Tag: greenhouse gas

ANSTO scientists help refine estimates of global methane emissions

ANSTO scientists help refine estimates of global methane emissions

A groundbreaking international study published in the Journal of Geophysical Research: Atmospheres has provided new insights into global fossil methane emissions, using innovative multi-isotopic atmospheric measurements.  

Principal Accelerator Scientist Dr Andrew Smith, a co-author who has investigated methane emissions for over two decades with A/Prof Vasilii Petrenko and others, contributed significantly to this collaborative research, which has improved the accuracy of greenhouse gas emission estimates and support more effective global climate mitigation efforts. 
 

The study, led by Dr Ryo Fujita of the Imperial College London and the Japanese Meteorological Research Institute in Tsukuba, used advanced isotopic analysis, including radiocarbon and stable isotopes of carbon and hydrogen, to accurately distinguish between different methane emission sources. This research is the first research to integrate multiple isotopic datasets to precisely quantify global methane emissions from fossil fuels, biogenic, geologic, and biomass burning sources across the historical timeframe from 1750 to 2015. 

One key finding of the study was that global fossil methane emissions are about 130 teragrams per year for the period 2003–2012, which closely matches the Global Carbon Project estimates, a network of scientists and institutions investigating greenhouse gases. To put this into perspective, a teragram is one trillion grams, approximately equivalent to the mass of water in 400 Olympic-sized swimming pools.  
 

Importantly, the study contradicts earlier claims of significantly underestimated fossil methane emissions, bringing clarity to previously conflicting scientific assessments. 

Dr. Smith highlighted the importance of multi-isotopic measurements for resolving uncertainties in methane emission inventories. “This study demonstrates that combining multiple isotopic constraints significantly reduces uncertainties in methane emission estimates. Such precise data are crucial for effective climate policy and mitigation strategies,” he said. 

ANSTO’s Centre for Accelerator Science, a world leader in extracting and accurately measuring radiocarbon from minuscule carbon samples.  This intricate process requires the identification and counting of individual atoms through accelerator mass spectrometry.  

Read more on ANSTO website

New catalyst could cut pollution from millions of engines

New catalyst could cut pollution from millions of engines

Researchers demonstrate a way to remove the potent greenhouse gas from the exhaust of engines that burn natural gas.

Individual palladium atoms attached to the surface of a catalyst can remove 90% of unburned methane from natural-gas engine exhaust at low temperatures, scientists reported today in the journal Nature Catalysis. 

While more research needs to be done, they said, the advance in single atom catalysis has the potential to lower exhaust emissions of methane, one of the worst greenhouse gases, which traps heat at about 25 times the rate of carbon dioxide. 

Researchers from the Department of Energy’s SLAC National Accelerator Laboratory and Washington State University showed that the catalyst removed methane from engine exhaust at both the lower temperatures where engines start up ­­­and the higher temperatures where they operate most efficiently, but where catalysts often break down. 

“It’s almost a self-modulating process which miraculously overcomes the challenges that people have been fighting – low temperature inactivity and high temperature instability,” said Yong Wang, Regents Professor in WSU’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering and one of four lead authors on the paper. 

A growing source of methane pollution 

Engines that run on natural gas power 30 million to 40 million vehicles worldwide and are popular in Europe and Asia. The natural gas industry also uses them to run compressors that pump gas to people’s homes. They are generally considered cleaner than gasoline or diesel engines, creating less carbon and particulate pollution.

However, when natural-gas engines start up, they emit unburnt, heat-trapping methane because their catalytic converters don’t work well at low temperatures. Today’s catalysts for methane removal are either inefficient at lower exhaust temperatures or they severely degrade at higher temperatures. 

“There’s a big drive towards using natural gas, but when you use it for combustion engines, there will always be unburnt natural gas from the exhaust, and you have to find a way to remove that. If not, you cause more severe global warming,” said co-author Frank Abild-Pedersen, a SLAC staff scientist and co-director of the lab’s SUNCAT Center for Interface Science and Catalysis, which is run jointly with Stanford University. “If you can remove 90% of the methane from the exhaust and keep the reaction stable, that’s tremendous.”

A catalyst with single atoms of the chemically active metal dispersed on a support also uses every atom of the expensive and precious metal, Wang added. 

“If you can make them more reactive,” he said, “that’s the icing on the cake.”

Unexpected help from a fellow pollutant 

In their work, the researchers showed that their catalyst made from single palladium atoms on a cerium oxide support efficiently removed methane from engine exhaust, even when the engine was just starting. 

They also found that trace amounts of carbon monoxide that are always present in engine exhaust played a key role in dynamically forming active sites for the reaction at room temperature. The carbon monoxide helped the single atoms of palladium migrate to form two- or three-atom clusters that efficiently break apart the methane molecules at low temperatures. 

Then, as the exhaust temperatures rose, the clusters broke up into single atoms and redispersed, so that the catalyst was thermally stable. This reversible process enabled the catalyst to work effectively and used every palladium atom the entire time the engine was running – including when it started cold.

Read more on SLAC website