Europe’s overreliance on imported natural gas from Russia has been a shocking wake-up call in light of Russia’s invasion of Ukraine. Last year, the European Union imported more than 400 million cubic meters per day of natural gas — almost 40% of the EU’s total gas consumption — mainly for power generation and heating.
Atlas Copco ZH compressor and XD dryer setup. (Image courtesy of Atlas Copco)
Europe is between a rock and a hard place, to say the least, arming and supplying Ukraine’s forces while at the same time helping fund Putin’s devastating onslaught.
The EU has announced a plan to reduce reliance on Russian energy imports by two-thirds by the end of this year. Measures include turning to alternative energy suppliers, accelerating solar and wind projects, and ramping up biogas production.
And part of the REPowerEU plan includes aggressively investing in improving energy efficiency in homes, buildings and industries, which it estimates can save 25 billion cubic meters of gas each year.
Fluid power users can make a significant dent in reaching that goal. Compressed air alone accounts for 10% of industrial power usage. Yet the over-all efficiency of a typical compressed air system is only 10 to 15%, meaning most of the energy required to generate compressed air is never used to do productive work and instead is wasted as heat. Many systems could see significant energy savings through immediate, low-cost improvements without long lead times or major capital investments. Here are seven proven techniques.
Eliminate leaks.
Compressed-air leaks can be a major source of wasted energy, causing a 20 to 30% loss of a compressor’s output. They also lower the effectiveness and productivity of equipment; cause compressors to run more often, which consumes more energy and shortens equipment life; and mean adding unnecessary compressor capacity.
Leaky valves, deteriorated seals and loose connections on tubes and hoses are common sources. Fixing leaks may be as simple as tightening fittings or replacing inexpensive seals. Conducting a leak assessment using ultrasonic detection equipment is a cost-effective way to find and eliminate leaks.
Run equipment only when required.
Shutting off machinery and equipment when not in use, especially overnight and weekends, can cut energy consumption up to 20%. Even during production, an idling compressor uses around 40% of its full load. Where appropriate turn it off. Installing automatic air-reduction controls can also significantly increase machine efficiency. They’re particularly useful when it’s too cumbersome to have maintenance personnel manually turn off air to numerous machines. They can even maintain pressure to certain functions even when there is no production, such as for cleaning.
Reduce operating air pressure.
Pneumatic systems waste energy when they supply higher pressure than an actuator or tool needs. Every 2 psi reduction in compressor discharge pressure reduces compressor energy by 1%. Thus, lowering pressure to a machine can result in sizeable reductions in energy use with no effect on operations. It also cuts leakage and other losses. For instance, in many applications cylinders either push or pull a load, but not both. Yet most often machines use the same pressure for both extend and retract strokes, which is extremely inefficient. Using pressure regulators to supply the right pressure for each task can realize energy savings of more than 25%.
Minimize pressure drop.
Pressure drops as compressed air travels through the treatment and distribution system. A properly designed system should have a pressure loss less than 10 % of the compressor’s discharge pressure, measured from the receiver tank to point-of-use. Maintain filters to ensure they’re not clogged, switch to more energy-efficient filter elements, and eliminate unnecessary flow restrictions in undersized piping and connections.
Variable speed drives.
A variable-speed drive adjusts electrical motor speed to ensure a rotating device delivers optimum performance based on the required rpm, and at the lowest energy demand. They routinely control and adjust the performance of pumps, compressors, blowers and fans. Fixed-speed design is fine for industrial applications that need continuous power to generate near-constant output, while VSD arrangements provide significant advantages in applications with fluctuating demand or relatively long dwell periods.
Servo drives regulate the speed and, thus, the power consumption of electric motors in line with demand and have been used with great success in applications like injection-molding machines, stamping presses and machine tools, where energy savings over conventional circuits is up to 80%.
And most systems today, tens of thousands of them, still mate asynchronous motors running at fixed speed with variable-displacement pumps to drive their hydraulics systems – which can be quite inefficient. Newer digital motor-pump drives with hydraulic “intelligence” can control motor speed and pump displacement based on sensor inputs and system demands. With no other changes to the system, it can result in energy savings of 50%.
Smarter point-of-use.
Compressed air is used extensively to operate equipment as well as to cool, dry and clean. Some estimates say around 70% of all compressed air is used in blow-off and similar applications. Unfortunately, inefficient uses are common. For example, many blow guns are simply open-ended pipes; and sections of pipe with drilled holes along the length are common in industrial environments as they are inexpensive and simple to make. However, homemade blow-offs waste lots of compressed air.
Better solutions are air amplifying nozzles and air knives. These devices employ aerodynamic shapes to take a small amount of compressed air to entrain large amounts of ambient air and create a high velocity laminar sheet of air. Exiting air experiences less pressure drop and noise, and can do more useful work over a greater distance. Today there is extensive use of this technology, which can cut air consumption in half.
High-efficiency hydraulic fluids.
Using the right hydraulic fluid can noticeably improve the overall efficiency of mobile and industrial machines. Fluids engineers have developed polymer additives that improve the viscosity index of standard hydraulic fluids. Compared to monograde fluids, such fluids generate less friction when cold, exhibit less internal leakage when hot, and offer high shear stability, all which equate to higher overall efficiency.
Conventional wisdom holds that a monograde is fine for indoor applications. But that assumes all parts of a system run at the same temperature. Complex equipment rarely has the same temperature conditions everywhere and will exhibit local differences throughout. A shear-stable, high-VI fluid minimizes any viscosity variations. Tests with energy-efficient hydraulic fluids in equipment like excavators and injection-molding machines demonstrate efficiency increases ranging from around 8% to above 25%.
Filed Under: News, Pneumatic Tips