Grain drying moves enormous volumes of air and removes large amounts of water, making it a major on-farm and port energy cost. Continuous-flow and batch dryers exhaust warm, moisture-laden air that is ideal for heat recovery.
Recovering that exhaust heat to preheat incoming air - or using heat-pump dehumidification that recirculates the latent heat - cuts fuel use sharply while keeping the drying air at the right condition for the grain.
Rotary or large plate exchangers sized for high airflow are typical. Corrosion from mildly acidic off-gassing of damp grain must be addressed with appropriate coatings and drainage so condensate does not pool on the core.
Match airflow and temperature to the grain's safe drying window, avoid over-drying that causes weight loss and cracking, and integrate ambient versus heated make-up air. Savings of 20-40% of fuel are common, with better germination and milling quality.