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Bio-based ethylene able to replace petroleum as a feedstock

National Renewable Energy Laboratory

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Technology Marketing Summary

Ethylene is the most produced gaseous organic compound in the chemical industry and future demand is forecasted to grow at an average of 4.1 % per year.  It is the raw material used to manufacture polymers such as polyethylene, polyester, polyvinyl chloride, and polystyrene as well as fibers and other chemicals used in the industrial and consumer markets of packaging, transportation and construction. It can be used directly as a fuel, or serve as a precursor for longer carbon chain compound synthesis.

Currently, ethylene is produced commercially by the steam cracking of petroleum-derived feedstocks. However, the rising cost of petroleum has led to the exploration and development of alternative, biological production systems for fuels and chemicals.  Algal production systems have been developed since the 1970’s and NREL is one of the preeminent laboratories developing biological systems for the production of fuels and chemicals.  Recently, a number of organizations have successfully applied closed-loop photobioreactors to the production of hydrocarbon feedstocks.  One such system developed at NREL utilizes the freshwater photosynthetic cyanobacterium, Synechosystis in the production of ethylene and its derivative fuels in a process that improves the energy conversion efficiency and reduces operational costs.

Description

NREL scientists have engineered the carbon metabolism of Synechosystis to create a strain that produces ethylene photosynthetically.  Furthermore, it maintains production in an extended stationary phase of at least ten days, when cell densities remain stable and cells function as ethylene-producing catalysts, using C02 and water as the ultimate carbon and hydrogen sources.  The estimated photosynthetic ethylene production rate is at least 41 kilograms per acre per year, and it is still being improved.

A photobioreactor can be used to produce and capture the ethylene.  In such a system ethylene may be produced continuously for months, without additional nutrient input.  Ethylene can be collected from the head space, and catalytically polymerized to produce fuels and chemicals.  This continuous production system improves the energy conversion efficiency and reduces the operational cost.  The principles established in this innovation can theoretically be applied to other cyanobacteria and algae for ethylene production.  Ethylene can also be a value-added co-product and thus will enhance the overall economics of algal biofuel production.

Benefits
  • Improved genetic stability of EFE gene
  • Environmentally friendly replacement for petroleum feedstock
Applications and Industries
  • Ethylene production
  • Bio-polymers and chemicals
  • Biofuel  production
More InformationA United States Provisional Patent Application has been filed.Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
11-55Development - Bench-scale production and testing of various growth conditions to improve production rates.Available - Available for licensing and currently seeking sponsored research opportunities.08/24/201108/24/2011

Contact NREL About This Technology

To: Eric Payne<eric.payne@nrel.gov>