Carbon Chemist

Tag: greenhouse gas emissions

  • Crushed rocks and fertiliser switches can cut nitrous oxide from farms

    Crushed rocks and fertiliser switches can cut nitrous oxide from farms

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    Spreading rock dust on fields can sequester carbon and reduce nitrous oxide emissions

    SO-Photography/Alamy Stock Photo

    Spreading crushed basalt on cropland and using special fertilisers that stop nitrogen loss could cut global agricultural emissions of a potent planet-warming gas by 25 per cent.

    Nitrous oxide is a greenhouse gas with 270 times more warming power than carbon dioxide. Global emissions have risen by 40 per cent in the past 40 years. Agriculture is a major driver, due to increased use of nitrogen-based fertilisers and growing livestock numbers.

    Microbes in the soil convert ammonium from fertilisers and animal waste into nitrate and release nitrous oxide in the process. Chemical compounds that hamper this process, called nitrification inhibitors, can be added to fertilisers to reduce nitrous oxide emissions. Spreading basalt rock dust on soils, a technique known as enhanced rock weathering (ERW), can also help by making the soil more alkaline.

    But as well as being a planet-warming pollutant, nitrous oxide emissions also have a complex relationship with the ozone layer, in some circumstances aiding its recovery. It has therefore proved difficult to find the best approach to mitigate nitrous oxide emissions without inadvertently harming the ozone layer.

    To address this, Maria Val Martin at the University of Sheffield, UK, and her colleagues modelled the impact of widespread use of both ERW and nitrification inhibitors on nitrous oxide emissions and the ozone layer, under two different climate scenarios.

    They found a “moderate” approach, in which ERW is deployed in key regions around the world, and where most farmers except the poorest use nitrification inhibitors, could lower nitrous oxide emissions from agriculture by 25 per cent. Overall nitrous oxide emissions would be cut by 5 per cent. These gases also come from combustion engines and industry.

    What’s more, up to 2 gigatonnes of additional carbon would be sequestered in the soil thanks to the ERW, and there would be no harm to the ozone layer under both scenarios, says Val Martin.

    “We get the [carbon] sequestration from enhanced rock weathering; we have the decrease in nitrous oxide, which is 300 times more powerful than CO2, so we have the climate benefit from reducing nitrous oxide emissions. And then we safeguard the ozone layer,” she says.

    Deploying nitrous oxide reduction efforts on this scale would cost billions of dollars. Using ERW to sequester carbon will cost $80-180 per tonne of CO2, according to previous studies, with reduction in nitrous oxide emissions a “free” co-benefit of carbon sequestration, according to Val Martin. Using nitrification inhibitors costs around $28-45 per hectare, and to cover 600 million hectares, as modelled in the study, would cost $17-27 billion annually. That area is around an eighth of all farmland.

    Nevertheless, Val Martin says the scenario is deliberately cautious in its ambition, so it could be deployed in the real world. “With this work, what we wanted to do is come up with a scenario that could be realistic. So if governments want to mitigate nitrous oxide, they can do it with [these] strategies that we have in place.”

    Parv Suntharalingam at the University of East Anglia, UK, says new strategies to curb nitrous oxide emissions are urgently required, and the study is especially valuable for its focus on curbing emissions without harming the ozone layer.

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    • agriculture/
    • greenhouse gas emissions

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  • Shipping companies are testing biofuel made from cashew nut shells

    Shipping companies are testing biofuel made from cashew nut shells

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    Cashew nut shells contain an acid that can be made into biofuel

    Janet Horton/Alamy Stock Photo

    As the shipping industry hunts for ways to slash greenhouse gas emissions, companies are experimenting with cleaner fuels made from cashew shells and other types of biomass to power their vessels. But it is unlikely there will be enough of such biofuels to make much difference for an industry that consumes hundreds of millions of tonnes of fossil fuels each year.

    “The shipping industry has been on this walk through the desert just trying to find stuff that works in their existing infrastructure,” says …

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  • Is climate change accelerating after a record year of heat?

    Is climate change accelerating after a record year of heat?

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    The record-breaking heat of 2023 has seen a rare disagreement break out between climate scientists, with some saying it shows Earth may have entered a new period of warming

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  • Plastic pollution treaty would be ‘failure’ without tackling emissions

    Plastic pollution treaty would be ‘failure’ without tackling emissions

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    People took part in a rally in Ottawa to support ending plastic pollution

    Canadian Press/Shutterstock

    Delegates from nearly every country are gathered in Canada to hammer out the details of a global treaty to address ballooning plastic pollution. One source of division at the summit, which concluded 29 April, was how to address the greenhouse gas emissions generated by producing and using plastic, a growing and under-recognised driver of climate change.

    “When people think about plastic, they think about what they see visually,” says Alice Zhu at the University of Toronto in Canada. But extracting and processing the fossil fuels and other chemicals used to make plastic produces substantial greenhouse gas emissions, as does generating the energy required to make plastic products. Plastic now accounts for around 10 per cent of total demand for oil and natural gas; coal is also increasingly used to power plastic production.

    Incinerating plastic waste is another source of greenhouse gas emissions. As it degrades, plastic in the environment can also produce carbon dioxide and methane emissions. Plastic may even reduce how much carbon ecosystems can store, although these effects are poorly quantified, says Zhu.

    The numbers on emissions from producing plastic are clearer. In a study published this month, Nihan Karali at Lawrence Berkeley National Laboratory in California and her colleagues estimated plastic production in 2019 generated the equivalent of 2.24 billion tonnes of CO2, or about 5 per cent of global greenhouse gas emissions. That is roughly 4 times more emissions than were produced by aviation that year.

    Assuming no changes to how plastic is produced, they found these emissions could triple by 2050 with increases in plastic production. Since most of the emissions are associated with extracting and processing the fossil fuels and other chemicals used to make plastics, they also found decarbonising the power grid has only a small effect on projected emissions.

    The global plastic treaty now under debate could offer a “historic” chance to limit those emissions, the researchers wrote. In 2022, more than 175 countries agreed to join a legally binding treaty that would address plastic pollution across the full life cycle of the material, with final details to be agreed by the end of this year.

    However, a group of petroleum-producing countries, including China and Russia, argued during negotiations that the treaty should only address plastic waste through clean-up and recycling, and not limit or change production, which is the main source of greenhouse gas emissions from plastic. A group of countries including the UK and EU have argued the treaty should include provisions to reduce production to keep emissions in line with global climate targets.

    “There’s so many things on the table, and climate is certainly not being discussed too much,” says Neil Nathan at the University of California, Santa Barbara, who attended the meeting to advocate for an ambitious treaty.

    According to modelling from Nathan and his colleagues, he says a strong treaty that limits production and take other steps, like mandating that plastic products contain a high proportion of recycled material, could keep emissions at their current levels. He says the plastics treaty would be “a failure” if it didn’t address production.

    Sarah-Jeanne Royer at the University of California, San Diego says reducing the use of new plastic through recycling or switching to more sustainable materials to make plastic, such as bioplastics or captured CO2, would also reduce greenhouse gas emissions, even if the treaty didn’t address them explicitly.

    However, Paul Stegmann at TNO, a research organisation in the Netherlands, cautions that some alternatives to plastic, such as steel, may generate more emissions, depending on how they are reused and recycled. “In the end we need policies that ensure that we do not just shift the problem elsewhere but that reduce the system-wide impact of our society,” he says.

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  • The incredible new tech that can recycle all plastics, forever

    The incredible new tech that can recycle all plastics, forever

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    RGY487 Used plastic crushed, Prepared to be re-melted into recycled plastic pellets

    Satakorn Sukontakajonkul/Alamy

    I spend an inordinate amount of time in my kitchen scrutinising pieces of plastic, trying to discern whether they are recyclable or not. If they are, they go into a bag alongside glass, cans, cardboard and paper. If not, or if I am unsure, I put them in a plastic bag (non-recyclable) and shove it into the cupboard under the stairs. My intention is to deposit it in a container for non-recyclable plastics in a nearby supermarket. But the road to landfill is paved with good intentions. Sometimes I get exasperated and just end up chucking it.

    Whether my obsessive sorting actually makes any difference, I don’t know. I hope the recyclables do end up being recycled. As for the other stuff, which makes up about half of my plastic waste, I have no idea of its fate. I presume it is called “non-recyclable” for a reason.

    Hopefully, I soon won’t have to waste any more of my precious time triaging this type of waste. A suite of “advanced recycling” technologies is gradually coming on stream, promising to take used plastic of any type and convert it into something extremely useful: plastic. The goal is to create a circular economy for this material where there is no longer any need to make virgin plastic from crude oil, just endlessly recycle what we already have. Plastic, rightly demonised as a scourge of the modern world, could be fantastic again.

    There is plenty of it to work with. Since the 1950s, we have produced over 10 billion tonnes…

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  • Methane leaks from US oil and gas are triple government estimates

    Methane leaks from US oil and gas are triple government estimates

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    A methane plume detected by NASA's AVIRIS-NG in summer 2020 indicates a leaking gas line in oil field in California

    A methane plume in California detected by an airborne spectrometer

    NASA/JPL-Caltech

    Major oil and gas-producing regions in the US are leaking much more methane than current estimates suggest, according to nearly a million aerial measurements of the potent greenhouse gas.

    “Our study used the largest such dataset that’s ever been assembled,” says Evan Sherwin at Lawrence Berkeley National Laboratory in California, who conducted the research while at Stanford University.

    He and his colleagues combined data from numerous aerial surveys that used infrared sensors to measure methane leaking from wells, pipelines…

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  • Satellite launched to track down leaks of potent greenhouse gas

    Satellite launched to track down leaks of potent greenhouse gas

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    methaneSAT

    An artist’s impression of MethaneSAT

    Environmental Defense Fund/NASA

    A satellite expected to transform our view of planet-warming methane emissions from oil and gas production has launched from the Vandenburg Space Force Base in California. Called MethaneSAT, the satellite will orbit the planet 15 times per day, using infrared sensors to measure methane leaking from all of the world’s major production centres.

    “We designed MethaneSAT explicitly to serve one goal,” says Steven Hamburg at the Environmental Defense Fund (EDF), the non-profit advocacy group that developed the satellite along with a consortium of universities and aerospace firms. “To produce policy-relevant data to track methane emissions from the oil and gas industry, globally.”

    Methane is the most significant greenhouse gas behind carbon dioxide. And oil, gas and coal production are among the largest sources of anthropogenic methane emissions. Many governments have set targets to slash methane emissions by 30 per cent by 2030, and at the COP28 climate summit last year, a number of large oil and gas companies pledged to zero out all methane emissions from their operations by 2050.

    But assessing progress towards those pledges is difficult. Current methane emissions remain poorly quantified, leaks are challenging to track and aerial surveys and on-the-ground monitoring are expensive – and some countries don’t allow them. MethaneSAT joins a growing constellation of methane-sensing instruments in orbit aiming to provide a better view. Existing satellites, like the European Space Agency’s TROPOMI, sense methane emissions across large regions. Others, like the 11 methane-sensing instruments run by Canadian company GHGSat, focus on identifying specific point sources of methane.

    In contrast, MethaneSAT will regularly monitor methane at high resolution in between these scales, enabling researchers to quantify emissions across the areas relevant to oil and gas production as well as map their probable sources. “We needed to be able to see all the emissions and resolve them in space,” says Hamburg.

    Once running full bore, the satellite will deliver up to 30 different 40,000 square kilometre “scenes” of measured methane flux per day, according to Hamburg. He says they will prioritise monitoring oil and gas production regions – such as the Permian basin in west Texas – but will also be able to measure methane from other major sources like agriculture, wetlands and landfills. “Methane is methane,” he says.

    Along with developing the satellite, Hamburg and his colleagues have produced a pipeline to rapidly turn the raw data it generates into publicly available estimates of the amount of methane emissions, and the probable sources of plumes. This includes a global database of oil and gas infrastructure created in partnership with Google to help link detections of methane with their sources.

    “We’re mapping the whole thing,” says Hamburg. He says the satellite will generate more data on methane emissions from oil and gas in its first year of operation than was collected over the past 50 years. Full data collection is expected to begin in early 2025.

    “The data is here, and the technology is here to start taking action,” says Jean-Francois Gauthier at GHGSat, who expects MethaneSAT will help identify sources of emissions that GHGSat’s focused satellites can then measure in more detail.

    Rob Jackson at Stanford University in California says the satellite will provide an independent check on emissions reported by companies and countries. “There will be nowhere to hide,” he says. The flood of data could also help explain the still-uncertain source of rising rates of methane since 2007, he adds.

    “The big question for me is how people will use the information,” says Jackson. “There’s an assumption out there that once we have all the information the emissions will go away somehow. But having information from aircraft and on-the-ground sources has not stopped those emissions.”

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  • Sinking plankton poo could help store more carbon in the ocean

    Sinking plankton poo could help store more carbon in the ocean

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    When the faecal matter produced by plankton sinks, it carries carbon from shallow waters to long-term storage deep in the ocean – now, researchers want to make the stuff sink faster

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  • Rising greenhouse gases actually cool Antarctica – because it’s so dry

    Rising greenhouse gases actually cool Antarctica – because it’s so dry

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    Antarctica

    Above some parts of Antarctica, there is a curious negative greenhouse effect

    imageBROKER.com GmbH & Co. KG / Alamy

    Rising concentrations of methane and carbon dioxide have led to a “negative greenhouse effect” above parts of Antarctica, but this slight cooling effect could reverse as the air becomes more humid alongside rising temperatures.

    Greenhouse gases like CO2 and methane heat the planet by trapping radiation from its surface. However, in certain rare circumstances they can have a cooling effect, where the atmosphere radiates more heat out into space from its warm upper layers than it traps nearer to…

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  • Rising greenhouse gases have cooling effect on Antarctica’s atmosphere

    Rising greenhouse gases have cooling effect on Antarctica’s atmosphere

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    Antarctica

    Above some parts of Antarctica, there is a curious negative greenhouse effect

    imageBROKER.com GmbH & Co. KG / Alamy

    Rising concentrations of methane and carbon dioxide have led to a “negative greenhouse effect” above parts of Antarctica, but this slight cooling effect could reverse as the air becomes more humid alongside rising temperatures.

    Greenhouse gases like CO2 and methane heat the planet by trapping radiation from its surface. However, in certain rare circumstances they can have a cooling effect, where the atmosphere radiates more heat out into space from its warm upper layers than it traps nearer to…

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