Liverpool-based DefProc Engineering has secured a place in this year’s Hydrogen Innovation Challenge, organized by climate tech hub Sustainable Ventures.

Developed for Northern Gas Networks, the sensor monitors low-pressure gas supply at NGN’s Low Thornley site near Gateshead; successful testing and trials will see it rolled out to consumers across Yorkshire, the North East and Cumbria, says DefProc.

The firm will now receive one-to-one support for the rest of the year and the opportunity to present the Smart Gas Pressure Sensor at an innovation showcase in front of potential partners and regional end users.

The aim is that the Hydrogen Innovation Challenge will connect them to a wider network of gas distributors looking to decarbonise their networks by innovative means.

Jen Fenner, managing director and co-founder of DefProc Engineering, said: “The Hydrogen Innovation Challenge is an incredible opportunity to showcase our capabilities as end-to-end design engineers and a market-leading innovation partner.

“We’ve worked on some revolutionary projects in recent years and the support from the Hydrogen Innovation Challenge will allow us to present these to a wider network of potential clients and make a tangible difference to the future of sustainability.”

In addition to the Smart Gas Pressure Sensor, which works with natural gas, blended hydrogen supply or 100% hydrogen, DefProc Engineering has designed and delivered what it describes as the UK’s first low-cost domestic hydrogen sensor, H2Go for the EIC, Northern Gas Networks and Wales and West Utilities.

Similar to the look and operation of a traditional smoke alarm, H2Go will be the basis for manufactured domestic hydrogen sensors in the future.

Lee-Ann Perkins, Sustainable Ventures hydrogen program manager, added: “Through the Hydrogen Innovation Challenge, we’re empowering startups to lead the charge in the UK’s energy transition, providing the tools and partnerships to bring innovations to market.”

Earlier this year, DefProc Engineering was also one of five pioneering UK businesses chosen for a new Hydrogen Sensor Accelerator Programme with Digital Catapult, a first-of-its-kind eight-week programme to deliver the UK strategy for hydrogen technology.”

Researchers at the University of Sheffield are exploring new exhaust aftertreatment systems for heavy-duty engines capable of running on clean, zero-carbon fuels such as ammonia. This four-year project is funded by an EPSRC grant and supported by the industrial partner Eminox. The project is led by Bill Nimmo, Professor of Energy Engineering and Sustainability, with PhD student Madhumitha Rajendran.

Background
The decarbonisation of transport represents a vitally important component of global initiatives to minimise the impacts of climate change. However, whilst the electrification of light vehicles is a logical way forward, heavy vehicles used in the rail, marine and construction sectors have high torque requirements that are unsuited to electric power. In addition, diesel engines burn fossil fuels releasing carbon dioxide, a greenhouse gas (GHG), as well as other pollutants, such as nitrogen oxides (NOx). Some oxides of nitrogen are not GHGs but they do perform a role in the formation of tropospheric ozone which is a GHG. Nitrous oxide (N2O) however, is produced by combustion processes, and is a potent GHG.

Alternative solutions are necessary across the entire transport sector, hence the drive toward clean fuel engine development, alongside new exhaust treatment technologies.

New exhaust treatment systems for heavy-duty engines
The research focuses on ammonia as a clean fuel. The first stage involves modeling dual fuel combustion and emission characteristics of ammonia with a carbon-based promoter. Ammonia requires a combustion promoter because of its higher absolute minimum ignition energy than traditional fuels. The second stage of the work will evaluate the NOx reduction efficiencies of commercial catalysts for the ammonia-based dual fuel, utilising a suite of Signal Group gas analysers donated to the project by Eminox.

Why ammonia?
Ammonia is considered a clean fuel because its (complete) combustion products are nitrogen and water. However, NOx gases are a byproduct of ammonia combustion. Nevertheless, ammonia represents a relatively good energy source and global infrastructure for its production and transportation already exists because of ammonia’s role in agricultural fertilizers.

There are several types of ammonia, each attributed a colour according to its production method. Traditional ammonia is known as ‘grey’ because it uses natural gas, but if carbon capture is used to remove carbon dioxide emissions, the ammonia is labelled ‘blue’. ‘Green’ ammonia is made using green hydrogen, created by electrolysis from renewable energy, so no fossil fuels are required.

In contrast with hydrogen, ammonia does not require cryogenic conditions for transportation as a liquid. Also, ammonia can be produced from hydrogen, and ammonia can be ‘cracked’ back to hydrogen after transportation, which means that ammonia can help resolve the transport issues associated with hydrogen.

Ammonia presents a number of challenges as a fuel for engine combustion. In addition to the requirement for a promoter fuel, these include NOx in the exhaust as well as ammonia slip, which is important because ammonia is both corrosive and toxic, and because unburned fuel represents inefficiency.

Research phase 1 – Dual fuel combustion modelling
Initial work is being undertaken with ‘Ansys Chemkin-Pro’ a chemical kinetics simulator program that models idealised reacting flows and provides insight into results. Madhumitha has been using the modelling program to investigate predicted effects on engine efficiency and emissions profile, by adjusting a number of different variables, such as stoichiometry, fuel energy shares, and fuel injection parameters. The results of the modelling are being used to inform subsequent work.

Research phase 2 – Post-combustion treatment
The second phase of the research, which is due to commence at the end of 2024, will evaluate the NOx reduction efficiencies of commercially available selective catalytic reduction (SCR) materials under a range of different conditions. Three different SCR catalysts will be trialled, based on zeolite, vanadium oxide and titanium.

The research laboratory in Sheffield contains a controlled temperature furnace reactor using simulated exhaust gases. Catalyst studies will be performed at Sheffield while partners at Brunel University in London will be conducting similar work with a diesel engine test bed; primarily to investigate combustion and fuel injection issues relating to ammonia fuel, but also to help verify exhaust gas composition under a range of conditions. Combined with the kinetic simulation work at Sheffield, realistic exhaust gas composition will be fed to the experimental reactor.

Gas analysis
The post catalyst exhaust gases will be analysed by the Signal Group analyser rack, after treatment by the catalysts. This instrumentation includes a heated vacuum chemiluminescence gas analyser for the measurement of NOx, NO and NO₂. A flame ionisation detector to analyse hydrocarbon levels, and a non-dispersive infrared multi-gas analyser for continuous measurements of carbon monoxide and carbon dioxide. This instrument is also fitted with an oxygen sensor.

Initial results
So far, modelling work has indicated that the use of an ammonia dual fuel could increase

N₂O emissions under certain operating conditions, particularly in cold starts. Exhaust gas temperature will reduce, while moisture and hydrogen levels can be expected to increase, and the effects of this on SCR catalyst deNOx efficiency will be studied further.

The model also showed that the utilisation of ammonia dual fuel has a number of implications for prospective SCR catalysts. For example, ammonia in the exhaust can help reduce NOx, and both hydrogen and hydrocarbons in the exhaust can enhance NOx conversion at moderate temperatures. However, N₂O will be difficult to decompose at low temperatures. By identifying regimes of operation and emissions, recommendations can be made on catalyst specification and operating conditions to mitigate any operational issues.

Summary
The development of clean fuel technology will be critically important to the decarbonisation of heavy vehicles. For example, the International Maritime Organisation (IMO) has a GHG emissions reduction strategy to reach net-zero by 2050, including a 20% reduction by 2030 and a 70% reduction by 2040, compared to 2008 levels. To reach these ambitions, the IMO will implement regulatory measures to be adopted in 2025 and enter into force around mid-2027. The achievement of these decarbonisation goals will depend heavily on the use of carbon-neutral fuels. This, in turn, means that new engine technology will be necessary, operating efficiently under known stoichiometric conditions, combined with effective aftertreatment systems to ensure the release of non-toxic, climate-friendly emissions.

Madhumitha explains, “The challenge for the project is to consider the minimisation of all potentially harmful emissions from new fuels, and we will be keeping a close eye on any N₂O, NO_x and ammonia when developing the new SCR systems.  However, the successful achievement of our goals will play an important role in helping the heavy vehicle sector to reduce its GHG emissions, so we are hugely excited about the prospects for this important project.”

Edinburgh start-up Chromacity shares details of the development of a next-generation optical solution for the detection of contaminants in renewable hydrogen.

While renewable hydrogen is widely acknowledged to play a growing role in decarbonising the economy, challenges remain to control its purity. With supply from diverse sources including green, blue and regasified hydrogen from storage media, users need confidence that the gas they use is of sufficient quality that it will not damage key components such as fuel cells or infrastructure.

Working in partnership with the Herriot Watt University* and Frauhofer UK*, a new solution combining high brightness, coherent Optical Parametric Oscillator (OPO) laser technology from Chromacity, with advanced FTIR spectroscopy techniques, has been shown to offer advantages over current technologies. ISO 14687:2019, which defines thresholds for a wide range of contaminants in hydrogen for fuel cells, is being used to benchmark this exciting development.

Julian Hayes, CEO of Chromacity Ltd commented: “Existing optical solutions for determining the purity of renewable hydrogen either compromise on spectral resolution and detection sensitivity or are overly complex making them expensive which limits deployment. Likewise, the implementation of sensitive gas chromatography techniques is limited because the instrumentation is costly, bulky, and online sampling is challenging.”

He added: “Based on a single light source, our solution removes the complexities of multi-source optical techniques and so lowers the cost of ownership. The broad, tuneable bandwidth of the OPO laser allows many contaminants to be detected, including broad or complex chemical signatures. Our instrument is designed to be used in-line and has been shown to monitor the five key contaminants in the renewable hydrogen production process (as detailed in ISO 14687) in real time”.

Mr Hayes concluded “Having been successfully tested in the lab on representative gas samples, the next stage of developing the system is to enable users to use live real-time data to drive optimisation of the production process.”

For further information contact Chromacity on +44-131-449-4308, or email sales@chromacitylasers.com.

*This development project received investment from Scottish Government Emerging Energy Technologies Fund (EETF) – see https://www.gov.scot/publications/emerging-energy-technologies-fund-hydrogen-innovation-scheme-successful-projects/

Gas and flame detection
Oil and gas companies constantly scrutinise new technologies that reduce the risks to personnel, property or the environment. At ONS 2024, Teledyne GFD will exhibit a range of portable and fixed detectors. The GD1 hydrogen sulphide (H2S) open-path laser detector, for example, offers high performance while overcoming the obstacles provided by challenging offshore environmental effects that include sun, rain and fog. “This popular device provides fail-safe, rapid responses in up to 98% obscuration,” says the firm.

Visitors can also learn about the GD10P infrared gas detector, which houses features that provide an effective response to the detection of gas hazards in high demand mode SIL2-approved applications. One differentiator of this product is its silicon-based solid-state infrared source. Long service life and robust detector stability help users reduce maintenance and service costs.

The stand will also exhibit the recently introduced Spyglass flame detector. “The product’s integrated high-definition CCTV video delivers clear, rapid imaging of fires,” says the firm. Colour video detects fuel fires like gasoline and jet fuel, while the near-infrared video option detects fires caused by other fuels such as hydrogen and methanol.

Thermal imaging
On the same stand, FLIR a Teledyne technologies company will demonstrate its prowess in helping oil and gas inspectors, managers, and technicians deliver quick thermal imaging solutions to problems that include leak detection and maintaining system integrity. Highlights at ONS 2024 are set to include the G-Series cameras, designed to detect hydrocarbons, methane (CH₄) and other Volatile Organic Compound (VOC) emissions from multiple stages of the oil and gas supply chain, as well as other industrial markets.

Under the new EU Methane Regulation, which aims to reduce methane emissions in the energy sector, companies are now required to quantify methane emissions at both the source and site levels. The G-Series range features advanced gas quantification analytics within the camera itself, capable of measuring leak type and severity, ensuring compliance with the new regulation.

Elsewhere on the booth will be the advanced QL320, a quantitative optical gas imaging system for measuring the leak rate of methane and other hydrocarbon emissions captured by FLIR OGI cameras. By adopting the QL320, users no longer require a toxic vapor analyser or similar tool for secondary sampling.

Marine products
Teledyne Marine provides offshore energy equipment for reliable operation in oil fields and wind farms. Although offering a vast plethora of solutions, the focus at ONS 2024 will be subsea distribution units and downhole optical connectors.

The Modular Connectorized Distribution Unit (MCDU), for instance, is a factory-qualified subsea distribution unit that provides oil-filled, pressure-balanced junctions for flexible underwater configurations. ROVs (remote operated vehicles) can easily install and retrieve the unit from the sea floor thanks to the latest compact-frame design which eliminates the requirement for lifting wires.

A further product focus from Teledyne Marine will be the Optical Feedthrough System (OFS). This downhole, ‘wet mateable’ optical connector is for high-pressure/high-temperature environments within a vertical Xmas tree (VXT) valve stack on a subsea wellhead. Providing pressure integrity barriers and optical continuity, the OFS on display will measure 2” (50mm) in diameter and 12” (300mm) long. An associated display screen will show an animation of its operation.

Teledyne experts will be present throughout ONS 2024, ready to discuss the optimal solutions for new projects or existing challenges.

This article contains paid for content produced in collaboration with Dräger.

Ryan is a Fixed Gas Detection Regional Account Manager based in Wiltshire, responsible for Dräger’s Fixed Gas Detection customers in the South-West of England. Ryan joined the FGDS Dräger team in March.

How are you finding things with the Dräger team so far?
I’ve only joined the team a little less than a month ago but so far, it’s been great! I’m learning a lot about the company, its values, all the interesting safety products we have, and getting to know my co-workers. We have a fun team here in Dräger’s Fixed Gas Detection Team and they’ve been very welcoming and helpful while I’m getting up to speed. It’s made my first few weeks here a great experience overall and I’m happy to have joined the Dräger team.

It’s great to have you onboard, Ryan. Can you tell us a bit about yourself and your background?
I am Wiltshire born and bred, however I do not own a combine harvester or tractor. I maintain a very active lifestyle, exercising and eating healthy, and I’m passionate about Crossfit – both in participation and in coaching. I coach children and seniors. In fact, my youngest athlete is 7 and my oldest is 83, so that shows you that anyone can do it! I am a firm believer that everyone should just get up and move as much as they can. I also enjoy Football and Jujitsu, as well as taking trips to Old Trafford with my nephew. And you can’t beat a good holiday to take some time to refresh – even if it’s just a short break!

I know it’s still early in your time with Dräger, but what do you think about the company and its contributions to the industry?
I still have much to learn about, but I really appreciate Dräger’s approach to safety and the value it puts on using technology to create products that keep people safe from harm. It’s so interesting to me to think that Dräger has been around for more than 130 years and still coming up with new ideas all the time, utilising wireless and smart technology to stay in line with industry needs and employing cloud storage to make it easier to access and transfer data.

Do you have a favourite Dräger product yet?
I do! I’m really impressed with the Dräger X-node. It’s a wireless gas detection product that can measure gas concentration levels, temperature, humidity, pressure – pretty much everything you need! Being wireless is obviously a huge benefit since the customer doesn’t need to worry about connecting the X-node to wired power or a cable for transmitting data, so you can install it virtually anywhere you want to, and the rechargeable battery is reliable for up to 12 months. And you can access the X-node via a Bluetooth-connected device to make adjustments or access data.

What can your customers expect from working with you?
I’ve always been a people person and I naturally fell into a junior sales role at 19. I enjoyed working in sales and was good at it, so I’ve stuck with this type of role trying different products, from glass radiators to luxury holiday homes. Once I moved into technical sales about six years ago, I knew I’d found my feet. I enjoyed meeting and working with a variety of customers, helping them with their projects and offering them real solutions. I love the variance in customer sites too, already I have visited a dairy, a well-known crisps maker and water treatment works. It’s great. Now I get to learn all about new products and services from Dräger and meet new customers. I get a lot of satisfaction from meeting new people, hearing about each customer’s unique challenges and then offering a suitable solution. It makes for an exciting and rewarding experience at work!

A laser-based technology developed at TU Graz can provide continual real-time analysis of air pollutants and their interaction with other gases and sunlight – with revolutionary import, suggest the group.

Sunlight has a major influence on chemical processes. Its high-energy UV radiation in particular is strongly absorbed by all materials and triggers photochemical reactions of compounds present in the air. A well-known example is the formation of ground-level ozone when UV light hits nitrogen oxides. A research team led by Birgitta Schultze-Bernhardt from the Institute of Experimental Physics at Graz University of Technology (TU Graz) is now utilising this high reaction potential for a new method of environmental monitoring. They have developed the world’s first broadband UV dual-comb spectrometer with which air pollutants can be continually measured and their reaction with the environment can be observed in real time. A paper on the development has been recently published in the journal Optica.

Dual-comb spectrometers have been around for almost 20 years. A source emits light in a broad wavelength range, which, when arranged according to its optical frequencies, is reminiscent of the teeth of a comb. If this light penetrates a gaseous material sample, the molecules it contains absorb some of the light. The altered light wavelengths allow conclusions to be drawn about the ingredients and optical properties of the analysed gas.

Making molecules vibrate
The special feature of the spectrometer is that a laser system emits double light pulses in the ultraviolet spectrum. When this UV light meets gas molecules, it excites the molecules electronically and also causes them to rotate and vibrate – exhibiting so-called rovibronic transitions – in a manner unique to each gaseous substance. In addition, the broadband UV dual-comb spectrometer combines three properties that conventional spectrometers have so far only been able to offer in part: (1) a large bandwidth of the emitted UV light, which means that a great deal of information about the optical properties of the gas samples can be collected with a single measurement; (2) a high spectral resolution, which in future will also enable the investigation of complex gas mixtures such as our Earth’s atmosphere; and (3) short measurement times when analysing the gas samples. “This makes our spectrometer suitable for sensitive measurements by which changes in gas concentrations and the course of chemical reactions can be observed very precisely,” said Lukas Fürst, PhD student in the Coherent Sensing working group and author of the publication.

Test case: formaldehyde
The researchers developed and tested their spectrometer using formaldehyde. The air pollutant is produced when fossil fuels and wood are burned, as well as indoors through vapours from adhesives used in furniture. “With our new spectrometer, formaldehyde emissions in the textile or wood processing industries as well as in cities with increased smog levels can be monitored in real time, thus improving the protection of personnel and the environment,” said Schultze-Bernhardt. The application of the spectrometer can also be transferred to other air pollutants such as nitrogen oxides and ozone and other climate-relevant trace gases. The team hopes this will provide new findings about their effects in the atmosphere. Based on this, new strategies for improving air quality could be derived.

Black carbon (BC) – comprising airborne soot-like carbon particles – is gaining prominence on the radar of those concerned with air quality. Envirotec spoke to Acoem about the measurement challenges it presents, and how these are being addressed.

With its significant health and climate impacts, BC is a pollutant that would seem to be ripe for the appearance of legislation or at least clear WHO air quality guidelines to assist with curbing it. But it’s not quite that simple.

In contrast to many other pollutants, for which standardised measurement protocols are available, with numerical air quality guidelines issued by the WHO,¹ BC measurement is not backed by this kind of detail, which would support the introduction of an enforceable limit. As Jost Lavric of Acoem Environment explains, the absence of standardisation may still stand in the way of implementing routine BC measurements on a large scale.

However, efforts to standardise the metrics used for BC measurement appear to be making progress. One prominent initiative is stanBC, a European project carrying the full title, “Standardisation of Black Carbon Aerosol metrics for air quality and climate modelling”, a group in which Acoem is a stakeholder.

BC is produced by the incomplete combustion of fossil fuels and biomass. It is estimated that, on average, household energy and transport are responsible for about 75% of the BC emissions globally, with the source proportions varying between different regions.² BC is formally defined as an ideally light-absorbing substance composed of carbon,³ and optical methods have dominated approaches to measuring it. The designation generally applies to the smaller-sized fractions of particulate matter – between 0.5 µm and a few nanometres in diameter.

PM2.5 mass concentration, a well-established parameter in air quality monitoring regimes, is defined as particulate matter with an aerodynamic diameter of 2.5 µm or less. It will thus include an unknown of quantity of BC, which will also have the tendency to represent a significant part of the ultrafine particles fraction (UFP; smaller than 0.1 µm).

As BC’s distinct, negative impacts and provenance come into sharper focus, there will likely be greater impetus to monitor and regulate it separately. Its health effects are considered more insidious than the larger particle PM fractions, since the smaller the particles, the deeper they can penetrate the body – with the finest particles being able to infiltrate blood vessels and organs. In addition, BC is also recognised as a significant contributor to global warming.⁴

Origins story
BC measurements are often focused on establishing the provenance and age of particles. As Jost Lavric explains, the system under study is a very dynamic one. If you put the same particle in different environments, the materials that absorb to its surface will vary. Typical adherents include condensing rainwater, volatile organic compounds, salts, and other materials (metals deriving from certain combustion processes and so on). With these additions, the light absorption properties of a particle will change, an effect that means optical measurements can probe into its history.

“Every component in the system will influence how the particle absorbs light of different wavelengths,” says Lavric. There are several instrument types that can help uncovering such details, but they can often be large, expensive and difficult to use. Tape-based absorption photometers such as the Met One Instruments powered by Acoem’s BC1054 multi-wavelength black carbon analyser provide a convenient solution for reliable and autonomous real-time measurements of BC concentrations. They are based on measuring light transmittance across a filter media, where the particles accumulate, at ten different wavelengths between the UV and IR part of the spectrum.

With the BC1054, it is possible to characterize the properties of a particle very accurately, probing deep enough into its history to ascertain, for example, whether it was produced by a combustion process in one type of engine as opposed to another, says Lavric.

The instrument can be used in many settings but is aimed primarily at the scientific researcher. It can, says the product literature, be used to provide BC data with levels of accuracy and precision on a par with industry standard reference monitors, but at a fraction of the cost.

For applications, where an increased granularity of BC data or rapid and uncomplicated deployment are prioritised (e.g., for emergency responder situations, or roadside monitoring), Acoem’s BC 1060 & 1065 portable or rack-mounted, and the C-12 low-cost portable monitors are a good choice, says Lavric.

They are intended for users with less exacting requirements for depth of characterisation (compared to the BC1054), and offer a greater focus on portability and affordability. The BC 1060 and 1065 instruments measure the absorption of two wavelengths of light – 370 nm (UV) and 880 nm (IR) – and are suitable for determining the source of a BC particle (i.e., did it come from a wildfire or a car engine?), and providing a basic exploration of its origin. The same measuring technology is used in both, but the BC1060 comes in a weatherproof enclosure, while the 1065 is a rack-mounted system for installation in a laboratory or suitable enclosure.

The C-12 is described as a revolutionary device, packaged in a weatherproof and optionally solar powered compact enclosure. It can be deployed quickly to deliver remotely and autonomously high-quality data from urban or remote locations.

As Acoem’s Derrick Jepson explains, such instruments fit well within a larger picture of BC measurement. He underlines the importance of our developing knowledge on BC (and ultrafine particles in general) being backed by continuous technological and analytical advancements.

Whatever the instrument, the requisite backdrop of standards and calibration metrics is still evolving, making projects like stanBC a very important piece of the puzzle.

Notes
[1] WHO global air quality guidelines: particulate matter (‎PM2.5 and PM10)‎, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide (2012) https://www.who.int/publications/i/item/9789240034228
[2] https://www.ccacoalition.org/short-lived-climate-pollutants/black-carbon
[3] https://stanbc.com/wp-content/uploads/2024/04/Ciupek_STANBC_EAC2023.pdf.
[4] https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM_final.pdf

A new study attempts to disentangle the global interplay of particulate matter (PM2.5) and ozone (O3) pollutants, and makes an urgent call for integrated strategies to curb their detrimental impacts on human health and the environment. Its authors say the research unveils the spatial and temporal dynamics of compound pollution, offering a blueprint for a coordinated global response.

Air pollution is a severe risk to human health and the environment, particularly from fine particulate matter (PM2.5) and ozone (O3). Despite global efforts, many cities continue to face significant exposure risks from these pollutants. PM2.5 and O3 originate from similar sources and interact in complex ways, compounding their harmful effects. Addressing these intertwined pollutants requires innovative strategies. In-depth research is needed to develop effective strategies for joint PM2.5 and O3 control.

In this latest study, the research team – from Hubei University of Economics, Nanjing University, and Yangtze University – looked at  the spatial and temporal patterns of PM2.5-O3 compound pollution. Published in Eco-Environment & Health, in April, the research analyzed data from 120 cities worldwide between 2019 and 2022, proposing a framework for synergistic pollution control.

The study appeared to reveal that nearly 50% of cities worldwide are affected by PM2.5-O3 compound pollution, with hotspots in China, Korea, Japan, and India. Significant spatial correlations between PM2.5 and O3 concentrations are apparent, driven by common precursors such as nitrogen oxides (NOx) and volatile organic compounds (VOCs).

It seems to be a particular problem with cities in Asia, especially India and China. The study attributes this to the high speed of economic development, with its concomitant anthropogenic emissions, “particularly of VOCs and NOx, which are precursors that promote O3 production”.

The study findings highlight the potential for joint pollution control measures, say the authors. The proposed framework aims to manage emissions from both pollutants simultaneously, leveraging their spatial and chemical interactions. Key findings included the identification of cities with high exposure risks and the demonstration of a positive spatial correlation between PM2.5 and O3 concentrations, suggesting that integrated control strategies could significantly enhance urban air quality and public health.

One recommendation is that areas particularly affected by compound pollution – such as India and China – could focus on strengthening control measures in sectors like transport and industry. More sustainable sources could be sought for processes like petrochemicals, industrial painting, and wood furniture. Another promising avenue would be to “optimize the energy structure of motor vehicles”.

Dr. Chao He, lead author of the study, said, “Our findings underscore the critical need for integrated pollution control strategies. By addressing PM2.5 and O3 together, we can more effectively reduce the health risks and environmental impacts associated with these pollutants.”

The authors believe the proposed synergistic control framework offers a promising approach to managing global air pollution.

A lot of the methane simply dissolved in the surrounding water of the southern Baltic Sea following the September 2022 explosion, according to measurements taken by the University of Gothenburg, and reported in Nature Scientific Reports.

At the end of September 2022, the Nord Stream gas pipeline on the bottom of the Baltic Sea exploded east of Bornholm and one of the largest unnatural methane gas emissions of all time was initiated. The methane gas from the pipeline created large bubbles at the water surface and measurements showed elevated levels of methane in the atmosphere.

“Thanks to fortunate circumstances, we were able to organise an expedition to the area of the leak in less than a week. Based on what we measured, we estimate that between 10,000 and 50,000 tonnes of methane remained in the sea in dissolved form,” says Katarina Abrahamsson, professor of marine chemistry at the University of Gothenburg.

The methane spread over a large area of the water, where some will have been consumed by bacteria. Some methane is normally present in the water anyway, created by the decomposition of organic material in the bottom sediments.

Isotopes pinpoint leaked gas
“In our study, we have been able to distinguish the methane coming from the Nord Stream leak from that naturally present in the water, thanks to the fact that the methane from the gas pipeline has a different isotopic composition than that which seeps up from the bottom sediments,” says Katarina Abrahamsson.

The water in the sea normally lies in different layers due to differences in temperature and salinity. Despite the fact that the methane leaked out of the gas pipeline at great speed and in large quantities, the researchers could not observe any major mixing in the water masses. The stratification that normally occurs at the end of September was stable. The levels of the leaked methane therefore varied greatly in the water. The researchers assume that the methane was diluted in a larger body of water later in the autumn when the water was remixed due to falling water temperature.

Plume puzzle
In the immediate aftermath of the incident, on 26th September 2022, a surface bubble plume appeared, according to satellite and air reconnaissance observations at the time. And this confirmed that there was sufficient methane discharge from the pipe to transport large amounts of gas to the surface of the sea.

As the paper notes, there is some debate and uncertainty regarding the rate of release to the surrounding seawater and atmosphere. “It has been suggested that between 100,000 and 500,000 tonnes of gas were leaked at a rate of 500 tonnes per hour to the sea during the initial phase of the leakage of approximately one week,” notes the paper. It goes on to assume that 300,000 metric tonnes were released in total.

The authors observe that the direct gas transfer to the atmosphere by bubble bursting stopped a week after the detonations, but “sea-air gas flux initiated by supersaturated surface water” continued into the second week. The investigators were able to observe the elevated presence of natural gas from the pipeline via a shift towards carbon-13 isotopes in the methane in the air.

The paper documents an apparent shortfall in the quantities of fossil-fuel methane detected from seawater measurements, compared to what might be expected.

One possibility is that the plume could have provided a boost to aerobic methanotrophic bacteria wihch would have been responsible for increased methane oxidation – mirroring phenomena observed following the DeepWater Horizon spill.

Unclear biological impact
It is too early to say what impact the increased methane levels will have on biological life in the southern Baltic Sea.

“The expedition also included researchers who took plankton samples in the affected area, the analyses of which are not yet complete,” says Katarina Abrahamsson.

Three months after the first expedition, a return visit was made to the area and new measurements were taken. Preliminary results show that bacterial activity has been high during these three months. The researchers do not yet know how the phytoplankton and zooplankton have been affected by this.

Participate in insightful discussions with leading experts about mid-infrared detection at the free upcoming hybrid event, Beyond Gas Sensing Panel Discussion, hosted by Hamamatsu Photonics.

Explore how the mid-infrared space can be transformed using advanced mid-infrared technology and its transformative potential. Expect to delve into the future of IR detectors, identify industry challenges, uncover recent developments, and learn about potential applications across various sectors.

Event Details:

Date: Wednesday, June 19th, 2024.

Time: In person from 13:00 to 16:00 BST OR online from 14:00 to 16:00 BST

Presence: Online or in-person

Venue: Science Gallery, King’s College London, Guy’s Campus, Great Maze Pond, London SE1 9GU

Catering: Lunch and refreshments will be provided for all in-person attendees.

Why Attend?

Industry Insights: Gain valuable perspectives from panelists with diverse application backgrounds including biotech, environmental science, industrial applications, security, and academic research.

Advanced Technology: Gain valuable perspectives and expert advice on developing advanced technologies that redefine gas sensing boundaries.

Networking Opportunities: Connect with peers and professionals in the industry, fostering collaboration and knowledge exchange.

Come and join this engaging discussion!

Register for your free ticket here.