title: Enhancing low-grade thermal energy recovery in a thermally regenerative ammonia battery using elevated temperatures.
abstract: A thermally regenerative ammonia battery (TRAB) is a new approach for converting low-grade thermal energy into electricity by using an ammonia electrolyte and copper electrodes. TRAB operation at 72 °C produced a power density of 236 ± 8 Wm(-2), with a linear decrease in power to 95 ± 5 Wm(-2) at 23 °C. The improved power at higher temperatures was due to reduced electrode overpotentials and more favorable thermodynamics for the anode reaction (copper oxidation). The energy density varied with temperature and discharge rates, with a maximum of 650 Wh m(-3) at a discharge energy efficiency of 54% and a temperature of 37 °C. The energy efficiency calculated with chemical process simulation software indicated a Carnot-based efficiency of up to 13% and an overall thermal energy recovery of 0.5%. It should be possible to substantially improve these energy recoveries through optimization of electrolyte concentrations and by using improved ion-selective membranes and energy recovery systems such as heat exchangers.
authors: Department of Civil and Environmental Engineering, Penn State University, 212 Sackett Building, University Park, PA 16802 (USA), Fax: (+1) 814-863-7304; School of Environment and State Key Joint Laboratory of Environment, Simulation and Pollution Control, Tsinghua University, Beijing 100084 (PR China).
authors: Fang
authors: F
authors: Zhang
authors: Nicole
authors: N
authors: LaBarge
authors: Wulin
authors: W
authors: Yang
authors: Jia
authors: J
authors: Liu
authors: Bruce E
authors: BE
authors: Logan
mesh_terms: D000641:Ammonia / Q000737:chemistry*; D011211:Electric Power Supplies; D004566:Electrodes; D004579:Electron Transport; D013696:Temperature
chemical_list: D000641:Ammonia
keywords: ammonia; copper; electrochemistry; energy conversion; sustainable chemistry