Rural municipal waste-to-energy system and methods

Abstract

A rural municipal waste-to-energy system and method converting waste to fuel gas through anaerobic digestion (AD) and pyrolysis/gasification. Fuel gases derived during the processes are combined and used to generate electricity. The amount of MSW normally collected by a municipality may be inadequate in volume to produce enough fuel gas with which to generate electricity sufficient to serve the entire community. It may be necessary, therefore, for additional wastes from the surrounding area to be included. The municipality must have its own public electric utility to be able to charge rates necessary for profitability.

1 . A method for a rural municipality to convert solid waste to energy, comprising the steps of:
 a. selecting a rural municipality having an area surrounding the municipality capable of supplying a quantity of solid waste or having other capabilities to supply solid waste sufficient to produce fuel gas to generate a quantity of electricity sufficient to serve the electrical energy needs of all of the residents of the municipality;   b. establishing a public electric utility to serve the rural municipality;   c. providing a facility for the conversion of the solid waste to fuel gas through anaerobic digestion and pyrolysis/gasification;   d. providing a facility for the conversion of the fuel gas to electricity; and   e. selling the electricity at retail rates to the residents of the municipality.   
     
     
         2 . The method of  claim 1 , further comprising the steps of:
 providing a material recovery facility and separating the solid waste into a wet stream comprising wet biomass, animal wastes and sewage sludge and a dry stream comprising dry biomass, tires, plastic and wood waste, converting the wet stream into fuel gas by anaerobic digestion and converting the dry stream into fuel gas by pyrolysis/gasification.   
     
     
         3 . The method of  claim 2 , further comprising the step of recovering recyclable materials from the solid waste for sale. 
     
     
         4 . The method of  claim 2 , further comprising the step of collecting a tipping fee for solid waste brought to the material recovery facility. 
     
     
         5 . The method of  claim 2 , further comprising the step of selling residues from pyrolysis/gasification of the dry stream. 
     
     
         6 . The method of  claim 2 , further comprising the step of selling residues from the anaerobic digestion of the solid waste. 
     
     
         7 . The method of  claim 2 , further comprising the step of pyrolysis/gasification of residues from the anaerobic digestion of the solid waste. 
     
     
         8 . The method of  claim 2 , further comprising the step of combining the fuel gas produced from anaerobic digestion and the fuel gas produced by pyrolysis/gasification. 
     
     
         9 . The method of  claim 8 , further comprising the step of selling the combined fuel gas. 
     
     
         10 . The method of  claim 8 , further comprising the step of generating electricity from the combined fuel gas. 
     
     
         11 . The method of  claim 10 , wherein the electricity is generated in at least one of an internal combustion engine with a generator, a mini-turbine and a fuel cell. 
     
     
         12 . The method of  claim 10 , further comprising the step of recovering heat generated from electricity production and used in the anaerobic digestion and pyrolysis/gasification of the solid waste.