Freeze drying is actually an expensive process, energy wise. It consumes large amounts of energy to generate both the cold and the vacuum needed. However, once you’ve got the vacuum and the cold, neither of these items are strongly tied to the amount of stuff you are freeze drying. And the drying process proceeds at a specific speed in the stuff being dried regardless of how much is there. So, the more stuff you can get in your chamber, the less it costs on a per unit basis to do the drying. I’ve been doing very small runs of drying using a bench top freeze drier. It only had a roughly 5 1/2″ diameter tray that could only be piled up with about 1″ deep of stuff. Well, that’s no more. I still have the bench top unit, but I plan on getting rid of it. Instead, I bought and reconditioned a roughly 30 year old unit (that was in fabulous shape for its age…) that has 4 shelves, and each shelf has a 12″ x 17″ x 2″ deep tray for holding material. I fired it up for its first real run tonight. I expect it to take a day or two to complete the run, but instead of having a few tablespoons full of product when it’s done, I’ll literally have multiple cups of stuff.

Upper portion of unit with bench top freeze dryer sitting on top for comparison
Whole machine
Contents of a tray currently being dried
An unused tray in my freezer, shows how bif these trays actually are