Energy: Solid Waste Advanced Thermal Technology

Abstract

Solid waste (SW) outputs of industrial nations, mostly biomass, could fuel much more of their increasing energy needs than they currently do while creating good local jobs and industries. Using U.S. data as an example, 24 types of wasted or underutilized organic solids are identified. Now usually disposal problems, most of these SWs can be converted into useful gas, liquid, and solid (charcoal) fuels via pyrolysis. The non-condensable and condensable pyro-volatiles can be used by direct combustion as a clean source of heat energy or with advanced cleaning, in high-efficiency gas turbines or fuel cells. Pyrolysis processing has some important energy, environmental, economic, and security (EEES) advantages with respect to direct combustion or air or oxygen-blown partial combustion–gasification. An analytical semi-empirical model (ASEM) that points to some order in pyrolysis yields that could be helpful in optimizing the outputs of Solid Waste to Energy by Advanced Thermal Technologies (SWEATT) systems is described. We describe an analytical cost estimation (ACE) model that can be used to relate the cost of electricity for diverse electrical generating technologies including SWEATT systems to capital, operation, environmental control, cost of fuel (COF), and estimated costs of environmental and security externalities (ESE) such as climate change and terror threats. ACE can be useful particularly in estimating the impact of changes in COF and ESE, usually the most uncertain independent variables. The EEES issues related to soil applications of biomass pyrolysis products, i.e., biochar, are outlined. A growing International Biochar Initiative is underway to use biochar to sequester carbon in the soil, thereby mitigating climate change while enhancing soil fertility. High transportation costs due to the low energy densities of biomass/SW, compared to coal or petroleum, imply that siting SWEATT systems close to the SW source would have a number of cost and environmental advantages. The application of SWEATT systems in support of agricultural programs that grow high-yield vegetable oil crops intended for biodiesel production on non-food-producing lands is considered as a means of providing additional revenue streams. Additional SWEATT applications in conjunction with the other forms of the 24 types of SW are to be expected. energy type is very sensitive to its physical form as indicated in Table 2 which gives prices of various forms of energy in the United States at the beginning of 2010. The large carbon dioxide neutral (neither net producing nor consuming CO2) plant matter components in Table 1 can help in greenhouse heating mitigation. The great diversity of physical and chemical characteristics of fuel wastes (feedstock) in Table 1 implies that the world now needs “omnivorous feedstock converters” (OFCs) to change these solid fuels into much more usable liquid or gaseous fuels or better solid fuels. Fig. 1 is a conceptual illustration of an OFC adapted from a number of prior papers in which a SW pyrolyzer–gasifier–liquifier–carbonizer is coutilized with a natural gas-fired combined cycle (NGCC) system, as will be discussed below. Table 3 shows major ranks of coals as well as of peat, wood, and cellulose and their ultimate and proximate analyses as measured by industry for over a century. The SOLID WASTE, SOLID FUELS, AND THEIR PROPERTIES In 2011 the United States was heavily (~50%) reliant on foreign sources for its liquid fuels and somewhat (~10%) dependent upon imports for its gaseous fuels. Our country is now expending “blood and treasure” in its efforts to stabilize regions of the globe that supply these premium fuels. Yet the United States is well endowed with solid fuels in the form of coal, oil shale, and substantial quantities of renewable but wasted solids. As part of a continuing long search for alternatives to oil, this entry is focused on converting our solid waste to energy by advanced thermal technologies (SWEATTs) while mitigating environmental and economic problems. Table 1 is a list of United States’ abundant supply of solid waste (SW) whose organic matter can be converted into gaseous and liquid fuels as well as charcoal. The value society places on a specific fuel or D ow nl oa de d by [ T & F In te rn al U se rs ], [ M eg an H ila nd s] a t 0 6: 09 3 0 Ju ly 2 01 3 Energy: Solid Waste Advanced Thermal Technology 831 En er gy E ffi ci en cy –