Chapter 23: fuel cells based on biomass

Sustainable source of energy is the emergent necessity for the near future which comes from the simultaneous two issues: The growing request for energy and the necessity to strictly limit and control carbon emissions with warning on global warming. Although there are very terrible statistics of CO2 emission worldwide (110 billion metric tonnes in 2010 with estimated 140 billion metric tonnes by 2035), there are also hopes in that the plants and biomasses may sequester more than 260 Giga tonnes of CO2 annually. Interestingly, approximately 183 Giga tons of CO2 are annually fixed through microalgae to produce about 100 Giga tons of its biomass. These are other great motivations to invest in microalgae-based technologies such as microbial fuel cell (MFC) which are the cells to produce power from simultaneous CO2 sequestration and wastewater treatment. In this chapter, we present an overview of the current status together with the future prospects on the fuel cells based on biomass. Additionally, the necessities for scaling up the MFCs have been discussed. The main motivation for research and developments in this field is highlighted to develop green energy and technology for environmental protection. Specifically, latest researches and achievements in MFC technology are presented. The main constituents of MFC, i.e. anodes, cathodes, substrates, and microorganisms are discussed with the latest researches and developments. As a rule of thumb, for scale-up purposes, there is a threshold volumetric power density of 1 kWm-3, maintaining of which as the lab-scale one is challengeable. However, there are suggestions such as optimizing some key factors, such as and appropriately spacing the electrodes with the specific surface area. In this regard, three-dimensional electrodes with highly surface area for enhanced microbial attachment and anodic performance such as tenuous graphite rods have been introduced.