Environmental Engineering Reference
In-Depth Information
Chapter 1
Understanding the Distinguishing Features
of a Microbial Fuel Cell as a Biomass-Based
Renewable Energy Technology
Bruce E. Rittmann, Ce ยด sar I. Torres and Andrew Kato Marcus
Abstract Biomass-based renewable energy, which utilizes biomass derived
from photosynthesis, could sustainably provide 67-450 EJ of energy annually.
Biomass in organic wastes, for example, can annually provide 7.5 EJ of energy,
and utilization of organic wastes locally as an energy source can prevent
environmental pollution and reduce the energy losses associated with transpor-
tation. The technological challenge is to sustainably capture this biomass
energy without creating serious environmental or social damage.
A microbial fuel cell (MFC) is a novel biomass-based technology that
marries microbiological catalysis to electrochemistry. In an MFC, bacteria
present at the fuel-cell anode catalyze the oxidation of diverse organic fuel
sources, including domestic wastewater, animal manures, and plant residues.
As an electrochemical process, an MFC converts the energy value stored in the
organic fuel directly to electrical energy, avoiding combustion and combustion-
associated contaminants. The main product at the anode is CO 2 that is carbon
neutral. When oxygen is the oxidant at the fuel-cell cathode, an MFC produces
only H 2 O. An MFC is an attractive renewable energy technology, because it
produces electricity at the same time it treats wastes, and it does so without
producing harmful byproducts.
We introduce MFCs in the context of the general cycle for biomass-based
renewable energy technology. Tracking of carbon oxidation state highlights
the distinctly different approach that an MFC takes with respect to biofuels.
Then, we review some of recent progress in MFC research, with an emphasis on
mathematical modeling. At last, we conclude with our perspectives on biomass-
based renewable energy by comparing the MFC with two more mature tech-
nologies for generating biofuels: bioethanol and anaerobic digestion to
methane.
Keywords Anode bioenergy biofilm biomass microbial fuel cell
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