Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings. Filter-based absorption measurements were corrected and compared to photoacoustic absorption results. BC absorption was segregated from the total light extinction to estimate the BrC absorption from individual sources. Results were compared to elemental carbon (EC)/organic carbon (OC) concentrations to determine composition's impact on light absorption. Multiple-wavelength absorption coefficients, Angstrom exponent (6.9 to <1.0), mass absorption cross section (MAC), and Delta C (97 μg m À3 to~0 μg m
À3) were highly variable. Sources such as incense and peat emissions showed ultraviolet wavelength (370 nm) BrC absorption over 175 and 80 times (respectively) the BC absorption but only 21 and 11 times (respectively) at 520 nm wavelength. The bulk EC MAC EC, λ (average at 520 nm = 9.0 ± 3.7 m 2 g
À1; with OC fraction <0.85 =~7.5 m 2 g
À1) and the BrC OC mass absorption cross sections (MAC BrC,OC,λ ) were calculated; at 370 nm ultraviolet wavelengths; the MAC BrC,OC,λ ranged from 0.8 m 2 g À1 to 2.29 m 2 g À1 (lowest peat, highest kerosene), while at 520 nm wavelength MAC BrC,OC,λ ranged from 0.07 m2 g À1 to 0.37 m 2 g À1 (lowest peat, highest kerosene/incense mixture). These MAC results show that OC content can be an important contributor to light absorption when present in significant quantities (>0.9 OC/TC), source emissions have variable absorption spectra, and nonbiomass combustion sources can be significant contributors to BrC.
Researchers at the Forest Product Laboratory (FPL) and the University of Wisconsin-Madison (UW) envision a future for biofuels based on biomass gasification with hydrogen enrichment. Synergisms between hydrogen production and biomass gasification technologies will be necessary to avoid being marginalized in the biofuel marketplace. Five feasible engineering solutions have been suggested for this synergism. We are researching one solution to investigate cleaner and more-efficient wood gasification via high-temperature liquid metal as a carrier fluid and making use of hydrogen, power, and waste heat from future nuclear reactors. The enrichment of syngas with nuclear, windmill, or solar hydrogen permits full conversion of all carbon from biomass to produce competitive synthetic gasoline, diesel, or other liquid hydrocarbon or alcohol fuels.
The combustion properties of various biomass and wood materials from various references and from our laboratory were reanalysed. The net heat of combustion for cellulosic materials was found to be 13.23 kJ/g times the ratio of stoichiometric oxygen mass to fuel mass, r o , regardless of the material composition. Bomb calorimeter data for original, charred and volatilized material components provide gross heating values, while elemental analysis of the materials for carbon, hydrogen, oxygen and ash provide direct evaluation for r o . We corrected these data as provided in various references by converting gross heating values to lower heating values and converting elemental compositions, char fractions and r o to a moisture-free and ash-free basis. Some existing formulae were found to disagree with data from vegetation, charred wood with high ash content, and with volatiles from cellulose treated with the fire retardant NaOH. We also established various functional correlations of r o with elemental compositions, or volatization fractions of untreated and treated materials, or material fractions for cellulose, lignin and extractives, or volatile fractions for tar, combustible gases and inert gases in pure nitrogen carrier gas. An interesting predictive result provides nearly constant heat of combustion while the volatile tar fraction is decreasing and combustible and inert gas fractions are increasing with time during the charring of Douglas-fir wood. Published in
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