Open Access Journal Journal of Power Technologies 97 (5) (2017) 382–387 The effect of coal thermal pretreatment on the electrochemical performance of molten hydroxide direct carbon fuel cell (MH-DCFC) Andrzej Kacprzak * , Rafal Kobylecki, Zbigniew Bis Department of Energy Engineering, Faculty of Infrastructure and Environment,Czestochowa University of Technology, ul. Brzeznicka 60a, 42-200 Czestochowa, Poland Abstract The direct carbon fuel cell (DCFC) is a power generation device that converts the chemical energy of carbonaceous fuels (e.g. fossil coals, charred biomass, activated carbons, graphite, coke, carbon black, etc.) directly into electricity. However, the use of coal in the DCFC is sometimes problematic particularly if volatile matter evolves from the fuel during fuel cell operation. The recommended course of action to minimize that problem is to pre-treat thermally or even pyrolyze the coal and remove the volatiles before the fuel is used in the fuel cell. In this paper, three raw and thermally-treated coals of various origins have been compared for electrochemical activity in a direct carbon fuel cell with molten hydroxide electrolyte (MH-DCFC). The thermal pre-treatment of selected coals was carried out in an inert gas atmosphere at 1023 K. It was found that—compared to raw coals—the pyrolyzed coals presented lower maximum current and power densities at 723 K but simultaneously provided faster stabilization of the open circuit voltage. Keywords: Direct carbon fuel cell; molten hydroxice electrolyte; coal; thermal treatment 1. Introduction Coal is an abundant fuel source that is relatively inexpen- sive, easy to transport and can be converted into electric- ity by various energy conversion technologies, such as coal- fired power plants. However, the use of coal for power gen- eration is associated with a number of environmental chal- lenges, primarily emissions to the atmosphere such as SO 2 , NO x , fly ashes, mercury (Hg) and others. Therefore new technologies are sought, out of a desire to improve the envi- ronmental performance of coal-to-energy conversion. One such technology is the direct carbon fuel cell (DCFC)—a power generation device converting the chemical energy of carbon directly into electricity. No combustion or gasification processes are involved, as the energy is converted through direct electrochemical oxidation of the fuel. The basic struc- ture of the DCFC is similar to other cell types, such as the molten carbonate fuel cell (MCFC) or the solid oxide fuel cell (SOFC). However, in DCFC technology solid car- bonaceous fuels are used and directly oxidized at the an- ode surface and no clean gaseous fuels (e.g. H 2 or CO) are required, as is the case with MCFCs or SOFCs. There are four basic types of DCFC under development, which * Corresponding author Email address: (Andrzej Kacprzak) generally differ as to electrolyte types: molten carbonates (MC-DCFC) [1, 2, 3, 4], solid oxygen ion conducting ceram- ics (SO-DCFC) [5, 6, 7], aqueous [8] or molten hydroxides (MH-DCFC) [9, 10, 11, 12, 13, 14]. Composite electrolytes (termed ’hybrid electrolytes’) are also widely used in DCFC prototypes (H-DCFC) [15, 16, 17]. Compared to other tech- nologies solid carbon fuelled fuel cells have several unique features and advantages, offering higher thermodynamic ef- ficiency, lower emission of carbon dioxide per unit of the gen- erated electricity and no emissions of SO 2 , NO x , particulate matter, mercury and other trace element pollutants. Further- more, one of the advantages of DCFC is its fuel flexibility. Moreover, carbon fuel does not require any sophisticated preparation, since the solid carbon (primarily elemental car- bon, which is a basic fuel for DCFC) can be easily obtained from various resources such as coal, lignite, petroleum coke and charred biomass (e.g. grass, wood, nut shells, corn husks or even organic wastes) [2, 3, 6, 7, 13]. Coal fuels have various properties that could affect the DCFC work- ing characteristics, such as microstructure, carbon and sulfur content, volatile matter and impurities such as mineral sub- stances (ash). In previous research, testing was carried out on the use of coals directly on the anode surface in the dif- ferent DCFC prototypes with various electrolytes and config- urations. Li et al. [18] investigated the relationship between