Basic principles, tips and tricks
Energy-Efficient Compressed Air
Compressed air offers many opportunities for energy cost
savings. Here are the facts: Compressed air generation accounts
for around 10% of industrial electricity consumption. Compressed
air has many uses – as stored energy or as a process medium. It
is, however; also true that compressed air can be a relatively
costly form of stored energy if the opportunities for energy
savings are not actioned properly. In this context, previously
documented examples and case studies show that energy
consumption savings of up to 30% are possible, even if you think
that your current system is running efficiently.
Energy costs account for more than
two thirds of the total cost of ownership
Increasing energy costs and the threat of carbon and
emissions levies and taxes for businesses, mean that the
performance and efficiency of compressed air systems have never
been more important – especially when you consider that energy
constitutes the largest part of the total life-cycle cost of a
compressed air station.
Various studies on this topic have all concluded that around
80% of the total life-cycle costs can be attributed to energy
Surprisingly, in many cases, compressed air consumption is a
completely unknown factor (70% in one survey), and only 20% of
the surveyed companies had already tried to implement a process
of optimising their processes and networks.
To begin with: Measure your air
The process of finding potential savings starts by capturing
air usage data and making it readily available for analysis.
While doing so, it is also important to account for the
compressed air related energy costs, broken down into each
production area’s consumption. This process alone has led to
savings of up to 30 to 40% in compressed air consumption and
The biggest savings: Eliminating
The aim of this white paper is to highlight the possible
compressed air savings, and when looking at all of the options,
eliminating leaks in the compressed air network is one of the
most important consideration. Even in companies that maintain
their installations well, up to 30% of the compressed air
generated can be lost through leaks (statistics from the NRW
energy agency: 10% in industrial networks, up to a maximum of
30%). As an example, a single leak with a diameter of just 2mm
would lead to a loss of 0.4m3 per min in a 10 bar network.
This would amount to additional energy costs of thousands of
Euros per year. And yet, it’s a simple process to investigate
the network for leaks using a purpose-made ultrasound measuring
device. The time taken to recoup those additional energy costs
incurred, while fixing leaks and regularly monitoring the
network, is between six months and two years.
Compressed Air Generation Efficiency
When planning and optimizing compressed air systems, always
consider that a compressor converts only around 7% of the
electrical energy consumed by mechanical expansion energy. The
majority of the energy is released as waste heat, resulting in a
very low-efficiency rating, compared to an electrical drive. It
is, therefore, all the more important to use the available
energy efficiency and maximize all possible energy saving
Inaction costs more in the long run
In practice, there may be many reasons not to take action and
look for cost savings, however this shouldn’t prevent
decision-makers from considering the points raised in this
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Pressure increases and energy usage correlate at a ratio
of 2:1. This means that for every 1 PSl increase in system
pressure there will be a 0.5% increase in energy
consumption of the compressed air system. For example,
increasing system pressure by 20% (perhaps from 100 PSIG
to 120 PSIG) will result in an energy increase of 10%.
Conversely, reducing the pressure of the compressed air
system has the same effect. If we can solve inefficiencies
and reduce the main line pressure by 20 PSIG, we will
reduce the energy requirement by 10%.
Compressed Air Handbook,
Compressed Air and Gas Institute, pg. 211
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efficient compressed air systems.