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       Chris Callahan
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       Bennington, VT 05201
       802-447-7582 x256
       chris.callahan@uvm.edu

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       andrew.chamberlin@uvm.edu

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UVM Extension AgEngineering Blog

Grass and “Ag Biomass” Competitive with Wood Chips

Posted: May 1st, 2016 by Chris Callahan

Chris Davis (Meach Cove Trust) prepares the boiler and combustion testing equipment for a trial run of the new fuel.

Chris Davis (Meach Cove Trust) prepares the boiler and combustion testing equipment for a trial run of the new fuel.

Recent testing at the Meach Cove Trust has demonstrated strong economic and technical feasibility of grass-based biomass combustion fuels.  The use of solid, densified, cellulosic biomass fuels has been well demonstrated with wood pellets in residential and light commercial systems and wood chips in larger, often centralized systems.  The Grass Energy Partnership of the Vermont Bioenergy Initiative has been exploring an alternative form of fuel; grasses densified in a specially developed processor to take the form of 1.5”-2.0” round cylindrical pucks.  Grass fuels may be produced on otherwise marginal agricultural land, sometimes in perennial production and even in buffer strips offering environmental benefit.  Additionally, fuel can be made by densifying agricultural residue or biomass harvested from idle pasture or fields.  We have referred to this fuel as “Ag Biomass”. The testing summarized in this report has demonstrated the technical and economic feasibility of such fuels.

Read the rest of this entry »

Finish Surfaces for Produce and Food Areas

Posted: April 29th, 2016 by Chris Callahan

This cooler space was finished with Trusscore PVC panels resulting in a smooth, cleanable surface.

Smooth and cleanable surfaces are an important aspect of areas where produce is washed, packed, stored and processed.  Many farms are investing in renovations and expansions of these areas and are seeking materials to meet this “finish surface” need regardless of specific regulation.  Meanwhile, food processing companies are often required to incorporate these materials due to regulation.  This is a summary of some of the finish surface materials that are available, their pros, cons and pricing at this time.

Download an updated PDF version of this information here.

Notes:

A properly outfitted cooler results in a clean install both visually, and physically. Note the use of trim pieces to close gaps at corners.

  • These are not necessarily compliant for food contact surfaces; they are meant to be finish materials for areas where food is being washed, packed or stored.  The general guidance is “smooth and cleanable.” Check with the appropriate local and/or state enforcement agency to confirm applicability to your project.
  • The prices listed are material cost only. The products differ in with regard to installation labor.  For example, flexible sheathing like FRP will require some sort of rigid wall material to mount to where as rigid panels such as Trusscore, Extrutech and Utilite can be installed on top of furring strips.  No installation costs have been captured in the prices listed.
  • Links to manufacturer info are included.  Most manufacturers sell via distribution channels.  Check with your local building supply company for availability and current pricing. As with most materials, higher volume purchasing generally results in lower unit costs.
  • The pricing on these materials is quite variable depending on the source, when you obtain a quote, the quantity being ordered and how it is delivered. The listed price is the best information available at the time of writing.  Shop around and obtain quotes from several distributors.

    Several manufacturer’s use panel locking mechanisms such as the tongue and groove system found in Trusscore. This provides for a smooth finish and hides the fasteners.

    Common shapes of available trim options to cover and seal all edges and seams. This keeps water from seeping behind the finish surface and entering the walls which can lead to molds and mildews and structural damage.

  • Most manufacturer webpages include an easy to find, specific, installation guide for their product that will be helpful in guiding installation.
  • FRP panels use H or J channel trim between pieces and corners which are calked in place to ensure a moisture proof seam. Follow the manufactures installation procedures.

    Ribcore 3’ or 9’ rib pattern options for ceilings

 

New Crop Storage Planning Tool

Posted: January 21st, 2016 by Chris Callahan

DSCN1606I have been toying with an Excel-based crop storage planning tool for several years.  I finally have it at point where I want to make it available to others and start collecting feedback for improvement.  You can download the tool here, and instructions are available in the tool and at this page.  Enjoy and please be in touch with feedback.

 

Update on Heating Greenhouses with Biomass

Posted: September 14th, 2015 by Chris Callahan

Get the report.

Get the report.

This project demonstrated the use of biomass heating for greenhouse vegetable production at sites across Vermont. From 2008 through 2015, 25 growers received cost-share funds for greenhouse biomass heating systems. Read the rest of this entry »

Final Report – Increasing Supply and Quality of Local Storage Vegetables

Posted: September 14th, 2015 by Chris Callahan

We recently completed a project aimed at improving the ability of Vermont vegetable farms to store crops such as beets, carrots, parsnips, potatoes, onions, squash and sweet potatoes, all of which have unmet demand in late winter when local supplies run out.

Beets can be stored in bulk bins for months at the right conditions.

Beets can be stored in bulk bins for months at the right conditions.

The physiology of these crops allows them to be stored for many months after harvest if specific storage conditions are met. However, several distinct sets of conditions are optimal for different groups of crops, and achieving each condition requires careful control and monitoring of temperature and relative humidity in storage. Currently, Vermont’s commercial vegetable farms rarely achieve the optimal conditions due to lack of sufficiently separated storage compartments, and lack of modern environmental monitoring and control equipment.

Installing a remote monitoring system to keep track of temperature and humidity of a storage facility.

Installing a remote monitoring system to keep track of temperature and humidity of a storage facility.

This project installed environmental monitoring equipment to improve storage conditions and ultimately the quality of 1,736 tons of winter storage crops at 9 farms throughout Vermont .  The cumulative market value of these storage crops produced during the 2012-2014 growing seasons was $3.5 million.   Improved storage monitoring led to better control of storage conditions, in part through automated notification to farmers when abnormal conditions were occurring. This allowed for prompt correction of problems such as open doors and failing or inoperative cooling equipment. Losses of storage crops (cull rates) were reduced from ~15% to ~5% of stored volume. Sixty-six  energy efficiency measures were also implemented at 5 of these farms, saving a total of 40,269 kWh of electricity and $5,800 annually.  The systems deployed have increased the confidence of growers to expand their winter storage of Vermont-grown vegetables, leading to an increased supply of local produce outside of the traditional growing and marketing season.

You can download the complete report here.

Doser for Small Scale Vegetable Washing with Sanitizer

Posted: June 16th, 2015 by Chris Callahan

I recently put together a simple doser for manually measuring accurate doses of sanitizer into wash water solutions.  It is really just a homemade burette. The process of mixing a treatment dose of santizer requires metering a specific dose of concentrate into a larger volume of water.  I have also created a calculator to help with that. The UVM Extension Produce Safety Program maintains a great set of resources for general guidance on use of sanitizers including this guide sheet.  It is important to always have a copy of the official product “label” (not necessarily the same thing as the label on the container).  For easy reference, labels for typical sanitizers are linked below. Please check with your supplier to be sure you have the most recent version for the product you are using and the intended application.

There are a number of options available to avoid actually pouring these chemicals when dosing a mix tank.  You can download a summary of these options here.  When pouring them, splashing and spills can occur which are best avoided due to the corrosive and hazardous nature of the chemicals at stored concentrations. Even when using enclosed dispensing options, wear proper personal protective equipment including goggles and resistant gloves in case there are unexpected leaks or spills.

2015-06-14 005

Some of the dispensing options available include:

  • Dosatron – $940-$1000 – Allows for injection of sanitizing chemical directly into the flow stream of water being used in the process.  Measurement is done by adjusting flow ratio similar to a fertigation system.
  • Goat Throat – $299 – GoatThroat 300 Pump with Viton seals. Allows a manual, enclosed pumping with integral valve.   No closed measurement.
  • EnviroSelect Dispensing Pump (BioSafe Safety Value Pack) – $75 – Allows a manual pumping of liquid directly from container without pouring.  No integral valve, and no closed measurement.

When I reviewed these options, I felt there was still a need for something at the lower end of use volume.  Something that would work for 30 to 300 gallon washing batches.  So that is why I put together the assembly that is posted on FarmHack with a parts cost of less than $50 and assembly time of less than 1 hour.  I think it may be helpful. Let me know what you think, and feel free to join in the design discussion on FarmHack.

Farm Building Plans

Posted: June 15th, 2015 by Chris Callahan

I sometimes receive requests for help designing barns, sheds and other structures. It is a bit out of my scope of practice, but there are loads of designs available from the Midwest Plan Service (at Iowa State University) including their free building plans section.  There are also other plans available from the Canadian Plan Service and North Dakota State University.

 

Calculating Greenhouse and High Tunnel Heat Loss

Posted: April 1st, 2015 by Chris Callahan

I am often asked by growers to help estimate what size heater is needed for a greenhouse or what minimum temperature their high tunnel will reach at a certain outside temperature.  Below are some tools to help you do this yourself.  I have presented them in a range of complexity depending on how much you really want to get into the math.  Enjoy.

1. SIMPLEST – Online greenhouse heat load calculator. http://www.greenhousemegastore.com/greenhouse_btu_calculator This online calculator allows you to enter the dimensions, construction material and temperatures you are interested in and it estimates the heat (and cooling) load.

2. LITTLE MORE COMPLEX – VirtualGrower – http://ars.usda.gov/services/software/download.htm?softwareid=309. This is a free software tool from USDA ARS that is a bit more complicated than the simple form above. But there is benefit to the complication. As with any analysis, the more you put into it, the more you get out of it. VirtualGrower allows easier management of multiple “what-if” scenarios, includes regional weather and light data automatically, and accounts for heating and ventilation systems. You may find it interesting and useful.

3. HEAVY LIFTING, but FULFILLING – Do the calculations yourself! The formulae behind all of the tools above are well described in “Greenhouse Engineering, NRAES-33” by R. A. Aldrich and J. W. Bartok. Available here as a PDF: http://host31.spidergraphics.com/nra/doc/Fair%20Use%20Web%20PDFs/NRAES-33_Web.pdf. See p. 65-71 specifically.

4. HEATING BENCHES, ROOT-ZONE or GROUND – When heating the root zone locally, different heater sizing approaches are needed.  This is covered well by “Root Zone Heating Systems” in Wilkinson KM, Haase DL, Pinto JR, technical coordinators. National Proceedings: Forest and Conservation Nursery Associations—2013. Fort Collins (CO): USDA Forest Service, Rocky Mountain Research Station.Proceedings RMRS-P-72. 62-65. Available at: http://www.fs.fed.us/rm/pubs/rmrs_p072.htm.

LED Lights – Status, Cost/Benefit and Pro’s and Cons

Posted: February 25th, 2015 by Chris Callahan

I have been receiving several inquiries recently on supplemental lighting for greenhouse production. The most common question is “Should I install LED lights to support growing?”
I have found one report to be the most complete and current on this topic and wanted to share it here.

Economic Analysis of Greenhouse Lighting: Light Emitting Diodes vs. High Intensity Discharge Fixtures by Jacob A. Nelson and Bruce Bugbee. Published: June 6, 2014. DOI: 10.1371/journal.pone.0099010. http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099010. Erik Runkle at Michigan State University also summarizes some of this work in Greenhouse Product News here.

There are some industry responses to this including this one from Inda-Grow. And a recent USDA report is somewhat contradictory in its findings here.

There is a also a nice summary by Robert Morrow in Hort Science (HortScience December 2008 vol. 43 no. 7 1947-1950) available here.

Nelson and Bugbee conclude;

The most efficient HPS and LED fixtures have equal efficiencies, but the initial capital cost per photon delivered from LED fixtures is five to ten times higher than HPS fixtures. The high capital cost means that the five-year cost of LED fixtures is more than double that of HPS fixtures. If widely spaced benches are a necessary part of a production system, LED fixtures can provide precision delivery of photons and our data indicate that they can be a more cost effective option for supplemental greenhouse lighting.

Manufacturers are working to improve all types of lighting technologies and the cost per photon will likely continue to decrease as new technologies, reduced prices, and improved reliability become available.

My take-away from all of this; LED’s have a higher initial cost, can have lower recurring costs, can be more effective for specific physiological benefit, and can support certain production layouts.  But the cost/benefit does not seem to pencil out quite yet.

Hops Harvesting and Beyond

Posted: December 7th, 2014 by Chris Callahan

I presented an update on small-scale hops harvesters at the 2014 Northeast Hops Alliance (NEHA) Winter Meeting yesterday.  We also talked a bit about drying and pelletizing at small scale.  The presentation is available here.

A summary of harvesters is provided in the table below.

Hops Harvester Table

One of the really exciting things for me to see is the number of small-scale, mobile harvesters available to people is increasing.  Mendon Precision, LLC (HopsHarvester.com), Wolverine, and LaGasse Works all have produced harvesters that they intend to have available in serial production.These are in addition to the Bine Implement and Steenland harvesters noted previously

Mendon Precision, LLC - HopsHarvester.com harvester.

Mendon Precision, LLC – HopsHarvester.com harvester.

Wolverine Harvester

Wolverine Harvester

This past year also saw more grower builds using the UVM mobile platform design including Aroostook Hops in Westfield, ME.

A harvester based on the UVM Mobile design by Aroostook Hops.

A harvester based on the UVM Mobile design by Aroostook Hops.

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