When a customer's energy usage varies throughout the day, efforts are made to match the fluctuations in demand with the generating capacity at the power plant. Since generators are large, cumbersome pieces of equipment that cannot be started and stopped quickly, energy companies must work closely with their customers to overcome the problem of matching energy demand to power plant capacity.
The best way to enhance this process is through improved communication.
The primary method of communication to help a power plant reduce the variation in a customer's load profile is through pricing; lower off-peak pricing to encourage energy use during off hours, and higher demand peak pricing to discourage energy use during prime energy periods. A load profile (see images below) can be shown by a recording demand meter, where data is taken over a 24-hour period to help understand energy usage patterns. Customers who are metered for demand have a vested interest in load profiles to determine where peak demand use (and peak demand charges) occur.
From both the utility and customer perspective, the most desirable load profile is as near to a flat line as possible, with minimal peaks and valleys. For this situation, the utility has an easier job of matching generating capacity to meet demand in a given time period and the customer has a lower peak demand charge. However, flat load profiles are the exception. As an example, the load profile below represents the electrical usage of a commercial customer during two summer days (Friday, July 26th and Sunday July 28th). The curve shows the impact of the additional load during a workday compared to the weekend, likely the result of the computers and other office equipment, lighting, and the resulting increased air conditioning load.
Compare this to a load profile of a nearby manufacturing company for these same two days.
It should be noted that a larger manufacturing operation with higher process energy use and a fairly even workload throughout the day would have less variation. Though there are predictable patterns for load profiles, they can vary considerably, even for customers within the same business segment. The key drivers tend to be high summer air conditioning loads, winter heating peaks, and the prevalence of the 8 to 5 PM workday. The following graph represents the load curves for three days (Friday, January 19th; Friday, April 5th; and Friday, July 26th).
Flattening Load Profiles
Most energy users can take steps to influence the factors that contribute to the peaks, thereby reducing demand usage and costs. In the coming years, efforts by utilities to provide real-time energy use information will increase, further enhancing the communication between energy provider and energy user. The energy user is motivated to keep energy costs as low as possible without creating business or process disruptions. The better the communication, the better that this dynamic market can meet the needs of all participants. The hope is that a larger portion of these demand peaks can be minimized by improving the efficiency of the equipment that is having the most impact on usage, or by using operational strategies to shift electrical load away from the high usage periods.
Photo by aresauburnTM
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