|Sub-Metering and Monitoring Electrical Energy Use: Part 1|
|Written by John Alleman|
|Thursday, 10 June 2010 11:34|
Sub Metering and Monitoring Electrical Energy Use Part 1:
Understanding your Industrial Electric Bill
By John Alleman
This is the first of a three-part series to help food processors understand why they should evaluate the use of electrical energy sub metering in their industrial facilities. Sub metering is an often-used, but rarely understood, piece of the energy efficiency puzzle. The commercial building sector has used electrical sub metering for years to help understand which tenants, or functions, are consuming the most energy. Commercial and industrial facilities in California and other regions with high peak demand energy tariffs are using sub metering and energy monitoring to help understand how to best manage urgently high energy costs.
For food processors in the Northwest, the question is: “Why should we sub meter and monitor our electrical energy use?” There are several compelling reasons:
Table 1 and Figure 1, show the typical breakdown of these charges for a typical mid-sized industrial user.
Table 1: Example Summary of Electrical Energy Charges for an Industrial User
* Assumes there is no peak demand tariff applied.
Figure 1: Graphical Breakdown of Charges
The green portion of Figure 1, representing the demand charge is also referred to as the ratchet charge because the facility only has to reach this highest value once and the rate will be based on this value for the entire billing period. In the example in Table 1 and Figure 1, the plant averaged 1,600 kW of demand only once but was billed for it for the duration of the billing period. The utilities charge this rate based on the “spinning reserve” power that has to be retained in case this plant starts this combination of loads again.
In the next Catalyst, we will introduce a basic electrical energy sub metering and monitoring system.