Tag Archive for: Farm Energy

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Automation Lends a Helping Hand in High Tunnels and Greenhouses 

By Chris Lent, NCAT Agriculture Specialist 

It’s a chilly morning in late March and the seedling house heater kicked on several times overnight to keep the plants happy. The skies are cloudy as you get the kids to the bus and run to the hardware store. On the way back to the farm after your errands, you notice that the clouds are gone, the strength of the late morning sun taking you by surprise after what had been a cool late winter. Oh no… the seedling house! You rush home to make sure your plants aren’t getting cooked.  

If you can relate to this scenario, it may be time to consider the benefits of automating the control points in your high tunnels and seedling houses. Those benefits include more consistent watering, less severe temperature swings, better production results, labor and energy savings, and better work-life balance.  

The tools and systems available for automation are many and varied. The size of your farm, business goals, and lifestyle goals can all help inform decisions on the type and level of automation to move toward on your farm. A good first step is to identify components in your high tunnels and greenhouses that can be automated. For example:

  • Heating (hot air units, boilers, hot water heaters)
  • Cooling (ventilation fans, pad and fan cooling units, A/C) 
  • Humidity control (fans, roll-up sides, ridge vents, fog) 
  • Air circulation (horizontal airflow fans) 
  • Irrigation (pumps and valves) 
  • Lighting 
  • Thermal control (shade, screens, thermal blankets) 

For many years, the default automation used in high tunnels and greenhouses on small to midsize farms relied on dedicated controls. Dedicated controls operate only one piece of equipment at a time. Examples of dedicated controls include in-line irrigation timers and individual thermostats for heating units or fans. These controls require monitoring and manual resetting as weather conditions change. 

Integrated control systems are a newer alternative to dedicated controls. These systems use feedback from sensors and electronic processing to control the frequence and sequence of equipment operation to keep a tunnel or greenhouse very close to temperature and humidity set points. Once installed and programmed, they work autonomously. Integrated controls can operate motors for roll-up sides, ventilation fans, and heating units cooperatively with little manual input.  

An integrated control system for heating and ventilating a seedling house on a farm in PA. Photo: Chris Lent, NCAT

Integrated automation systems can save costs in labor, decrease the risk of losing a crop, and save energy. There are many brands and styles of integrated control systems, so it can be time-consuming to search for the best option. If you have an established relationship with a trusted greenhouse supplier, they can help guide decisions on DIY automation projects.  

Previously, it was primarily large-scale producers who used these kinds of systems, but there are now companies that offer design and installation guidance for smaller scale integrated automation systems. Some brands have screens on the equipment to enable the user to enter set points, while other brands rely entirely on Wi-Fi and a device app for user interface. These systems can range in price between $2,000 and $4,000 per tunnel or greenhouse depending on the complexity and the brand of the system. Some companies also lease system components to the farmer and will automatically replace parts of the system if they fail. This lowers upfront costs and decreases hassle for the farmer.   

Fully integrated systems are something to aspire to, but most growers automate irrigation control and temperature and humidity control separately. For irrigation, a good example of a dedicated control is the simple, low-cost ($10 to $20) controls for irrigation in the form of in-line timers. You can purchase these from greenhouse supply companies, but garden centers and hardware stores also usually carry some version of these devices. They allow you to set an irrigation line to water for a certain amount of time, then automatically shut off.  

A dedicated in-line irrigation timer requires manual setting for each watering event in a tunnel. Photo: Chris Lent, NCAT

Battery powered digital programmable irrigation timers are available as well and can be sized to the irrigation line. These can cost from $100 to $150 for control over a single irrigation zone but give the grower much more control, and once programmed, they can give you freedom from the task of turning water on and off manually. Multi-zone digital controllers allow growers to control multiple valves in a more customized irrigation system.   

Some tips to keep in mind for automation: 

  • Assess the need first: Count the number of heating, cooling, and ventilation units you will need to control and estimate the cost to manually control these. 
  • Get advice and pricing from greenhouse suppliers and companies that focus on greenhouse automation. 
  • Get quality sensors with solar guards and place them near the crop. 
  • Install an ambient air and soil monitoring system to monitor all growing conditions and send notices to your phone. 
  • Consider installing camera monitors so you can visually check conditions in a tunnel or greenhouse on your phone. 
  • Make sure your infrastructure is compatible with the automation system you want. Does it require electricity and reliable internet to work? 

Automating the environmental controls in high tunnels and greenhouses can improve productivity and give some freedom from everyday tasks, but it doesn’t mean growers can become Ron Popeil and “set it and forget it.”  Frequent visits to monitor high tunnel conditions and the health of a crop are still necessary. However, being able to rely on automatic control systems to manage conditions in a tunnel or greenhouse and being able to check those conditions and receive alerts from anywhere gives peace of mind when you decide to step off the farm.   

Ultimately, choosing the right level of automation is about finding a balance that supports both your crops and your daily life. Whether you start with a few dedicated controls or invest in a fully integrated system, each step toward automation can reduce stress, protect your plants, and make your operation more resilient. Automation systems can’t fully replace a grower’s attention and experience, but they can serve as a reliable partner in maintaining optimal conditions, preventing costly mistakes, and creating more time for the many other demands of running a farm. 

Related ATTRA Resources: 

Season Extension Techniques for Market Gardeners 

Sustainable Season Extension: Considerations for Design 

Purchasing and Siting a High Tunnel to Extend the Growing Season 

Organic Greenhouse Vegetable Production 

Additional Resources: 

Greenhouse and High tunnel suppliers: 

High Tunnels Supplier Directory – HighTunnels.org 

Integrated automation companies: 

Link4 Controllers | Link4 Controls 

Orisha | Get Your Tomato Yields Up! 

Agrowtek Inc. :: Grow Controls for Greenhouses, Hydroponics & Indoor Growing

This blog is produced by the National Center for Appropriate Technology through the ATTRA Sustainable Agriculture program, under a cooperative agreement with USDA Rural Development. ATTRA.NCAT.ORG.

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A Mid-Scale Anaerobic Biodigester Creates On-Farm Renewable Energy

By Chris Lent, NCAT Agriculture Specialist

Finding ways to turn “waste materials” into useful resources on the farm has always fascinated me. On my farm, I tried to reuse and recycle resources as much as possible to close the off-farm input loop. I think farms can become more resilient as they rely on fewer off farm inputs. So, when I heard of the mid-scale anaerobic digester being installed at Dickenson College Organic Farm as a demonstration of how small dairy farms can utilize manure and other waste streams to produce on farm energy, I was eager for the opportunity to visit the farm and help spread the word to other farms.

In November 2023, NCAT Agriculture Specialist Eric Fuchs-Stengel and I had that opportunity. We traveled to Dickenson College Organic Farm in Carlisle, PA to visit Matt Steiman, Farm Energy and Livestock Manager at the farm. The farm is a beautiful certified organic working farm situated on 90 acres in the south-central part of the state where they grow vegetables and raise beef, lamb, and layers. Eric and I were there to shoot a video tour of the newly installed, mid-scale anaerobic biodigester that transforms manure from a neighboring dairy, as well as food waste from the college dining hall and local restaurants, into natural gas that can be used to generate heat and electricity.

This biodigester project comes after years of biofuel research and experimentation by Steiman at the college. The idea of using waste products from the farm and local area to produce fuel and power greatly intrigued Steiman, so he started making biodiesel that converted waste cooking oil into fuel to run equipment on the farm. Since the glycerin byproduct from biodiesel production can be useful in anaerobic digestion of organic matter that produces natural gas, he started experimenting in 2010 with small anaerobic digester systems to utilize glycerin, leading to a series of larger systems and culminating with the latest farm-scale biodigester.

The process of anaerobic digestion for production of natural gas is straightforward. A sealed tank creates an anaerobic, or oxygen-free, environment where a slurry of organic matter can be “eaten” or digested by microbes that thrive at certain temperatures in low-oxygen conditions. The methane gas given off from the microbes in this process rises to the top of the tank to an outlet tube where it can be collected and used as a fuel source for heat or electric production. The leftover digestate, which contains all the nutrients from the original waste material, is collected and spread on farm fields.

The size and cost of this new biodigester project required very specific design considerations to ensure that it was sized properly to match the expected waste flow and operate as intended. The digester tank is a 10-foot tall, 115,000-gallon, 50-foot-diameter cement tank buried 8 feet in the ground and sealed with a heavy-duty rubber covering. In the tank are heater pipes and an agitator to mix the slurry. A free-style barn was built next to the tank to house the dairy cows and heifers. At one end of the barn are three in-ground cement tanks that make up the waste-collection system for the digester. One tank is for daily manure collection, the second is for food waste collection (up to 3 tons per day), and the third is for collecting the digestate material remaining after the digestion process. The digestate goes through a liquid removal process and can then be used for bedding in the barn. The liquid portion of the digestate is staged to be used as a nutrient source for the farm’s crop fields and compost piles.

This digester is sized to produce enough gas to match a 50-kilowatt (kW) combined heat and power (CHP) engine. An engine from the European company TEDOM adapted to biogas was chosen for the job. The power produced will first be used to supply the power needs of the farm and the biodigester itself with excess electric production being sold back to the local utility company. This unique 150-cow-scale digester is small compared to other on farm digesters in the United States.

Matt Steiman explaining how an industrial grinder works to break down up to 3 tons of food waste a day so it can be pumped to the digester tank

Matt Steiman explaining how an industrial grinder works to break down up to 3 tons of food waste a day so it can be pumped to the digester tank. Photo: NCAT

Funding for this project was secured from multiple sources, including NRCS’s Environmental Quality Incentives Program (EQIP). For farmers looking for biodigester funding, Steinman had several suggestions. First, he said, talk to your Natural Resources Conservation Service (NRCS) county office. In addition, the Rural Energy for America Program (REAP) is a grant program administered through USDA’s Rural Development office. Through REAP, farmers and rural businesses who meet grant criteria can apply for grant funding up to 50% of the cost of an on-farm alternative energy project, including anaerobic biodigesters. Steiman also suggested talking to your state Department of Agriculture and Department of Environmental Management or Protection as funding sources. It is also worth investigating local conservation districts and utility companies that may offer funding for on-farm alternative energy projects.

With this new biodigester, Steiman and Dickenson College are using farm and food-waste streams to generate renewable energy right on the farm and reduce greenhouse gas emissions. With nearly 5,000 dairy farms in Pennsylvania alone with an average herd size of 100 cows, this project is intended to showcase how biogas production can work for mid-sized farms across the state and the country. The college is partnering with Penn State University and agriculture producer groups like PASA Sustainable Agriculture to use this project as an on-the-ground demonstration of properly sized biodigester design and implementation and to educate farmers on the benefits of biogas production at this scale.

Related ATTRA Resources:

Episode 350. Mid-Scale Biodigester with Matt Steiman of Dickinson College

Biodiesel Use, Handling, and Fuel Quality 

Micro-Scale Biogas Production: A Beginners Guide 

Anaerobic Digestion of Animal Wastes: Factors to Consider

Other Resources:

Biogas – Dickinson College Organic Farm 

Organic Farm Dickinson College – YouTube 

Rural Energy for America Program Renewable Energy Systems & Energy Efficiency Improvement Guaranteed Loans & Grants 

On-Farm Energy Initiative, NRCS 

This blog is produced by the National Center for Appropriate Technology through the ATTRA Sustainable Agriculture program, under a cooperative agreement with USDA Rural Development. ATTRA.NCAT.ORG.