Compressed air is used in virtually all industries. In fact, it is often called the “fourth utility” because of its tremendous importance to millions of businesses.
However, producing it comes at a cost – primarily energy expenses, which make up the biggest share of the total cost of ownership of an air compressor. In addition, the energy a compressor consumes also constitutes 99% of its CO2 emissions.
Fortunately, there are opportunities for companies to minimize these costs. Most notably, they can invest in energy-efficient equipment, like a variable speed drive compressor, which can reduce energy consumption by up to 50%.
In addition, they can optimize their compressed air system to ensure that no energy is wasted. This can be done by preventing air leaks and making sure that the working air pressure is not too high. But all these measures are about eliminating waste.
The big question is, how can you eliminate the energy required for compressed air production.
However, there is another source of tremendous waste that is often overlooked: The compression of air generates a lot of heat, which is typically dissipated to ensure that the compressor does not overheat and that the compressed air is cool enough when it reaches its destination. In most cases, this heat literally vanishes into thin air.
That is particularly wasteful, especially considering that over 90% of the electrical energy a compressor uses is converted into compression heat.
There is an energy-efficient solution. By adding waste energy recovery technology to a compressed air system, much of the energy that a compressor uses can be recovered by using the generated heat elsewhere.
This reduces operating costs because the vast majority – up to 94% - of compression heat can be recovered, which is why such an energy recovery system usually pays for itself in less than three years.
Before deciding to invest in a waste energy recovery system, it is important to make the distinction between air-cooled and water-cooled compressors. The energy recovery process in the former is particularly easy and inexpensive, which makes it suitable even for small compressors.
The heat recovery in the case of water-cooled compressors is a bit more complicated and may involve additional components, such as pumps, a heat exchanger (which is optional in most Atlas Copco compressors) and control valves. That is why it only makes economic sense for compressors of more than 22 kW. However, the resulting cooling water can generate hot water with a temperature of up to 90°C, which can be used for a variety of processes.
That brings us to the next important topic: What can a business do with the recovered heat? Actually, a lot. The most obvious example is to use the heat from an air-cooled compressor to heat a production hall or another building, but this is limited by the time required for space heating, ie during cold weather. water heating for laundries, industrial cleaning and sanitary facilities.
The hot water or steam from a water-cooled compressor has many versatile uses in a wide range of industries. These include the following sectors and applications: Automotive (various production processes), pharmaceuticals (drying and sterilization), food and beverage (pasteurization, drying and cleaning), textiles (coloring), chemicals (various refinery processes), electronics (clean room sterilization) and many more.
While it is possible to predict the percentage of energy a green technology like a variable speed compressor or dryer can save compared to a conventional model, the savings of an energy recovery system depend on a wide range of factors.
These include the types and sizes of compressors, how often they run, what type of cooling they use, the compressed air system, and the opportunities a company has to use the recovered heat. In most cases, however, the savings are substantial and some energy recovery systems even pay for themselves after just one year.
An added benefit is that such a system not only lowers production costs but can also significantly reduce the CO2 footprint of a business. This in turn, might make such an investment eligible for government incentives offered for the purchase of green technologies.
There are lots of reasons to switch to a waste energy recovery system, but if you are still not sure whether your business will benefit, simply check in with your Atlas Copco representative, who can give you all the information you need.