Turn your air compressors into a sustainable source of energy

Converting recycled heat energy is a positive step forward to sustainability and reducing the carbon footprint of a plant.

By Matt Mazanec, Compressor World, LLC February 17, 2016

Resources are limited and consumption is huge. While we are talking about sustainability and optimum use of unrenewable energy, the ground fact is that a large section of industrial fuel is still coming from natural gas, heating oil, and other forms of hydrocarbon. At one end, we are fighting to find out alternative ways to produce energy, at the other, continuous use of such bio-fuel is making it hard to stay competitive.

Industries and manufacturing units are only viewing water, air, and sun as alternative energy sources, while a whole lot of energy is being wasted on a regular basis in their immediate vicinity. If this energy were capitalized optimally, it would add remarkably to our energy supply and bring in unimaginable difference to the overall cost of production. This unattended (or poorly capitalized) source is the large amount of heat decapitated from industrial compressed air systems. By harnessing this heat energy, we can save huge money on our energy spending.

If you analyze closely, you will find that 100% of electrical energy used by a rotary screw air compressor is converted into heat energy. Out of this, 96% is recovered by industries and the remaining 4% is wasted. It is either radiated into the atmosphere or released through the compressor cooling system. If you look at a larger picture, converting recycled heat energy is a positive step forward to sustainability and reducing the carbon footprint of a plant.

How to harness the Heat into an Energy Source

Both oil injected and oil-free rotary screw compressors are well suited for energy conversion. Usually an oil injected type compressor operates at as high as 185 F or more, while the oil-free design exceeds 300 F. They release warm air, which can be harnessed by integrating the compressor system with standard HVAC (Heating, Ventilating, and Air Conditioning) dust work and controls.

The warm air coming out of the compressor can effectively be used for space heating. Simple methods, such as transferring the warm air generated to an area that requires heat can accomplish many purposes. This can be done by passing air across the after-cooler and lubricant cooler of the compressor. This improves air quality, extends lubricant life, and minimizes back pressure on the cooling fan of the air compressor.

Another useful application of rejected heat coming from air-cooled or oil-injected compressors is heating water or other process fluids. The compressor itself discharges water, which is as hot as 160F. The discharged hot water can be directly connected to the process that required continuous heating.

-Matt Mazanec is co-founder of Compressor World, LLC, a worldwide distributor of air compressors. Edited by Erin Dunne, production coordinator, CFE Media, edunne@cfemedia.com.