Supplemental Heating of High Tunnels by Energy-Producing Compost Piles

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2015: $15,000.00
Projected End Date: 11/09/2018
Grant Recipient: Sunspot Urban Farm
Region: Western
State: Colorado
Principal Investigator:
Dr. Amy Yackel Adams
Sunspot Urban Farm

Annual Reports


  • Vegetables: greens (leafy), greens (lettuces)


  • Crop Production: high tunnels or hoop houses, season extension types and construction
  • Soil Management: composting


    At Sunspot Urban Farm, we built two large compost heaters (2015 and 2016) for conveying heat to a nearby high tunnel via a hydronic system. The compost heater built in 2015 failed to maintain heat but the compost heater built in 2016 maintained adequate temperatures from October 2016 to February 2017. The hydronic system connected to the 2016 compost heater failed to deliver enough heat to raise soil temperatures in the high tunnel. In 2017, to further understand heat transfer to soil, we enlisted the help of an engineer consultant to help us develop and evaluate a small-scale compost heater system to heat the soil in a small greenhouse; this smaller system conveyed heat to the soil but again not sufficiently to consistently raise soil temperatures. In 2018, we professionally analyzed the compost generated from the compost heaters built in 2015 and 2016. Compost analysis results indicated the creation of a high quality finished compost. For educational and outreach purposes we have discussed this project on farm tours associated with Colorado State University, Front Range Community College, and other organizations and posted all annual reports (2015-2018) associated with this project at our farm's website Feedback from tour participants emphasized their support for sustainable farm practices. 

    Project objectives:

    1. Build a compost heater and hydronic system for delivery of compost-heated water to a high tunnel to increase soil temperatures. 2. Monitor and evaluate the heat delivery of the compost heater to warm the soil in a high tunnel during winter and spring months. 3. Evaluate the quality of the compost for growing crops. 4. Disseminate information about the project.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.