Tag: heat recovery

Compressed Air Is Powering the Energy Transition — Not Just Manufacturing

Published on by Jordan T ShouseLeave a comment

A major breakthrough just hit the industry: researchers unveiled the world’s most powerful single-unit compressed air energy storage (CAES) compressor, rated at 101 MW.

  • Achieves ~88% efficiency at max discharge pressure
  • More than doubles the power of prior single-unit CAES compressors
  • Designed to store energy by compressing air for later electricity generation

This positions compressed air not just as a plant utility—but as a grid-scale energy storage solution.

From Shop Air to Grid Power

For decades, compressed air has been known as the “fourth utility” of manufacturing—powering tools, automation, conveying systems, and production lines across nearly every industrial sector.

But today, compressed air is stepping into a much larger role.

Recent breakthroughs in compressed air energy storage (CAES) technology are transforming compressed air from a plant-floor necessity into a grid-scale energy solution. Massive new compressor systems are now capable of storing surplus renewable energy and releasing it back into the electrical grid when demand spikes.

In other words, compressed air isn’t just powering production anymore—it’s helping power the future of energy.

What Is Compressed Air Energy Storage (CAES)?

Compressed Air Energy Storage is a method of storing energy for later use—similar in purpose to batteries, but very different in scale and operation.

Here’s how it works:

  1. Energy Capture
    Excess electricity—often from renewable sources like wind or solar—is used to power large compressors.
  2. Air Compression & Storage
    The compressed air is stored in underground caverns, tanks, or geological formations.
  3. Energy Release
    When electricity demand rises, the stored air is released, heated, and expanded through turbines to generate power.

Why CAES Matters

Renewable energy plays a critical role in the global shift toward sustainability, but it comes with a fundamental challenge: intermittency. Solar power only generates electricity during daylight hours, wind output fluctuates based on weather conditions, and grid demand changes constantly throughout the day. This mismatch between energy production and consumption creates reliability challenges for utilities. Compressed Air Energy Storage (CAES) helps solve this issue by capturing excess energy when supply is high and releasing it when demand spikes. The technology provides long-duration energy storage, supports grid stabilization, helps meet peak demand, and reduces reliance on fossil fuel peaker plants. While lithium-ion batteries currently dominate short-term storage solutions, compressed air stands out for its ability to store massive volumes of energy over longer periods—making it especially well suited for utility-scale applications.

A Breakthrough Moment for Compressed Air

Recent advancements in high-capacity compressors designed specifically for energy storage are pushing the boundaries of what compressed air technology can achieve. These next-generation systems deliver unprecedented compression power, achieve significantly higher efficiency levels, and are engineered to support renewable energy integration at grid scale. By reducing energy loss during compression and discharge cycles, they make large-scale air storage more practical and economically viable than ever before. This innovation marks a turning point for the industry: compressed air is no longer confined to manufacturing facilities—it is now being positioned as a core component of national energy infrastructure planning and the broader transition to renewable power.

Jordan Shouse, CCASS

Application Engineer / Sales Operations Engineer

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Schematic of the compressed air energy storage method courtesy of (Image: https://voltatechnique.com/technology/) Creative Commons License

Air Compressors: Savings Found on the Supply and Demand Side

Published on by John BallLeave a comment

Producing compressed air can be expensive, but it is necessary for pneumatic systems.  And a large part of that expense is wasted energy, in the form of heat.  Waste will add to your overhead and affect your bottom line.  EXAIR has a line of products to help reduce air consumption at the point-of-use to save you money.  This would include replacing open-pipes and tubes with EXAIR Super Air Nozzles and Super Air Knives.  But, let’s look at the supply side inside your compressor room.  The air compressor operates at about 10% efficiency where most of that loss is in a form of heat. 

Wouldn’t it be nice to recover some of that expense?  You can.  By equipping your air compressor with a heat recovery system.  These systems are designed to recover the loss of heat for other uses.  Today, they can recover somewhere between 50% for liquid-cooled compressors to 80% for air-cooled compressors.  The heat can come from the after-coolers, the electric motor, the “heat of compression”, and the oil cooler.  This reclaimed heat can be used to heat water, warm rooms, pre-heat steam systems, and dry parts. 

Let’s create an example.  A company has a 100 HP air-cooled compressor that is running 8 hours per day for 250 days per year.  The heat recovery system will be able to reclaim 60% of the heat to warm city water in the plant.  If the electrical cost is $0.10 per KWh, we can calculate the savings.

Annual Savings:

100 HP * 0.746 KW/HP * 0.6 (reclaim) * 8 hours/day * 250 days/yr * $0.10/KWh = $8,952.00 savings per year.

In practice, reclaiming the maximum percentage may not be cost effective.  Your company can determine the best percentage for heat recovery by calculating the Return on Investment (ROI).  I wrote a blog post that can help you estimate (Click Here). 

As mentioned above, EXAIR saves you money and increase efficiency on the demand side.  EXAIR has engineered nozzles to help reduce compressed air usage.  The following is a quick calculation by replacing an open-end blow-off with an EXAIR Super Air Nozzle.  If you have a ¼” (6mm) copper tube, it will use 33 SCFM (935 SLPM) of compressed air at 80 PSIG (5.5 bar).  As a common replacement, EXAIR uses a model 1100 Super Air Nozzle which will use 14 SCFM (396 SLPM) at 80 PSIG (5.5 bar).  With a simple tube fitting, you can mount the ¼” NPT Super Air Nozzle to the end of the ¼” copper tube.  If we use the same pretext as above, we can find the annual cost savings.  With an air compressor that produces 5 SCFM/hp, we can get a cost savings with the Super Air Nozzle.  The difference in air flow at 80 PSIG (5.5 bar) is:

33 SCFM (copper tube) – 14 SCFM (Model 1100) = 19 SCFM savings

Annual Savings:

19 SCFM * 1 HP/ 5 SCFM * 0.746 KW/HP * 8 hr/day * 250 days/yr * $0.10/KWh = $566.96 savings per year per nozzle.

Whether it is on the supply side or the demand side, companies are looking to reduce or reuse the wasted energy to have a more efficient compressed air system.  The heat recovery system is a bit more complex, but should be considered.  The EXAIR engineered nozzles are more simplistic, and they can give you a return on your investment in a short period of time.  If you would like to discuss how to improve your compressed air system from the supply side to the demand side, an Application Engineer at EXAIR will be happy to assist you. 

John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb

Photo: Idea by Saydung89.  Pixabay License.

Supply Side Review: Heat of Compression-Type Dryers

Published on by Brian FarnoLeave a comment

The supply side of a compressed air system has many critical parts that factor in to how well the system operates and how easily it can be maintained.   Dryers for the compressed air play a key role within the supply side are available in many form factors and fitments.  Today we will discuss heat of compression-type dryers.

Heat of compression-type dryer- Twin Tower Version

Heat of compression-type dryers are a regenerative desiccant dryer that take the heat from the act of compression to regenerate the desiccant.  By using this cycle they are grouped as a heat reactivated dryer rather than membrane technology, deliquescent type, or refrigerant type dryers.   They are also manufactured into two separate types.

The single vessel-type heat of compression-type dryer offers a no cycling action in order to provide continuous drying of throughput air.  The drying process is performed within a single pressure vessel with a rotating desiccant drum.  The vessel is divided into two air streams, one is a portion of air taken straight off the hot air exhaust from the air compressor which is used to provide the heat to dry the desiccant. The second air stream is the remainder of the air compressor output after it has been processed through the after-cooler. This same air stream passes through the drying section within the rotating desiccant drum where the air is then dried.  The hot air stream that was used for regeneration passes through a cooler just before it gets reintroduced to the main air stream all before entering the desiccant bed.  The air exits from the desiccant bed and is passed on to the next point in the supply side before distribution to the demand side of the system.

The  twin tower heat of compression-type dryer operates on the same theory and has a slightly different process.  This system divides the air process into two separate towers.  There is a saturated tower (vessel) that holds all of the desiccant.  This desiccant is regenerated by all of the hot air leaving the compressor discharge.  The total flow of compressed air then flows through an after-cooler before entering the second tower (vessel) which dries the air and then passes the air flow to the next stage within the supply side to then be distributed to the demand side of the system.

The heat of compression-type dryers do require a large amount of heat and escalated temperatures in order to successfully perform the regeneration of the desiccant.  Due to this they are mainly observed being used on systems which are based on a lubricant-free rotary screw compressor or a centrifugal compressor.

No matter the type of dryer your system has in place, EXAIR still recommends to place a redundant point of use filter on the demand side of the system.  This helps to reduce contamination from piping, collection during dryer down time, and acts as a fail safe to protect your process.  If you would like to discuss supply side or demand side factors of your compressed air system please contact us.

Brian Farno
Application Engineer
BrianFarno@EXAIR.com
@EXAIR_BF

 

Heat of compression image: Compressed Air Challenge: Drive down your energy costs with heat of compression recovery: https://www.plantservices.com/articles/2013/03-heat-of-compression-recovery/

 

Heat Recovery from an Air Compressor

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On the whole most of us are quite aware of the considerable savings that can be accomplished by wise use and recovery of energy.   One way that a plant can save substantially is to capture the energy that an electric motor adds to the compressed air from the air compressor.  As much as 80% to 93% of the electrical energy used by an industrial air compressor is converted to heat.  A properly designed heat recovery system can capture anywhere between 50% to 90% of this energy and convert it to useful energy.

The heat recovered is sufficient in most cases to use in supplemental ways such as heating water and space heating, however generally there is not enough energy to produce steam directly.

IngersollRand_R-series-R110
Ingersoll Rand Rotary Screw Compressor

 

Packaged air cooled rotary screw compressor lend themselves easily to heat recovery, supplemental heating or other hot air uses very well due to their enclosed design.  Since ambient air is directed across the compressors aftercooler and lubricant cooler where the heat can be easily collected from both the compressed air and the lubricant.

Packaged coolers are normally enclosed cabinets that feature integral heat exchangers and fans.  This type of system only needs ducting and an additional fan to minimize back pressure on the air compressors cooling fan.  This arrangement can be controlled with a simple thermostat operated vent on a hinge and when the extra heat is not required it can be ducted outside the facility.

The recovered energy can be used for space heating, industrial drying, preheating aspirated air for oil burners or  other applications requiring warm air.  Typically there is approximately 50,000 Btu/Hr of energy available from each 100 SCFM of capacity (at full load).  The temperature differential is somewhere between 30°F – 40°F above the air inlet temperature and the recovery efficiency is commonly found to be 80% – 90%.

We all know the old saying there is “no free lunch” and that principle applies here.  If the supply air is not from outside the plant a drop in the static pressure could occur in the compressor cabinet thereby reducing the efficiency of the compressor.  If you choose to use outside air for makeup, you might need some return air to keep the air above freezing to avoid compressor damage.

Heat recovery is generally not utilized with water cooled compressors since an extra stage of heat exchange is required and the efficiency of recovering that heat is normally in the 50% – 60% range.

To calculate annual energy savings:

Energy Savings (Btu/Yr) = 0.80 * compressor bhp * 2,545 Btu/bhp-hour * hours of operation.

If we consider a 50 HP compressor:

.080 * 50bhp * 2,545 Btu/bhp-hour * 2080 hrs/year =  211,744,000 Btu/yr

Where 0.80 is the recoverable heat as a percentage of the units output, 2,545 is the conversion factor.

Cost savings in dollars per year = [(energy savings in Btu/yr)/Btu/fuel) x ($/unit fuel)]/primary heater efficiency.

If you would like to discuss saving money by reducing compressed air demand and/or any EXAIR product,  I would enjoy hearing from you…give me a call.

Steve Harrison
Application Engineer
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Photo courtesy of Ingersoll Rand CC BY 3.0, https://en.wikipedia.org/w/index.php?curid=32093890