Most homeowners know they can save energy by changing lightbulbs, turning down thermostats, and closing the door. But how do you save energy in a factory? How do you do it fast? The answer may not come as quick to mind or be as easy to see. There are scores more ways to save energy in a factory than inside a house. Here are few of what professionals in the field call “Low-hanging fruit” – or, perhaps Low-Hanging Lightbulbs!
Is it Really “Off”?
Everbody says the machines/process/compressor/(fill-in-the-blank) is “off” – but are they? In order to save energy in a factory with this step, you must understand why a thing/process/machine is “On”. There are two basic types of electric loads that constitute a waste of electric energy 1) Sleeping Loads, 2) Idle Loads.
Machines and processes that are on when no one is in the building, or when there is no production being run are Sleeping Loads. Examples of this include lubricating oil heaters, or injection molding band heaters that go on and off to keep the barrel warm even when the plant may be on holiday. Other sleeping load examples include transformers used to change voltage for a specific piece of equipment (sometimes detectable by the loud hum they make), and networked computers, display screens and machine control screens that are not on a sleep-wake software program.
An Idle Load is the energy used by a machine or process while waiting to do work. Most metalworking machines, injection molding machines, and other process equipment have idle loads. These are motors that spin without being engaged by a clutch, cooling pumps and fluid distribution systems that run when no parts are passing through. Even calibrated gauges, that test finished parts through the use of compressed air, will be blowing that air all the time regardless of whether a part is in its jig to be measured. Ask is it really off? Does it really need to be on?
Find All the Types of Leaks
The second easiest way to save energy in a factory is to find the leaks. The first easiest set of “leaks” are the gaps in the windows and doors around the shop/factory.
Outside to Inside Leaks
In a regular house, you might have two “people” doors, a garage door and maybe a cellar hatch. In a factory, the numbers of doors and sources of heating/cooling loss to the outside can be much larger. For example, I have seen as many as (23) people doors, (9) loading dock doors as well as roof access hatches and passive ventilation grilles (fancy word for holes in the wall covered with chicken wire), in a 100,000sqft facility. Every single one had a gap or misaligned closure that let energy out.
Inside to Inside Leaks
But that’s not the only type of “Leak” you can have in a factory. The manufacturing processes can leak energy too. Hot air used for drying parts in a cabinet can be blowing out of all sides of the cabinet. Or the opening into which a motorized line of parts moves into the cabinet can be much too large, allowing most of the air to come blowing out. Hot water process tanks often sit open and uncovered, with hot steam rising into the factory.
Process Fluids Leaks
The third category of leaks is what I call Process Fluid Leaks, and other people call “everything else” This includes hot process water, or hot steam, chilled water, rinsing water, waste water and of course, compressed air.
I can not tell you how much money gets wasted on compressed air leaks. I can say with confidence, most factories waste 10% of their compressed air. In several cases I have found enough air leaks that the company stoppped running one of their air compressors! Your best bet here is to hire a professional to find the first batch of leaks and then teach you how to implement a Total Preventative Maintenance (needs link to article) program for the air system.
Use New Technology to Replace Old
For example, use inductive heating and melting instead of natural gas fired furnaces. One metal foundry we worked with discovered that replacing the old hearth furnaces with induction would cut the natural gas used by the factory by 50%, and also allow more precise mixing of additive trace compounds – ultimately improving product quality. The same benefits occur when plastic injection molders change from electric coil heater bands, to embedded filament heater wires. Electric energy use drops by 30% on this process AND there is an increase in uniformity of resin flow and melting.
Another common technology upgrade is to retrofit factory lighting with LED lighting (see: Lighting retrofits) – Lighting is usually 10 to 20% of a factory’s energy bill, and LEDs can reduce that portion by 30 to 50%
Save Energy by Optimizing Machines you Cannot or will not Replace
It would be great to just write check and buy or elase the latest technology for the shop floor. But, capital can be hard to come by, and sometimes there are machines that wree custom built for one purpose and exist no-where-else-in-the-world! For these cases we Optimize! Do not fear the process of “optimizing” a machine or process. Listed below is probably, the fastest, easiest “optimization processs” ever!
Start here with an Overall Equipment Effectiveness (OEE) calculation (See this article here).
Document your downtime issues and their frequency.
Create a Pareto chart of the problems.
Tackle the top (3) issues found on the production line.
Solving these issues allows you to increase the production output per unit of energy used, thereby reducing overall energy consumption for the same amount of product going out the door.
Save Energy through Optimizing the Process Example:
Lets say you have a production process that can create 100 pieces per hour, but is well known to jam in the process of creating these parts, and uses 100kWh in the process of creating and jamming. Now, if you fix the reason for the frequent jams, the machine can create 120 pieces per hour but uses the same amount of energy to do so because the machine’s idle loads are shorter and productive use of the energy is higher. Congratulations! Go forth and save energy in a factory! You have saved energy on a per-unit-of-product basis!
Question: What other ways have you found to save energy? Comment below!