Scientists Question EPA Estimates of Greenhouse Gas Emissions
The anaerobic lagoon at the Cal Poly, SLO Dairy. The dairy can be seen in the background and the 25-kW power plant fired using the biogas is on the right. (By kjkolb /Released under GFDL and cc-by-sa-2.5)
The approach the U.S. Environmental Protection Agency (EPA) uses to estimate greenhouse gas emissions from agricultural anaerobic lagoons that treat manure contains errors and may underestimate methane emissions by up to 65%, according to scientists from the University of Missouri.
Anaerobic lagoons treat manure on some animal feeding operations prior to application to crops as a fertilizer. Methane, one byproduct of the treatment process, has 21 times the warming potential of carbon dioxide.
A 2007 U.S. Supreme Court ruling mandated the EPA consider greenhouse gases a pollutant. This led the EPA in 2009 to approve greenhouse gas reporting requirements for any facility that annually releases 25,000 metric tons or more of carbon dioxide equivalents to the atmosphere. The objective of these reporting requirements is to quantify emissions as a first step towards developing strategies to reduce greenhouse gas losses.
Direct measurements of methane emissions from anaerobic lagoons are technically difficult and very expensive, so the EPA adopted a calculation method to estimate methane emissions from anaerobic digesters. They relied on the method used by the International Panel on Climate Change (IPCC) in their 2006 worldwide estimate of greenhouse inventories. (more…)
Higher Wetland Methane Emissions Caused by Climate Warming 40,000 Years Ago
40,000 years ago rapid warming led to an increase in methane concentration. The culprit for this increase has now been identified. Mainly wetlands in high northern latitudes caused the methane increase, as discovered by a research team from the University of Bern and the German Alfred Wegener Institute for Polar and Marine Research in the Helmholtz Association. This result refutes an alternative theory discussed amongst experts, the so-called “clathrate gun hypothesis”. The latter assumed that large amounts of methane were released from the ocean sediment and led to higher atmospheric methane concentrations and thus to rapid climate warming.
Earlier measurements on ice cores showed that the atmospheric methane concentration changed drastically in parallel to rapid climate changes occurring during the last ice age. Those climate changes – so-called Dansgaard-Oeschger events – were characterised by a sudden warming and an increase in methane concentration. However, it was not yet clear to what extent the climate changes 40,000 years ago led to the methane increase or vice versa.
Climate researchers from the Universities in Bern and Copenhagen and from the Alfred Wegener Institute for Polar and Marine Research in Bremerhaven now conclude that the methane increase at that time was largely due to higher methane emissions from wetlands. As published by the researchers in the current issue of the magazine Science, these natural methane sources produced more methane especially in high northern latitudes in response to the warming. (more…)
Methane Releases from Arctic Shelf May Be Much Larger and Faster Than Anticipated
A section of the Arctic Ocean seafloor that holds vast stores of frozen methane is showing signs of instability and widespread venting of the powerful greenhouse gas, according to the findings of an international research team led by University of Alaska Fairbanks scientists Natalia Shakhova and Igor Semiletov.
The research results, published in the March 5 edition of the journal Science, show that the permafrost under the East Siberian Arctic Shelf, long thought to be an impermeable barrier sealing in methane, is perforated and is starting to leak large amounts of methane into the atmosphere. Release of even a fraction of the methane stored in the shelf could trigger abrupt climate warming.
“The amount of methane currently coming out of the East Siberian Arctic Shelf is comparable to the amount coming out of the entire world’s oceans,” said Shakhova, a researcher at UAF’s International Arctic Research Center. “Subsea permafrost is losing its ability to be an impermeable cap.”
Methane is a greenhouse gas more than 30 times more potent than carbon dioxide. It is released from previously frozen soils in two ways. When the organic material (which contains carbon) stored in permafrost thaws, it begins to decompose and, under anaerobic conditions, gradually releases methane. Methane can also be stored in the seabed as methane gas or methane hydrates and then released as subsea permafrost thaws. These releases can be larger and more abrupt than those that result from decomposition. (more…)
Researchers Make Key Step Towards Turning Methane Gas Into Liquid Fuel
UW chemistry professor Karen Goldberg. (UW)
Researchers at the University of Washington and the University of North Carolina at Chapel Hill have taken an important step in converting methane gas to a liquid, potentially making it more useful as a fuel and as a source for making other chemicals.
Methane, the primary component of natural gas, is plentiful and is an attractive fuel and raw material for chemicals because it is more efficient than oil, produces less pollution and could serve as a practical substitute for petroleum-based fuels until renewable fuels are widely useable and available.
However, methane is difficult and costly to transport because it remains a gas at temperatures and pressures typical on the Earth’s surface.
Now UNC and UW scientists have moved closer to devising a way to convert methane to methanol or other liquids that can easily be transported, especially from the remote sites where methane is often found. The finding is published in the Oct. 23 issue of the journal Science. (more…)
Climate Change: Researchers Cut Cattle Produced Methane By 25 Percent
Beef farmers can breathe easier thanks to University of Alberta researchers who have developed a formula to reduce methane gas in cattle.
By developing equations that balance starch, sugar, cellulose, ash, fat and other elements of feed, a Canada-wide team of scientists has given beef producers the tools to lessen the methane gas their cattle produce by as much as 25 per cent.
“That’s good news for the environment,” said Stephen Moore, a professor of agricultural, food and nutritional science at the University of Alberta in Canada. “Methane is a greenhouse gas, and in Canada, cattle account for 72 per cent of the total emissions. By identifying factors such as diet or genetics that can reduce emissions, we hope to give beef farmers a way to lessen the environmental footprint of their cattle production and methane reductions in the order of 25 per cent are certainly achievable.” (more…)
$11 Million Center to Make Methane Economically Feasible Fuel
A new center to develop technologies for converting methane gas and other hydrocarbon and fossil resources into readily transportable and higher-value liquid fuels is being established at the University of Virginia under a new $11 million grant from the U.S. Department of Energy.
U.Va.’s center is one of 46 new multi-million-dollar Energy Frontier Research Centers being funded by the Department of Energy. These centers, being established at universities, national laboratories, nonprofit organizations and private firms, will pursue advanced research to alleviate some of the most pressing energy problems facing the nation this century.
The 46 centers were selected for funding from a pool of 260 applications after a rigorous merit review process. Each will be funded at $2 million to $5 million per year for an initial five-year period. (more…)
Microbes Turn Electricity Directly to Methane
Bruce E. Logan, Shaoan Cheng and Defeng Xing with a microbial cell that produces methane directly from electricity. (Credit: Bruce Logan's Lab, Penn State)
A tiny microbe can take electricity and directly convert carbon dioxide and water to methane, producing a portable energy source with a potentially neutral carbon footprint, according to a team of Penn State engineers.
“We were studying making hydrogen in microbial electrolysis cells and we kept getting all this methane,” said Bruce E. Logan, Kappe Professor of Environmental Engineering, Penn State. “We may now understand why.”
Methanogenic microorganisms do produce methane in marshes and dumps, but scientists thought that the organisms turned hydrogen or organic materials, such as acetate, into methane. However, the researchers found, while trying to produce hydrogen in microbial electrolysis cells, that their cells produced much more methane than expected. (more…)
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