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Low carbon heat pump grain drying in Ontario conditions

Principal Investigator: William Lubitz and Gregory Dineen

Research Institution: University of Guelph and Dineen Farms

Timeline: April 2022 – March 2025  


  • Build and commission a next generation stand-alone modular dryer incorporating custom- built air source heat pumps and high efficiency airflow routing.
  • Test prototype dryer on-farm drying corn, soy, cereals, and edible beans. Dry crops from    S&M Dineen Farm’s 430 acres regardless of harvest timing, varying moisture levels load to load, fines, red dog/bee’s wings, or any other practical challenges not necessarily present in    a lab testing environment.
  • Characterize maximum drying rate, energy used and total costs for varying ambient conditions and initial crop moistures. Attempt to dry as many batches and crop types as possible.
  • Demonstrate the drying efficiency in “BTU/lbs moisture removed” (and similar units) achievable in full-scale prototype system at S&M Dineen Farms by experimentally measuring the systems operation and compare it to existing systems.
  • Examine historical energy costs and examine select future energy cost scenarios to generate a broader picture of whether this technology might be viable broadly in Ontario. Consider variable availability of energy to Ontario farmers (natural gas access or not, limits on electrical service).
  • Based on dryer performance, energy cost trends and availabilities, consider the maximum initial cost this design must meet to justify being adopted by Ontario farmers.
  • Develop guidelines for low energy and natural aeration batch drying in Ontario, based on the datasets collected for the prototype dryer.
  • After operating and assessing the dryer, outline the improvements and performance upgrades to be expected in the next iteration of the design. Assess the development stage of the dryer – is additional prototyping at this size required? Prototype at a larger size?


  • Ontario farmers will get highly accurate drying rate and cost numbers on a dryer which presents a credible, cost-effective alternative to conventional drying. This represents a potential long-term solution to drying costs which can complement shorter-term solutions such as efficiency upgrades to current dryers and field drying improvements.
  • This technology can diversify Ontario’s drying infrastructure beyond propane and natural gas, both produced out of province, and both transported long distances. Propane was disrupted recently by rail problems. Natural gas prices are highly variable: the US spot price has doubled in the past six months and increasing liquid natural gas (LNG) export capacity means North American prices that were low compared to global norms will likely not continue in the future.  In contrast, much of rural Ontario is near-viable for net-metered solar power without government support – meaning some farms now (and more in the future) will find it economical to power grain dryers electrically with energy produced on-farm.
  • Ontario grain farmers will benefit from practical information about the feasibility of low temperature drying in general. This data will support low temperature applications regardless of whether they are heat pump, bio-mass or low-temperature propane burner.
  • This research will provide information needed to build capacity for Ontario manufacturers to provide alternative fuel drying equipment. Dryer manufacturers need support to move ahead with these designs.
  • Switching grain drying systems to alternate energy would reduce GHG emissions by 80-95%. Transitioning 5% of Ontario grain drying to alternate energy would save 18,000-21,000  tonnes of CO2 equivalent annually.
  • Models and research results will also benefit food processing, HVAC, and related industries.

Scientific Summary:

Almost all corn and significant amounts of wheat, soybeans and other crops require post-harvest drying in Ontario. Fuel price volatility, environmental impacts and carbon pricing mean there is an immediate need to develop non-fossil fuel methods for drying Ontario grain. A prototype dryer was constructed in Ontario in 2017 which used heat collected with an air-source heat pump (also called a “reverse air conditioner”) which required electricity only. This small dryer achieved ‘per metric ton’ drying costs of as little as $6 for corn dried from 30% moisture while cutting emissions by 96%. However, the drying rate was slow, and the design could not be scaled up to keep pace with a modern combine.

This research effort will build and assess a dryer based on the same process and technology but with a modular architecture which can scale up to support larger farms. The project team has been working together since 2015 and will use measuring techniques, sensors and practices learned through multiple years of developing and testing the previous design.

There is little directly relevant research literature on the low temperature process used by this dryer, particularly research under Ontario conditions which includes both low temperatures and high humidity. It is anticipated that this project will yield data on this specific design and also broadly on   low temperature drying in Ontario conditions. These data should help refine new guidelines for aerating and slow drying of bins which are otherwise not used for drying.

External Funding Partners: