Energy is a major cost for most businesses. Whether they need it for producing goods, heating buildings or cooling computer servers, running machines or storing data, energy often takes up the bulk of their operational budget.
Following decades of taking this energy for granted, companies have begun using it much more responsibly in recent years. One way they have done so is by getting their power from renewable energy sources, such as wind and solar power. Another way is the investment in more energy-efficient equipment. This is beneficial for the environment and their bottom line. After all, less energy used means less money spent.
However, there is another way in which businesses can use energy much more efficiently that is often overlooked: Energy recovery.
A professional building typically contains a number of systems that generate waste heat. For example, hvac and compressed air systems typically convert much of the electrical energy they require to work into heat, which is subsequently dissipated. That is a lot of energy literally disappearing into thin air. However, this waste heat can be captured with energy recovery technology and used for applications such as water or space heating, industrial cleaning, and sanitary facilities. And as up to 94% of compression heat can be recovered, an energy recovery system will help companies save big on energy costs.
This means there are countless ways for businesses to recover energy – it is just a matter of identifying these opportunities and taking advantage of them. To do so, businesses first need to be aware of where they generate waste heat and whether these areas are suitable for energy recovery.
So-called “process heat,” which refers to the thermal energy used to prepare or treat materials during the manufacturing process, accounts for the majority (about two-thirds) of the European energy sector’s final energy consumption. The temperatures of this process heat range from a few degrees of added heat, e.g. for space heating, to more than 1,000 degrees, e.g. for metallurgical processes.
Some of that heat can be recovered and reused fairly easily while, in other cases, doing so would be much more difficult.
For example, it may not be possible to capture and re-use the heat emitted from the computer equipment in an office, but it is possible to recover the heat generated by a large data center and then use it to heat another building or a swimming pool.
Therefore, with current energy recovery technologies in mind, businesses should identify which of their processes and applications consume the most energy. These are a good starting point for determining potential recovery opportunities.
Among them should be compressed air applications, which are excellent candidates for energy recovery. First of all, they are abundant. Nearly 10% of all energy consumed by the industrial sector is used for compressing air.
During the compression process, heat is generated. That heat usually ends up being lost as waste heat – even though it could be recovered and re-used elsewhere. Put two and two together and it is easy to see why compressed air applications are perfectly suited for energy recovery.
However, identifying the applications that are best suited for energy recovery is only the first step – and it is of little benefit unless a new use for this energy is found.
Fortunately, there are many places in which waste heat can be repurposed. Some of them include the use in production and refinery processes, the cleaning and pasteurization of food, the sterilization of pharmaceuticals, and of course, the heating of water and buildings.
It should be noted that, because hot waste air is better suited for some of these applications and hot wastewater for others, the way a compressor is cooled – whether by air or water – should determine how the waste heat is used. As a rule of thumb, only compressors with a nominal power of 30 kW or more should be water-cooled. Otherwise, the energy recovery does not make sense (yet) economically. However, because of the tremendous potential of the technology – up to 94% of the compression heat can be recovered – energy recovery systems usually pay for themselves in three years or less.