Microbes commonly found in moist, natural environments could eventually be a source of ethylene, the building block for polyethylene resin and many other polymers.
Researchers at the U.S. Department of Energy's National Renewable Energy Laboratory are tweaking cyanobacteria to produce ethylene through photosynthesis. If they can get the yields up, the process might be an alternative to using oil and gas for making the raw material of plastics. The sustainable process could also have a role in cutting atmospheric levels of carbon dioxide, a greenhouse gas that could be contributing to global warming.
Jianping Yu leads a group at Golden, Colo.-based NREL that is working with a specific strain of cyanobacteria that makes ethylene when exposed to sunlight. Ethylene is one of the chemicals the microbe makes when it converts carbon dioxide to biomass as it grows.
So far the amount of ethylene produced represents about 10 percent of the biomass produced, but he hopes further work over the next few years could boost ethylene yields to 90 percent.
Researchers dissolve nutrients like nitrogen and phosphorus in water, add cyanobacteria and expose the mixture to sunlight. So far a liter of the mixture can make 35 milligrams of ethylene per hour but Yu hopes to boost that to 50 milligrams by the end of the year.
Such minute amounts have no practical application yet but if the process can successfully be scaled up it could be a viable source of ethylene. At current yields, that production rate would give one pound of ethylene per hour in 12,800 liters of mixture. That pound of ethylene could be the raw material for nearly a pound of polyethylene.