Civil Engineering Reference
In-Depth Information
Using a variable-frequency drive to operate at a more efficient point
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Replacing the pump with a unit that will operate more efficiently
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Create Equipment Inventory and Distribution of Demand and Energy
A typical equipment inventory accounts for the following information:
Name of equipment and process area
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Nameplate horsepower or measured kilowatts
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Load factor, that is, estimate of actual motor load divided by nameplate horse-
power (used if measured power is unavailable)
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Hours of operation per year
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Kilowatt-hours per year
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A worksheet for field use is presented in Figure 30-6. The information from the
inventory can be arranged by process and plotted to show the distribution of energy
or demand. A sample distribution of energy at a 10-mgd (38-ML / d) water treatment
plant is presented in Figure 30-4. Raw water pumping, rapid mixing, filtration, in-
plant pumping, and finished water pumping are the most energy-intensive; hence, con-
servation efforts should concentrate on these processes.
Develop ECMs and Implementation Strategies
The preceding tasks provide the background for identifying ECMs. These measures
can be generated by any member of the project team, and plant staff should be en-
couraged to participate. The project team should discuss ECM feasibility, because not
all ECMs will be viable. The following factors should be considered in determining
feasibility:
Capital cost and operating costs
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Energy and electrical demand savings
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Effect on plant processes or finished water quality
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Payback, cost / benefit ratio, present worth, or other means of quantifying the ECM
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Effect on plant labor or chemical costs
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Complexity
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Safety
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Availability of financing, funding, and rebates
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Implementation schedule: short, medium, or long.
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Risk
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Payback: no, low, or high
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Most ECMs at water facilities affect operation. ECMs should be discussed with
plant personnel as they are identified. ECMs that are difficult or impossible to imple-
ment should be deemphasized or eliminated.
Many electric utilities have rebate programs for lighting, heating, energy-efficient
motors, variable-speed drives, and other equipment upgrades. Rebate programs should
