Economics of Distributed Power Generation via Gasification of Biomass and Municipal Solid Waste

Abstract

More than one billion people worldwide still lack access to electricity. Rural electrification via gasification has the potential to satisfy electricity access and demand. This study conducts an economic evaluation of rural electrification through gasification of biomass and municipal solid waste (MSW) using a 60 kW downdraft gasifier, developed at Oklahoma State University. The effects of feedstock cost, electricity selling price, feed-in-tariff, tipping fee, tax rate, and the output power are evaluated using major financial parameters: the net present value, internal rate of return, modified internal rate of return, simple payback period, and discounted payback period, and sensitivity analysis. Results show that the downdraft gasification power system offers a payback period of 7.7 years, while generating an internal rate of return, modified internal rate of return, and net present value of 10.9%, 7.7%, and $84,550, respectively. Results from a sensitivity analysis indicate that the feed-in-tariff has the greatest positive contribution to the project’s net present value. Using MSW, the gasification power system potentially reduces carbon dioxide, nitrogen oxides, and sulfur dioxide emissions as compared to direct combustion and landfill. The technology provides a promising future for rural electrification utilizing biomass and MSW whilst offering economic and environmental benefits for local communities.

Prediction of Slag Characteristics Based on Artificial Neural Network for Molten Gasification of Hazardous Wastes

“…In order to establish a model with extensive applicability, a large amount of slag viscosity data was collected from the literature [1,[5][6][7]9,[12][13][14][15][16]18,19,23,25,[31][32][33]38,. It is widely accepted that the gas atmosphere affects the viscosity of hazardous waste slag at elevated temperatures.…”

“…When the viscosity-fluidity changes rapidly with temperature, it may cause slagging and clogging of the gasifier. Slags can be classified into glassy, plastic and crystalline (non-Newtonian) according to the viscosity-temperature curve [1,[5][6][7]. The viscosity of glassy slag decreases with increasing temperature in a gradual manner without abrupt changes.…”

“…The type, viscosity and other properties of slag can be measured at different temperatures, but the experiment is costly and time-consuming. It requires substantial professional knowledge and advanced instruments to obtain accurate data [5][6][7]. Therefore, the development of a universal model to predict slag viscosity would greatly promote the design of gasifiers and the selection of raw materials.…”

“…Some chemical components cannot be used as input variables for the model to calculate viscosity [2,3]. Molten slag will be converted into non-Newtonian fluid in the cooling process, which reduces the prediction accuracy of the model [5][6][7]. By comparison, the empirical formula S 2 is available when the silicon percentage is less than 55% and the iron oxide content is less than 5%; the Watt-Fereday formula is more accurate when the silicon percentage is greater than 80% or the iron oxide content is greater than 15% [15].…”

Emission and Neutralization of Methane from a Municipal Landfill-Parametric Analysis

“…The waste separation procedures allow to extract such wastes from the mixed mainstream of waste passed to the landfill. It seems that a clean waste stream can be used as input material for the fermentation process and the subsequent production of biogas as an energy carrier [5][6][7]. Biowaste fermentation processes are also possible to implement without a centralized system-for instance, in rural areas, contributing to the energy needs of the local communities.…”