Charcoals and carbonized charcoals (i.e., biocarbons) were prepared from a wide variety of biomass substrates, including pure sugars containing five- and six-membered rings with furanose and pyranose configurations, lignin, agricultural residues (corncob and nut shells), and a hard wood. These biocarbons were subject to proximate and elemental analysis, gas sorption analysis, and analysis by inductively coupled plasma mass spectroscopy (ICP-MS), scanning electron microscopy (SEM), X-ray diffraction (XRD), electron spin resonance (ESR), 13C cross-polarization magic-angle spinning (CPMAS) NMR, and matrix-assisted, laser desorption ionization coupled with time-of-flight mass spectroscopy (MALDI-TOF MS). All the carbonized charcoals contained oxygen heteroatoms, had high surface areas, and were excellent conductors of electricity. Doping the biocarbon with boron or phosphorus resulted in a slight improvement in its electrical conductivity. The XRD analysis indicated that the carbonized charcoals possess an aromaticity of about 71% that results from graphite crystallites with an average size of about 20 Å. The NMR analysis confirmed the highly aromatic content of the carbonized charcoals. The ESR signals indicated two major types of carbon-centered organic radicals. MALDI-TOF spectra of the charcoals and carbonized charcoals greatly differed from those of synthetic graphite. The biocarbons contained readily desorbed discrete ions with m/z values of 317, 429, 453, 465, 685, and 701. These findings were employed to develop a model for the structure of carbonized charcoal that is consistent with the biocarbon's oxygen content, microporosity and surface area, electrical conductivity, radical content, and its MALDI-TOF spectra.

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Because the carbon fuel cell has the potential to convert the chemical energy of carbon into electric power with an efficiency approaching 100%, there has been keen interest in its development for more than a century. A practical carbon fuel cell requires a carbon feed that conducts electricity and is highly reactive. Biocarbon (carbonized charcoal) satisfies both these criteria, and its combustion does not contribute to climate change. In this paper, we describe the performance of an aqueous-alkaline biocarbon fuel cell that generates power at temperatures of ∼500 K. Thermochemical equilibrium favors the reduction of oxygen on the cathode at temperatures of <500 K, whereas the chemical kinetics of the oxidation of carbon by hydroxyl anions in the electrolyte demands temperatures of >500 K. Nevertheless, an aqueous-alkaline cell operating at 518 K and 35.8 bar was able to realize an open-circuit voltage of 0.57 V, a short circuit current density of 43.6 mA/cm 2 , and a maximum power of 19 mW, using a 6 M KOH/1 M LiOH mixed electrolyte with a catalytic silver screen/platinum foil cathode and an anode composed of 0.5 g of compacted corncob charcoal previously carbonized at 950°C. A comparison of temperature-programmed desorption (TPD) data for the oxidized biocarbon anode material with prior work suggests that the temperature of the anode was too low: carbon oxides accumulated on the biocarbon without the steady release of CO 2 and active sites needed to sustain combustion. Consequently, the open-circuit voltage of the cell was less than the expected value (1 V). Carbonate ions, formed in the electrolyte as a product of the reaction of CO 2 with hydroxyl ions, can halt the operation of the cell. We show that the carbonate ion is not stable in hydrothermal solutions at 523 K and above; it decomposes via the release of CO 2 and the formation of hydroxyl anion. Consequently, it should be possible to regenerate the electrolyte through the use of reaction conditions similar to those used in the fuel cell. We believe that substantial improvements in performance can be realized from an aqueous-alkaline cell whose cathode is designed to operate at temperatures significantly below 500 K, and whose biocarbon anode operates at temperatures significantly above 500 K.

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Since the emerging of its idea circa four decades ago, Appropriate Technology (AT) had been proven as a comprehensive solution in a limited condition. However, practitioners & academia have different opinions with engineers on how an AT must be designed. Researchers had noted the crucial factors in the issue as such, and they gave a notion of the urgency for a dedicated design methodology for AT. This study, therefore, aims to provide it. Such methodology is developed by incorporating AT characteristics, fundamental issues in community empowerment, and the principles of existing design methodologies. The methodology emphasizes combination between bottom-up and top-down design approaches. It means that an AT must be started purely from local conditions rather than given technical specifications, and be given back to local people to be seamlessly integrated into their routines. It also underlines the crucial importance of community involvement throughout design stages. By looking at previous design methodologies that were developed based on pure Engineering Problem Solving (EPS), this study delivers a fresh and comprehensive one that covers surrounding issues and concepts to produce an AT based on the real meaning of technological appropriateness.

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