple organizations and will present performance results from studies focused on reversible hydride systems. Connecting this high level modeling to more detailed finite element design simulations will be one aspect of our framework approach. The complex hydride NaAlH 4 is representative of novel materials under development and will be used as the basis for properties, such as temperature dependent kinetics, which influence the integrated system configurations and component sizing. While system charging is included through the sizing of certain components, emphasis is placed on hydrogen discharge by the storage system, interrogated through drive cycle transients. Comparisons of performance relative to requirements, including effective gravimetric capacity, effective volumetric density and energy utilization, are given for the baseline material and for a sensitivity study on material density. Copyright ª 2011, United Technologies Corporation. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications, LLC. All rights reserved. 1. Introduction Energy-efficient cars emitting zero greenhouse gases: this ulti- mate goal makes fuel cell vehicles running on hydrogen (without on-board reforming of a carbon-based fuel) a very attractive concept. However, the extremely low volumetric density of hydrogen gas makes low pressure cylinders impractical for any space-constrained system, such as a fuel cell car, where we would want to store around 5.6 kg of hydrogen for a driving range over 300 miles [1,2]. Compressing the gas to high pressure, as in the currently used 350 and 700 bar tanks, adds weight and cost for the pres- sure vessel, while alleviating only partially the volumetric problems. By combining high pressure and low temperature, cryo-compressed systems obtain improved performance at the expense of increased complexity [3e5]. Another approach is to * Corresponding author. E-mail address: pasinijm@utrc.utc.com (J.M. Pasini). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 37 (2012) 2874 e2884 0360-3199/$ e see front matter Copyright ª 2011, United Technologies Corporation. Published by Elsevier Ltd on behalf of Hydrogen Energy Publications, LLC. All rights reserved. doi:10.1016/j.ijhydene.2011.05.169