Economic feasibility of using willow and poplar as bioenergy sources for heating small greenhouses in Canadian Northern communities

Community-based indoor farms, like greenhouses, offer a year-round solution to provide fresh and affordable food for Canadian Northern regions, addressing supply chain issues caused by long transportation distances, severe weather, and disruptions like pandemics. A growing trend is the shift from petro-fuel boilers to biomass heating systems to reduce reliance on propane, diesel, or electricity. To assess the economic feasibility of biomass heating systems for greenhouses, a case study was conducted in rural Northern Saskatchewan focused on using native and purpose-grown willow and poplar as feedstocks. The analysis evaluated biomass production and harvesting costs, greenhouse heat demand, capital and operating expenses of the biomass heating system, energy costs, and overall project profitability when replacing conventional fuel systems including natural gas, diesel, and electricity. The results showed a 60% decrease in the annual heat demand per hectare for Northern greenhouse, as the greenhouse floor area increased from 0.1 to 4 ha. The average production cost of using a biomass boiler ranged from $6.3 GJ⁻¹ to $18.5 GJ⁻¹, assuming a biomass cost of $55 per tonne over a 21-year system lifespan. Biomass boilers were not profitable compared to natural gas unless used in larger greenhouses with floor areas exceeding 4 ha. However, they proved to be cost-effective compared to diesel and electric heating systems across all greenhouse sizes. A sensitivity analysis examined factors such as discount rate, greenhouse size, costs of fuel, biomass, labor, installation, and maintenance that affect profitability. Fuel and biomass costs have the highest impacts.