News•May 29, 2014

CO2 Monitoring Could Be 'Space-Based' in Future

The measurement of carbon dioxide emissions from coal-fired power plants and other sources could be on its way to entering the space age.

Using satellites to measure atmospheric concentrations of climate change-fueling carbon dioxide originating from coal-fired power plants could help verify other countries’ claims about their emissions of greenhouse gases, helping regulators in the U.S. and abroad to enforce current and future international greenhouse gas emissions regulations, a new Los Alamos National Laboratory study shows. The study also showed the extent to which the plants, soon to be subject to new EPA emissions rules, pollute the local atmospere.

NASA's rendering of its Orbiting Carbon Observatory-2. Credit: NASA

The researchers used remote spectrometers on the ground to measure and compare emissions from the San Juan Generating Station with those of the Four Corners Generating Station, two large coal-fired power plants in northwest New Mexico, near the city of Farmington. Both plants together release about 30 megatons of CO2 into the atmosphere each year, making the area, ravaged by climate change-influenced drought, the largest point-source of pollution in both North America and South America.

By using remote sensors on the ground to measure the carbon emissions from two of the Southwest’s largest coal-fired power plants, the study, published in May in the Proceedings of the National Academy of Sciences, demonstrated the strategy and technology satellites may use to measure carbon emissions from CO2 sources all over the globe.

The use of satellites to measure carbon emissions is called “space-based verification,” and it could be a way to check the accuracy of other countries’ claims about how much carbon they emit.

For example, coal accounts for 70 percent of energy used in China today, primarily for electricity production, and its coal use is increasing, according to a Climate Central analysis.

But there are discrepencies in China's greenhouse gas emissions data, and satellite remote sensing could eventually provide accurate data that would help make it easier to enforce international emissions regulations.RELATEDThe Navajo Nation’s Shifting Sands of Climate Change
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“Chinese provincial and national CO2 emissions do not agree,” said Manvendra Dubey, an earth and environmental scientist at Los Alamos National Laboratory and one of the lead authors of the study. “There is a large gap between the two. We need to know which is right for accurate accounting and future targets.”

Scientists have had technical challenges using satellites to measure greenhouse gases because of their limited coverage area and low resolution, Dubey said.

“Our ground-based measurements provide a metric to examine and assess future satellite monitoring strategies,” he said, adding that research in using satellites to monitor atmospheric greenhouse gas concentrations will flourish when NASA launches its Orbiting Carbon Observatory-2 satellite in July.

The Los Alamos team clearly demonstrated the value of remote sensing for monitoring greenhouse gas emissions said David Crisp, the Orbiting Carbon Observatory-2 (OCO-2) science lead at NASA’s Jet Propulsion Laboratory. Crisp is unaffiliated with the Los Alamos study.

“To fully exploit this capability, we need to acquire measurements like this at high spatial resolution over the entire globe,” Crisp said. “One way to do this (is) to collect remote sensing observations from sensors deployed on space-based platforms. We have started down this road and we are making good progress.”

The Four Corners Power Plant in Northwest New Mexico. Credit: Carleton College

Today, sensors on the ground are more accurate at measuring greenhouse gases than satellites, but the OCO-2 is expected to take the next technological leap in satellite-based greenhouse gas measurement technology, he said.

For CO2 emissions to be accurately monitored from space, it would take a coordinated network of satellites similar to existing weather satellites, he said.

That network isn’t yet being built, but some countries have greenhouse gas-detecting satellites being launched within the next five years.

Beyond the demonstration of possible satellite-based greenhouse gas detection technology, the Los Alamos study had some surprising results about the two New Mexico power plant’s emissions.

The study found that 70 to 75 percent of the regional atmosphere within about 6 miles of the power plants is polluted with their emissions.

The key finding from the researchers’ analysis was that the polluted fraction of the regional atmosphere was “substantial,” relatively constant and mainly linked to the power plants.

The U.S. Environmental Protection Agency is releasing a proposed rule on June 2 that is expected to help reduce greenhouse gas emissions from existing coal-fired power plants, including the two New Mexico plants included in the Los Alamos study.