Futile to Utile: Waste Plastics to Fuel

Oregon onion farmers are encountering a growing waste crisis from accumulating agricultural plastics. i.e, irrigation supplies such as drip tubing, plastic film coverings, buckets, etc. Unfortunately, mechanical recycling is cost-prohibitive and unavailable in these rural Oregon communities, resulting in the accumulation of tons of agricultural plastics with no plan to manage them. Chemical recycling technologies, like pyrolysis, could provide a reliable means to convert waste plastics into fuels for tractors, generators, etc. off-setting diesel needs and reducing farm operating costs.

The Plastic to Fuel (PTF) project is bringing together experts from transdisciplinary fields and backgrounds, in academics, industry, and the community to assess the techno economic, environmental, and social impact for use of small-scale chemical recycling units to efficiently convert waste agricultural plastics into a farm-fuel, i.e., a blend-stock for red diesel. A common agricultural waste product in the greater Malheur community is drip-tape which is used for irrigation of many crops, the most prominent of which is onions. The drip-tape is polyethylene, which has been experimentally confirmed with the Differential Scaling Calorimetry (DSC). In Summer 2024, four OSU chemical engineering students provided a technology demonstration on two field days at the OSU Malheur Ag Experiment Field Station. A bench scale kiln pyrolysis reactor was used to convert the drip-tape to a liquid hydrocarbon product (farm/red diesel). The pyrolysis diesel was run in a tractor at a 1:3 blend of pyrolysis diesel to farm diesel. In addition to the demonstration, oral and poster presentations were made and surveys were handed out to gauge the local interest and concerns. There were about 150 people in attendance between both events and students fielded questions from regional economic development, growers, vendors, and community members. At one event, one of the students donned an onion costume (provided by the station head) to discuss the process with curious participants! Upon returning to the lab, Gas Chromatography Flame Ionization Detection (GC-FID) and Nuclear Magnetic Resonance (NMR) were used to analyze the diesel and confirm it compared favorable to standard farm diesel. The current plan is to construct a small-scale reactor to place permanently at the Malheur Field Station and train local Community College students give demonstrations more frequently to spark interest in supporting a full-scale reactor (500kg capacity) for the region. This will be accomplished through collaboration with a local pyrolysis company.