Bioplastics company Metabolix has devised what it hopes is an efficient way to manufacture its product: growing grass.
The company on Monday said that it has has created "significant amounts" of its bioplastic by growing it in the leaves of switchgrass. The details of the greenhouse trial are published in Plant Biotechnology Journal.
A close-up of a leaf of switchgrass with bioplastic material growing in it. The plastic will be extracted and turned into pellets. Remaining biomass can be used for other purposes such as biofuels, according to the company.
Metabolix has developed a process for making plastics by combining genes of several naturally occurring substances. It plastics, marketed under the brand Mirel, can be made from corn or other sources of sugar.
Mirel bioplastic, called polyhydroxybutyrate (PHA), are biodegradeable alternatives to petroleum plastic. A manufacturer of gardening stakes is using the plastic and it can be used for credit cards or containers of consumer products.
Growing the plastic in a plant will allow for the switchgrass to produce both bioplastics and use residual biomass for energy, according to the company. The plastic would be culled and turned into pellets for plastic production.
Switchgrass is a perennial native grass that grows quickly. Researchers and several companies are developing methods for converting the plant biomass into ethanol.
"This result validates the prospect for economic production of PHA polymer in switchgrass, and demonstrates for the first time an important tool for enhancing switchgrass for value-added performance as a bioenergy crop," Oliver Peoples, chief scientific officer, said in a statement.
Last year, company executives said that they expected that their process for growing plastics would be commercial by 2012.
A number of bio-energy companies are looking at bioplastics production. Earlier this month, energy crop company Ceres said that it intends to use genetic engineering to grow plastics directly in plants as well.
Update on August 13, 1:50 p.m. PT with different photo of switchgrass leaf.
A large-scale test on the effectiveness of switchgrass to make ethanol gave the native grass high marks on energy production and greenhouse gases.
Switchgrass is a favorite of politicians and cellulosic ethanol advocates who say that the grass, which can grow to nine feet, is a better feedstock than corn--the source of most ethanol made today.
A study published on Monday by the Proceedings of the National Academy of Sciences (PNAS) found that switchgrass contains five times more energy than it takes to grow it, which makes it significantly more cost-effective than corn.
The average greenhouse gas emissions from cellulosic ethanol derived from switchgrass were found to be 94 percent lower than gasoline. By contrast, corn ethanol generates slightly less greenhouse gases in its production than gasoline, according to studies.
Other advantages of switchgrass are that it can grow in a range of climates and it does not require as much water as other processes. It also does not pose the same risk of raising food prices as corn ethanol.
The PNAS study, funded by the U.S. Department of Agriculture, attempted to have a more comprehensive look at growing switchgrass for ethanol than previous studies. Researchers grew the crop across 10 farms in the Midwest with varying precipitation and temperatures.
Although the study echoes other research in concluding that switchgrass is a promising feedstock, it still remains in the research phase of development.
There have been a number of companies seeking to commercialize cellulosic ethanol, but they have chosen more readily available feedstocks such as wood chips or agricultural wastes.
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