Method of combining wastewater treatment and power generation technologies

Abstract

Applicant's preferred embodiment utilizes municipal wastewater effluent to replenish a depleted geothermal field. Condensate produced by expanding steam produced in the geothermal field through a steam turbine-generator may be pooled with cooked water collected from said field, and then directed through a penstock from a higher elevation to a lower elevation where further energy is extracted through a traditional hydroelectric turbine-generator. The cooked water and condensate may be treated to produce potable water and/or distributed for public consumption either before or after being directed to the hydroelectric turbine-generator. The effluent is pumped up to the geothermal field during off-peak periods of electric consumption, and the hydroelectric generation is accomplished during periods of peak electric demand. A fraction of the effluent may be used as cooling water for the steam turbine-generator and its associated condenser before injection into the geothermal field. At least a portion of the pipeline to transport the wastewater effluent is preferably routed along an undisturbed riverbed and/or through an excavated tunnel.

1 . A method of employing wastewater effluent in power generation comprising the steps of:
 delivering wastewater effluent to a geothermal steam field;   injecting said effluent into said field;   collecting steam from said field;   extracting energy in the form of electricity from said steam by expansion in a steam turbine-generator system thereby producing condensate; and   distilling at least a fraction of said condensate to produce potable water.   
   
   
       2 . A method according to  claim 1  further comprising the step of:
 pumping said effluent to said geothermal steam field through a piping system.   
   
   
       3 . A method according to  claim 2  wherein:
 said pumping is performed in at least one stage.   
   
   
       4 . A method according to  claim 1  further comprising the step of:
 directing at least a fraction of said condensate to a lower elevation by force of gravity, through a hydroelectric turbine-generator, extracting energy in the form of electricity.   
   
   
       5 . A method according to  claim 4  further comprising the step of:
 directing other than said fraction of said condensate to a holding pond.   
   
   
       6 . A method according to  claim 4  further comprising the step of:
 treating said condensate exiting said hydroelectric turbine-generator to produce potable water.   
   
   
       7 . A method according to  claim 1  further comprising the steps of:
 distilling cooked water collected from said field; and   directing at least a fraction of said cooked water to a lower elevation by force of gravity, through a hydroelectric turbine-generator, extracting energy in the form of electricity.   
   
   
       8 . A method according to  claim 7  further comprising the step of:
 treating said cooked water exiting said hydroelectric turbine-generator to produce potable water.   
   
   
       9 . A method according to  claim 2  wherein:
 at least a portion of said pumping system is routed along an undisturbed riverbed.   
   
   
       10 . A method according to  claim 2  wherein:
 at least a portion of said piping system is routed through a utili-tunnel.   
   
   
       11 . A method according to  claim 1  further comprising the step of:
 distributing said potable water for public consumption.   
   
   
       12 . A method of employing wastewater effluent in power generation comprising the steps of:
 delivering wastewater effluent to a geothermal steam field, said delivery being accomplished by at least one stage of pumping said effluent through a piping system;   injecting said effluent into said field;   collecting steam from said field;   extracting energy in the form of electricity from said steam by expansion in a steam turbine-generator system thereby producing condensate;   re-injecting a fraction of said condensate into said geothermal steam field; and   distilling a fraction of said condensate producing potable water.   
   
   
       13 . A method according to  claim 12  further comprising the step of:
 directing a fraction of said condensate to a lower elevation by force of gravity in a penstock through a hydroelectric turbine-generator, extracting energy in the form of electricity.   
   
   
       14 . A method according to  claim 12  wherein:
 said pumping of said effluent takes place during off-peak periods of electricity consumption; and   said hydroelectric generation is accomplished during peak periods of electricity consumption.   
   
   
       15 . A method according to  claim 12  further comprising the step of:
 distributing said potable water for public consumption.   
   
   
       16 . A method according to  claim 12  wherein:
 at least a portion of said pumping system is routed along an undisturbed riverbed.   
   
   
       17 . A method according to  claim 12  wherein:
 at least a portion of said piping system is routed through a utili-tunnel.   
   
   
       18 . A method of employing wastewater effluent in power generation comprising the steps of:
 delivering wastewater effluent to a geothermal steam field;   injecting said effluent into said field into at least one existing steam well which has been substantially exhausted of geothermal steam;   collecting steam from said field; and   extracting energy in the form of electricity from said steam by expansion in a steam turbine-generator system.   
   
   
       19 . A method according to  claim 18  further comprising the step of:
 pumping said effluent to said geothermal steam field through a piping system.   
   
   
       20 . A method according to  claim 18  wherein:
 the step of injecting said effluent comprises injecting said effluent into a plurality of wells which have been substantially exhausted of geothermal steam.