The bioeconomy at work: Metabolix to build 50,000 ton per year PHA bioplastics factory

Biotech company Metabolix, which is developing a biofuels and plant-based products biorefinery around (genetically altered) green tissue plants, announced it is to construct a factory that will produce 50,000 tons (110 million pounds) per year of biodegradable polyhydroxyalkanoates (PHA). The facility, to be constructed at an investment of €154/US$200 million in Iowa, expected to begin in 2008, will meet rising demand for plant-based plastics.

PHA is produced from a fermentation process using starch derived from potatoes, wheat or corn, as an alternative to petrochemical-based plastics. Metabolix brands its version of PHA as 'Natural Plastic'. Natural Plastic biodegrades in hot, cold, marine and wetland environments, in contrast to the currently available petrochemical products which decompose in hot industrial environments only and poison our environment and our oceans (earlier post).

The 'Natural Plastics' product can be used for coated paper, film or bags, and thermoformed and molded packaging. Metabolix currently operates a pilot PHA manufacturing plant with ADM to produce pre-commercial quantities of the material in a bid to develop applications with selected customers.

The sharp rise in feedstock prices of polyethylene terephthalate (PET) and other packaging plastics has made bioplastics a competitive alternative. A combination of pricing and retail uptake has led more and more processors to look at biodegradable natural polymer products as an alternative to PET.

Energy balance
An important consideration in the broader application of PHAs is the energy efficiency of the overall production process. Metabolix has developed highly efficient production strains that produce Natural Plastics at higher yield and productivity than strains used in the past. In addition, Metabolix has achieved significant simplifications in the recovery process that have resulted in additional energy savings. Natural Plastics are now more sustainable in their energy consumption than many of the important synthetic materials in widespread use today. Comparative energy consumption figures are indicated in the chart (click to enlarge):
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As has occurred with synthetic materials over the years, further improvements in yield and efficiency are possible, and Metabolix is already working to realize these. The energy requirements for microbially produced Natural Plastics will then be further reduced as indicated in the chart.

Carbon dioxide is a major green house gas and production of energy, chemicals, and polymers from non-renewable fossil fuel resources is the major human contributor to these emissions. Metabolix's PHA Natural Plastic production process achieves a very significant reduction in net carbon dioxide generation, in large part because the carbon contained in PHAs is derived from atmospheric carbon dioxide.

While PHA Natural Plastics produced by fermentation are more sustainable and require less energy input for their production than most synthetic polymers, PHAs produced directly in plants, when coupled with use of the energy content of the remaining plant biomass will contribute, rather than consume, energy. A thorough analysis (1) has been presented by Kurdikar et al., in the Journal of Industrial Ecology in which the authors concluded that, "an integrated system, wherein biomass energy from corn stover provides energy for polymer processing, would result in a better greenhouse gas profile for PHA than for polyethylene." Natural Plastics produced in switchgrass would be expected to be even more favorable than in corn stover (although the technology to transform switchgrass did not yet exist at the time of that study).


Metabolix is a biotech company developing and commercializing environmentally sustainable and totally biodegradable polymers and plastics. The facility being constructed in Iowa is part of a joint venture agreement with Archer Daniels Midland Company , a world leader in agricultural processing and fermentation.

“Initiating construction of this first commercial manufacturing facility for Natural Plastic in Clinton, Iowa marks a major milestone for Metabolix and our strategic alliance with ADM,” said Jim Barber, President and CEO of Metabolix. “We believe that Natural Plastic is a breakthrough technology that has the potential to provide environmentally-conscious companies and consumers with a renewable and sustainable alternative to petrochemical-based plastics, and to positively impact climate change, pollution and energy security.”

The Natural Plastic commercial manufacturing facility will be located adjacent to ADM’s corn wet mill in Clinton, Iowa. The plant will utilize starch from the mill’s existing corn grind capacity as raw material for Natural Plastic production. ADM and Metabolix are working together in a strategic alliance to commercialize Metabolix‘s patented and proprietary Natural Plastic technology. Permits enabling the start of construction were issued on November 30, 2006 by the Iowa Department of Natural Resources.

Biorefinery
In 1998, Metabolix experimented with the production of PHA Natural Plastics directly in plants. Since that time, it has recruited a plant science team, supplemented by programs with leading universities in the field of plant transformation. In 2001, the company received a US$15 million cost-share grant from the U.S. Department of Energy to develop a biomass biorefinery based on switchgrass. The goal of this five-year program is to produce PHA Natural Plastics in green tissue plants, such as switchgrass, tobacco and alfalfa and, after polymer extraction use the residual plant biomass for fuel generation.