Atlas Copco claims to have developed the first compressors to be certified independently as operating with “net zero energy consumption” under certain conditions. The water-cooled, oil-free ZR compressors recover the electrical input energy in the form of hot water. This water can be used directly in a variety of plant processes, or as preheated boiler feed water, thus cutting the user’s energy bills and carbon footprint.

The challenge in designing the compressors was to collect the waste heat from the compressor’s oil cooler, intercooler, aftercooler and compression components. The recovery system (shown above) circulates water through these elements to produce hot water at up to 90ºC.

Atlas Copco’s claims have been tested by the German TÜV test organisation which compared a compressor’s electrical energy input with its hot water output. TÜV found that under specific conditions (an ambient temperature of 40ºC and a relative humidity of 70%), all of the input electrical power could be recovered.

“With the Carbon Zero compressor, customers can get compressed air virtually for free, which has significant impact towards preserving the environment and also the bottom line” says Stephan Kuhn, president of Atlas Copco’s Compressor Technique business.

According to the company, users that will benefit most will be those with a continuous need for hot water and steam in their processes. These include the food and beverage, pulp and paper, textile, pharmaceutical, chemical and power generation industries.

Energy consumption typically represents more than 80% of a compressor’s lifetime costs. Compressed air systems account for around 10% of industrial electricity consumption but, in some plants, the figure can be as high as 40%.

♦ The heat-recovery compressors will be launched in the UK at The Energy Event at the National Motorcycle Museum on 9–10 September.