Biomass waste products, like maize stalks, grass or wood chunks, are burnt to create heat and gas. The drier has ducts, which control airflow to and from the furnace. This ensures that heat is distributed evenly throughout the drier, so that the product – which is fed through the container on rollers – is dried uniformly.
The drier replaces traditional methods of crop preservation like refrigeration and dehydration, both of which use large amounts of energy.
Before developing DryMac, mechanical engineer Adrian Padt had designed and sold more than 120,000 natural draft stoves across Africa. After massive post-harvest losses in Malawi due to frequent power outages, a local organisation asked Padt to develop something that would dry agricultural produce using the same concept.
A DryMac installation in Malawi is being used to dry groundnuts and tobacco, while two South African DryMacs are being used on rosehip to extract oil to make cosmetics and skincare products. Padt is also adapting DryMac to dry macadamia nuts in South Africa.
Padt hopes to expand to various African countries, specifically those where electricity is limited or unreliable, and climate conditions are unpredictable.