As governments and factory owners worldwide race to reduce their energy consumption and energy bills, it is becoming obvious that the change is not happening fast enough, for a variety of reasons.
Unlike for commercial and office buildings, significant energy conservation for factories cannot come from making tweaks to air conditioning or lighting, because a very large portion of energy consumed in factories is for the machineries and equipment.
And this is where the nub lies.
It has been found that the decision making duration is long for tens of thousands of factories worldwide to shift to energy efficient equipment by discarding old ones.
Not surprising given the extent of complexities, not to mention the additional capital cost, involved in shifting from existing equipment to new ones. And also the fact that the engineers who need to be involved in such replacements do not have their interests and objectives aligned with energy cost savings.
Let us just say that it is going to take a while for hundreds of thousands of factories worldwide to shift to energy efficient equipment and machinery.
So, is there some other energy conservation avenue that could be instituted in the short term in factories?
Yes, there is one, and that is: Waste heat recovery
You see, in many process industry companies (food, chemicals, pharma, beverages), there is a significant amount of heating involved in the operations, and a good part of this heat goes waste after doing useful work.
Today, there is a range of technologies available, many of them fairly mature, that can enable capture of waste heat from a range of processes and enable it to be used for further useful work – either for heat or for power generation.
In fact, things are getting so good that technologies available today can recover waste even when the temperatures of the exhaust air/gas are fairly low (less than 150 deg C).
I reckon waste heat or waste energy recovery is one of the better ways for manufacturing plants and factories worldwide to start “conserving” energy in a short time and in a painless manner. This can start making a significant difference at least for some of the industrial sectors.
Today, I am aware of a number of industry standard waste heat recovery systems available from leading vendors. Some of these are available even for waste heat at fairly low temperatures, implying that these can used in a wider range of industrial applications to recover waste heat.
Other, equally effective, but perhaps not so immediately doable ideas for factory environments are:
Focus on HVAC efficiency
Heating, ventilation and air conditioning contribute a significant amount to factory setups too, though they contribute a much higher % of energy expenses to the typical office setup. Increasing the efficiency of these while going for new purchases can decrease energy consumption significantly.
By replacing inefficient motors with premium efficient motors equates to significant cost savings over the life of the motor, not to mention the additional benefits of reduced down-time and increased productivity and reliability. Here are a few suggestions for greater motor efficiency:
- Choose energy efficient motors when buying new motors. While these could cost about 25% higher, the payback periods for this extra expenditure is fairly short.
- Do not oversize your motor and end up running them at a low load factor. This decreases the operating efficiency.
- If your loads vary significantly over time, consider using a variable speed drive motor system instead of traditional motors.
Compressed Air Equipment
Similar to motors, compressed air also contributes significantly to energy use in many factory environments. In facilities that require compressed air, approximately 10% of the energy used in that facility is used by the compressor alone. Here are some ways by which you can optimize the energy use by compressors.
- Compressors can be staged with controls to optimize performance.
- Use smaller compressors for operations during periods of lower demand.
- By reducing leaks based on analyses of compressor operations, you can significant reduce compressor energy consumption and consequently, costs