Patent Application
20130099499
1. Field
The present disclosure relates to urban sewage and storm water flow systems, using small turbines in assemblies, arrays, and onsite power plants.
2. Background
Energy, particularly in the United States, is primarily derived from non-renewable energy sources. Oil, coal, and natural gas, for example, are some non-renewable energy sources, which are being depleted to provide communities around the world with electrical power. Although alternatives to non-renewable energy sources exist, they are underutilized. In the United States, for example, less than 10% of the total U.S. electricity production is derived from renewable energy sources. (2009 Annual Energy Review, U.S. Energy Information Admin., August 2010).
Use of some non-renewable energy sources can also cause significant environmental issues. As a result, many countries have increased their efforts to reduce emission of pollutants and consumption of nonrenewable sources. Many countries, therefore, continue to seek renewable and environmentally friendly sources of energy.
Renewable energy sources generally can be classified into two groups: continuous and intermittent sources of energy. Wind and solar energy are primarily intermittent. Thus, power plants, relying on wind and/or solar energy are literally at the mercy of nature. Because these sources are unpredictable, they are frequently used alongside non-renewable energy sources. In some cases, power plants, which primarily use non-renewable sources of energy, are able to reduce or idle their power production through use of wind and solar power. Nonetheless, implementing wind and solar power in this manner is still not cost-effective and over time may increase overall production costs.
In contrast, geothermal and hydrodynamic energy sources can be harnessed for continuous energy production. Geothermal energy, at least in the United States, is currently derived from just few areas. Unfortunately, these sources of geothermal energy merely produce less than one half of one percent of electricity in the United States.
Hydrodynamic energy is available from a significant number of sources—both natural and man-made. Traditionally, large scale reservoirs, which are elevated in excess of 100 feet, are used to generate large quantities of electricity at various locations. Dams and waterfalls may also be used to provide the necessary head to turn water turbines. Unfortunately, large scale reservoirs require significant capital costs and alter ecosystems of surrounding areas.
It would be desirable, therefore, to provide methods and systems for generation and use of energy from alternative sources, that overcome the limitations and disadvantages as summarized above.
The present disclosure is directed to sewage and storm water flow systems and methods, which use generator and small turbine assemblies positioned within one or more conduits (e.g. sewage or storm water conduits). One such system is a sewage or storm water flow power generation system comprising a generator, at least one electrical connector coupled to the generator, and a small turbine coupled to the generator. The turbine includes a shaft mountable to a lower conduit base and at least one anchor coupled to the shaft, which is mountable to a conduit wall. In a preferred arrangement, the turbine, generator, and shaft are oriented along the same vertical axis. The turbine can also include a plurality of hydrofoil blades, which are oriented in a substantially vertical position. Each turbine blade is coupled to a support arm, which is also coupled to the shaft.
Another system for sewage flow power generation comprises an array of turbine and generator assemblies positioned in a sequential arrangement along a conduit. The sequential arrangement may include arranging the assemblies in an alternating offset pattern along a length of the conduit. Each turbine and generator assembly includes a generator, a turbine coupled to the generator and positioned within a conduit, and at least one anchor coupled to the shaft and mounted to an upper conduit section. Turbines included within the assembly can each have a shaft mounted to a lower conduit base. A plurality of electrical connectors may also be coupled to each assembly for transmitting energy output from each assembly to an electrical grid, for example.
This type of power generation system may be located in a sewage system or a storm water discharge system. Where the power generation system is located in a sewage system, the system preferably has an average minimum liquid sewage depth, which is not less than about 3 feet. Alternatively or in addition, the sequential array may be arranged in a sewage conduit of a sewage system located at one or both of within about 1000 feet downstream of a sewage treatment facility or within 1000 feet upstream of the sewage treatment facility (i.e. after treatment to a purer, but still non-potable state). A typical sewage treatment plant (e.g. Tillman, Van Nuys, Calif.) has multiple channels, which flow into the plant, offering multiple locations for insertion of turbines for compounding energy production at processing sites.
Also disclosed herein is a sewage flow power generation method, which includes the steps of maintaining an array of turbine and generator assemblies located in a sewage conduit; contacting the array with sewage flowing through the sewage conduit; and generating electricity through use of the turbine and generator assemblies. Such methods may also include one or more steps for directing sewage flow from either a gravity-fed urban sewage system or gravity-fed storm water discharge system into the sewage or storm water conduit. The City and County of Los Angeles are examples of large areas, which utilize gravitational flow so that treatment plants are placed in low lying geographical areas, where less than approximately 5% of sewage movement is pump driven.
Electricity generated by the systems and methods disclosed herein may have several “green” applications. For example, the generated electricity may be used to purify water or to desalinate water to a potable state. In yet another method or system, the generated electricity may be used to manufacture hydrogen fuel from water. Although since the 1920's many patents have disclosed small water turbines, only a few are known to have mentioned small turbine use in sewage or storm water drains for energy generation. In addition, none of these patents are known to disclose specific applications of energy generation for “green” technologies or the use of a treatment plant as an onsite source of power production, as further described herein.
A more complete understanding of the sewage and/or storm water flow systems and methods disclosed herein will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by consideration of the following detailed description. Reference will be made to the appended sheets of drawings which will first be described briefly.
The drawings described herein are for illustrative purposes and are not intended to limit the scope of the present disclosure. Like element numerals may be used to indicate like elements appearing in one or more of the figures.
The present disclosure relates to a source of continuous hydrodynamic energy that can have minimal impact on the environment and significantly lower implementation costs for power generation. Large cities virtually can have thousands of miles of rivers flowing under streets and sidewalks, bearing wastewater and watershed runoffs from garden and surface areas. Currently, these rivers add a cost burden to municipalities. The present disclosure explains how these rivers can serve as a source of substantial, continuous, non-polluting hydrodynamic energy, which may be exploited by cities for revenue and cost reduction.
Sewage flow may therefore be an untapped source of continuous hydrodynamic energy. Wind and sunshine may wane, but sewage flow, particularly in urban areas, remains relatively constant. In some major cities, for example, between 700 and 900 million gallons of sewage flows continuously through sewage lines each day. Harnessing hydrodynamic energy from continuous sewage flow, however, may present significant challenges. The following facts illustrate the potential of harnessing energy from sewage flow in just one metropolitan area:
Considering this information, one prior proposal indicates a method for harnessing hydrodynamic energy from sewage flow includes using turbines positioned above sewage flow. According to this method, turbines are encased at least partially within housings located at intervals along sewage lines and pipelines. In the proposed arrangement, each turbine is coupled to a generator located outside of each housing. Unfortunately, significant excavation and modification to existing sewage lines and pipelines may be required, which may render this proposed method both impractical and cost prohibitive.
Another previously proposed method for harnessing hydrodynamic energy from sewage flow describes a computerized system positioned near an outflow end of a wastewater pipe. The computerized system attaches at the outflow end and uses a flapper controlled by a computer to monitor outflow. This type of system, however, is described as an add-on to the outflow end of existing wastewater lines. The complete installation may require a computer control room and an electrical cable control room at the outflow end of wastewater pipes. Thus, implementing this system may require significant construction and modification to existing wastewater lines, also making this proposed method both impractical and cost prohibitive.
These proposed methods have also not fully considered the application of the power generated after energy from sewage flow has been harnessed. As non-renewable energy sources are depleted, the need for new applications and development of “green” technologies, utilizing energy harnessed from sewage flow becomes clearer. New “green” technologies, as described herein, may be implemented by generation of power at major collection sites where sewage and storm drain runoffs are processed, for example.
Turning in detail to the drawings,
The system 10 may include a plurality 30 of turbine and generator assembles 32, with each assembly being coupled to one or more electrical connectors 34, which integrate into a collection of cables contained in a housing 35. These connectors may include cables or wiring used to link with an electrical grid, which can provide power to local and distant recipients, for example. The housing 35 may be positioned above ground for coupling with the electrical grid. To avoid line loss, however, onsite energy conveyance is one aspect of a preferred system embodiment.
Referring to
Hydrofoils 48, which are aerodynamically shaped, may be used as turbine blades 40. Hydrofoil blades are less likely to trap particles flowing through sewage flow. In one configuration a plurality of turbine blades 40 are oriented to a substantially vertical axis a and positioned in a symmetrical arrangement with respect to the vertical axis a to spin 360 degrees around the shaft 38.
In one blade arrangement, four turbine blades are positioned in about 90 degree increments with respect to the vertical axis, as shown in
The turbine 36 and its respective components are used to convert power from sewage and/or storm water flow 14 into mechanical power via the shaft 38. The turbine may be configured to have an overall height ranging from about three feet to about five feet, depending upon conduit depth and anticipated flow heights. Therefore, the turbines specified herein are small, meaning each turbine has an overall height of less than about four feet. The height of the turbine, however, should be high enough for complete or at least partial submersion of turbine blades when flow is initiated within a conduit.
All turbine components are preferably manufactured from one or more materials, which are substantially resistant to chemicals likely present in sewage flow 14a and/or storm water flow 14b. In each turbine and generator assembly 32, torque from the shaft 38 is transmitted to a generator 50 or another type of power transfer device. In one configuration, the generator may include one or more electrical components 54 (not shown) and a gearbox 56 for converting rotation from the shaft to a higher rotation suitable for generating electricity. Various types of gearboxes may be included within the assembly 32.
The generator 50 may be encased within a housing 58, which is substantially impervious to water, sewage, weather and environmental moisture.
In one arrangement of a turbine and generator assembly 32, the shaft 38 is coupled to the lower conduit section 24, using bolts 60 or alternative fastener types, which are coupled to an assembly base 62. In an alternative arrangement of a turbine and generator assembly (not shown), the shaft 38 may extend through to a generator positioned above a street 18 and/or sidewalk 20 (
Turbine and generator assemblies 32 may also include at least one anchor 70 coupled to the shaft 38 and to at least one wall section 72 of the conduit 12. For example, an anchor 70 may be coupled to a conduit sidewall 28, as shown in
This type of arrangement may avoid interference with shaft rotation via an aperture in the end of the anchor distal from the wall section 72. The aperture in the anchor may be dimensioned with sufficient clearance for the shaft to freely rotate. The anchor 70 allows an assembly 32 to resist movement when subject to sewage and/or storm water flow. The anchor may include an anchor base 74 that is coupled to the wall section 72 or a narrowing component 84 (
Flows in a sewage and/or storm water system 10 typically flow at lower flow rates. Incoming flows, for example, can range from about 5 feet per second to about 15 feet per second. As such, a turbine and generator assembly may be positioned at one or more inflow passages, i.e. a passage typically within about 50 to about 100 feet of a water treatment facility. Sewage and storm water flow rates at inflow passages are likely to be greater compared to outflow passages. Nonetheless, the system 10 may also be placed close to outflow passages, where outflow rates are sufficient. Narrowing components 84 (
In addition, the system 10 is preferably located in a conduit, having an average minimum liquid sewage depth not less than about 3 feet. Alternatively or in addition, an array 80 may be arranged in a sewage conduit of a sewage system located at one or both of within about 1000 feet downstream of a sewage treatment facility or within 1000 upstream of the sewage treatment facility.
Turbine and generator assemblies 32 may be uncoupled to computer systems, flapper gates, or valves required for flow regulation. Each turbine used in an assembly is configured such that its rate of rotation may vary, depending on incident variations of sewage and/or storm water flow in the system. In some assembly arrangements, however, flow meters may be utilized to monitor energy produced by the assembly 32 or the plurality 30 of turbine and generator assemblies.
In a preferred arrangement, a turbine and generator assembly may also be positioned close to one or more points of access 22 so that one or more maintenance workers 64 (
The plurality 30 of turbine and generator assemblies 32 may be maintained in an array 80 such as a sequential array within the conduit 12, as shown in
When and if necessary, conduits may be modified to narrow conduit width, thereby increasing velocity of sewage and/or storm water flow. Wider sewage conduits may be modified to add a structural material, (e.g. concrete), to wall areas 82 adjacent an array 80. In addition, as shown in
Energy generated by turbine and generator assemblies is effectively renewable energy, which may be used to generate electricity for various types of “green” technologies. For example, generated electricity from the assemblies may be used for power consumption and include methods of water purification, water desalination, and production of hydrogen fuel. These “green” technologies, while greatly desirable, if previously proposed methods are used, have the potential to pull undesirable amounts of electricity from a community grid. As such, the flow systems 10 described herein can be utilized in a power plant, which would self-support system maintenance and repair and provide revenue for communities in surrounding areas.
Earth is about seventy-two percent (72%) water. But, only about two-percent (2%) of water on Earth is suitable for human consumption. And, most of this two-percent is primarily used for non-drinking purposes. Purification and desalination are just two of the viable uses for energy generated from the systems described herein.
Purification of sewage and storm water flow requires power which in many cases is derived from an already-stressed community grid. The energy intensity for reclamation and re-use of non-potable water can be 1.84 kilowatt-hours per kilo-gallon (kWh/kgal) at a cost of $0.46/kgal for at least one major city in the United States as of 2011. Desalination of sewage and storm water flow is also a process which demands significant power. For desalination, energy cost is 12 kWh/kgal or $3.10/kgal in at least one major city in the United States as of 2011. (See, “Water Re-Use Potential,” National Research Council, National Academy Press, 2011).
Many cities include up to six watersheds that empty into the ocean, providing water which could be used for desalination. Therefore, utilizing the electrical energy from this type of water flow could provide the additional energy necessary for providing potable water or hydrogen fuel without extracting energy from existing electrical grids. Line loss could also be prevented by providing onsite production of electrical energy, especially for desalination at ocean discharge sites.
Electrical energy generated from the systems and assemblies described herein may also be utilized to manufacture hydrogen fuel from water. High costs associated with manufacture of hydrogen fuel are typically cost prohibitive. At least one source indicates that producing hydrogen fuel from water or other compounds consumes more energy compared to the energy recovered when the hydrogen fuel is burned. In addition, approximately 3.58 gallons of liquid hydrogen fuel provide the same energy contained in approximately one gallon of gasoline. As of 2012, hydrogen fuel derived from water may cost up to $8.00 (US$) per gallon, or almost $30 (US$) to yield the same miles per gallon (mpg) as gasoline. Even if hydrogen fuels were derived from steam-injected methane hydrogen, costs to produce the hydrogen fuel may only be slightly less and still require electrical energy. According to one scenario, electricity produced at a selected wastewater processing plants could potentially lower the cost of hydrogen fuel production. This could revitalize use of hydrogen fuel. High costs typically associated with manufacture of hydrogen fuel could be offset by using the sewage and/or storm water flow systems and turbine and generator assemblies, and arrays described herein. Eventual development of a prototype may provide proof of concept for evolving these “green” systems from uneconomical technologies to useful and important assets.
As shown in
Accordingly, sewage flow power generation systems and methods, using generator and small turbine assemblies and arrays are disclosed. While embodiments of this invention have been shown and described, it will be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the following claims.
This application claims priority under 35 U.S.C. §119(e) to U.S. Application Ser. No. 61/549,100, filed Oct. 19, 2011, the entirety of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61549100 | Oct 2011 | US |
