Patent Application
20120073982
This application relates to the field of water treatment, and more particularly, to converting waste water into potable water.
Various alternative energy sources—solar, wind, wave, and tidal—are intermittent by nature. Demand for energy is often present when these intermittent alternative energy sources are not producing. Unfortunately, large-scale storage and release of electrical energy presents numerous cost and efficiency challenges, and suitable technologies have yet to developed which would enable power producers to store energy to service later demand. As a result, the potential for widespread use of clean energy from alternative energy sources remains unfulfilled.
One embodiment of this disclosure provides a method for converting waste water into potable water using power from an electrical grid; the grid is configured to receive power from an intermittent power source. The method comprises flowing the waste water through an electrolysis cell coupled to the grid, and, when power availability on the grid is above an upper threshold, biasing the electrolysis cell to form hydrogen. Hydrogen evolved in the electrolysis is then provided as fuel to one or more fuel cells. When the power availability on the grid is below a lower threshold, electric current and potable water are drawn from the one or more fuel cells.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description, which follows. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted herein.
The subject matter of this disclosure is now described by example and with reference to the illustrated embodiments listed above. Components, process steps, and other elements that may be substantially the same in one or more embodiments are identified coordinately and are described with minimal repetition. It will be noted, however, that elements identified coordinately may also differ to some degree. It will be further noted that the drawing figures included in this disclosure are schematic and generally not drawn to scale. Rather, the various drawing scales, aspect ratios, and numbers of components shown in the figures may be purposely distorted to make certain features or relationships easier to see.
In one embodiment, the waste water discharged by the community may include storm-drain outflow. In another embodiment, the waste water may include treated sewage. In yet another embodiment, the waste water may include untreated sewage. Accordingly, water-treatment facility 14 may be configured to receive and treat any of these kinds of waste water, or any combination thereof.
Community 12 includes a plurality of resource consumers, such as resource consumer 16. The resource consumers within the community may consume heat and electricity in addition to potable water. Accordingly,
Continuing in
Electrolysis cell 22 includes at least one cathode where hydrogen is evolved and at least one anode where oxygen-containing anode off gas is evolved. The anode and the cathode may be biased with power from electrical grid 18 via suitable electronic componentry, such that positive electric current is supplied to the anode and drawn from the cathode. The electrolysis cell may also include at least one polymer-electrolyte membrane (PEM) arranged between the anode and the cathode. To avoid admittance of materials that could degrade the anode, cathode, PEM, or other components of the electrolysis cell, pretreatment stage 24 is included upstream of the electrolysis cell. The pretreatment stage may comprise a settling tank, a filtration stage, and/or an ion exchange bed, for example.
In one particular embodiment, some or all of the anode off gas released from electrolysis cell 22 may be pressurized via pump 25 and readmitted to the outflow from the electrolysis cell. The anode off gas may be dispersed (e.g., bubbled) into the outflow to minimize the footprint and/or odor from the final stages of water treatment. Compared to atmospheric aeration of the outflow, readmittance of the anode off gas will expose the outflow to a much greater mole fraction of oxygen, even when minor amounts of chlorine or other oxidation products are also present in the off gas. As shown in
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From hydrogen-storage reservoir 28, hydrogen is also supplied to community fuel cell 32. The community fuel cell may have a much larger capacity than local fuel cell 30. The community fuel cell may be configured, via appropriate electronic componentry, to supply electric power to electrical grid 18. Due to its larger capacity, the community fuel cell may generate a significant outflow of potable water. Accordingly, the potable water discharged from the community fuel cell is routed to water-storage reservoir 34, where at least some of the potable water supply for community 12 is stored.
The configurations described above enable various methods for converting waste water into potable water. Accordingly, some such methods are now described, by way of example, with continued reference to above configurations. It will be understood, however, that the methods here described, and others fully within the scope of this disclosure, may be enabled via other configurations as well.
After 42, or if it is determined at 54 that the power availability is not above the upper threshold, then method 48 advances to 44. At 44 hydrogen from the electrolysis cell flows and is distributed to one or more fuel cells. At 56 it is determined whether the power availability on the electrical grid is below a lower threshold. If the power availability is below the lower threshold, then the method advances to 46, where electric current and potable water are drawn from the one or more fuel cells, as further described hereinafter. Accordingly, the conversion of stored chemical energy back into electrical energy may be coordinated to conditions where power on the electrical grid is below a threshold. Furthermore, by virtue of decision block 52, the conversion of waste water to potable water may be coordinated with a high demand for or low availability of potable water. Then, from 56 or 46, method 48 returns.
At 58 the demand for heat at a point of use relative to a demand for potable water in the community is assessed. At 60 it is determined whether the relative demand thus assessed is above a threshold. If the relative demand is above the threshold, then the method advances to 62, where hydrogen from the electrolysis cell is distributed to a local fuel cell at the point of use. The method then advances to 64, where electric current and potable water are drawn from the local fuel cell at point of use. Under these conditions, a demand for heat at the point of use may be above a heat-demand threshold, or, a demand for potable water may be below a potable-water demand threshold.
However, if the relative demand is not above the threshold, then the method advances to 66, where electric current and potable water are drawn from a community fuel cell arranged upstream of a potable-water reservoir. The method then advances to 68, where potable water from the community fuel cell is stored in the potable water reservoir. Under these conditions, a demand for potable water in the community may be above a potable-water demand threshold, or, a demand for heat at the point of use may be below a heat-demand threshold. From 64 or 68, method 46A returns.
It will be understood that the example control and estimation routines disclosed herein may be used with various system configurations. These routines may represent one or more different processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, the disclosed process steps (operations, functions, and/or acts) may represent code to be programmed into computer readable storage medium in an electronic control system.
It will be understood that some of the process steps described and/or illustrated herein may in some embodiments be omitted without departing from the scope of this disclosure. Likewise, the indicated sequence of the process steps may not always be required to achieve the intended results, but is provided for ease of illustration and description. One or more of the illustrated actions, functions, or operations may be performed repeatedly, depending on the particular strategy being used.
Finally, it will be understood that the articles, systems, and methods described hereinabove are embodiments of this disclosure—non-limiting examples for which numerous variations and extensions are contemplated as well. Accordingly, this disclosure includes all novel and non-obvious combinations and sub-combinations of the articles, systems, and methods disclosed herein, as well as any and all equivalents thereof.
