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The Problem

After World War II, a labor-saving agricultural technology using plastics was introduced. Termed "plasticulture" the process uses film and rigid plastics to make operations more efficient while saving time, reducing water usage, controlling weeds, and more. Although agricultural production has soared, piles of waste plastic have continued to mount all over the world.

Common Agricultural Plastics

HDPE (#2): nursery pots, trays, flats, pesticide containers, drums

LDPE (#4): mulch, greenhouse covers, fumigation film, silage bags and wraps, irrigation tubing

PP (#5): row covers, nursery pots

PS (#6): nursery pots, tray inserts, flats, clamshell containers

The Solution: Plastofuel™ — The Penn State Fuel Nugget

Our prototype machine works by taking waste plastics and forcing them through a heated extrusion die, melting a thin jacket that locks unmelted pieces within. A hot knife cuts the extruded material into easily stored and readily shipped nuggets called Plastofuel™, which can be burned with coal in a coal-fired boiler or, eventually, combusted directly in the boiler system described. High-temperature combustion (2,000°F) ensures clean burns with minimal emissions.

The key to Plastofuel™ is that the production process is tolerant of dirt and debris, and because only the outer portions are melted during processing, it requires only about one-tenth the energy to form when compared to producing plastic pellets.

As shown in the table, agricultural plastics contain a high energy value that can be used to supplement or even replace existing fuels.

Material	Btu/;b
Fuel oil	20,900
Polyethylene (PE)	19,900
Polypropylene (PP)	19,850
Cross-linked PE (PEX)	19,780
Gasoline	19,200
Polystyrene (PS)	17,800
Pennsylvania coal	13,900
Wyoming coal	9,600
Newspaper	8,000
Textiles	6,900
Wood	6,700
Yard wastes	3,000
Food waste	2,600
Average municipal waste	4,500-6,700

Extruded plastic — This former Plastofuel™ machine was designed, built and tested by a graduate student. A hydraulic cylinder forced compacted plastic over a gridwork of knives, then onward through four heated dies. Heated knives cut the extrudate to any length while sealing cut ends with melted plastic.

Current Plastofuel Prototype — The current Plastofuel™ prototype is shown during fabrication in the Department of Agricultural and Biological Engineering.

Cylindrical Heated Die and Plastic — The current prototype uses hydraulic cylinders to force shredded plastic through cylindrical heated dies. Shown are blue mulch and white nursery pots being extruded.

A Fuel Supply and Fuel Combustion System Now in Pennsylvania

A novel high-temperature, plastic-fueled burner was invented in Seoul, Korea, in 1999 by GR Technologies Company, Ltd. A subsidiary of GR Technologies called Eco-Clean Burners, LLC, was formed in spring 2008 in the Greater Allegheny region to market this combustion system across the United States.

Eco-Clean Burners will begin leasing units to select customers in autumn 2008. The first installation of an Eco-Clean unit is near completion at Iannetti's Garden Center in Burgettstown, Pennsylvania. The 800,000-Btu/hr unit is designed to heat two production greenhouses. The garden center has been a supporter of this plastic-derived fuel technology for several years and will serve as a demonstration site.

Besides recovering energy via high-temperature combustion, providing an ample supply of plastic fuel for this venture has led to the creation of Atlas Certified Fuels, L3C. Atlas will supply plastic fuel for those customers who have leased combustion systems from Eco-Clean Burners. Atlas Certified Fuels ensures that all plastic fuels will meet rigid quality standards, thus guaranteeing the highest operating efficiency with minimal air emissions from the Eco-Clean hot-water heating systems. Incidentally, Atlas Certified Fuels will create approximately fifteen new jobs as part of its social mission to employ disadvantaged individuals from within the region.

This plastic-derived fuel boiler is installed in a working greenhouse near Pittsburgh. Plastic fuel supply issues will be evaluated along with boiler operation. The inset shows the original test unit at Penn State.