The next time someone sips from a plastic bottle or lugs home groceries in a plastic bag, consider this: Those products could either end up in a landfill for the next 1,000 years or be recycled into liquid fuel to power vehicles and homes.
Methods to convert waste plastics into hydrocarbon fuel have been in development for decades. But the associated costs to commercialize the technologies were prohibitive in previous years when crude oil was relatively inexpensive.
As costs for crude oil have risen, concerns about energy security and the environment are renewing efforts in plastics-to-fuel recycling processes. Scientists hope the technologies will soon provide the nation with cheaper, alternative fuels that can help reduce foreign oil dependency.
Natural State Research Inc., based in Stamford, Conn., has developed a technology that converts waste plastics into hydrocarbon liquid fuel through a thermal degradation process. First, the waste plastics are heated. They melt into a slurry that vaporizes when the temperature reaches between 370 degrees to 420 degrees Celsius. The vapor then travels through a tube and condenses into a liquid.
“That liquid is fuel,” says the technology’s inventor, Moinuddin Sarker, who serves as the company’s vice president of research and development. “It ignites and works in any internal combustion engine.”
Following condensation, the liquid proceeds through a commercial purifier to produce the final product, called NSR fuel. Unlike conventional gasoline that contains sulfur, nitrogen and phosphor, the fuel is composed of only carbon and hydrogen because it is derived from plastic material — an already refined petroleum product.
In a laboratory-scale plant, the firm has demonstrated the ability to produce five gallons of fuel per day from a variety of plastics that do not have to be cleaned and sorted in advance. The technology will work for most types of plastics, which are made from combinations of elements and chemicals. These include ethylene, propylene and benzene that are derived from naphtha, which are flammable liquid mixtures of hydrocarbons obtained during petroleum refining processes, Sarker says.
A single plastic grocery bag can be converted into 10 milliliters of fuel. It takes 100 grocery bags to make a liter of fuel, which could power an automobile for five or six miles, Sarker says.
As the third largest manufacturing industry in the United States, plastics touch nearly every facet of human life, says the Society of the Plastics Industry. But the downside to this ubiquitous product lies in its disposal.
The Environmental Protection Agency estimates that Americans produce about 31 million metric tons of waste plastics annually.
Only about 10 percent is recycled because there are so many kinds of plastics. The majority still ends up in landfills.
Sarker says one metric ton of plastic waste can yield eight to nine barrels of NSR fuel. A barrel is equivalent to 42 gallons. If the nation’s annual plastic waste tonnage were converted to fuel, it would add up to 270 million barrels, or 11.3 billion gallons, he says. The United States consumes 21 million barrels of oil each day.
To help commercialize the technology, the company is seeking partners. So far, it has signed a licensing agreement with a firm to set up a pilot plant in California. If all goes as planned, the plant could be in place as early as next year and begin converting plastics into fuel for as little as .50 cents to .75 cents per gallon.
“We want to take the technology to every corner of the United States and to every corner of the world,” Sarker says. The company can install its reactor next to existing machines that collect clean or dirty plastics. “If you have a plant where you are recycling that plastic, you don’t need to build an extra building,” he adds.
A city with a population of one million would require a 50,000 square-foot facility to process 100,000 tons of waste plastics per year. The initial capital cost to build that conversion plant is estimated at $17 million. Its output would be 800,000 to 900,000 barrels of fuel. For a municipality that generates only 25,000 tons of waste plastics annually, $5 million would fund a plant that could produce 200,000 barrels of fuel, Sarker says.
Company officials want to partner with government agencies, in particular with the Defense Department. Aboard Navy ships, waste plastic is shredded, compressed and heated into 30-pound disks that are sealed in bags and stored until they can be disposed of ashore.
NSR’s technology could fit aboard an aircraft carrier and integrate with the ship’s waste treatment system to generate alternative diesel fuel, says Sarker.