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OKIsItJustMe

(19,933 posts)
Fri Sep 28, 2012, 07:04 PM Sep 2012

NREL Produces Ethylene via Photosynthesis

(Please note, News Release from US Government Lab—Copyright concerns are nil.)

http://www.nrel.gov/news/press/2012/1996.html

[font face=Serif]News Release NR-3512

[font size=5]NREL Produces Ethylene via Photosynthesis[/font]
[font size=4]Environmentally-friendly process offers intriguing alternative to fossil-fuel based ethylene for chemicals and transportation fuels[/font]
[font size=3]September 25, 2012

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have demonstrated a better way to use photosynthesis to produce ethylene, a breakthrough that could change the way materials, chemicals, and transportation fuels are made, and help clean the air.

NREL scientists introduced a gene into a cyanobacterium and demonstrated that the organism remained stable through at least four generations, producing ethylene gas that could be easily captured. Research results were published in the journal Energy & Environmental Science.

The organism – Synechocystis sp. PCC 6803 – produced ethylene at a high rate and is still being improved. The laboratory demonstrated rate of 170 milligrams of ethylene per liter per day is greater than the rates reported for the photosynthetic production by microorganisms of ethanol, butanol or other algae biofuels.

The process does not release carbon dioxide into the atmosphere. Conversely, the process recycles carbon dioxide, a greenhouse gas, since the organism utilizes the gas as part of its metabolic cycle.

Ethylene is the most widely produced petrochemical feedstock in the world. But currently it is produced only from fossil fuels, and its production is the industry’s largest emitter of carbon dioxide. Steam cracking of long-chain hydrocarbons from petroleum produces 1.5 to 3 tons of carbon dioxide for every ton of ethylene produced.

The NREL process, by contrast, produces ethylene by using carbon dioxide, which is food for the bacteria. That could mean a savings of six tons of carbon dioxide emissions for every ton of ethylene produced -- the three tons that would be emitted by tapping fossil fuels and another three tons absorbed by the bacteria.



“Our peak productivity is higher than a number of other technologies, including ethanol, butanol, and isoprene,” Yu said. “We overcame problems encountered by past researchers. Our process doesn’t produce toxins such as cyanide and it is more stable than past efforts. And it isn’t going to be a food buffet for other organisms.”



The ethylene would be produced in an enclosed photobioreactor containing seawater enriched with nitrogen and phosphorous. The ethylene gas would rise and be captured from the reactor’s head space. It could then undergo further processing, including a catalytic polymer process to produce fuels and chemicals. The continuous production system improves the energy conversion efficiency and reduces the operational cost.

NREL is initiating discussions with potential industry partners to help move the process to commercial scale. Interested companies include those in the business of producing ethylene or - transportation fuels, as well as firms that build photobioreactors.

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