Improving the energy efficiency of the industrial motors, pumps, air compressors and other equipment in your business can reap significant rewards.
All equipment can deliver efficiency savings if regularly maintained. However, the shrewd addition of sensors, Variable speed drives and continually re-tweaking your system to best practice efficiency will save thousands of dollars over the life of these systems.
The most efficient businesses save the most money, and create opportunities to prosper.
How to do it now!
Regularly or constantly used electrical equipment can be optimized to improve its efficiency and save you money through lower electricity bills. Some of the common specialist equipment that can be optimised includes: Air compressors, electrical motors and pumps.
Fix air compressor leaks
Air compressors pressurize and compress air which is then delivered via hoses to equipment (nail guns, cleaning, etc… ). Wear and tear on the hoses and joins can result in this system leaking air and the compressor having to work harder to compensate.
To find and fix any leaks run the hose and joins through a bucket of water to find out where your system is leaking then replace/repair the leaking part or hose.
Implement best practice pumping
Existing pumping systems can provide an excellent opportunity for efficiency improvements, with improvements often having a payback period of a couple of years.
The Sustainability Victoria manual on best practice pumping highlights that “Improving the efficiency of just one pump can save substantial energy. For example, a continuously operated centrifugal pump, driven by a fully loaded 100 kW motor, requires 973,000 kWh per year and costs more than $97,000 to operate, assuming average electricity costs of 10 cents per kWh and a 90% motor efficiency. With a 20% reduction in operating costs, savings of $19,400 per year can be realised.”
These efficiencies can be achieved in one of two ways:
1. Improve the efficiency of your existing pumping system
The following table provides a list of common problems in existing pumping systems and their likely remedy.
|Common Problem||Potential Measures to Improve Efficiency|
|Unnecessary demand on pumping system||Reduce demand on system|
|Oversized pumps||Select pump that operates near to BEP, Change impeller, Trim impeller, Fit multiple-speed pump, Use multiple-pump arrangements, Fit lower speed pump/motor|
|Inefficient pump throttling controls||As for oversized pumps Fit adjustable or variable-speed drive|
|Inefficient piping configuration||Change piping inefficiencies|
|Oversized motor||Change motor|
|Inefficient motor||Change to high efficiency motor|
|Lack of monitoring and/or documentation||Install monitoring Conduct a survey|
The Sustainability Victoria manual on best practice pumping suggest the following seven step process for improving the efficiency of an existing pumping system:
- Assess & analyse your existing system
- Prioritise opportunities
- Reduce unnecessary demand
- Review your pump
- Review flow rate controls
- Optimise piping configurations
- Review your motor
2. Design a new system
Sometimes the best solution is to re-design and replace the existing system with a “best practice” energy efficient pumping system.
When designing a new pumping system the following process is suggested:
- Assess production requirements & minimise needs
- Design with whole-systems approach
- Design efficient pump stations
- Select efficient pumping components
- Improve your design
Install efficient motors.
When replacing a motor in your business, ensure it is a high efficiency motor and in heavy use applications (and with rising energy costs) the payback period will be less than a year.
In Australia, it is estimated that three-phase electric motors account for up to 40% of the total electricity consumed in the commercial and industrial sectors.
Ensure your motors are not ‘oversized’
Motors operate at their highest efficiency at between 60% and 100% of their full-rated load, dropping off sharply in efficiency below 50% loading. About one-third of motors in the field are so oversized that they operate below 50% of rated load most of the time. Oversized motors not only operate inefficiently, but they also carry a higher first cost than appropriately-sized units. They can also contribute to reduced power factor, which may increase your electricity costs.
When buying new motors
Ask whether high efficiency motors (especially motors that operate for more than 3,000 hours each year) can be fitted to the equipment you are about to order. Also, request efficiency figures and price premium from the supplier.
Tips on replacing standard motors with high efficiency motors
- For centrifugal pump and fan applications, make sure that the speed of the high efficiency motor is identical to the motor it will replace. Higher speeds can cause a net increase in the consumption, especially for flow applications.
- Unless the motor operating hours are high (eg. over 3,000 hours per year), it may not be economical to replace operating standard efficiency motors (which have not yet been re-wound) with high efficiency motors
- Motors that are lightly loaded or infrequently used (eg. control valve drives) may not consume enough electricity to make installing a high efficiency motor cost-effective.
Install Variable Speed Drives (VSDs) on motors
Electric motors are used throughout industry, often set at constant speeds. Variable speed drives (VSDs) allow loads driven by AC induction motors (such as fans and pumps) to operate in a wide range of speeds compared to the motor fixed speed. VSDs are also called variable-frequency drives, adjustable-speed drives, variable-frequency inverters, or frequency converters. The introduction of variable speed drives (VSDs) controlled with sensors allows these motors to be run at the various appropriate speed(s). As fans, pumps, winders and tools can be just as effective at lower speeds, the addition of a VSD can result in considerable energy savings over the life of the motor.
Some of the ideal situations for the introduction of a VSD include:
- Variable air volume air conditioning systems
- Chilled water pumping
- Exhaust air systems, such as dust extraction, paint shop exhaust, and fume cupboards
- Refrigeration systems
- Some modern compressors (including air and refrigeration compressors)
Choosing, installing and commissioning a VSD is a job for a specialist. The installation and commissioning engineer will set and calibrate the control system so that the VSD matches the requirements of the process or equipment. Correct set-up is essential for maximum savings.
The benefits of installing VSDs include:
- Savings in electricity costs of 15% to over 50% are achievable
- Enhanced control performance
- Less mechanical devices = less maintenance
- Reduction of noise pollution & mechanical stress
- Very quick return on investment: between 9 and 24 months
To find a local electrician that has experience in this field:
- Find an Electrician – to check the NECA (National Electrical & Communications Association) database of electricians.
- EcoSmart Electricians – also have a database of electrician.
Information on pumping system efficiencies
- Energy Efficiency Best Practice guidelines, Sustainability Victoria.