OK, I'm not trying to pick on these Dutchess Hops guys, but let's quickly evaluate this dryer design using the criteria I had laid out earlier. I'll mention this is a common setup for 1st and 2nd year growers and can work well.
- Does this maintain and/or improve the final quality?
Well, it won't get above 140F in there. No alpha acid reduction. Will it get above 100F and drive away a lot of the oils and other flavor compounds that craft brewers will pay extra to obtain? It may.
Will the sunlight cause degradation of the hops? My experience is yes.
- Why aren't people doing this now? Or how could this fail?
I see 3 potential problems:
1. Labor to load and unload. It will take quite a while to spread the hops out on those beds and to gather them up. More importantly, how do you empty those beds without dropping hops everywhere? Maybe tarp on the floor with a roofrake to pull them forward? Maybe tip the trays forward? When they are dry, those hops float everywhere but are still circular enough to roll when they hit the ground. Not insurmountable problems but could be dealbreakers as their harvest grows.
2. Airflow through the hops. There are fan's pointed at the top of the beds and lets also assume at the bottom. So that means air contact with those hops but what about the stuff in the middle? Those side walls look like 1x4" or 1x6" boards. Either way, there will be a lot of hops in the middle that won't see airflow. Either they have to force air through the hop beds or they are going to have to turn them. This set up won't force air through and turning is dangerous as you may loose lupulin.
3. Space. I covered this previously in this thread but let's assume those bed are 4' x 8' x 6" deep. That is 16 cubic feet. That is enough to hold roughly 21 lbs (properly dried) of hops. Assuming 1,000 lb/acre (a bit low), that would cover 2.1% of the drying capacity for 1 acre of hops. I don't know how big they are or intend to go but that makes this infeasible.
So the big guys in the PNW aren't doing this because it would take up too much space. That's why they go with 3 to 4 foot deep beds. I'm not saying that is the best for small scale growers but it is something to consider.
- How long will it take to go through the entire drying process and is that feasible?
Assuming this is ambient drying without heat (beyond the warming of the greenhouse) or other moisture removal, this will be very weather dependent. The bare minimum is 2 days but I've seen conditions where it took 7 days. If they don't need the drying space, this works just fine. If there is another crop coming in the next day, they are screwed.
- What will it cost in labor to load, unload and operate?
Previously discussed.
- What will it cost to operate in energy/electricity/fuel?
Negligible assuming they aren't trying to heat the air with fuel.
- What will it cost to build?
Negligible assuming the greenhouse is a sunk cost.
- Will it hold an entire day's harvest? Can I fit it within my allotted space?
Previously discussed but to expand, if they are hand harvesting the rate is typically 1 hour/bine. If we assume 1 lb/bine, 6 to 7 people working a 10 hour day would pick around 60 to 70 lbs (properly dried). 3 of those trays would hold around 63 pounds. So its would be sufficient for what they have.
Is this a feasible design?
For the first two years, sure. You can do it this way though I would like to see the beds shallower and get them out of the light. If they are growing an acre or more, will this work for years 3 and beyond? If they hit proper growing marks of 1,000 to 1,500 lbs or more, they may have a capacity problem. It depends on the number of varieties, how they are picking and how much time between harvest on those varieties.
