Process optimization for large-scale hydrogen liquefaction U. Cardella a,b,* , L. Decker a , J. Sundberg b , H. Klein b a Linde Kryotechnik AG, D€ attlikonerstrasse 5, 8422 Pfungen, Switzerland b Institute of Plant and Process Technology, TU Mu ¨ nchen, 85748 Garching, Germany article info Article history: Received 19 January 2017 Received in revised form 16 March 2017 Accepted 21 March 2017 Available online xxx Keywords: Hydrogen liquefaction Efficiency Costs Model Simulation Optimization abstract The investment in the hydrogen infrastructure for hydrogen mobility has lately seen a significant acceleration. The demand for energy and cost efficient hydrogen liquefaction processes has also increased steadily. A significant scale-up in liquid hydrogen (LH 2 ) pro- duction capacity from today's typical 5e10 metric tons per day (tpd) LH 2 is predicted for the next decade. For hydrogen liquefaction, the future target for the specific energy con- sumption is set to 6 kWh per kg LH 2 and requires a reduction of up to 40% compared to conventional 5 tpd LH 2 liquefiers. Efficiency improvements, however, are limited by the required plant capital costs, technological risks and process complexity. The aim of this paper is the reduction of the specific costs for hydrogen liquefaction, including plant capital and operating expenses, through process optimization. The paper outlines a novel approach to process development for large-scale hydrogen liquefaction. The presented liquefier simulation and cost estimation model is coupled to a process optimizer with specific energy consumption and specific liquefaction costs as objective functions. A design optimization is undertaken for newly developed hydrogen liquefaction concepts, for plant capacities between 25 tpd and 100 tpd LH 2 with different precooling configurations and a sensitivity in the electricity costs. Compared to a 5 tpd LH 2 plant, the optimized specific liquefaction costs for a 25 tpd LH 2 liquefier are reduced by about 50%. The high-pressure hydrogen cycle with a mixed-refrigerant precooling cycle is selected as preferred lique- faction process for a cost-optimized 100 tpd LH 2 plant design. A specific energy con- sumption below 6 kWh per kg LH 2 can be achieved while reducing the specific liquefaction costs by 67% compared to 5 tpd LH 2 plants. The cost targets for hydrogen refuelling and mobility can be reached with a liquid hydrogen distribution and the herewith presented cost-optimized large-scale liquefaction plant concepts. © 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction There is a growing worldwide concern for the impact of climate change and pollution. Alternative clean energy fuels for the mobility and stationary power sector are an option to meet the targets for future greenhouse gas emissions and global warming, as indicated at the Paris Climate Conference in 2015 [1]. Hydrogen in combination with fuel cell technology is one of the most promising energy carriers [2]. Fuel cell * Corresponding author. Linde Kryotechnik AG, D€ attlikonerstrasse 5, 8422 Pfungen, Switzerland. E-mail addresses: umberto.cardella@tum.de, umberto.cardella@linde-kryotechnik.ch (U. Cardella). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2017) 1 e16 http://dx.doi.org/10.1016/j.ijhydene.2017.03.167 0360-3199/© 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Cardella U, et al., Process optimization for large-scale hydrogen liquefaction, International Journal of Hydrogen Energy (2017), http://dx.doi.org/10.1016/j.ijhydene.2017.03.167