Month: October 2021

Does gas hold a future with the Paris climate targets?

FaceLeonie Marie Emilie Orhan is a student on the MSc Sustainable Energy Futures course at Imperial College. She previously did her undergraduate at the University of Warwick in Mechanical Engineering. Leonie wrote a summary blog post about the latest white paper, ‘Best uses of natural gas within climate targets’ and launch event.

The sixth white paper from the Sustainable Gas Institute ‘Best uses of natural gas within climate targets’ focuses on the future uses of natural gas within the 1.5°C Paris climate targets for both 2050 and 2100. Through the analysis of different gas use scenarios (and energy mixes) from the Intergovernmental Panel on Climate Change (IPCC), it highlights the uncertainties in the future use of natural gas and highlights the potentials of Carbon Capturing and Storage (CCS) and of hydrogen in decarbonisation. It also focuses on the impact policies have on the development and growth of these industries through investment attractivity.

The presentation (watch the launch video) was hosted by the author, Dr Jamie Speirs, a Research Fellow at the Sustainable Gas Institute and the Centre for Environmental Policy, and co-authors, Luke Dubey, a Research Assistant at the Sustainable Gas Institute, and Naveed Tariq, a PhD Researcher from the Department of Chemical Engineering at Imperial College London.

Gas use differs across regions

It is evident that natural gas usage must be reduced not only to attain the 1.5°C targets, but also to conserve fossil fuel reserves for applications which do not yet have viable substitutions. A large majority of the scenarios agree with this, with large variations in different regions. The report shows that Europe’s consumption is set to drop rapidly through substitutions to greener solutions, while in Asia, natural gas would increase until 2050 (before decreasing) due to a growing middle class which relies on affordable energies. I found that highlighting these differences brought light to the individuality of solutions required if they are to consider not only the environmental perspective, but also the social and economic facets.
The importance of carbon capture and storage

 

Natural gas use was also shown to decrease significantly faster without carbon capture and storage (CCS) than with CCS. This demonstrates that to meet the 1.5°C targets while allowing a more significant transition period to other more sustainable energies, CCS must develop quickly. However, CCS development is controlled by economic incentives and policies as these are needed to be in place to draw in investments to enable the growth of the CCS industry.

Natural gas and hydrogen

In sectors for which decarbonisation is more difficult, such as domestic heating or transport, hydrogen could provide a substitute for the use of natural gas. Currently, hydrogen can be separated into blue and green hydrogen: blue hydrogen is produced using natural gas and green hydrogen using renewable energies. Due to the high costs of green hydrogen production, blue hydrogen is currently more favourable to the economy. Although its production does contribute to greenhouse gas emissions, its growth is necessary to pave the way for green hydrogen. This is due to the infrastructure needs of hydrogen production, storage, and distribution.

The UK government has stated in its recent Hydrogen strategy that both CCS and hydrogen will be essential to decarbonisations with notable milestones based on an increase in hydrogen production (1GW by 2025 and 5GW by 2030), an increase in CCUS clusters (2 by 2025 and 4 by 2030) and hydrogen heating and hydrogen town trials in 2025 and 2030. This shows a\strong interest from the government in these economies, as the UK seeks to transition quickly to enable a strong economic growth.

The White Paper points out that the scenarios analysed are based on the current knowledge of greenhouse gas emissions, which lacks an understanding of methane global warming potentials and may be affected by other factors in the future. This points out the need for a regular analysis and updated predictions and shows that there could be discrepancies between the scenarios presented and the future.

One of the main points I feel was conveyed in the report and presentation was the lack of policies to incentivise the growth of CCS and hydrogen production, which have the potential to play large roles in reaching the 1.5°C targets. Policies would need to centre around the development of the infrastructures required, the realignment market regulations to meet the demands of CCS and hydrogen, and agreements for international trade of hydrogen.The differences in hydrogen demand depending on how strong policies were really illustrated these points, with few and weak policies resulting in a demand over three times smaller than for strong ones, while with policies whose strengths and numbers are at a theoretical maximum, the demand came close to twice that of strong policies.

Expert views on the report

Dr Susana Moreira, a Senior Gas Specialist at The World Bank, offered a commentary which outlined the importance of investing in more electricity grids to cope with the demand and ease the changes in economy required to pave the way to a net zero future. Another pertinent point was that of connecting everyone to the grid and the adjustment that gas producing countries would have to make, not only to their electricity structures, but also to their economies. The impact of hydrogen production to the environment and communities was also pointed out. Overall, her commentary brought light on economic, social, and environmental issues which are key factors in the consideration of a net zero future.

Martin Lambert, a Senior Research Fellow at the Oxford Institute for Energy Studies, focused his commentary on emphasising the need of investments and policies required to do so.

Overall, the paper shows that to meet the 1.5°C targets, CCS and hydrogen must benefit from policies to encourage investments and regulations to direct the market as meeting the targets requires reliance on CCS and hydrogen. I feel more emphasis should have been placed on the idea that although the population is projected to increase to over 10 billion by 2100 (UN Population Facts, December 2019) natural gas usage is predicted to decline.

Speaking at the Royal Society’s Rising Methane Scientific Meeting

Blog post written by Dr Semra Bakkaloglu 

Dr Semra Bakkaloglu is a research associate at the Sustainable Gas Institute (SGI), who works on the Methane and Environment Programme. We asked her to write a short blog post about a recent Royal Society meeting on tackling methane emissions where she was an invited speaker. 

Scientists from all around the world gathered at the Royal Society ‘Rising methane: is warming feeding warming’ online meeting on October 4-7, to present and discuss the global methane budget, satellite observations of methane, natural and anthropogenic methane emission sources, and strategies for methane emissions mitigation and removal.

Despite efforts taken in many countries to reduce emissions, methane mole fraction (the amount of methane) is rising globally. It is important to understand what is causing the rise in methane concentrations as the rise makes meeting the goals of the 2015 Paris Agreement more difficult. However, the causes of methane growth and evidence from carbon isotopes (for example, the depletion in Carbon-13 isotope) is largely unknown: sources of methane emissions may be increasing, and sinks (methane being removed from the atmosphere) may be declining, or both processes may be occurring together (Nisbet et al., 2020). A sink occurs when methane is removed from the atmosphere by oxidation in a reaction with hydroxyl radical (OH).

A graph
UK methane emissions inventory between 1990-2019 (NAEI,2021)

I was excited to be invited to present the results of my PhD study on Day 4 during the industrial session. One of the points I emphasised during my presentation was the significance of methane emissions from biogas plants, as well as how these emissions are often overlooked in inventories. I also highlighted the differences in the isotopic signatures from waste sources, such as there being more depleted in Carbon-13 (13C) for active sites in landfill areas compared to closed sites, and different feedstock release different isotopic signatures. Wastewater treatment also influences the isotopic signature in terms of whether treatment is aerobic (requires oxygen) or anaerobic.

Understanding the evolution of waste generation and treatment processes can lead us to develop new methods to reduce emissions from these sources. The more information we have on the isotopic signature, the easier it is to evaluate specific waste sources on a regional and global scale. With these data, we can better understand the Carbon-13 temporal trends of the global methane record and gain a better understanding of the reasons for the rise in methane. More details can be found in our paper in Waste Management published in August.

My old PhD supervisor, Dr Dave Lowry from Royal Holloway University of London (RHUL), spoke next and demonstrated the changes in the isotopic signature of the UK source mix over time. Biogenic sources, such as wetlands, agricultural and waste sources, are dominant in rural areas, with Carbon-13 isotopic signatures ranging from -65 to -60‰, whereas gas leaks are the dominant methane source in urban areas. Over the last 30 years, the methane source mix has been depleted by 8‰ due to a number of reasons. For example, an increase in methane recovery systems and reductions in the amount of waste disposed at landfill sites, as well as a gradual decline in the proportion of isotopically-enriched southern North Sea Gas in the UK distribution network and a decline in anthracite (hard coal) production and move from deep to open cast mining. Julianne Fernandez, a PhD student in RHUL, assessed methane emissions from London gas network and found that London emits far more methane than Paris. Dr. Lowry and his team’s research will help local governments to prioritise methane mitigation strategies so as to meet the new target of the US-EU pact on the Global Methane Pledge of at least a 30% reduction in methane by 2030.

The next speaker was Prof. Grant Allen of the University of Manchester, who discussed how to quantify methane emissions. He talked about the progress being made in unmanned aerial vehicle (drone) measurements of methane and other greenhouse gases, as well as how drone-based sampling of methane concentrations can be used to calculate emission fluxes from landfills, fracking sites, and dairy herds.

The final speaker was Dr Stefan Schwietzke from the Environmental Defense Fund. Stefan highlighted the inconsistencies and low biases in many emission inventories, and emphasised the importance of measurements in guiding mitigation and tracking progress. His talk focused on the currently understudied offshore oil and gas sector. He concluded by drawing attention to ongoing efforts to improve transparency in the fossil fuel industry’s emissions reporting by incorporating empirical estimates and integrating them with independent datasets (for example, satellite data and field studies).

The industrial methane session informed us of ongoing international efforts to limit the global methane budget. Understanding and quantifying the anthropogenic methane emissions and their isotopic signature are critical to improving our understanding of the methane cycle and its anthropogenic component. This way, we can mitigate climate change and achieve emission reduction strategies outlined in the 2015 UN Paris Agreement on Climate change.

The entire discussion can be viewed on the Royal Society’s YouTube channel.

How important could blue hydrogen assumptions be?

Co-authored by Luke Dubey, Dr Jasmin Cooper and Dr Semra Bakkaloglu from the Department of Chemical Engineering at Imperial College 

In this short blog post, researchers at the Sustainable Gas Institute examine the literature to explore the environmental footprint and carbon credentials of blue hydrogen. 

As COP26 approaches attention towards decarbonising and meeting climate targets has intensified. Hydrogen has been pitched as a solution to reducing emissions in hard to decarbonise sectors, such as heavy industry, maritime freight, and aviation but now questions have been raised over whether hydrogen could actually make it harder to meet our climate targets. In August 2021, a paper was published by researchers at Cornell University (Howarth and Jacobson, 2021) which found that blue hydrogen would emit 20% more CO2 equivalent (the metric used to measure and compare emissions from multiple greenhouse gases) than burning natural gas. The findings were widely reported in the media but there has been some backlash due to key assumptions made in the paper. The publication also coincided with the release of the UK government’s hydrogen strategy, in which there is the intention to invest heavily in blue hydrogen. It is important the UK’s blue hydrogen ambitions do not conflict with the climate change action leadership it is aiming to set during COP26.

The validity of (methane leak rate, capture rate) made in the paper have already been highlighted by experts at SINTEF in a recent blog. Our team decided to compare the paper’s assumptions with values we found in the literature (Table 1) and run a sensitivity analysis to place the results against contemporary literature. For the methane leak rate, research by Paul Balcombe and others at the Sustainable Gas Institute in 2017 found emissions from the natural gas chain to range from 0.5 to 3.5%. This compares to the higher level in the Cornell paper at 3.5%. The Oil and Gas Climate Initiative (OGCI) has also committed to a total loss rate of 0.2% by 2025, which would reduce emissions even further.

In ‘A greener gas grid: what are the options?’, Dr. Jamie Spiers (2017) looked at the efficiency of the blue hydrogen conversion process and found a range of values between 60 and 90% for steam methane reforming (SMR) process. The efficiency rate was assumed to be much lower in the paper at 55%. The capture rate of the carbon capture and storage (CCS) process also has a wider range of values from 72 to 96% for a new hydrogen plant in a IPCC report (2018) than reported in the paper. Other recent studies have also found even higher efficiencies and capture rates are expected when producing hydrogen using autothermal reforming (ATR) processes, which was not considered in the original paper.

Table 1: Assumptions made in Howarth and Jacobson paper and our current analysis

Assumption Howarth and Jacobson Current analysis
Steam methane reforming (SMR) Conversion efficiency 55% 55-90%
Methane leak rate 3.5% 0.5-3.5%
CO2 capture rate from SMR process 85% 72-96%
Global Warming Potential (GWP) of methane 86 (20-year time horizon) 36 (100-year time horizon) and 86 (20-year time horizon)

 

We then ran a sensitivity analysis using these literature values found as the limits of the assumptions, including the Howarth and Jacobson estimate when it fell outside the range. This allowed us to examine a fuller range of possible outcomes and more clearly compare blue hydrogen to natural gas. By assuming a uniform distribution between the literature values, we ran over 2 million combinations of these assumptions to see where the estimate in the Howarth and Jacobson paper placed against the current literature. We kept all other assumptions from the paper the same.

Histogram

Figure 1: Histogram of results from changing assumptions in this work. The x axis shows the percentage greenhouse gas footprint (CO2 eq) of blue hydrogen is larger or smaller than natural gas. E.g. 10 = 10% higher GHG emissions, -20 = 20% lower emissions.

When we examine these alternative assumptions/inputs we can see that the Howarth and Jacobson estimate is on the periphery of all possible results. Demonstrating that the headline results, while possible, portray blue hydrogen in an unfairly bad light. Moreover, this is only possible as we have included the assumptions made in the paper as possible literature results. The estimate from the paper lands in the bottom 1% of all the results assessed. Therefore, while it could be argued the results are possible, they are certainly not a fair representation of the current state of knowledge.

Overall, while the Howarth and Jacobson paper raises some good points surrounding capturing the whole life cycle emissions of any alternative fuel source, it also fails to accurately represent the systems in which the energy is being used. Pushing for green hydrogen appears a sensible option at first glance, however, it may be necessary to use some blue hydrogen in the near term to enable the greater use of green hydrogen later. This is reflected in the IPCC scenarios that meet 1.5°C, with considerable quantities of blue hydrogen used in the pre-2050 period (IPCC, 2021).

As governments worldwide attempt to reach net zero, accurately representing the carbon credentials of emerging solutions is of paramount importance. It is also important to be credible with any assumptions made in any assessment of all possible solutions. Here, I feel this paper has fallen short. Yet we must still ask ourselves whether blue hydrogen, although not as bad as the paper proclaims, has a place in future energy systems, particularly in the post-2050 years. As the UK hosts, COP 26 is this investment in blue hydrogen, rather than solely green hydrogen demonstrating the leadership expected from a country such as ours.