By Elizabeth Gooding, Inkjet Insight
Note: This article was updated on 4-23 to correct a calculation error. (Yes, it happens to us too.)
I recently attended a panel presentation on the business justification process for production inkjet (not as boring as it sounds). Naturally, the conversation came around to Total Cost of Ownership (TCO) analysis and the moderator asked the panelists if there were any big differences between their pre-purchase analysis and the actual TCO. Here’s the answer:
“We forgot to estimate for power consumption.”
Ouch. I’m not mentioning who said it because that’s kind of a big deal. The difference in power consumption between one inkjet device and another can be significant. A difference in power specs could also result in a significant difference in annual costs, depending on the number of shifts you run and a number of other variables.
When looking at specifications for power consumption, you need to find the amperage, or current, measured in amps and the voltage measured in volts. Some device brochures are straight forward and call out the amperage and voltage per engine, some have ranges and others say that power consumption “varies” (more on that in a minute). Most production printers use 240-volt power, but not all of them. The same amperage with a 120 volt “plug” uses half the power.
Here’s how the math works:
- AMPs x Volts gives you Wattage
- Wattage / 1,000 gives you Kilowatts
- Then you need to apply this to one or two engines in the device – and don’t forget finishing add-ons or drying units.
When you are looking for what your power actually costs (without going to your CFO and asking for a copy of the bill), you can get a good estimate from the Choose Energy website which provides average commercial power costs by state and type of power.
Power is charged in cents per kilowatt hour. Costs in the U.S. range from a low of 7.1 cents in Oklahoma to 30.4 cents in Hawaii. Your device will only draw top power when printing at top speed. For comparative purposes, we have assumed that the device is running for 7 hours out of each 8-hour shift. Annualized results are shown for 15, 20 and 25 amp devices (with 2 engines) running 6 and 12 shifts per week. See Table 1 below.
As you can see from the table above, a 5-amp difference in power consumption can mean a difference in annual cost of anywhere from $2,600 to over $30,000 for a single twin engine machine. When you factor in multiple machines, additional dryers and finishing equipment, energy cost becomes and important factor.
Power Consumption Varies
As noted earlier, power consumption varies. The configuration of your device can impact power consumption – particularly with respect to air circulation, paper path and drying options. Power consumption will also be affected by ink coverage, ink type and media type used. Also, the climate control of the print room can impact power consumption; the more air flow and natural cooling in the print room, the less that needs to be spent counteracting heat from printers. Conversely, if there is less heat thrown off by the printer, you will spend less on cooling the room.
Keep in mind that some devices have been designed with longer paper paths that help to reduce power needed for drying. However, in some cases, this comes with the tradeoff of increased paper wastage if the printer can’t engage until the device approaches top speed.
If you are evaluating printers for purchase, make sure that the cost of power is reviewed in detail for the specific configuration of the device you are considering. If you already have installed a printer and are concerned about power consumption, there are potentially some things that can be done to positively impact power consumption (drop us a note). We have power statistics for many different machines on Device Finder, but you will want to get the specifics for your configuration from your OEM.