How much electricity does a freeze dryer use?

A Blue Alpine Medium draws an average 1,080W. Over a published 12 to 20 hour cycle that is 13 to 21.6 kWh, which costs between $2 and $8.60 depending entirely on your electricity rate. The Large draws 1,440W average and costs proportionally more.

The arithmetic

Manufacturers publish average power draw, so this is straightforward multiplication rather than anything mysterious. Average watts, times hours, divided by 1,000, gives kWh. Multiply by your rate.

	Blue Alpine Medium	Blue Alpine Large
Maximum draw	1,560W	2,040W
Average draw	1,080W	1,440W
Published cycle	12–20 h	12–20 h
Energy, 12-hour run	13.0 kWh	17.3 kWh
Energy, 20-hour run	21.6 kWh	28.8 kWh
20-hour run at $0.12/kWh	$2.59	$3.46
20-hour run at $0.20/kWh	$4.32	$5.76
20-hour run at $0.28/kWh	$6.05	$8.06
20-hour run at $0.40/kWh	$8.64	$11.52

Why the range is so wide

Two reasons, and neither is the machine misbehaving. First, electricity prices vary by a factor of three or more between regions — the same cycle that costs $2.59 in one place costs $8.64 in another. Second, cycle length depends on the load: thick slices, a full tray set, high-moisture food or no pre-freeze all push a 12-hour cycle toward 30 hours, and the meter runs the whole time.

What actually draws the power

• The compressor runs almost the entire cycle, cooling the chamber and the cold trap. This is the bulk of the load.
• The vacuum pump runs continuously through primary and secondary drying.
• The tray heaters cycle on and off, drawing most during secondary drying when heat is being added deliberately.
• Peak draw happens early, during freeze-down, which is why the maximum figure is 40% above the average.

Three ways to cut it

1. Pre-freeze the load overnight in a normal freezer. The machine then skips most of the freeze-down phase. This is the single biggest saving available and it costs you a domestic freezer running for a night.
2. Slice thinner and load evenly. Twelve to fifteen millimetres. A tray mounded in the middle finishes at the pace of the thickest point, and every extra hour is another kilowatt-hour.
3. Run full batches. A half-full machine uses nearly the same energy as a full one, because the compressor is cooling the same chamber either way.