ELECTRICAL LOAD MANAGEMENT
Electrical energy consumption at water and wastewater
treatment plants is increasing because of more stringent
regulation and customer concerns about water quality. As a
result, more facility managers are turning to energy
management to reduce operating costs. Reducing energy
consumption, however, is only part of the equation.
Electricity is typically billed in two ways: by the quantity of
energy used over a period of time, measured in kilowatt-
hours; and by demand, the rate of flow of energy, measured
in kilowatts. By choosing when and where to use electricity, facilities can often save as much (or
more) money as they could by reducing energy consumption.
RATE SCHEDULES
Because it is costly for electric utilities to provide generating capacity for use during periods of
peak electrical demand, they often structure rates to encourage customers to minimize demand
during peak periods. That's why plants should investigate the variety of rate schedules offered by
electric utilities. They may achieve substantial savings simply by selecting a rate schedule that
better fits their pattern of electricity use.
• Time-of-Use Rates
In most areas of the country time-of-use rates, which favor off-peak electrical use, are available.
Under time-of-use rates, energy and demand charges vary during different block periods of the
day. For example, energy charges in the summer may be only five cents per kilowatt-hour with
no demand charge between 9:30 p.m. and 8:30 a.m., but increase to nine cents per kilowatt-hour
with a demand charge of $10 per kilowatt between noon and 6:00 p.m. The monthly demand
charge is often based upon the highest 15-minute average demand for the month.
• Interruptible Rates
Interruptible rates offer users discounts in exchange for a user commitment to reduce demand on
request. On the rare occasions when a plant receives such a request, it can run standby power
generators.
• Power Factor Charges
Power factor, also known as "reactive power" or "kVAR," reflects the extent that cu