Benelux_Infrastructure_Forum_171
17 November 2016 2016 01:04 PM GMT

NREL Scientists Discover How Bacterium Uses CO2 And Cellulose To Make Biofuels

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) made the surprise discovery that a metabolic pathway to take up CO2 exists and functions in a microorganism capable of breaking down and fermenting cellulosic biomass to produce biofuels including hydrogen and hydrocarbons.

Clostridium thermocellum is among the most efficient bacteria indirectly converting cellulosic materials into hydrogen and hydrocarbons biofuels. Most bacteria feeding upon organic carbon compounds, such as glucose or xylose, release CO2 as a waste byproduct, decreasing the maximum amount of products the microorganism can produce per carbon atom measured as carbon efficiency.

Other scientists have found the addition of a form of CO2, known as bicarbonate, into the medium containing the bacterium actually promotes the growth of C. thermocellum, yet its mechanistic details remained a puzzle. This enhanced growth implied the bacterium had the ability to use CO2 and prompted NREL researchers to investigate the phenomena enhancing the bacterium’s growth.

“It took us by surprise that this microbe can recapture some of the CO2 released during growth while they consume sugars derived from cellulosic biomass,” said Katherine J. Chou, a staff scientist with NREL’s Photobiology group and co-author of the new paper “CO2-fixing one-carbon metabolism in a cellulose-degrading bacterium Clostridium thermocellum.” The research is in the new issue of the journal Proceedings of the National Academy of Sciences of the United States of America.

Using carbon isotopes coupled with mass spectrometry analysis, the researchers were able to track how CO2enters the cell, identify the enzymes critical to CO2 uptake, and how CO2 incorporates into products thereby discovering a new metabolic route unknown to the scientific community. Many species of bacteria have the pathway in place for CO2 uptake, but before the new research, the pathway was not associated with the role of carbon dioxide assimilation (otherwise known as CO2 fixation).

The pathway enables the bacterium to use both CO2 and organic carbons during its growth, which is counter-intuitive because it’s much more common for this type of organism to use one and not the other, especially in heterotrophic microbes.

NREL researchers and their collaborators determined adding bicarbonate increased the apparent carbon efficiency of C. thermocellum from 65.7 percent to 75.5 percent. The finding underscores the metabolic plasticity of the microbe and raises various possibilities on how the bacterium is able to use both organic carbons and CO2 without breaking the rules of thermodynamics in energy conservation. The discovery also provides a paradigm shift in the fundamental understandings of carbon metabolism in a cellulose degrading bacterium.

“Our findings pave the way for future engineering of the bacterium as a way to improve carbon efficiency and to reduce the amount of CO2 released into the environment,” Chou said. With the observed improved carbon efficiency, this work inspires future research to redirect more cellular electrons in support of increased hydrogen production, a key goal for the funded research. In addition to Chou, the co-authors from NREL are Wei Xiong, Lauren Magnusson, Lisa Warner, and Pin-Ching Maness. Two BioEnergy Science Center (BESC) co-authors are Paul Lin and James Liao from the University of California, Los Angeles, where Chou earned her Ph.D. in chemical and biomolecular engineering.

The latest research into the bacterium was financed by the NREL Director’s Fellowship Program, Energy Department’s Fuel Cell Technologies Office, as well as Office of Biological and Environmental Research in the DOE Office of Science. NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy, LLC.

Photo: Courtesy of National Renewable Energy Laboratory (NREL)

August 5th 2017
Invenergy, GE Renewable Energy Announce 2GW Facility: Largest Wind Farm In US

Invenergy and GE Renewable Energy have announced a 2GW wind farm that will be the largest in the U.S. and second-largest in the world, once operational, in 2020. The Wind Catcher facility is under construction in the Oklahoma panhandle and will use 800 state-of-the-art GE 2.5 MW turbines. It will link more than 1.1 million customers with wind energy harvested domestically, saving them more than $7 billion, and will support 4,000 direct and 4,400 indirect jobs annually during construction and 80 permanent jobs once operational. “Wind Catcher shows American leadership in bringing low-cost clean energy to market at Giga scale,” said Invenergy’s Founder and CEO Michael Polsky.

August 4th 2017
Enel Awarded 339 MW Of Solar Capacity In Spanish Renewables Tender

Enel S.p.A., acting through its Spanish subsidiary Endesa’s renewable company Enel Green Power España (EGPE), has been awarded 339 MW of solar capacity in Spain. The award followed the tender aiming at collecting 3 GW from renewable energies, launched by the Spanish Government to help the country achieve its target to cover 20% of energy consumption from renewables by 2020. The solar capacity adds to the 540 MW of wind power capacity that EGPE was already awarded last May. “This new milestone confirms our commitment to green energy in Spain, a country which continues to offer growth opportunities for our renewable projects,” said Antonio Cammisecra, Enel’s Head of Global Renewable Energies.

August 17th 2017
Siemens Gamesa Installs Asia’s Tallest Turbines, Whilst Stepping Up Integration

Siemens Gamesa has set a new record in Asia by installing this year the tallest wind turbines on the continent. The turbines are equipped with 153-metre tall towers, and with the 56-metre blades, they reach a total height of 210 metres. Presently, a major focus for the company is the integration of the entities of Siemens and Gamesa. This has the objective of realising the new company’s substantial potential, thanks to its bigger scale and global reach: a presence in more than 90 countries, an installed base of 75 GW, and an order book of €21bn.

August 14th 2017
Offshore Wind Drives 6.1 GW Of European Wind Installations In First Half Of 2017

6.1 GW of extra wind energy capacity was installed in Europe in the first half of 2017, according to figures released by WindEurope. The figure puts Europe on course for a bumper year for installations, although hides some worrying trends. WindEurope Chief Policy Officer, Pierre Tardieu, said: “We are on track for a good year in wind capacity installations but growth is driven by a handful of markets. At least ten EU countries have yet to install a single MW so far this year. Although this won’t translate into lower installations for another few years, the industry needs clarity on volumes for the post-2020 period to maintain the current cost reduction trend”.

August 9th 2017
35% Of German Electricity Consumption Now From Renewables: Grid Challenges Ahead

The Centre for Solar Energy and Hydrogen Research in Baden-Württemberg (ZSW) and the German Association of Energy and Water Industries (BDEW) have stated in an initial assessment that electricity generated from clean energy accounted for 35% of Germany’s consumption in 1H 2017. It’s the first time that this mark has been reached. The total share of electricity generated from renewables was up 2% from last year. The growth from onshore wind was 13.6%; offshore wind saw the steepest growth at 47.5%; growth from biomass increased by 2.2%, whilst the growth from PV systems was 13.5%, compared with the 1H 2016.