Three steps to improve compressor energy efficiency
Want to reduce your energy bill for your compressor house?
There are three steps that I think every industrial compressor owner should consider when optimizing his energy spending.
Pressured air from compressors is widely used but it is energy intensive. In Europe, compressors excluding refrigerators consume the same amount of electricity as Belgium and Finland combined or more than European wind power turbines produced in 2010.
Compressors are operated in very different conditions and annual running hours vary a lot. Hobby compressors – let’s say up to few kilowatts of motor power – run for a few hours a year and cost of ownership is determined by the purchasing costs. On the industrial side the situation is different. Studies show that investment costs are only about 10 – 15% of life time costs while energy costs make up 75% of total cost of ownership. Service makes up the rest.
Studies and my experience demonstrate that there is space for energy efficiency improvements. European Union’s studies indicate that the improvement potential is on average 15%. However, the range is wide and in many cases energy efficiency specialists have easily made 30% in savings.
Three elements are needed to achieve major savings. The first is the awareness. Changing electricity supplier or light bulbs are not the only ways to reduce your energy bill. You should also carry out energy appraisals and pay a visit to the compressor house.
The second element is control. Replacing simple on-and-off control with a sophisticated variable speed drive (VSD) based control system keeps the pressure in air pipes stable and supplies the required air flow. It also reduces compressor motor starts, service requirements and extends the motor’s life time. It even supports leakage detection. As of today only about 5% of compressors are controlled by VSD.
The third element is an energy efficient motor to drive the compressor shaft. Reluctance motors, which are a brand new motor technology, reach efficiencies better than IE3 premium efficiency. For a typical 75 kW motor which is used 24/7 it means 21 000 kWh in savings compared to usual IE2 high efficiency motors. And 21 000 kWh represents a saving of €1 700 in energy costs and 10,5 tons fewer CO2 emissions. With a VSD based control system it is much more – every year during its entire lifetime.
I think it makes sense to visit your compressor house and take these three steps. What do you say?