UVM Extension AgEngineering Blog
Posted: January 27th, 2014 by Chris Callahan
Posted: January 7th, 2014 by Chris Callahan
I recently presented a summary of mechanical hop harvesters at the 2013 NEHA Hops Conference in Morrisville, NY. As I prepared that material I was struck by how far we’ve come since 2010. In just three years since our small team embarked upon the development of the UVM Mobile Hops Harvester, several independently designed mechanical harvesters have become available and several builds of the UVM type harvester have also been developed by others. These are summarized in the presentation file linked above including videos of some of them.
Does Mechanical Harvesting Pay?
I also thought it may be helpful to show the impact of mechanical harvesting on a small hop farm. The reality is that hand picking hops is only realistic early in the development of a hop farm and only at very small scales of production. It depends on the interest of the pickers and the community atmosphere that many growers develop around their young enterprises. However, it is unlikely that the hand picking can support larger volume production at current labor rates and the rate of harvest will also be slower than necessary for preserving maximum hop quality.
So how expensive is a mechanical harvester? And can it actually pay for itself? Let’s do the numbers.
Assume a machine cost of $20,000, assembled, installed and ready to go (actual costs for the available machines are included in the presentation file above). Let’s say that machine is capable of harvesting 60 bines per hour (a light load for most) and that each bine is yielding 1 dry pound of hops. Let’s also assume 1000 bines per acre, and a one acre yard. We’ll look at high volume scenarios later. The benefit of mechanical harvesting is labor savings, so we need to assume the base case is paid hand picking at a wage of $7.25 per hour and a rate of 1 dry pound per hour (about one bine). Let’s also note that the machine might require 4 people vs. the one person we’re comparing it to, so it has a higher “per hour” labor rate. We’ll also assume that the machine has a life of 20 years, over which it’s initial cost is spread (as though it is being depreciated like other assets).
We have to make one simplification to the calculation before proceeding. We need to assume a common gross profit prior to harvest. In other words, the cost of the yard structure, the rhizomes, water, nutrients, any pest and disease management, etc. is all the same between the two cases and allows for a gross profit of, say, $10 per dry pound. With all that laid out, we can summarize the case as shown in the following table.
|Density||1000||bines per acre|
|Plant yield||1||dry pound per bine|
|Gross profit prior to harvest||$10.00||per dry pound|
|Machine rate||60||bines per hour|
|Labor cost||$7.25||per hour|
|Hand picking rate||1||bines per hour|
|Machine harvest cost||$1.48||per dry pound|
|Hand picking cost||$7.25||per dry pound|
|Mechanical advantage||$5.77||per dry pound|
|Simple payback period|
Admittedly, we can argue over the assumptions presented here. A machine could cost more to build or buy than I have assumed. Someone may be able to hand pick much quicker than I have presented. The machine rate could (and probably will be) higher than assumed above. The gross profit of $10 per dry pound assumed may be more or less. But I think it is safe to say that mechanical harvesting can pay for itself and, perhaps as important, allows a certain scale and quality of production that isn’t supported by hand picking.
Posted: October 24th, 2013 by Chris Callahan
The UVM Mobile Hops Harvester visited six hop yards this year, harvesting approximately 400 dry pounds of hops, over a 4 week period plus harvesting the UVM Extension NW Crops and Soils Team’s research hop yard. This harvester, developed as a result of a Northeast Hops Alliance, UVM Extension, VT Agency of Ag Food and Markets, and MA Department of Agriculture sponsored project, aims to provide proof of concept of a mobile hops harvester in support of the re-emerging hop industry in the Northeast US.
The reintroduction of hops to the northeast requires scale-appropriate harvest and processing equipment. At the start of this project there was no feasible mechanized harvest options for a 1-2 acre hop producer. Handpicking is the most wide-spread current practice which is labor intense and time consuming leading to expense and quality impact due to delayed harvest.
As a result of this project, cooperative use of a single, mobile harvester has been demonstrated and logistics for this operation are being continually improved. The harvester has a demonstrated capacity of 60-120 bines per hour compared to 1 bine per hour per person for manual picking. This rate enables the harvest of a 1 acre yard within 8 hours resulting in optimal harvest timing and improved quality. Assuming a harvest team of 4 people in either case, this translates to a harvest labor cost savings of 97% or $3,120 per acre at $15 per hour wage (approximately $2 per lb of dried hops (10-20% of retail price)).
“The hop harvester significantly sped up harvesting. With the size of the bines this year, some may not have been harvested at all without it’s use. Knowing the UVM harvester is available helps me plan for hopyard expansion over time. Without a large harvester, such a UVM’s, expansion would not be practical.”, notes Kris Anderson of Addison Hop Farm in Addison, VT.
Trevor Lewis of Mad Mountain Hop Farm in Berlin, VT concurs, “Absolutely amazing! My harvest time went from 5 days to 5 hours! Though I am unsure of expansion at this time, this machine makes it possible to expand beyond a half acre which really isn’t an option without a harvester.”
This mobile, trailer-based mechanized hop-harvester was developed and documented as an open-source design for others to replicate and adapt to their needs. The design was the result of a collaborative design effort involving growers, brewers, agronomists, fabricators and engineers. Additionally, 255 people have downloaded the plans for the machine and 5 others have built harvesters at least partially informed by this work. This harvester pulls a complete bine (central bine/vine, leaves and cones) through a section of stripping fingers that separate the cones and leaves from the bine. The cones and leaves are conveyed to a secondary sorting section with rolling dribble belts against which the leaves lie flat while the cones roll backward down the belts. In this way the machine takes a loaded bine and produces two output streams of cones and leaves.
We’ve been reasonably pleased with capacity and efficiency of the machine. There is still room for improvement, and we plan to install chutes and fences over the winter to better contain all matter within the machine, improve separation and, thus, net yield. We also had two bearings fail this harvest season and will likely upgrade them to heavier duty bearing housings.
The entire machine is placed on an 18 foot equipment trailer for ease of transport. This year, the machine traveled approximately 3,400 miles visiting some yards multiple times as different varieties matured. Each year, the harvester travels further afield for an outreach demonstration. This year we traveled to Westfield, Maine (Aroostook County) to Aroostook Hops to help with their harvest and to give them some experience with the harvester.
“Having the UVM mobile hops harvester had a HUGE impact on our success this year. We had a hops picking party the previous weekend (Labor Day) with many volunteers handpicking hops (we estimate about 60 people passed through that weekend) and we got about 40% of our crop harvested,” says Krista Johnston, ” We had two articles in the local press about us and lots of interest was generated, so we couldn’t have done better on “many hands”, but without the harvester here the following weekend we could not have gotten all the hops in this season by handpicking alone.”
Krista and her husband, Jason are thinking ahead to building a harvester of their own.
“We plan to fabricate a version of the mobile machine, so being able to use it ourselves and have our fabricators come out and operate it (for about 2 hours of time x two men) was absolutely invaluable to us. We had thought that “mobile” was less important to us and that we would build stationary with electric motors, but seeing how convenient it was to move around different locations made us reconsider that. Also, we recently expanded (last year) 3 acres so can’t even think about getting bigger any time too soon, but having the capacity to harvest at the rate that the harvester can accomplish will remove that as a limiting factor when we catch our breath and consider future operations. We do plan to contract our harvester to other growers, and had thought we’d have bines come to us, but mobile is looking attractive.”
Others have replicated and adapted the UVM design to their needs for the 2013 harvest season.
“We wouldn’t have been able to build our harvester without the knowledge and research from the UVM machine,” says Dean Heltemes of Lunatic Fringe Farms in Wisconsin. “I’m sure this picker will create a lot of buzz around our co-op. We might have the opportunity to do some harvesting for a farm a couple hours from here. The more hours we can get on this thing, the better off we will be for next year.” Video of Lunatic Fringe Farms’ harvester can be viewed on YouTube.
And so it goes, each year more hours are accrued on the harvester, more variations are built and we all continue to learn and improve together using this open source design. Plans for the machine can be downloaded from the UVM Hops Project Wiki at http://www.uvm.edu/extension/cropsoil/wikis. Chris Callahan can be reached by email or phone at 802-773-3349.
Posted: August 30th, 2013 by Chris Callahan
UVM Extension with support from the USDA’s Northeast Sustainable Agriculture Research and Education program will offer five one-day workshops on crop storage throughout Vermont this fall. Workshops will focus on long-term storage of crops for sale through the winter and into early spring, but will be relevant to many agricultural and food storage needs.
- the growing importance of long-term crop storage
- principles of energy and heat transfer
- basic heating and refrigeration
- construction for utility and efficiency
- maintaining temperature, airflow and humidity
- biological processes of crops in storage
- storage characteristics of various crops, and
- sizing and design of storage systems.
- Brattleboro – 9/17
- Rutland – 9/19
- White River Junction – 10/9
- St. Johnsbury – 10/10
- Shelburne – 10/16
Posted: May 21st, 2013 by Chris Callahan
I recently co-authored a summary of the economics of on-farm biodiesel with Netaka White from the Vermont Sustainable Jobs Fund. This report collects the economic and logistic learning from the past seven years of the Vermont Bioenergy Initiative (VBI). The VBI has supported a wide range of sustainable fuel related efforts in Vermont. Along with agronomic research by Heather Darby’s Northwest Crops and Soils team funding has supported efforts to streamline on-farm processing and production systems, improve safety, expand storage capacity and ultimately to expand adoption of sustainable fueling practices.
We showcase five Vermont on-farm biodiesel operations that use a variety of equipment to reach their different biodiesel and feed production goals. We use data from these farms, collected over several years, to run a detailed economic analysis of a hypothetical 100,000-gallon per year on-farm biodiesel facility. A second hypothetical case based on a 13,000-gallon per year facility is also reviewed. Finally, we explain in ten steps how to estimate breakeven and profitability in both cases. The information and steps are applicable to any farmer interested in fuel and feed self-sufficiency or generating additional farm income. The analysis was done using the Oilseed Cost and Profit Calculator I developed under this program.
In the two examples above, one a 100,000 gallon per year commercial enterprise, and the other a 13,000 gallon per year operation, both used representative sunflower production data from five Vermont farms. Over a range of crop production costs between $100 and $200 per acre, and yields between 1,000 and 2,000 pounds per acre, at current market prices the combined worth of the meal and the oil, or the meal plus the biodiesel are shown to be profitable.
Both scales of operation can also see a payback on their investment within a reasonably short time frame when selling meal and biodiesel or selling meal and using biodiesel to reduce enterprise expenses; 100,000 gallon per year payback is 6.4 years & 13,000 gallon per year payback is 9.4 years. This is based on current, relatively low fuel costs. Should diesel prices reach $5 a gallon, simple payback could occur in less than 12 months for the 100,000 gallon per year case and less than 3 years for the 13,000 gallon per year case.
Posted: May 10th, 2013 by Chris Callahan
1944 US Office of Education video on refrigeration principles. Excellent.
Posted: April 12th, 2013 by Chris Callahan
Had a great time talking about all the ways we can get sick from produce related pathogens yesterday. The good news is that the bulk of the workshop was focused on ways to mitigate the risks.
The Practical Produce Safety workshop series coordinated by Ginger Nickerson (UVM Center for Sustainable Agriculture) and Hans Estrin (UVM Extension Community Food Network) is an informative and pragmatic way to get up to speed on produce safety measures in field practices, harvest, rinsing, packing and storage. This session was co-sponsored by Annie Harlow with ACORN.
I was glad to contribute a little bit on the latter topic; storage. Slides from my presentation are available here.
Thanks also to Rachel Shattman of Bella Farm for hosting a charrette walkthrough of her wash/pack and storage facilities. That provided a very real component to the course (and the Apple Crisp was excellent as well!)
Posted: March 20th, 2013 by Chris Callahan
Demand for on-farm cold storage of produce and other Vermont agricultural products is increasing as local markets for these goods expand. I receive many inquiries regarding CoolBotsTM, an adaptation of a window air-conditioner to make a cooler out of an insulated space. This article is intended to collect related resources in one place and to also highlight some considerations adopters of CoolBots should be aware of.
In a nutshell:
- Understand your storage needs;
- Build a good cooler box
- Understand the limitations of the CoolBot
- Use an AC unit with a proven track record in these applications, and check the sizing
- Plan for maintenance (cleaning the coil, off-season storage, protection from elements, etc.)
These systems utilize a commercially available controller ($299) to allow the AC unit to run with a lower temperature than normal. Store-It-Cold, The manufacturer’s website has excellent resources and FAQ’s. They include a list of AC units that they have had positive experiences using. They are also very clear about who should consider NOT using a CoolBot. Applications for which the CoolBot is not well suited, according to the manufacture, include;
- rapid “pull down” of temperature (e.g. high levels of field heat or frequent exchanges of product)
- freezers – CoolBots perform best above 36 °F.
- sites with many door openings per day (e.g. > 6 times per hour)
- running through the winter – not a show stopper, but you need to be more careful about which AC unit you choose
Other things to be very aware of, according to the CoolBot controller manufacturer, include
- A well-constructed cooler box – Start with a well-insulated (>R24), well sealed (caulk and spray-foam everything, no gaps) cooler box. The University of Kentucky has an excellent set of documentation, plans, bill of materials and costs, and animation for a low cost cooler design. North Carolina State University also has a fact sheet with guidance on cooler sizing and construction.
- A well-suited AC unit – avoid portable AC units, see the Store-It-Cold website’s list of selected units. The AC unit will need to have a digital display.
- Cooling a space above 61 °F.
A report commissioned by NYSERDA summarizes the cost, energy efficiency, and greenhouse gas emission benefits of a CoolBot installation when compared to a conventional walk-in cooler system at certain conditions. The cost estimate of the CoolBot system (15,000 BTU/hr) is $750 installed compared to $4,400 for a conventional system (8’x10′ cooler box cost not included).
The authors conclude that a CoolBot system can result in approximately 230 kWhr/year of energy savings ($30/year at $0.13/kWhr VT average) when cooling 100 ft2 of cooler floor area to 35 °F (assumes Albany, NY conditions). It is important to note that this analysis highlights the main energy efficiency benefit of the CoolBot system comes from the reduced operating time of evaporator fans. High efficiency fans and improved controls exist for conventional walk-in systems and they are even supported by rebates from Efficiency Vermont. When the CoolBot system was compared with a conventional cooler that also had evaporator fan controls, the savings went the other way; i.e. the conventional walk-in system resulted in 74 kWhr/year savings.
Posted: March 5th, 2013 by Chris Callahan
Although estimates vary, we invest about 14 calories of fossil fuel-based energy and 15-20 calories of energy in general into every 1 calorie of food produced. And (here’s the kicker) 30-50% of the food produced never makes it to a digestive track. So those energy input numbers are actually low by any true measure of efficiency and productivity.
A recent report from the USDA ERS sums it up this way, “use of energy along the food chain for food purchases by or for U.S. households increased between 1997 and 2002 at more than six times the rate of increase in total domestic energy use. … The use of more energy-intensive technologies throughout the U.S. food system accounted for half of this increase, with the remainder attributed to population growth and higher real (inflation-adjusted) per capita food expenditures.”
Here is a similar idea, displayed in a slightly different way by the University of Michigan Center for Sustainable Systems (this uses units of millions of pounds, not energy).
And it isn’t all about energy efficiency and renewable energy and boring engineering BTU, calorie and bean counting (although I do like counting beans). The food wasted post-harvest is a real loss that we can do something about. (NOTE: The report linked above where I take the 30-50% waste figure from was done by a UK engineering trade organization, IMECHE).
Some of the loss occurs in storage, and I think we all can agree that we can do better with our storage practices. Regardless of whether you are root cellaring, using a CoolBot(TM) or a commercial walk-in cooler, the principles remain the same. Some loss occurs in transport and distribution which speaks to the benefit of the broader food system considerations espoused by UVM’s Food Systems Spire and the Vermont Farm to Plate Initiative. Some, of course, occurs in the kitchen or in consumer storage and suggests we have some work to do with consumers as well.
As one grower recently said to me, “By the time we put food in our farm cooler, 99% of our cost is sunk into that product. We gotta pay attention to what goes on in there and make sure we get paid for it.“
Posted: March 2nd, 2013 by Chris Callahan
As I’ve mentioned in several other posts, I think the continual monitoring of conditions in greenhouses and food storage spaces is incredibly important for quality and safety and insightful for any operation. There is a really clever design for a do-it-yourself temperature monitoring system called Fido, on the FarmHack site. It uses an Arduino control and electronics platform, a cheap cell phone, and a few other pretty inexpensive pieces to do the job.
“A farmer-built electronic tool that can monitor greenhouse temperature, record greenhouse data, and alert the farmer to problems in the greenhouse via cell phone text message. This tool will be much more affordable and useful than commercially available greenhouse alarms (which rely on landline connections or internet connections, which usually aren’t available in the greenhouse).“
I’ll be trying to add RH monitoring to this soon, and will update the post when that is complete.