Biogas upgrading and utilization from ICEs towards stationary molten carbonate fuel cell systems

ABSTRACT

Biogas production from anaerobic digestion has increased rapidly in the last years, in many parts of the world, mainly due to its local scale disposition and to its potential on greenhouse gases (GHG) emissions mitigation. Biogas can be used as fuel for combined heat and power systems (CHP), in particular for internal combustion engines (ICEs). In recent investigations, fuel cells have been considered as alternative CHP systems. In the present article, two different energy conversion systems are compared: a 1.4 MW class MCFC system, running on pipeline natural gas, and an in situ ICE, running on biogas. In the first case, biogas is considered as a source fuel to obtain upgraded gas to be injected in the natural gas grid. In such scenario, the location of the fuel cell power plant is no longer strictly connected to the anaerobic digester site. Several energy balances are evaluated, considering different upgrading techniques and different biogas methane/carbon dioxide ratios.

KEYWORDS:

• Anaerobic digestion
• biogas upgrading
• CHP systems
• ICEs
• molten carbonate fuel cell

Acknowledgments

This work was carried out under the auspices of the special project “Sceneries of adaptation of the Italian agriculture to the climatic changes” (AGROSCENARI) D.M. 8608/7303/2008 of 7.8.2008 of the Agricultural Research Council, and Italian Ministry of the Agricultural and Forestry Politics.