Sustainable Gas Institute Blog

By Dr Jasmin Cooper, Research Associate, Sustainable Gas Institute

Since 2020 the EU has been proactive in its approach to tacking methane emissions and in October 2020, the Commission published its Methane Strategy (European Commission, 2020), which outlined the Commission’s goal of cutting emissions by 35-37% by 2030 (relative to 2005) across Member States. In October 2021, the EU co-launched the Global Methane Pledge (European Commission, 2021a) and in December 2021 the European Commission released their framework on how to tackle methane emissions in the energy sector (European Commission, 2021b). This framework outlines the Commissions legislative approach for how cuts to methane emissions are to be made, and how to ensure all Member States achieve the necessary cuts. The Regulation introduced addresses methane from oil and gas and coal but emissions from biomass are not included. It aims to develop a union-wide framework that is homogenous in its approach and standards, with a large focus on transparency in emissions reporting and verification. To cut methane emissions, the Regulation focuses on improving emissions monitoring and reporting, eliminating venting and flaring and establishing minimum standards in leak detection and repair.

Improve accuracy and transparency in emissions reporting

The Regulation outlines the rules on how methane emissions from oil, gas and coal production, storage, transport and distribution within the EU’s borders are to be accurately measured, reported and verified. To ensure operators are implementing the measures set out in the Regulation, each Member State must appoint at least one competent authority to oversee compliance with the Regulation. To verify emissions, independently accredited verified will review the emissions reports submitted by the operators and ensure these follow the requirements set out in the Regulation. The International Methane Emissions Observatory will be given a verification role in emissions data and the information produced will be made available to the public and the Commission.

Actions to cut emissions in the oil and gas sector

The Regulation specifies that upon entry of the Regulation, operators must submit emissions reports for all of their operated and non-operated assets on an annual basis. The first report gives source level emission estimates estimated using emission factors. In subsequent reports, emissions are estimated using direct measurement methods with emissions verification by site-level emissions measurements.

To mitigate methane emissions in oil and gas, the Regulation sets out specific rules for leak detection and repair (LDAR), venting and flaring:

 Leak detection and repair

Within three months of entry of the Regulation, operators need to submit their LDAR programme, which outlines the surveys to be carried out. By month six of entry of the Regulation, all relevant components an operator is responsibility for must have been surveyed. In the surveys, a leak is defined as 500 ppm methane and all components found to emit this amount or more must be repaired or replaced immediately, or as soon as possible (but no later than five days after detection).

Limits to venting and flaring

Under the Regulation, both venting and flare are banned except under specific circumstances e.g. emergencies and malfunctions. Flaring is preferred over venting, but only when re-injection, on site utilisation or entry into a gas market is not possible for non-economic reasons. If an operator wishes to vent or flare gas, they must demonstrate that venting or flaring is necessary and must notify the necessary authorities of any venting and flaring event within 48 hours of the event initiating.

Actions to cut emission in the coal sector

To tackle methane emissions from coal mines, an approach similar to oil and gas is outlined. Specifically, the Regulation focuses on ventilation shafts in underground mines, drainage systems and open coal mines. The Regulation largely focuses on improving emissions measurement and monitoring but also prohibits venting and flaring in mines, except for emergencies. For abandoned coal mines, operators are required to measure and monitor emissions from all abandoned and closed coal mines and to report the emission measured on a yearly basis.

Addressing emissions from outside the EU’s borders

The Regulation has a large focus on transparency in emissions data but states that the Union is committed to working with exporting countries to tackle methane. To improve transparency, countries who supply fossil fuels to EU Member States are required to provide the Member State with data on methane emissions: emissions measurements, reporting and what emission abatement measures are being carried out. To aid in improving transparency in emissions data, exporting countries will be incentivised to sign up to international partnerships and coalitions that aim to cut methane emissions, such as OGMP 2.0. The Commission will assess the submitted information on data quality and detail of monitoring, reporting and emissions verification applied by the exporting country. This data will use used to create a methane transparency database, which will be made available to the public for free.

In addition to this database, the Commission will also establish a global methane monitoring tool, using satellite data and emissions data provided by operators. This tool will also be made available to the public and will be used to provide information and updates on the magnitude, occurrence and location of high methane emitting sources.

Does it go far enough?

Following on from the EU Methane Strategy, it is good to see the Commission lay out clear rules for how methane emissions are to be cut. However, while it does tackle key areas in methane abatement such as emissions data quality and accuracy, there are areas which are lacking and could be improved upon revisions to the Regulation:

• The Regulation does not outline technologies to be used in emissions monitoring, particularly in LDAR and instead chooses to allow Member States flexibility such that LDAR technologies can be innovated and developed.
• Emissions from coal outside of mining are not included. Methane can also be emitted during coal waste management, handling, processing and transportation.
• It does not specify penalties to Member States or operators who fail to meet the obligations outlined, and individual Member States are to lay down their rules on penalties. However, the Regulation does specify that penalties must be effective, proportionate and dissuasive.
• The Regulation could go further in applying pressure to fossil fuel exporters. It does not specify actions for exporters whose emissions and reporting standards are not on par with what is to be expected.

References

European Commission 2020. COMMUNICATION FROM THE COMMISSION TO THE EUROPEAN PARLIAMENT, THE COUNCIL, THE EUROPEAN ECONOMIC AND SOCIAL COMMITTEE AND THE COMMITTEE OF THE REGIONS on an EU strategy to reduce methane emissions. Brussels, BE: European Commission

European Commission. 2021a. Launch by United States, the European Union, and Partners of the Global Methane Pledge to Keep 1.5C Within Reach [Press Release]. Brussels, BE. Available: https://ec.europa.eu/commission/presscorner/detail/en/statement_21_5766.

European Commission 2021b. Proposal for a REGULATION OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL on methane emissions reduction in the energy sector and amending Regulation (EU) 2019/942

COM/2021/805 final. Brussels, BE: European Commission

Read Cutting methane in the EU energy sector- is the new Regulation doing enough to tackle emissions? in full

By Ellie Martin

The 2021 Sustainable Gas Institute Annual Lecture was delivered on 3 December and focused on hydrogen’s role in heating. It was contextualized by the challenges to decarbonizing heat, a comparison of hydrogen boilers and heat pumps, the importance of listening to consumers, and the steps that need to be taken to achieve net-zero gas with the help of hydrogen. Content was delivered by the engaging Dr. Angela Needle, who serves as strategy director at Cadent Gas, founder of the Women’s Utility Network, and VP of the Hydrogen UK Trade Association.

Challenges to Gas Alternatives

Given the impending state of climate change and a 300 TWh yearly dependence on natural gas for domestic heating, it is clear that decarbonizing gas is key to achieving net zero emissions for the UK by 2050. Fortunately, a few alternatives to natural gas are inching across the market – namely heat pumps, district heating, and now potentially hydrogen. Current gas boilers are reliable, easily tucked into cupboards and other discrete areas, easy to control and adjust, and generally problem-free. These are some big shoes to fill. What’s more, over £11,000 per home would be needed to cover the energy efficiency improvements, appliance replacements, and electricity and gas network changes necessary for net zero gas. On top of this, homes in the UK are quite literally the worst in Europe when it comes to retaining heat. UK homes lose an average of 3°C over five hours (surpassing all European neighbors), with 61% of EPC ratings falling at or below the D level.

There’s also the difficulty of determining who owns buildings, with the UK moving towards outright ownership. This is a huge challenge to achieving net zero because homeowners are the hardest to reach when it comes to government policy. Diversity in ownership types also presents an issue: solutions will need to be tailored to each property instead of adopting a one-size-fits-all policy.

Heat Pumps vs. Hydrogen Boilers

An all-hands-on-deck approach will likely be required for natural gas replacements, particularly during the early stages of development when it is unclear which technology will turn out to be the best investment. While hydrogen boilers and heat pumps are often unfairly pitted against each other, there are some key differences between the two that bear mentioning.

One of the most obvious advantages to heat pumps is that they’re currently deployable and proven to work. They’re also highly efficient and thus a good fit for well-insulated homes, and the low energy requirements afforded by these high efficiencies can produce lower running costs. Downsides to this technology include its high upfront cost, supply chain limitations, and the need for consumers to change their behavior.

On the flip side, hydrogen boilers are expected to cost around the same amount as gas boilers and could fit in the same exact spaces, and thus the switch would require less adaptation by consumers. They don’t need to rely on electricity at critical times of the day due to the capacity for storage, and they don’t produce any carbon monoxide. However, hydrogen boilers are not yet commercially available and could temporarily increase gas prices during the initial scale-up stages. Another issue is public perception, namely safety concerns regarding flammability and a general view that these systems are inefficient because energy is required to make hydrogen, and hydrogen is required to make heat.

Since the two options excel in different areas, one technology might be a better fit for a given context. For this reason, it is important to approach deployment from an individual building level in addition to a national level. Resilience network planning will also be key to ensuring constant delivery, even in extreme circumstances like disruptive storms.

The Importance of Consumers

Decarbonizing gas is going to require a highly inclusive approach that considers technical, economic, and consumer perspectives. This last bit is especially important, as consumers tend to be left by the wayside when it comes to big picture solutions. And despite reports that 75% of the public is concerned about climate change, there is still a massive gap between public intent and public action – for example, only 39% of people have reported considering a switch from natural gas heating. Because the effort required to implement new technologies can be a major barrier to uptake, it is crucial for governments to make it easy for consumers to commit to action. A key part of this involves educating consumers with the help of trusted advisors, such as local tradespersons and NGOs, as opposed to energy suppliers or natural gas companies (for whom consumers are typically much less responsive).

Planning the Future

 Cadent is working on a range of projects related to net zero gas, and I was particularly impressed by their implementation approach, which is essentially this: don’t expect people to be comfortable with technologies they have to imagine, show them what’s possible. For example, one project is developing in-home applications for hydrogen: whether an odorant needs to be added, where hydrogen accumulates if it leaks, and how readily combustible it is, among other questions. An exciting product of this work is a hydrogen show home that has cropped up in Gateshead. The house features hydrogen boilers, stoves, and fires that boast a beautiful orange flame (to book a visit, email hydrogenhome@northerngas.co.uk ). Project “H21” is testing the feasibility of 100% hydrogen supply up and down the UK’s current gas network, and another scheme involves blends of hydrogen and natural gas that can provide CO2 emissions reductions of around 6% and could serve as a key stepping-stone in scaling up and encouraging public acceptance of 100% hydrogen in the near future. Residents who participated in this project consistently reported that they couldn’t tell the difference between regular and blended boilers.

So how much hydrogen do we theoretically need? According to predictive models, this number varies from 23 to 182 TWh depending on the interplay between customer acceptance of hydrogen and the adoption of heat pumps. While it’s difficult to plan for a future that has so much uncertainty, the gas sector can prepare by ensuring hydrogen is as safe, well-planned, and easy to implement as possible for when the time comes to deploy. If companies like Cadent continue to innovate in this direction, hydrogen has my full support.

Ellie Martin is a master’s student in Imperial’s Sustainable Energy Futures course. Her undergraduate background is in Biochemistry and Molecular Biology at the University of Miami, and she’s interested in developing energy technologies through the intersection of engineering and molecular science.

Read Future Heat for Everyone and the Role of Hydrogen in full

By Dr Jasmin Cooper

Methane is the second most important greenhouse gas and because of this, over 100 countries have pledged to cut their emissions of this potent greenhouse gas. All efforts so far to cut methane from the atmosphere have focused on reducing emissions, targeting sectors such as oil and gas, agriculture and waste management. While this is effective in reducing the amount of methane present in the atmosphere, they cannot reduce methane emissions to zero. Also, these actions could be hindered by methane emissions from thawing permafrost caused by current increases in global temperatures. Therefore, there may be the need to remove methane from the atmosphere, but this is an area with little ongoing research and many data gaps.

Unlike carbon dioxide which can be removed directly from the atmosphere, methane removal centres on enhancing the conversion of it into carbon dioxide, or other chemicals. The reasoning for this is because of methane’s strength as a greenhouse gas; 82.5 ± 25.8 times as powerful as carbon dioxide over 20-year time horizon and 29.8 ±11 times as powerful over 100-year time horizon (1). Therefore, by converting it into a less potent greenhouse gas, its global warming impacts are greatly reduced.

The methods which can be used to remove methane focus on increasing the size of existing methane sinks (natural systems which remove it from the atmosphere) or other ways of converting it into carbon dioxide and other chemicals:

Enhancing methane sinks

Physical

The main sink for methane is the reaction with hydroxyl (OH) radicals in the atmosphere, which coverts it into carbon dioxide. Therefore, methods of increasing the amount of OH radicals in the atmosphere would enhance the rate of methane removal. Iron-salts have been found to enhance OH radical formation from sea water by mimicking the reaction of mineral dust (2). By applying iron-salts to sea water, the formation of OH radical and Cl is enhanced, both of which react with methane.

Biological

The other sink for methane is microbes in the soil, which contain enzymes that can oxidise methane into carbon dioxide (3, 4). By increasing the concentration of these microbes in the soil or using them in equipment designed to remove methane from air e.g. biotrickling filtration (3), the concentration of methane in the atmosphere can be reduced.

Direct oxidation and conversion into other chemicals

Catalysts

Methane can be converted into carbon dioxide without OH radicals. Methane can react with oxygen in the presence of a catalyst, in a reaction similar to combustion, to produce water and carbon dioxide. Many catalysts can be used including photocatalysts, metal catalysts with zeolites and porous polymer networks (3). These are used in air contactors, like those used in direct air capture for carbon dioxide removal, where air flows through the materials containing the catalyst. Methane can also be oxidised to form methanol (3). It is also possible to directly converted methane into chemicals such as ethane and ethylene in the presence of a catalyst (5) and platinum-based catalysts have been found to be effective for this.

Barriers to methane removal

While it is possible to remove methane from the atmosphere, its direct removal is an area with little ongoing research. Reasons for this are that the concentration of methane in the atmosphere is much lower than carbon dioxide (~200 times lower; 1.88 ppm methane versus 410 ppm carbon dioxide). Therefore, it is more energy intensive to remove methane from the atmosphere because large volumes of air need to be processed to remove significant amounts of methane. Other reasons for why little scientific interest have been placed on methane removal is that it is currently much more effective to reduce the concentration of methane in the atmosphere by emissions abatement e.g., reducing venting and flaring in oil and gas or waste management practices in agriculture.

Could it help us reach our climate goals?

Overall, methane removal from the atmosphere could play a role in meeting future climate targets but this is dependent on how successful methane emission reduction initiatives are, as well as other decarbonisation strategies e.g. phasing out fossil fuels and ramping up renewable electricity. Methane removal is not a substitute for methane emissions abatement but could be complimentary to it if further sharper and deeper cuts to methane are needed to reach Paris Agreement goals. If net-zero pledges are successful and more initiatives like the Global Methane Pledge Methane are established, then methane removal is unlikely to play a role in future decarbonisation strategies.

References

1. IPCC. AR6 Climate Change 2021: The Physical Science Basis. Geneva, CH: Intergovernmental Panel on Climate Change (IPCC); 2021.
2. Oeste FD, de Richter R, Ming T, Caillol S. Climate engineering by mimicking natural dust climate control: the iron salt aerosol method. Earth Syst Dynam. 2017;8(1):1-54.
3. Jackson RB, Abernethy S, Canadell JG, Cargnello M, Davis SJ, Féron S, et al. Atmospheric methane removal: a research agenda. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2021;379(2210):20200454.
4. Lawton TJ, Rosenzweig AC. Methane-Oxidizing Enzymes: An Upstream Problem in Biological Gas-to-Liquids Conversion. Journal of the American Chemical Society. 2016;138(30):9327-40.
5. Li Z, Xiao Y, Chowdhury PR, Wu Z, Ma T, Chen JZ, et al. Direct methane activation by atomically thin platinum nanolayers on two-dimensional metal carbides. Nature Catalysis. 2021;4(10):882-91.

Read Methane removal from the atmosphere- could it help us reach our climate goals? in full

By Luke Dubey

In the first week of COP26 a ground-breaking methane pledge was announced by the US and the EU. Very quickly over 100 countries, representing 70% of the global GDP and almost 50% of anthropogenic methane emissions had signed up. The pledge agrees to cut methane emissions by at least 30% by 2030 compared to 2020 levels. It is estimated that delivering on the pledge would reduce warming by at least 0.2°C by 2050. So how is this going to be achieved, will it work, and why are over half of the emissions not covered?

Each country that has signed the pledge can decide how to reduce its emissions. This could be through new technology, regulations, switching fuels or changing practices. Due to the completely different emission profiles of each country, emissions reductions will take a completely different form. For example, the EU is a large consumer of gas, but a low producer compared to the US which has very high gas production. The strategies in place for one country will be very different to another. Due to how recently the pledge was announced, most countries do not have a detailed outline of how they plan to reduce their emissions. But these will be required very rapidly as 8 years is a short time for such a large emission reductions.

Thus far, only the US has a detailed national action plan on how to cut emissions within their borders. The US action plan was published in November 2021 following the announcement of the pledge at COP26 by President Joe Biden, and outlined their strategy to cut emissions. The action plan has considerable focus on the oil and gas sector, aiming to reduce emissions from sources covered by the action plan by 75%. This includes pipelines which will be covered by a new leak detection and repair rule which would establish standards to detect and eliminate leaks. Plugging wells, reducing flaring and venting and improving standards for new and existing oil and gas sources are also included. The action plan, should it be successful, will provide a playbook for reducing oil and gas sector emissions. Other emission sources are also covered in the action plan. For landfill emissions, a reduction in emissions via regulations and a drive to reduce the quantity of food in landfills, with the goal of 70% of emission captured from landfill. The agriculture sector is tackled via new technologies such as anaerobic methane digestors. The action plan has shown the 30% reduction can be achieved by slashing emissions from the lowest hanging fruit, in the USA’s case oil and gas and landfills, while providing jobs. This will allow the harder to abate sectors to survive while the technology to reduce their emissions becomes less expensive and more feasible to implement.

If the US has shown (in theory) how drastic emission reduction can be achieved, while also providing co-benefits to the economy, why have all countries not signed up? This is the main failing of the pledge. The 30% emission reduction, while significant enough to aid us on the path to 1.5°C (if all countries signed up) was a reduction too big for some of the world’s largest emitters such as China, Russia and India. Their omission is a huge blow to the 1.5°C target where methane emissions need to decrease by 25 – 53% for it to be achieved. Moreover, the 30% reduction in many countries is not enough to meet the IEA’s net zero pathway which sees a 75% methane reduction in energy use. So, it would seem that the pledge, by not being adopted by some of the largest emitters, will not be enough to meet Paris goals. However, should the signatories demonstrate that emissions can be reduced, while implementing a methane tax price (some in the US have suggested $1800/ton) then these countries, through purely economics may be persuaded to reduce emissions. Getting these high emitting countries onboard will be key to the long-term success of the pledge and will have a large impact in whether climate goals can be met.

Overall, the methane pledge must be seen as a positive as it is the first large scale attempt at tackling this potent greenhouse gas globally. The omission of many large emitters is a great loss but must be placed in the context of many unwilling participants at COP26. Should the reductions in emissions from the signatories be successful it will pave the way for other countries to join. This in turn will go a great way in meeting climate goals.

Read Will the global methane pledge make an impact in meeting climate goals? in full

By Dr Jasmin Cooper

Research Associate, Sustainable Gas Institute 

Methane is a major greenhouse gas and in recent year many companies in the oil and gas value chain have either joined initiatives or set ambitious targets in a bid to curb their emissions e.g. the oil and gas methane partnership (OGMP), the oil and gas climate initiative (OGCI) and methane intensity targets set by major oil and gas companies (GMI, 2020, OGCI, 2018, Shell, 2018, Xu et al., 2020). The quantification of emissions is undoubtably a key component of emission reduction strategies, but there is a high level of uncertainty in the emissions data globally. This is largely because, in comparison to carbon dioxide, there was a lack of interest until the second half of the 2010s when post the Paris Agreement, a spotlight was shone on short-lived climate forcers (e.g. methane, ozone, black carbon) and their role in reducing warming.

The global atmospheric concentration of methane has been increasing since preindustrial times and since the 1980s it has been rising rapidly (Dlugokencky, 2021). The International Energy Agency (IEA) reported in their Methane Tracker that oil and gas methane has been rising since the year 2000, with emissions peaking in 2019 (IEA, 2021b). The impacts of COVID-19 appear to have led to a drop in emissions, because of reductions in oil and gas demand because of slowdowns in industrial and economic activity. However, post COVID-19, it is imperative that 2019 remain the emissions peak if the sector is to contribute towards net-zero ambitions. This is because with methane being a potent greenhouse gas, reductions in emissions can lead to significant climate change and global warming benefits.

In the oil and gas sector, as well as in other sectors, methane emissions are quantified using one (or a combination) of three methods (National Academies of Sciences and Medicine, 2018): engineering calculations (including process modelling/simulation and using equipment specifications), emission factors (coefficient used to calculate emissions) and direct measurement. Out of these three, direct measurement is the most accurate for quantifying emissions and is also the only method which allows for the accounting and identification of emission sources. Data derived from direct measurement are also value inputs in emissions modelling via process simulation, as well as in updating or deriving emission factors. There is a broad spectrum of quantification technologies available, ranging from handheld devices, such as flow meters, to remote devices, such as observation stations and satellites. The measurement capabilities of these technologies also vary along the spectrum, from low level to extremely high emission rates and quick measurements to hours long measurement surveys.

However, quantifying emissions through direct measurement is expensive and time consuming. This, in combination with the lag in methane interest has results in a large proportion of global oil and gas related methane emissions being quantified using generic emission factor data. Major oil and gas countries such as the USA, Norway and Australia quantify their emissions using data derived from measurement campaigns, while others such as Egypt, Malaysia and Bolivia rely on default emission factors. Also, the sections of the oil and gas value chain (upstream, midstream and downstream) vary in how emissions are quantified. In countries which are major gas importers, such as Japan, Italy and Germany, emissions from the midstream and downstream activities are quantified using data derived from measurement surveys, while emissions from any upstream production and processing activities are quantified using either generic emission factors or country specific emission factors derived from expert estimates and industry reports.

Therefore, it is clear that actions need to be taken to homogenise the quality of both the emissions data and the emissions reporting, both between countries and within countries. The IEA launched in January 2021 their regulatory roadmap and toolkit (IEA, 2021a), which aims to provide guidance for policy makers who are looking to develop regulations to tackles their oil and gas methane emissions. A key step in this roadmap is developing an emissions profile.

For this step, accurate emissions data is needed, not just in magnitude of emissions and identifying all emission sources, but also in determining emission patters e.g., constant continuous, intermittent, episodic, inter-daily variable and intra-daily variable. These are important as they will directly impact any abatement measures and strategies developed, as well as any new regulations introduced to curb emissions. Hence, more efforts must be put into measuring emissions in all active oil and gas countries (both producers and consumers). The effectiveness of methane abatement measures will be hindered if the underlying emissions data is poor as either not enough or too many efforts could be put in, or efforts are not targeting the key emission sources.

References

Dlugokencky, E. 2021. Trends in atmospheric methane: Global CH4 monthly means [Online]. Boulder, CO, USA: National Oceanic and Atmospheric Administration/Global monitoring Laboratory (NOAA/GML). Available: https://www.esrl.noaa.gov/gmd/ccgg/trends_ch4/ [Accessed].

GMI. 2020. UNEP: Oil and Gas Methane Partnership Initiative to Manage Methane Emissions from Upstream Oil and Gas Operations [Online]. Global Methane Initiative (GMI). Available: https://globalmethane.org/challenge/ogmp.html [Accessed October 2020].

IEA. 2021a. Driving Down Methane Leaks from the Oil and Gas Industry, Paris, FR; International Energy Agency (IEA). Available:’ https://www.iea.org/reports/driving-down-methane-leaks-from-the-oil-and-gas-industry

IEA. 2021b. Methane Tracker 2021, Paris, FR; International Energy Agency (IEA). Available:’ https://www.iea.org/reports/methane-tracker-2021

National Academies of Sciences, E. & Medicine 2018. Improving Characterization of Anthropogenic Methane Emissions in the United States, Washington, DC, The National Academies Press.

OGCI. 2018. Oil and Gas Climate Initiative sets first collective methane target for member companies [Online]. New York, NY, USA: Oil and Gas Climate Initiative (OGCI). Available: https://oilandgasclimateinitiative.com/oil-and-gas-climate-initiative-sets-first-collective-methane-target-for-member-companies/ [Accessed June 2020].

Shell. 2018. Why shell has set a methane target [Online]. The Hague, NL: Royal Dutch Shell Available: https://www.shell.com/media/speeches-and-articles/2018/why-shell-has-set-a-methane-target.html [Accessed June 2020].

Xu, M., Aizhu, C. & Jacob-Phillips, S. 2020. China’s CNPC targets 50% slash in methane emission intensity by 2025. Reuters, 2 July 2020.

By Dr Jasmin Cooper

Research Associate, SGI

Read How much methane does the oil and gas sector emit? in full

Author: Luke Dubey, Research Assistant, Sustainable Gas Institute

Methane is the second most important greenhouse gas after CO₂. While emissions are far lower than CO₂ it has a far higher global warming potential and so is responsible for 25% of today’s anthropogenic climate forcing (Myhre et al., 2013). Methane is the main constituent of natural gas, which is important due to the increasing use of natural gas as a transition fuel. Measuring and estimating emissions from the natural gas supply chain is difficult due to methane being odourless and colourless, and emissions being widespread and intermittent. Should the emission rate of methane be higher than currently estimated the climate benefits of gas relative to coal could be wiped out.

How are emissions measured

Methane emissions from the natural gas supply chain are currently estimated using either bottom-up methods, such as handheld devices and mobile laboratories, or top-down methods such as aeroplanes and satellites. A current issue is that bottom-up methods tend to estimate lower emission rates than top-down methods, even in the same area, and it is not clear whether one is under or another over-estimating emissions.

Satellites have been used for detecting and measuring methane for 20 years. During this time their technology has improved massively, largely by lowering minimum detection limits and increasing resolution. As their technology has improved, their potential role in the natural gas industry has been realised. It is widely hoped they will be able to provide comprehensive coverage, detecting all emissions in an area (which may sometimes not allow access), while returning daily, providing constant measurements. This is highlighted within the EU’s methane strategy, which promotes the Sentinel 5P satellite as capable of measuring global emissions (European Commission, 2020).  However, there are many reasons why satellites might not be up for the task just yet, while still having immense potential in the future.

Limiting factors of satellites

1.      Cloud cover

Satellites have a few issues that are not widely enough discussed, the first being non-detectable pixels. A pixel is the base unit a satellite reports data in, these range from 60km² for Envisat to 7km² for Sentinel 5P all the way down to 50m² for GHGSat. There are many factors that can cause a no detect in a pixel, such as aerosols, albedo and terrain, but the most important is cloud cover. Spectrometers onboard the satellites are what measure the methane; there are many ways to do this but a common one is using sunlight that is backscattered from the earths surface into the spectrometer. The absorption peaks are then analysed and the total concentration of methane in the column is outputted (Jacob et al., 2016). It is clear then how clouds could interfere with this process, with thin clouds causing too much noise for accurate results and thick clouds completely blocking out the sunlight. Many places that produce gas are cloudy virtually year-round (Russia, Canada), meaning there is no way to measure every day of the year with many areas having at best a couple days coverage per pixel per year. Technology has improved over time and will continue to do so, and new methods of reducing the noise from low cloud coverage have been developed, but there is still a long way to go.

2.      Minimum detection limits

A second issue is the minimum detection limits (MDL) of satellites. The MDL is a consequence of the uncertainty within the satellite’s instruments. This will lower as technology improves, and it is possible to reduce over repeated measurements. However, many of the emissions from natural gas are low level and spread out, such as from wells, meaning satellites are unlikely to be able to discern these from the background noise. The saving grace of the MDL is that emissions from natural gas follow a superemitting profile, where a few high emitting sources are responsible for the majority of emissions (Brandt et al., 2016). These are far more likely to be detected by the current crop of satellites and have been a common use of satellites thus far.

3.      Time of overpass

Another aspect of satellites that does not receive enough, if any, attention is the time of overpass. This is fundamentally important when measuring emissions from intermittent sources prevalent across the natural gas supply chain. Should a large emission occur immediately before an overpass the methane will have no time to disperse, increasing the likelihood it is above the MDL and detected. Should the same emission happen hours before an overpass, there is a long time for winds to disperse the emission into nearby pixels, or even distant pixels if long enough has passed. This results in no detection happening and zero emissions being attributed to the pixel. Conversely, if the emission rate detected in the first scenario was extrapolated up to a daily or yearly average, it would greatly overestimate total emissions. Increasing the number of days measured would reduce this effect, or having several satellites working in tandem, measuring at different times of day would help solve the issue.

Newer satellites

The counter to some of the issues raised is in the newest crop of ‘paid for’ satellites. Where the data is not freely available online, but private institutions pay for access, such as GHGSat. These satellites have far higher resolution and lower MDLs. The higher resolution increases the likelihood of an individual pixel being cloud free (chance of no clouds in one of 10,000 100m² pixels or one 10km² pixel). However, I believe these satellites play a different role, more comparable to an aeroplane than a traditional satellite. These satellites do not have the ability to globally track emissions daily, but target specific facilities. A hope is that these satellites could work in tandem with more traditional satellites, where one would scan the globe and detect an area of interest, and the other then has a more detailed look. All of this being possible rapidly, stopping hidden emissions far quicker than ever before. With the recent launch of GHGSat C (Iris) and the upcoming launch of MethaneSat this seems a very real possibility.

Conclusion

So what’s the role of satellites now and in the future? Currently satellites are useful for research, but uncertainties are too high for commercial use in the most part. However, satellites can currently play a very helpful role in locating superemitters. As technology improves satellites will become more useful, this will be aided by more satellites coming online, working in tandem to mitigate some of the limitations. Satellites have the potential to comprehensively measure emissions globally at the drop of a hat, this potential has received, and deserves, the time and investment fitting of such a game changing climate change technology. I am hopeful in the near future satellites will be the primary way of measuring methane globally.

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EUROPEAN COMMISSION. 2020. EU Methane Strategy [Online]. Available: https://ec.europa.eu/energy/topics/oil-gas-and-coal/methane-emissions_en#eu-methane-strategy- [Accessed 6/1/21 2021].

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Author: Luke Dubey, Research Assistant, Sustainable Gas Institute

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