Jørgen Bjerg

Partner

Vesko ApS

jb@vesko.dk

Denmark

Energy consumption is one of the important factors in the calculations of the impact to the environment, so the question is what we can do when we want to increase energy efficiency in the company? Seen in the larger perspective there are three areas in which we can improve energy efficiency:

• Technical solutions
  • Energy Efficient Design of the equipment
  • Using Energy Efficient Components
  • Using regulators that adjust the load of the equipment to the actual need
• Commitment of the employees
• Increasing productivity of the equipment.

By identifying and implementing energy efficiency in the right way we can meet the results required by the energy and environmental policies, and at the same time have the possibility of financing part of the improvements to the installations through the savings on energy costs - improvements that in the best case may increase the Overall Equipment Efficiency (OEE).

Energy Consumption Over a 24-Hour Period of Time

The diagram in figure 1 shows the energy consumption of a production unit in a medium sized company over a period of almost 24 hours. The use of energy can roughly be divided into three categories. The division is not 100 % correct, but it gives a good starting point for the work of optimising the energy consumption.

Consumption During Idle Time

The consumption of energy during idle time is broadly speaking constant over the year. The consumption covers heating and cooling as well as energy for machinery and equipment that typically cannot be shut down such as pumps for the heating installations, computers - including servers – alarm and telephone centres and consumption to cover leakage from compressed air installations that are not turned off, etc.

To optimize this part off the consumption we must be sure that the equipment is energy efficient and is switched off when not in use. Go around the company after working hours and see what is still running and make a strategy for closing down equipment that is not supposed to run.

Figure 1. Energy consumption of a production unit in a medium sized company.

Basic Consumption

Basic consumption is the consumption during the company’s working hours: lighting, ventilation, and those parts of the production installation that are not directly a function of the size of the production. To optimize this part of the consumption we must make sure that the equipment is energy efficient and that the electrical control is set correctly to start/stop the equipment when wanted, and that the regulators are correctly set and can adjust the speed of the equipment to the actual need.

Consumption Dependent on Production

This is the energy consumption that is a direct consequence of production like heat used in the process. Moving the product - belt conveyors, blowers and pumps, electricity to power the production equipment, etc.

As can be seen in the diagram, a large part of the energy consumption is not a direct consequence of production so there are two distinct means of optimizing the energy consumption.

• We can work on reducing the use of energy (as shown in the former).
• We can work on improving the OEE. An improvement of the OEE will mainly affect the part of the energy consumption that is a direct consequence of the production, the rest of the consumption will not be highly affected. When speaking of energy efficiency it is important to realize that the company’s energy consumption must be seen in the light of the main activity, the production of a commodity. Energy efficiency is a measure of how efficient the company is in producing this commodity. A company can have all the newest and most efficient equipment that will make it possible to achieve low energy consumption, but if the OEE is low they can still have low energy efficiency.

Broadly speaking – energy efficiency is a matter of reducing the equipment’s use of energy and reducing the time where there is a cost of energy without effective production.

Looking at energy savings in this way suits the maintenance department as it is the same approach used for supporting equipment efficiency. Hereby we can achieve synergy between maintenance management and energy optimization.