May/June 2010

Cost savings realized with Energy Management Software

By Steve Norman

The process industry is a huge consumer of energy with the potential for major savings. With ever rising energy costs, a large proportion of a facility's overhead can be attributed to energy usage. The monitoring of these resources through Energy Management Software (EMS) can help you understand where and when these resources are being used and can give you the knowledge to target the areas of waste or overuse to reduce consumption, carbon emissions, and ultimately overall costs. 

Effective monitoring and targeting of energy is allowing industry to improve operations, identify savings, and track progress against energy and carbon emission targets. These measures can typically reduce energy consumption by 5-15% (U.K. Carbon Trust survey).  Ask yourself where else can you make those kinds of savings to the bottom line.

Once this data is available, it is possible to benchmark your current efficiency using a standard scatter or regression analysis graph. This shows, through the Line of Best Fit, your current energy consumption against the driving force for that process, such as tons of product made or cans of beer. The aim is to keep the Correlation Coefficient (r2) of your process as close as possible to the line-that is keep all points plotted on the graph uniform along the Line of Best Fit, which indicates a well-controlled process where, for example, twice the product made results in twice the energy consumed. 

Advances in metering, communications, and computer technology have made it more affordable than ever to monitor consumption data at intervals of a half hour or less and to view the results graphically. The idea of automatic meter reading has evolved into automatic monitoring and targeting of energy usage.

Most facilities will already have a Supervisory Control and Data Acquisition system or Building Automation System monitoring an array of metering and sub-metering, offering control and real-time information about what is happening on site at any given time. While this feature is important, it does not give the ability to view trends or allow comparisons of energy data, either within the site or, where EMS become extremely effective, in allowing the comparison of energy use across a number of similar sites.

As equipment is replaced or new equipment added, it is not unusual to see equipment from a number of different vendors at the same facility. An effective EMS will be able to take the energy data from all these disparate systems along with the data pulled directly from the end monitoring point using technology, such as OPC, should it be required.  In addition, the software should be able to bring in production information for the process, the real driving force behind the energy being used.

The data captured becomes your baseline from which you can calculate and validate future savings and return on investment when installing new equipment. This data can be highlighted through the use of a Cumulative Sum of Deviation from target, which cumulatively sums all the deviations from the target Line of Best Fit to give you the savings achieved as a kWh or Btu value or as a dollar and cents cost. 

You will not be able to eyeball this information all the time, so automated alarms contact you via e-mail or text messaging should the process deviate more than a set percentage away from target.  These alarms can also be set to send should the energy consumption move out of a set range or known profile of 15 minute data for that day. 

Analysis techniques, such as Load Factor Analysis, allow you to see where maximum demand on the grid occurs each day.  If it is spiking at a particular point, a change to the start time of each shift could be set to see if a production shift could be moved to another time of day, therefore ensuring your demands are kept as low as possible, along with costs.

You can see automatic meter reading of main utility meters, as well as sub-metering, has benefits beyond just the ability to visualize consumption patterns. Bringing together data relating to the driving factor behind the energy consumption also can give you a real insight into your plants efficiency in different scenarios. 

The buy-in and the cost savings can be dramatic when automating with an EMS that has the ability to proliferate energy saving data among staff through energy dashboard displays in public spaces.

ABOUT THE AUTHOR

Steve Norman (steve.norman@esightenergy.com) is vice president of Technology and on the company's board as technical director at eSight Energy, Inc.