MOLTEN CARBONATE FUEL CELLS FED WITH BIOGAS

摘要

Nowadays renewable and sustainable energy sources are taken in consideration to overcome problemssuch as energy security and climate change associated with fossil fuel. Drivers for bioenergy technologiesdevelopment are environmental and socio-economic politics. Indeed biomass has a carbon neutral life cycle andpromotes climate change benefits that can be realized through reduction of GHG emissions. Furthermore asustainable energy crops production, which does not compete with the use of land and water for food production, canhave a positive impact toward food security because promote rural development providing energy access to remotecommunities and creating employment. Finally bioenergy guarantee energy security because it promotes the energysupplies diversification and the reduction of dependency on a few exporters of oil and natural gas. Fuel cells play akey role in this context because they are able to overcome the issue related to low energy contents of the biomass dueto their high efficiency and environmental sustainability. High temperature fuel cells, such as molten carbonate fuelcell (MCFC) and solid oxide fuel cell (SOFC), are particularly suitable for bioenergy production not only for theirhighest energy efficiency due to the cogeneration of electricity and heat, but also for their potentiality to be fed withlight hydrocarbons fuels such as methane. Biogas, whose components are methane and carbon dioxide mainly, issuitable fuel for MCFC because methane can be transformed to hydrogen by internal reforming, carbon dioxideprevents electrolyte losses and carbon monoxide is both a fuel by itself and a hydrogen supplier by water gas shiftreaction. Unfortunately carbon monoxide can affect cell performance by carbon particles formations plugging thepores of the electrode. Also biogas contains other harmful biomass processing byproducts affecting cellperformances. Among them, hydrogen sulfide is the most important because is able to poison the cell at low ppmlevels.