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.
