REGULATING METHANE EMISSIONS FROM FRESHWATER WETLANDS

FROM:  NATIONAL SCIENCE FOUNDATION
Methane-eating microorganisms help regulate emissions from wetlands
Without this process, methane emissions from freshwater wetlands could be 30 to 50 percent higher

Though they occupy a small fraction of Earth's surface, freshwater wetlands are the largest natural source of methane emitted into the atmosphere. New research identifies an unexpected process that acts as a key gatekeeper in regulating methane emissions from these freshwater environments.

The study results are published this week in the journal Nature Communications by biologist Samantha Joye of the University of Georgia and colleagues.

The researchers report that high rates of anaerobic (no oxygen) methane oxidation in freshwater wetlands substantially reduce atmospheric emissions of methane.

New attention

The process of anaerobic methane oxidation was once considered insignificant in freshwater wetlands, but scientists now think very differently about its importance.

"Some microorganisms actually eat methane, and recent decades have seen an explosion in our understanding of the way they do this," says Matt Kane, program director in the National Science Foundation's Division of Environmental Biology, which funded the research. "These researchers demonstrate that if it were not for an unusual group of methane-eating microbes that live in freshwater wetlands, far more methane would be released into the atmosphere."

Although anaerobic methane oxidation in freshwater has been gathering scientific attention, the environmental relevance of this process was unknown until recently, Joye says.

"This paper reports a previously unrecognized sink for methane in freshwater sediments, soils and peats: microbially-mediated anaerobic oxidation of methane," she says. "The fundamental importance of this process in freshwater wetlands underscores the critical role that anaerobic oxidation of methane plays on Earth, even in freshwater habitats."

Without this process, Joye says, methane emissions from freshwater wetlands could be 30 to 50 percent greater.

Comparison of wetlands

The researchers investigated the anaerobic oxidation process in freshwater wetlands in three regions: the freshwater peat soils of the Florida Everglades; a coastal organic-rich wetland in Acadia National Park, Maine; and a tidal freshwater wetland in coastal Georgia.

All three sites were sampled over multiple seasons.

The anaerobic oxidation of methane was coupled to some extent with sulfate reduction. Rising sea levels, for example, would result in increased sulfate, which could fuel greater rates of anaerobic oxidation.

Similarly, with saltwater intrusion into coastal freshwater wetlands, increasing sulfate inhibits microbial methane formation, or methanogenesis.

So while freshwater wetlands are known to be significant methane sources, their low sulfate concentrations previously led most researchers to conclude that anaerobic oxidation of methane was not important in these regions.

Crucial process

The new findings show that if not for the anaerobic methane oxidation process, freshwater environments would account for an even greater portion of the global methane budget.

"The process of anaerobic oxidation of methane in freshwater wetlands appears to be different than what we know about this process in marine sediments," Joye says. "There could be unique biochemistry at work."

Adds Katherine Segarra, an oceanographer at the U.S. Department of the Interior's Bureau of Ocean Energy Management and co-author of the paper: "This study furthers the understanding of the global methane budget, and may have ramifications for the development of future greenhouse gas models."

Additional financial support for the research was provided by the Deutsche Forschungsgemeinschaft via the Research Center/Cluster of Excellence at the MARUM Center for Marine Environmental Sciences and department of geosciences at the University of Bremen, Germany.

-- Cheryl Dybas
-- Alan Flurry, University of Georgia
Investigators
Samantha Joye
Christof Meile
Vladimir Samarkin
Related Institutions/Organizations
University of Georgia Research Foundation Inc

WASTE METHANE MADE INTO BIODEGRADABLE PLASTIC BY SCIENTISTS

FROM:  NATIONAL SCIENCE FOUNDATION 

A biodegradable plastic made from waste methane

Scientists are making PHA (a biodegradable polymer similar to the polypropylene used in yogurt containers) from waste methane

What if we could make the Great Pacific Garbage Patch just disappear? What if plastics didn't accumulate in our landfills? What if we could reduce greenhouse gas emissions while replacing up to 30 percent of the world's plastics with a biodegradable substitute?

Researchers have tried for decades to achieve these goals. One approach being taken is the development of an efficient production process for poly-hydroxyalkanoate (PHA)--a biodegradable polymer similar to the polypropylene used to make yogurt containers.

Scientists at Stanford University and a Palo Alto, Calif.-based start-up company called Mango Materials have come up with a new way to make PHA from waste methane gas. And, with funding from the National Science Foundation (NSF), Mango Materials is advancing the process toward commercialization.

PHA is a biodegradable polyester that is produced naturally inside some bacteria under conditions of excess carbon and limited nutrient availability. Processes being developed to make PHA at a commercial scale typically involve bacteria strains that have been genetically modified to boost production and corn-based sugar as the carbon source.

The microorganisms feed on plant-derived sugars and produce PHA. The PHA is then separated from the bacteria and made into pellets that can be molded into plastic products. This approach has several shortcomings: It requires use of agricultural land and other inputs to produce feedstock, and it competes with the food supply.

Mango Materials' process uses bacteria grown in fermenters to transform methane and oxygen, along with added nutrients (to supply excess carbon), into PHA. Eventually, the PHA-rich bacteria--now literally swollen with PHA granules--are removed from the fermenters, and the valuable polymer is separated via proprietary techniques from the rest of the cell mass. The PHA is then rinsed, cleaned, and dried as needed.

After the products made of the PHA have reached the end of their useful life, the plastic can be degraded anaerobically (without air)--to produce methane gas. This closes the loop and provides a fresh feedstock for PHA production.  Because PHA's properties can be tweaked by varying the copolymer content or with additives, Mango Materials has identified a range of applications.

"We are currently focused on applications where biodegradability is key," says Molly Morse, CEO at Mango Materials. "However, we're open to all sorts of applications and are eager to bring PHA bioplastics to market."

This unique approach addresses challenges that have derailed previous attempts at PHA commercialization. Other processes use sugar as a carbon feedstock, whereas Mango Materials uses waste methane--which is considerably less expensive than sugar.

"By using methane gas as the feedstock, we can significantly drive down costs of production," Morse says.

In addition, the process relies on a mixed community of wild bacteria that are obtained through natural selection rather than genetic engineering. Using wild bacteria that are not genetically altered alleviates concerns of some toward genetically modified organisms. And, the use of a mixed community of wild bacteria reduces production costs because it eliminates the need to sterilize equipment.

"This stands in contrast to the processes many biotech companies use that require high-purity, genetically engineered cultures," says Allison Pieja, director of technology at Mango Materials.

As an added environmental benefit, the process sequesters methane, a potent greenhouse gas, and provides an economic incentive for methane capture at facilities such as landfills, wastewater treatment plants and dairy farms. The unused, vented methane from California landfills (based on 2010 data from the Methane to Markets Partnership)--if used as PHA feedstock--would yield more than 100 million pounds per year of plastic. (This estimate is based on Mango Materials' internal calculations using its own rates and yields).

Mango Materials has vetted this technology and achieved excellent yields at the lab scale. Field studies have shown that the methane-consuming cultures grow just as well on waste biogas, which includes contaminants such as sulfides, as on pure methane. Now, the company is setting out to achieve the same yields at a commercial scale. Mango Materials standard commercial plants will be sized to handle the methane produced at an average wastewater treatment plant--enough to produce more than 2 million pounds per year of PHA.

This technology was funded through the NSF Small Business Innovation Research Program.

This article was prepared by NSF for the American Institute of Chemical Engineers and appeared in the February 2014 issue of Chemical Engineering Progress.

Investigators
Molly Morse
Related Institutions/Organizations
Mango Materials

DEVELOPING VERY SENSITIVE METHANE-SENSING TECHNOLOGY

FROM:  LOS ALAMOS NATIONAL LABORATORY
Technologies to Characterize Natural Gas Emissions Tested in Field Experiments

LOS ALAMOS, N.M., October 28, 2013—A new collaborative science program is pioneering the development of ultra-sensitive methane-sensing technology.

“Given the importance of methane to global climate change, this study is essential,” said Manvendra Dubey of Los Alamos National Laboratory “This work aids both commercial and government sectors in an effort to better understand and mitigate fugitive methane emissions.”

“A significant part of understanding Man’s role in global climate change is the accurate measurement of the components that have a profound effect on climate. This project takes four of the top organizations in the discipline and sets their expertise to the test, that of measuring methane in the field and then making the results available to the larger scientific community,” he said.

The program is a joint effort on the part of NASA’s Jet Propulsion Laboratory (JPL), the Department of Energy (DOE), Los Alamos National Laboratory (LANL) and Chevron Corporation. The program was launched following a field experiment at DOE’s Rocky Mountain Oil Testing Center (RMOTC) some 35 miles north of Casper, Wyoming.

Why Measure Methane?

Methane, the principal component of natural gas, is one of many gases whose presence in the atmosphere contributes to global climate change. It is a goal of industry and scientists alike to better constrain the source flux of fugitive methane emissions from man-made activities. A key tool in the measurement of methane is to understand the capabilities of currently available airborne and ground-based sensors.

Los Alamos and Chevron have worked collaboratively on sensor technology development since 2001, while the more nascent collaborative agreement between Chevron and NASA has been effective since July 2011.

The organizations have worked hard to develop a range of technologies targeting effective and responsible exploration and production of petroleum and natural gas that will ultimately provide benefit to the environment. The majority of these research projects have been focused on upstream applications in the oil and gas sector. The recent methane controlled release airborne/in situ project marks the first time that JPL and Los Alamos have worked collaboratively on an experiment this significant, the researchers said.

The Work in the Field

The summer science campaign at RMOTC (held June 20-26, 2013) was designed to measure methane abundances released at different rates using three airborne instruments on separate aircraft, a small, unmanned aerial system (sUAS), and an array of in situ sensors. The goal is to understand the sensitivity and accuracy at measuring methane for airborne sensors.

The methane was released at metered, controlled rates and observed downwind by a 45-foot tower at each release site to examine the spatiotemporal variability of methane and local winds, while the four aircraft flew overhead to allow for sensor performance appraisal under controlled conditions.

Who’s Who on the Team

The RMOTC’s primary mission is to provide facilities for advancing technologies applicable to the energy sector to promote enhanced safety and efficient energy production. As such, it provided the testing grounds for the recent Chevron/JPL/LANL methane controlled-release experiment. JPL was responsible for deployment of remote sensing airborne instruments and Los Alamos provided ground-based sensor and modeling capabilities.

Los Alamos was responsible for the in situ science including quantifying methane using tower-mounted ground based sensors and a Picarro Global Surveyor vehicle for real-time assessment of methane concentrations and its isotopic composition while conducting driving surveys.

“We have assembled a world-class dream team that harnesses national assets at NASA's JPL and DOE's LANL, each contributing their expertise to methane detection and attribution, with JPL providing airborne remote sensing expertise and LANL focusing on modeling and in situ measurements,” said Dubey, LANL’s principal investigator.

“The project is pioneering the development of ultra-sensitive methane sensing technology to fill current gaps in quantifying fugitive leaks from petroleum extraction. With US energy independence a priority to the nation, understanding the effects of varied extraction techniques is important and calls for high-quality data.”

JPL deployed three different airborne sensors: the Next Generation Airborne Visible and Infrared Imaging Spectrometer (AVIRIS-ng), the Hyperspectral Thermal Emission Spectrometer (HyTES), and the CARVE instrument suite. All of the airborne sensors have capability to detect enhanced concentrations of methane from ground sources.

“We’ve organized deployment of a suite of state-of-the art instruments available for methane detection whose performance in controlled release testing will demonstrate their efficacy for methane remote sensing – preliminary results from our data analysis reveal detection of robust plume signatures from these controlled experiments,” said Andrew Aubrey, project manager at JPL.

“This study demonstrates tools that can be utilized for investigations of natural and anthropogenic methane emissions while also informing us to the performance expected from the next generation remote sensing instruments currently being designed at JPL.”

Over the coming months the team plans to publish and disseminate the results of their combined aerial and ground experiments. This study is particularly relevant given the importance of methane to global climate change and the co-aligned goals of commercial and government sectors to better understand and mitigate fugitive emissions. The tools tested at RMOTC include those technologies that can help to allow safe and responsible production of gas in future operations.

SCIENTISTS FIND REDUCTIONS IN FOUR POLLUTANTS CAN SLOW SEA LEVEL RISE

Black carbon, a short-lived pollutant (shown in purple), shrouds the globe.
Credit-NOAA

FROM: NATIONAL SCIENCE FOUNDATION
Cutting Specific Atmospheric Pollutants Would Slow Sea Level Rise
With coastal areas bracing for rising sea levels, new research indicates that cutting emissions of certain pollutants can greatly slow sea level rise this century.

Scientists found that reductions in four pollutants that cycle comparatively quickly through the atmosphere could temporarily forestall the rate of sea level rise by roughly 25 to 50 percent.

The researchers focused on emissions of four heat-trapping pollutants: methane, tropospheric ozone, hydrofluorocarbons and black carbon.

These gases and particles last anywhere from a week to a decade in the atmosphere and can influence climate more quickly than carbon dioxide, which persists in the atmosphere for centuries.

"To avoid potentially dangerous sea level rise, we could cut emissions of short-lived pollutants even if we cannot immediately cut carbon dioxide emissions," says Aixue Hu of the National Center for Atmospheric Research (NCAR) in Boulder, Colo., first author of a paper published today in the journal Nature Climate Change.

"Society can significantly reduce the threat to coastal cities if it moves quickly on a handful of pollutants."

The research was funded by the National Science Foundation (NSF) and the U.S. Department of Energy.

"Sea level rise and its consequences present enormous challenges to modern society," says Anjuli Bamzai, program director in NSF's Division of Atmospheric and Geospace Sciences, which supported the research.

"This study looks at projections of global sea level rise, unraveling the effects of mitigating short-lived greenhouse gases such as methane, tropospheric ozone, hydrofluorocarbons and black carbon, as well as long-lived greenhouse gases like carbon dioxide," says Bamzai.

It is still not too late, "by stabilizing carbon dioxide concentrations in the atmosphere and reducing emissions of shorter-lived pollutants, to lower the rate of warming and reduce sea level rise by 30 percent," says atmospheric scientist Veerabhadran Ramanathan of the Scripps Institution of Oceanography (SIO) in San Diego, a co-author of the paper. Ramanathan initiated and helped oversee the study.

"The large role of the shorter-lived pollutants is encouraging since technologies are available to drastically cut their emissions," says Ramanathan.

The potential effects of rising oceans on populated areas are of great concern, he says.

Many of the world's major cities, such as New York, Miami, Amsterdam, Mumbai, and Tokyo, are located in low-lying areas along coasts.

As glaciers and ice sheets melt, and warming oceans expand, sea levels have been rising by an average of about 3 millimeters annually in recent years (just over one-tenth of an inch).

If temperatures continue to warm, sea levels are projected to rise between 18 and 200 centimeters (between 7 inches and 6 feet) this century, according to reports by the Intergovernmental Panel on Climate Change and the U.S. National Research Council.

Such an increase could submerge coastal communities, especially when storm surges hit.

Previous research by Ramanathan and Yangyang Xu of SIO, a co-author of the paper, showed that a sharp reduction in emissions of shorter-lived pollutants beginning in 2015 could offset warming temperatures by up to 50 percent by 2050.

Applying those emission reductions to sea level rise, the researchers found that the cuts could dramatically slow rising sea levels.

The results showed that total sea level rise would be reduced by an estimated 22 to 42 percent by 2100, depending on the extent to which emissions were cut.

However, the study also found that delaying emissions cuts until 2040 would reduce the beneficial effect on year-2100 sea level rise by about a third.

If society were able to substantially reduce both emissions of carbon dioxide as well as the four other pollutants, total sea level rise would be lessened by at least 30 percent by 2100, the researchers conclude.

"We still have some control over the amount of sea level rise we are facing," Hu says.

Another paper co-author, Claudia Tebaldi of Climate Central, adds: "Without diminishing the importance of reducing carbon dioxide emissions in the long-term, this study shows that more immediate gains from shorter-lived pollutants are substantial.

"Cutting emissions of those gases could give coastal communities more time to prepare for rising sea levels," says Tebaldi. "As we have seen recently, storm surges in populated regions of the East Coast show the importance of making such preparations and cutting greenhouse gases."

To conduct the study, Hu and colleagues turned to the NCAR-based Community Climate System Model, as well as a second computer model that simulates climate, carbon and geochemistry.

They also drew on estimates of future emissions of heat-trapping gases under various social and economic scenarios and on computer models of melting ice and sea level rise.

The study assumes that society could reduce emissions of the four gases and particles by 30-60 percent over the next several decades.

That is the steepest reduction believed achievable by economists who have studied the issue at Austria's International Institute for Applied Systems Analysis, one of the world's leading research centers into the effects of economic activity on climate change.

"It must be remembered that carbon dioxide is still the most important factor in sea level rise over the long-term," says NCAR scientist Warren Washington, a paper co-author. "But we can make a real difference in the next several decades by reducing other emissions."

-NSF-