Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

California's N2O emissions may be nearly triple current estimates

05.12.2012
More Potent than Carbon Dioxide, Nitrous Oxide Levels in California May be Nearly Three Times Higher Than Previously Thought

Berkeley Lab researchers devise a new method to estimate state’s greenhouse gas emissions

Using a new method for estimating greenhouse gases that combines atmospheric measurements with model predictions, Lawrence Berkeley National Laboratory (Berkeley Lab) researchers have found that the level of nitrous oxide, a potent greenhouse gas, in California may be 2.5 to 3 times greater than the current inventory.

At that level, total N2O emissions—which are believed to come primarily from nitrogen fertilizers used in agricultural production—would account for about 8 percent of California’s total greenhouse gas emissions. The findings were recently published in a paper titled “Seasonal variations in N2O emissions from central California” in Geophysical Research Letters. Earlier this year, using the same methodology, the researchers found that levels of methane, another potent greenhouse gas, in California may be up to 1.8 times greater than previous estimates.

“If our results are accurate, then it suggests that N2O makes up not 3 percent of California’s total effective greenhouse gases but closer to 10 percent,” said Marc Fischer, lead researcher on both studies. “And taken together with our previous estimates of methane emissions, that suggests those two gases may make up 20 to 25 percent of California’s total emissions. That’s starting to become roughly comparable to emissions from fossil fuel CO2.”

Accurate estimates of the California’s greenhouse gas emissions are important as the state works to reduce emissions to 1990 levels by 2020, as mandated by a law known as AB 32. The vast majority of the reduction efforts have been focused on CO2.

Nitrous oxide, better known as laughing gas, is an especially potent greenhouse gas because it traps far more infrared radiation than both carbon dioxide and methane. “It’s present in the atmosphere at tiny concentrations—one-thousandth that of CO2—but it is very potent,” Fischer said. “It has a global warming potential of approximately 300, meaning it is 300 times more active than CO2 per unit mass. And it’s 10 to 15 times more potent than methane.”

Worldwide levels of N2O have been rising rapidly for decades, and the major culprit was recently confirmed to be the heavy use of nitrogen fertilizers to grow the world’s food. Other less significant sources of N2O emissions include wetlands, animal and industrial waste and automobiles.

The standard method for estimating emissions levels has been to do what is called a “bottom-up inventory.” This process involves listing all the activities that emit N2O, assigning an emission factor for each activity, then tallying up the emissions. However, this method can result in large uncertainties because of the way N2O is produced.

“The biogeochemical processes that produce N2O are sensitive to environmental conditions and very small changes in things like temperature, moisture, the type of soil and when the fertilizer is applied,” Fischer said. “All those factors can result in big differences in the amount of N2O that’s produced. If you try to use a single number for a given patch of land, you’re almost certainly going to get a variable result.”

While there are models that try to capture these factors, “it is still likely the numbers are going to have relatively large uncertainties, especially compared to thing like burning fossil fuels to make CO2, where pretty much every mole of carbon becomes CO2,” Fischer said.

The method that Fischer and his colleagues describe in their paper compares measurements taken from a 2,000-foot tower in Walnut Grove, California to model predictions of expected N2O levels based on the bottom-up inventory to arrive at the new estimate. “This is the first study of its kind to look at a full annual cycle of emissions—actually it’s two years—from a large region of California that includes the sources that we believe are most important,” Fischer said. “In general, we found that the measured signals were much bigger than the predicted signals.”

The predicted signal at the tower was calculated by taking the bottom up inventory (from EDGAR, the Emissions Database for Global Atmospheric Research) and running it through a weather model—which includes information on wind speed and direction. “From that we can estimate how much signal we should see at the tower per unit of emission on the land surface,” Fischer said.

He acknowledges that his new method also has sources of uncertainty. For example, the EDGAR model is weighted to urban areas with large populations, which may not be an accurate assumption for N2O emissions from California. “Further work in urban areas is necessary,” he said.”

Fischer is working with the California Air Resources Board to add measurement instruments for both nitrous oxide and methane at additional towers around the state to further refine the data and better understand emissions from urban areas.

As a way to verify the method, Fischer and his team are currently comparing measured and predicted fossil fuel CO2 signals at the tower since there is a much better understanding of how much fossil fuel is burned in California. If the predicted signal and measured signal are close, then that would be a good indication that the method is sound. “Initial comparisons of measured and predicted fossil fuel signals agree at the 10 to 20 percent level, suggesting that it is unlikely there are much larger errors in the transport model,” he said. “But we haven’t ruled it out.”

Fischer is head of the California Greenhouse Gas Emissions Measurement (CALGEM) Project at Berkeley Lab. This research was supported by funding from the California Energy Commission. Scientists from the National Oceanic and Atmospheric Administration (NOAA), Lawrence Livermore National Laboratory and the University of Colorado at Boulder contributed to the study.

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.

Julie Chao | EurekAlert!
Further information:
http://www.lbl.gov

More articles from Earth Sciences:

nachricht Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

A new technique isolates neuronal activity during memory consolidation

22.06.2017 | Life Sciences

Plant inspiration could lead to flexible electronics

22.06.2017 | Materials Sciences

A rhodium-based catalyst for making organosilicon using less precious metal

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>