Category: Greenhouse gas emissions

How big a setback is the Nord Stream gas leak for climate change goals?

The news that the Nord Stream gas pipelines have stopped leaking is a relief to all of us involved in curbing emissions from methane, but the consequences of such a massive gas leak are still of huge concern. In her latest blog, the Sustainable Gas Institute’s Dr Jasmin Cooper examines how big an effect the alleged sabotage of the pipelines might have on climate change goals.

The Nord Stream 1 and 2 pipelines are two large subsea pipelines which connect Russia to Germany. The pipelines are the primary source of Russian gas exports to Germany.  Until the Russian invasion of the Ukraine in February they transported up to 55 billion cubic meters of gas per year, accounting for most of Germany’s gas imports. On September 26th 2022 two small tremors were detected by the Geological Survey of Denmark. Whilst there was no active flow through the pipelines by this point, they were still full of gas. The tremors are believed to have been caused by deliberate explosions – alleged sabotage that has resulted in four major methane leaks.

The leaks have caused concerns around the security of energy infrastructure as well as the security of energy supplies globally. After the announcement of the first leak in the Nord Stream 2 pipeline, gas prices across Europe jumped – having been falling since a previous peak in August. The leaks also raised energy security concerns in Europe as the continent heads into winter. However, Germany secured two floating liquefied natural gas (LNG) terminals in August of this year and in mid-September was in talks with Qatar and the United Arab Emirates to secure LNG deliveries. In August of this year, the mainland EU member states agreed to a plan to cut gas use by 15%3, so the damage caused to the Nord Stream pipelines may not impact gas supply so much as the rise in gas prices.

While there is still a lot of uncertainty around the leak; including the cause, the extent of the damage to the pipeline and how much natural gas has leaked out – this incident has the potential to be one of the biggest climate disasters so far in the 21st century. Subsea pipeline leaks are unusual so there are no past examples to directly compare to.

Deep Water Horizon was a drilling rig in the Gulf of Mexico which exploded in April 2010 resulting in huge damage to the marine environment from oil. The Nord Stream leaks are natural gas, so the environmental impacts will be to climate change and global warming rather than a direct impact on the marine environment and wildlife. Our only comparable large gas leaks are the Aliso Canyon gas leak, which is estimated to have emitted 97,100 tonnes4 of methane between October 23rd 2015 and February 18th 2016 and the Raspadskya coal mine leak, which was found to be emitting nearly 90 tonnes of methane per hour5 earlier this year  – and could emit 764,000 tonnes of methane by the end of 2022. .

The Nord Stream pipelines while not actively transporting gas, did contain 778 million cubic meters of natural gas. This would be 360,000 to 460,000 tonnes of methane, which in CO2 equivalence is 11 million to 14 million tonnes of CO2eqb. In the context of total global methane emissions, between 2008 to 2017 total global emissions were 576 Tg CH4 per year (1 Tg = 1,000,000 tonnes), with 80 Tg CH4 per year from the oil and gas sector. So, the amount of gas stored is equal to less than 0.1% of total global methane emissions, or 0.5-0.6% of annual oil and gas methane emissions. While this may seem like a small percentage, they are similar to the methane emissions of Denmark, Ghana or Yemen in 2021. That volume of gas has an economic value – based on prices on 05 October 2022 – of €1.4 billion and is approximately 5 days’ worth of supply to Germany based on Nord Stream transport when it was operational.  So from a climate, social and economic perspective, this is a catastrophic loss.

How much of the methane stored in the two pipelines will be emitted is yet to be determined. From the amount of gas stored and the images of the leak, it is evident the leak will be a big blow to ambitions to meet climate change targets. The Global Methane Pledge – launched in November 2021 – has seen over 120 countries pledge to cut their methane emissions by 30% (relative to 2020 levels) by 2030. Since then, many have launched new regulations on how their methane emissions can be slashed. The Nord Stream leaks will likely negate much of the progress made so far.

assuming natural gas is 70 to 90% methane and methane density of 0.7 kg per cubic meter
assuming GWP100 of 30 TFF
assuming gas price €174.76 per MWh; 36 PJ per 1 bcm of natural gas

How successful is the UK’s Net Zero strategy in the biowaste sector?

Greenhouse gas (GHG) emissions from the waste sector are primarily composed of methane (CH4) released from landfills. Biodegradable wastes such as food, garden waste, manure, paper and cardboard emit methane during anaerobic decomposition in landfills. In our latest blog, SGI emissions scientist Dr Semra Bakkaloglu explains some of the key findings from her newly published paper into emissions of CH4 from biowaste.

We know that CH4 is around 28 times more potent as a greenhouse gas than carbon dioxide (CO2) over a 100-year period (IPCC 2021). So, reducing CH4 emissions – from all sources – is critical to keeping global median temperature rise well below 2 degrees Celsius. In the UK, the waste sector is the second largest CH4 emitter after agriculture, so waste sector emissions deserve significant attention if we are to achieve the UK’s net zero targets.

The UK biodegradable waste strategy aims to divert progressively more waste from landfills into anaerobic digestion or composting facilities for recycling. Recent studies (Gua et al. 2020, Bakkaloglu et al. 2022a, Cusworth et al. 2020) indicate that anaerobic digesters and composting facilities can be a significant source of CH4 emissions, and our latest study aims to evaluate the UK’s biowaste strategy to better understand future CH4 emissions.

We use the term biowaste in this study to cover food and garden waste, because the broader term – biodegradable – encompasses a wider variety of wastes such as manure, sewage sludge, paper, cardboard and more. The objectives for our research were to compare the environmental impacts of biowaste treatment in the UK and to assess the effect of CH4 emissions. We considered four different waste treatment methods anaerobic digestion, composting, incineration, and landfill), as well as seven different scenarios for waste in various ratios treated using current and future waste management technologies. Full details of those scenarios are explained in full paper.

The four biowaste treatment methods assessed: anaerobic digestion; in-vessel composting; landfill; incineration with energy recovery. The dashed line indicates the system boundary and blue text indicates recovered resources.

In our latest study, we combined mobile CH4 emissions data for anaerobic digesters (AD) – rather than relying on the default emission factors for life cycle assessment (LCA). Approximately 19% of biowaste in the UK is currently landfilled, while 38% is incinerated. Of the remaining 53%, the waste strategy set a target for AD of 15% in 2020.  It is reasonable to assume that 15% of biowaste is sent to AD and the remaining 28% is sent to the composting facility. Combining the mobile methane emissions from AD and composting facilities, we can estimate that current annual UK average methane emissions are approximately 58.2 kilotonnes.

If we sent 90% of biowaste to AD and 1% to landfills as a strategy for the reducing landfilled biowaste by 2050, annual emissions would decrease to 30.3 kilotonnes. Therefore, sending more biowaste to AD can reduce emissions, but if we want to achieve net zero emissions from the waste sector, remaining emissions must be offset. Therefore, we recommend that future UK waste management policies should also focus on eliminating fugitive emissions from treatment technologies, especially AD, in order to achieve net zero emissions by 2050.

Biogas and biomethane emissions – a quick win for decarbonising future energy systems?

In our latest blog, Dr Semra Bakkaloglu reflects on our newly published research into biogas and biomethane emissions.

Over 100 years, methane has 27.2 times the global warming potential of carbon dioxide. So when it comes to climate change, it’s pretty potent stuff. Methane concentrations in the atmosphere are increasing, which makes it a quick-win target in the drive to decarbonise our global energy system.

It’s no coincidence that over 100 countries signed the Global Methane Pledge at COP26 in Glasgow. The pledge is a commitment to reduce methane emissions by 30% (from 2020 levels) by 2030. But a 30% reduction is ambitious, not to mention a complete reversal of the current trajectory of increasing methane emissions. Achieving that will require a combination of measures, which include reducing emissions from the existing supply chain whilst also reducing reliance on natural gas as a fuel by switching to cleaner energy alternatives, such as electrification or hydrogen.

But those new energy alternatives are at wildly different stages of technological readiness and require major infrastructure changes and investment. They are unlikely to happen overnight – and many are unlikely to become mainstream within the next 8 years.

One sector that is expected to grow and contribute to decarbonisation in that transition period is biogas and biomethane – a mixture of gases (mostly methane (CH4 and carbon dioxide (CO2)) produced from biodegradable materials. It’s a technology with a lot of factors in its favour: the volume of organic waste – known as feedstock – generated by modern societies is increasing, it provides a beneficial alternative disposal method for that waste, and conversion of energy from waste to biogas can begin to replace fossil fuel gas – which in turn reduces overall greenhouse gas (GHG) emissions. Ultimately it contributes to meeting those government commitments.

But biogas and biomethane production can also emit methane and it’s an area that’s been lacking in research. No study has assessed methane emissions from the biogas and biomethane supply chain – until now.

For our recent study, we synthesised methane emissions from the biogas and biomethane supply chains by breaking down stages and identifying key elements from direct measurements studies. We used a statistical model Monte Carlo approach to estimate aggregate methane emissions with uncertainty assessment, which can account for up to 343 g CO2-eq. We observed that biogas and biomethane supply chains exhibit similar emission characteristics to oil and natural gas with super-emitters present at all stages. In our study, 62% of the emissions come from just 5% of the point sources – these super-emitters waste a disproportionately large amount of methane

“..62% of the emissions come from just 5% of the point sources – these super-emitters waste a disproportionately large amount of methane.”

The International Energy Agency’s (IEA) inventory, (the only other benchmark data currently available) estimated total methane emissions from bioenergy to be 9.1 Tg in 2021.

Our study, which only looked at one aspect of bioenergy (biomethane), discovered that methane emissions are more likely to be in the range of 6.4 – 7.8 Tg per year (95th percentile), but the average methane emissions are around 2.8 Tg according to the IEA’s global biogas and biomethane generation rate 1.47 EJ in 2018. If biogas and biomethane production are expanded to the same scale as the oil and natural gas industries and no action is taken, they could emit almost 4 times as much methane as oil and gas supply chains (82.5 Tg in 2021). At present, our results indicate they are high – higher even than natural gas, which is clearly a worry.

Considering the latest IPCC-AR6-WG3 climate change mitigation scenarios that achieve the Paris Agreement 1.5°C temperature rise mitigation target with low or no overshoot, we can see that biogas and methane could have up to 28 EJ of production by 2050. Using our mean emissions rate (52.3 g CO2-eq per MJHHV) from this study, this would result in 53.8 Tg methane emissions. This drives home the point that it is extremely important to reduce biogas and biomethane emissions for these energy sources to play a constructive role in our future energy system.

Finding and removing these large emitters is a critical step toward significantly reducing overall emissions from biomethane and natural gas supply chains. It’s not just about controlling greenhouse gases either. There’s a significant economic argument for addressing emissions – all that lost gas has a commercial value.

According to the European Biogas Association (EBA), biomethane can be produced for as little as €55 per MWh, while natural gas costs around €80 per MWh. When our findings are combined with the cost of biomethane, we can calculate that emitting 2.8 Tg of methane per year in average (based on the IEA’s global biomethane and biogas generation rate for 2018) can result in an average a global economic loss of 2.4 billion euros in average.

“… emitting 2.8 Tg of methane per year can result in a global economic loss of €2.4billion in average.”

Through improved design, detection, measurement, and repair techniques, much of the observed emissions can be avoided. If we focus on super-emitters, there are some potential quick wins too. We found that the digestate stage and upgrading units need the most attention in this regard. There’s a lot of overlap with oil and natural gas supply chains too – preventing gas venting, reducing flaring activities and designing a closed unit with a vapour recovery system can all contribute to reducing emissions.

Additionally, we need better regulations, continuous emission measurements, and close collaboration with biogas plant operators in order to address methane emissions and meet the Paris Agreement temperature target.

We know what we need to do to tackle those emissions; the important thing is to get started right away. Biomethane is an important renewable energy source, but it could be even better! Combating biomethane emissions is not only significant for meeting Paris Agreement’s target but also boosting the global economy.

Hydrogen and other short lived climate pollutants – is the time horizon important?

 

Dr Jasmin Cooper, Research Associate here at Imperial’s Sustainable Gas Institute, shares the work being done to model the potential global warming impacts of H2 emissions in possible future supply chains.


Short lived climate pollutants are greenhouse gases which stay in the atmosphere for much less time than carbon dioxide (CO2). Despite this, they are much more powerful than CO2 and can trap as much heat as thousands of kilograms of CO2 on a mass-to-mass basis (Table 1).

Table 1: Properties of different greenhouse gases (Derwent, 2018, Derwent et al., 2001, Derwent et al., 2018, Derwent et al., 2020, Field and Derwent, 2021, Forster et al., 2021, Myhre et al., 2013, IPCC, 2007).
Greenhouse gas GWP over 500-year time horizon GWP over 100-year time horizon GWP over 20-year time horizon Lifetime in the atmosphere
Carbon dioxide 1 1 1 Hundreds of years
Methane 7.6 29.8±11 82.5±25.8 12 years
Black carbon 900±800 3,200 (+300/-2,930) A few weeks
Hydrofluorocarbonsa 435 1,526±577 4,144±1,160 15 years
Hydrogen 4.3 to 10 Four to seven years
afor the hydrofluorocarbon HFC-134a.

In recent years methane (CH4) has emerged as the most important short lived climate pollutant with the IPCC’s AR6 report finding that emissions of it must be cut for 1.5°C or 2°C temperature targets to be met (IPCC, 2021, McGrath, 2021). This is because it is, at present, the second most important greenhouse gas, being responsible for around 30% of global warming to date (McPhie, 2021). It is also the second most emitted greenhouse gas e.g. in 2019 the UK’s total greenhouse gas emissions were 80% CO2, 12% CH4, 5% nitrous oxide and 3% fluorinated gases (BEIS, 2021). As energy systems move away from fossil fuels, hydrogen (H2) could replace natural gas in areas that are difficult to decarbonise through electrification, such as heavy industry and heat.

H2 is a greenhouse gas, but unlike CH4 it is an indirect greenhouse gas. It does not absorb and trap heat but interferes with other (direct) greenhouse gases by enhancing their warming potential (Derwent, 2018). Therefore, in a world where H2 is used in a way akin to natural gas is now, there is the potential for H2 to be emitted into the atmosphere and contribute towards global warming. While there is limited literature available which estimates the impacts of it in the atmosphere, some as-yet to be peer reviewed research suggests short-term forcing from H2 could be higher than that of methane.

Here at the SGI, we have been modelling the potential global warming impacts of H2 emissions in possible future supply chains. When a 100-year time horizon is considered, H2 will likely not impose extra burdens to meeting Paris Agreement goals. However, if shorter time horizons and other climate metrics are considered, the impacts of H2 could be greater, as short-lived climate pollutants exhibit the majority of their warming impacts in the first few years of being emitted. This is an area where more research is needed, as it is important to fully understand the climate impacts of H2 if it is to become a key energy source.

Figure 1: Temperature response curve of various greenhouse gases (Myhre et al., 2013).

Whilst short lived climate pollutants are important, CO2 is still the most important greenhouse gas because its atmospheric lifetime is long (hundreds of years), and its warming effect is stable (Figure 1). Therefore, when comparing greenhouse gases and creating strategies to tackle global warming, it is important that attention not be drawn away from CO2 i.e. making large cuts to methane emission cannot be used as an excuse to slow down rates of decarbonisation. While short lived climate pollutants are important in the fight against climate change, caution should be used when pitting greenhouse gases against one another based on their GWP, especially GWP over 100-year horizons.

This could lead to unintended consequences either side. For example, a shift away from the importance of CO2 resulting in decarbonisation rates slowing down, or non-CO2 greenhouse gases not being given enough attention and consequentially little action being taken to mitigate emissions.

Overall, the time-horizon considered when comparing greenhouse gases to other another is important but what is more important is the quantity of greenhouse gases emitted. GWP is a useful metric to promote the importance of emissions abatement of non-CO2 greenhouse gases, but its importance becomes less pronounced when emissions are vastly reduced.


References 

BEIS. 2021. 2019 UK Greenhouse Gas Emissions, Final Figures London, UK; Department for Business, Energy and Industrial Strategy (BEIS). Available:’ https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/957887/2019_Final_greenhouse_gas_emissions_statistical_release.pdf

Derwent, R. 2018. Hydrogen for heating: atmospheric impacts – a literature review London, UK; Department for Business, Energy and Industrial Strategy (BEIS). Available:’ https://www.gov.uk/government/publications/atmospheric-impacts-of-hydrogen-literature-review

Derwent, R. G., Collins, W. J., Johnson, C. E. & Stevenson, D. S. 2001. Transient Behaviour of Tropospheric Ozone Precursors in a Global 3-D CTM and Their Indirect Greenhouse Effects. Climatic Change, 49, 463-487. 10.1023/A:1010648913655

Derwent, R. G., Parrish, D. D., Galbally, I. E., Stevenson, D. S., Doherty, R. M., Naik, V. & Young, P. J. 2018. Uncertainties in models of tropospheric ozone based on Monte Carlo analysis: Tropospheric ozone burdens, atmospheric lifetimes and surface distributions. Atmospheric Environment, 180, 93-102.

Derwent, R. G., Stevenson, D. S., Utembe, S. R., Jenkin, M. E., Khan, A. H. & Shallcross, D. E. 2020. Global modelling studies of hydrogen and its isotopomers using STOCHEM-CRI: Likely radiative forcing consequences of a future hydrogen economy. International Journal of Hydrogen Energy, 45, 9211-9221. https://doi.org/10.1016/j.ijhydene.2020.01.125

Field, R. & Derwent, R. 2021. Global warming consequences of replacing natural gas with hydrogen in the domestic energy sectors of future low-carbon economies in the United Kingdom and the United States of America. International Journal of Hydrogen Energy.

Forster, P., Storelvmo, T., Armour, K., Collins, W., Dufresne, J. L., Frame, D., Lunt, D. J., Mauritsen, T., Palmer, M. D., Watanabe, M., Wild, M. & Zhang, H. 2021. The Earth’s Energy Budget, Climate Feedbacks, and Climate Sensitivity. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge, UK and New York, USA; Cambridge University Press. Available:’ https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Full_Report.pdf

IPCC. 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge, UK and New York, USA; Cambridge University Press. Available:’ https://www.ipcc.ch/site/assets/uploads/2018/05/ar4_wg1_full_report-1.pdf

IPCC. 2021. AR6 Climate Change 2021: The Physical Science Basis, Geneva, CH; Intergovernmental Panel on Climate Change (IPCC). Available:’ https://www.ipcc.ch/report/ar6/wg1/

McGrath, M. 2021. Climate change: Five things we have learned from the IPCC report. BBC News.

McPhie, T. 2021. International Methane Emissions Observatory launched to boost action on powerful climate-warming gas [Press Release]. Brussels, BE. Available: https://ec.europa.eu/commission/presscorner/detail/en/IP_21_5636.

Myhre, G., Shindell, D., Bréon, F. M., Collins, W., Fuglestvedt, J., Huang, J., Koch, D., Lamarque, J. F., Lee, D., Mendoza, B., Nakajima, T., Robock, A., Stephens, G., Takemura, T. & Zhang, H. 2013. Anthropogenic and Natural Radiative Forc- ing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge, UK and New York, USA; Cambridge University Press. Available:’ https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter08_FINAL.pdf

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.

What are the best options for road freight transport?

Pedro Gerber Machado, a visiting researcher from the University of São Paulo, Brazil, summarises his recent review paper examining the life cycle emissions for road freight transport. The review was carried out in collaboration with the Institute of Energy and Environment at the University of São Paulo, Brazil.

Author: Pedro Gerber Machado

The transport sector is responsible for around 30% of the world’s energy consumption and 16% of greenhouse gases (GHG) emissions.  To achieve an energy transition to guarantee net-zero emissions, reducing emissions from road transport is fundamental. Diesel is still the most common fuel used for heavy road transport and freight. While worldwide there is a move towards electric vehicles, their environmental benefit in reducing emissions depends on the area’s electricity sources. Our review paper examines the total environmental life cycle emissions of different fuel options and technologies for road freight transport (trucks) in 45 studies.

Electric vehicle
Source: Pixabay

Source of electricity

The source of electricity can make a big difference to greenhouse gas emissions. We found that with greenhouse gas emissions, higher values (3,148–3,664 g/km) are found in places where coal has a significant share in electricity generation. Lower emissions are found where renewables have higher percentages in electricity generation (496 g/km). In China, emissions can reach 5,479 g/km since electricity generation “is mostly from coal.”

Compressed Natural Gas (CNG)

For Compressed Natural Gas (CNG) technology, greenhouse gas emissions vary due to differing efficiency and assumptions about methane leakage during natural gas transportation. But future projections are optimistic due to the potential for improvements in controlling methane emissions (514 g/km in 2050).

Biodiesel

In the analysis, biodiesel had a higher energy consumption and higher emissions profile in the production phase equal to diesel, which is the main reason for its low environmental performance.

Hydrogen

The greenhouse gas emissions intensity from hydrogen varies as it is depends on its method of production such as coal gasification, steam methane reforming (SMR), and hydrolysis. The use of carbon capture and storage (CCS) and liquid or gaseous use also influences its final emission profile.

Fuels vs. diesel

On average, the review showed that biogas, fuel-cell hydrogen, and Liquefied Natural Gas (LNG) have lower emissions in their life cycle than diesel, with a chance of a 57% reduction in emissions for biodiesel, 77% for fuel-cell hydrogen, and 100% chance for biogas. Interestingly, even though biodiesel is a renewable source of fuel that receives significant attention due to its capacity to reduce greenhouse gas emissions, in our review, it had a higher average emission than diesel.

Electric car
Source: Pixabay

Battery electric, hydrogen fuel cells and biogas

We found that if a clean electricity matrix is available, with high renewable energy shares, battery electric vehicles provide the best option. Hydrogen fuel-cells, when hydrogen comes from renewable sources, are also comparable to battery electric vehicles. Biogas can serve as a feedstock for hydrogen production in substituting natural gas in steam methane reform or liquefied for use in Liquid Natural Gas (LNG) trucks.

Further research into biogas emissions, fuel consumption, and its economics is essential. Since biogas production is possible from several sources, it could be suitable for different countries, such as Brazil.

Analysing air pollutants

There is a lack of studies exploring the life cycle of these options when it comes to air pollutants. Even though pollutant emissions in the use phase (for internal combustion options) have received more attention from the scientific community, emissions for the whole life cycle should also be studied. Even so, uncertainties related to the Tank-to-Wheel evaluation can increase the inaccurate values from this side of the analysis and the error propagation, directly impacting the policymakers. For PM2.5, hybrid and LNG options have greater changes in reducing the emissions. Fuel-cell, LNG, CNG, and hybrid trucks have higher chances of reducing nitrogen oxide (NOx) emissions. In contrast, sulphur oxide (SOx) emissions came out inconclusive due to a lack of studies.

But what about the economics…

CNG, LNG, and hybrid trucks were the best options from an economic perspective. CNG has lower life cycle costs and fuel costs in most analyses, with values ranging from 50% lower life cycle costs than diesel to a 2% reduction, to 16% average increase. CNG is the most economical fuel for large fleets that conduct urban operations and can support private infrastructure.

LNG could have a payback time of 2.5 years or lower, considering the price differential mostly in long-haul operations due to its lower fuel costs. However, economic viability could be achieved due to the higher cost of LNG vehicles and maintenance and the limited range of LNG trucks relative to diesel. The studies also showed that the fuel efficiency in LNG trucks could dictate its economic viability. Relative efficiencies of less than 80% reduce the chances of lower costs by 50%.

Finally, hybrid trucks show a total life cycle cost from 10% lower to practically no difference. Although the incremental cost of hybrid trucks is expected to become close to zero in the future, additional investments of more than $35,000 in hybrid technology hinder its viability, especially with low diesel fuel costs.

In the developing world…

The question arises then if the best options regarding GHG and local pollutant emissions will ever be a possibility for developing regions. Even though authors point out that electric trucks could cause an increase in emissions in several places in the world and that it is still necessary to evaluate peak power demand to understand the operational aspects of transport electrification, electric trucks in countries with a high share of renewables have the most radical reductions in GHG. However, being the most expensive options, there is a slight chance that governments in poorer countries or even the private sector will be willing to pay the price, based solely on environmental reasons.

The way to go in these countries has been to continue to depend on diesel. Most recently, the discussion on natural gas use in the transport sector has gained some momentum. Cheaper than other alternative options, natural gas might be an option due to its lower PM emissions, even though other pollutants, or GHG emissions, are higher.

 

Exploring ways to decarbonise heat in Chilean cities

Jorge Salgado Contreras

Chile is committing to decarbonising its electricity sector with a target of 60% renewable power by 2035, but there are still some challenges with decarbonising the heat sector. Chileans still rely heavily on natural gas to heat their homes. Jorge Salgado Contreras from Chile, visited the Sustainable Gas Institute for two months, funded by the Chilean National Commission for Science and Technology, and tasked with investigating ways of developing heat decarbonisation pathways for cities in Chile. We interviewed Jorge about his research.

What is your background?  

I am an industrial engineer and now Head of the Electrical and Electronics Department at Inacap in Punta Arenas University, Chile. I have combined experience in the energy sector, working in academic, private and public sectors. In the private sector, I have worked for both the national gas retailer (Intergas Inc) on both business development and the technical side, as well as in an energy start-up. I also worked for the Ministry of Energy of Chile, on renewable energy and energy efficiency projects, where I was in charge of cogeneration initiatives and lead the long-term energy plans for two cities in Patagonia.

How did you find out about the Sustainable Gas Institute, and what first sparked your interest in working here?

I found the Sustainable Gas Institute website, and it was actually the name that first caught my attention. I really liked the aims of the Institute as it is clear we cannot move to 100% renewables straight away, and a transition is necessary. I also thought the White Paper Series is really trying to address some unresolved issues. Even though the reports are written by academics, they are very influential from a policy context.

The energy mix in Chile (Source: Ministry of Energy, Chile).

Your project is to understand how to decarbonise heat for Chile. Can you tell us why it’s so important an issue?

Chile is actually very cold, especially the southern end which is where I am from; it can go below -10 °C. While Chile has ambitious climate targets to increase renewables to 70% by 2050, these targets have only been set for the electricity sector and there are little targets, plans or research taking place to reduce the emissions intensity of the heat sector.

We currently use so many energy to heat our homes in Chile.  Fortunately, Chile does have a good renewables portfolio (22% renewables),  increasingly with solar and wind. However, in my region (Magallanes and chilean Antarctica, Chile), we still use natural gas to heat our homes, as you do in the UK. We do have access to our own natural gas and biomass but in other regions, for example in Southern Chile, natural gas is imported from overseas. The natural gas subsidy for residential and commercial use in the Magallanes region is around 100 million US$/year and represents about 70% of the Chilean Ministry of Energy National Budget.

What is the project about and who have you been working with?  

I have been trying to understand whether we can work with low-carbon options such as hydrogen to decarbonise the existing gas grid infrastructure. In Chile, there is not much research taking place to understand the role of hydrogen in heat decarbonisation.

I have also been looking at the use of electrification and technologies, such as heat pumps. The recent report by the UK Committee on Climate Change into this was very useful as a case study. The idea is to adapt for the Chilean context, and we could move forward towards a low carbon economy by replacing natural gas with hydrogen.

At the Institute, I have been mainly working with both Dr. Paul Balcombe (an expert in the supply chain for hydrogen) and Dr. Francisca Jalil Vega  (who is highly knowledgeable about various heat decarbonisation options).

And finally, have you enjoyed your time at Imperial College? What do you plan to do next?

Map of Magallanes and Chilean Antarctica Region (Source: Wikimedia Commons)

I am hoping to publish a paper with Francisca and Paul, and I will continue working on this during the coming months. I might be speaking in a congress and will present my work to the Ministry of Energy in Chile.

It has been great working at Imperial College because it such a world-class international university and I really like the interdisciplinary environment. There are so many people doing relevant research here!


Read Jorge’s biography on the Sustainable Gas Institute website.

Header Photo: Picture of Torres del Paine in Patagonia in Chile (Source: Pixabay).

VIDEO: My research in a nutshell – Sandro on reducing industry emissions

How to reduce emissions from industry?

By the time you finish your masters, you’ll know your thesis inside out. We challenged one of our researchers at the Sustainable Gas Institute to explain their research in a short one minute video as part of the ‘Research in a Nutshell Series’.

Sandro Luh is a visiting Masters student from the ETH Zurich. He is using the MUSE energy systems model to examine the potential of different strategies for reducing CO2 emissions in the industrial sector. This includes measures such as fuel switching, electrification and Carbon Capture & Storage.

The industrial sector is a key sector to decarbonise as it accounts for 24% of the total global CO2 emissions (2014).

If you want to find out more about Sandro’s work, read our short interview with him.

Investigating the state of low-carbon transport policies at COP22

Last week, Arnaud Koehl, a PhD researcher at the Department of Primary Care and Public Health at Imperial College, attended the United Nations Conference of the Parties COP22 climate conference in Marrakech. Arnaud is investigating the kind of sustainable transport policies that could co-benefit health and the economy while addressing climate change.

cop22-marrakech

The importance of transport in combating climate change

The transport sector represents about 14% of worldwide greenhouse gases emissions (Intergovernmental Panel on Climate Change IPCC, 2010). More worryingly, the International Energy Agency (IEA) projects a huge growth in private motorised modes of transport; according to these estimates, there will be around 2 billion cars on the roads by 2040! It is therefore paramount that we find low-carbon pathways that will meet the increasing demand for mobility.

So how will these transport emissions (addressed by the Paris Agreement) be enforced by 2020? The way the Agreement is framed relies on the good will of each nation or signatory: countries put forward policies to reduce greenhouse gases emissions for each economic sector (e.g. industry, agriculture, housing) themselves. The legal name for these voluntary targets is “Intended Nationally Determined Contribution” (INDC). This architecture provides the flexibility needed to address climate policies according to the local context. This strategy proved to be quite successful as three out of four of all countries mention transport in their INDCs.

bikes-small
Cycle-sharing demonstration scheme in front of COP22

Lessons from COP22: Chinese engagement, policy trends and international cooperation

In the spirit of the Paris Agreement, COP22 proposes a “strong vision, light touch”. I was particularly interested in what this meant for China. The National Development and Reform Commission (NDRC), an important governmental body, just released a report titled “China’s policies and actions for addressing climate change – 2016” .

This report mentions that fuel efficiency improved by 15.9% (2005) for private cars and ships and by 13.5% (2016) for the civil aviation sector. A director at the NDRC, whom I interviewed, stressed that this was the result of an emphasis on “green, circular, low-carbon” policies imposed on the private sector within the 12th (2011 -2015) and 13th  (2016-2020) five-year plans of the Chinese government. He was also clear on the fact that these policies are being tested and implemented through thousands of projects around China.

In terms of transport modes, I found a clear consensus on acknowledging the benefits of implementing bus-1678945_640Bus Rapid Transit systems across populated urban areas. These are dedicated lanes, typically in the center of the road. The increased use of trains and trams were also leading to a consensus between representatives from differing nations, such as Ethiopia and the United States. Smarter forms of using private motorised modes, such as carpooling, car-sharing, on-demand taxis were also seen as potential ways of reducing emissions.

mobilise-your-city-small

Beyond its final results, COP22 was also the opportunity to seal partnerships to spread good practices internationally. Initiatives from official actors and civil society are soaring in an attempt to implement green policies on time. A good example is Mobilise Your City, gathering 100 cities around the world supporting local governments in developing countries to plan and foster sustainable low-carbon urban mobility. A core belief that Mobilise Your City is promoting among its members is that improving mobility is only relevant if there is a net well-being effect.

How research at the Sustainable Gas Institute can help

muse-2At the start of the year, I was working on the transport module of a new energy systems model developed by researchers at Sustainable Gas Institute (SGI), Imperial College London. The model is called MUSE (Modular Universal energy system Simulation Environment). The aim is that industry will be able to use the model for technology and R&D roadmapping, while it will help international governments make future plans for climate change mitigation.

Uses of the MUSE Model

MUSE could help answer key COP22 issues. Many participants at COP-22 stressed the lack of research on freight transport, despite the fact that it represents half of overall transport emissions. By taking into account freight-related transportation, MUSE enables us how to assess how policy-makers could avoid unwanted developments, such as a spread of high polluting cars, by looking at the incidence of the price of new technologies based on factors such as economic growth.

Another major opportunity would be to look at the improvement in fuel efficiency of current technologies, such as diesel, petrol and hybrid. Indeed, the share of electric vehicles in the world’s fleet will soar, but fossil fuel powered vehicles will remain an important part of the equation until 2050.

electric-car-558344_640Finally, the MUSE model allows to test such interventions at the national level, which is a relevant scale as powerful policy-makers are often found in capitals. Sanjay Sath, from The Energy and Resources Institute, and Jose Viegas, from the International Transportation Forum expressed the necessity of adopting a dual approach, by implementing national policies at the local level. In that perspective, many highlighted the critical need to get more indicators measuring the progress of environmental policies on the ground to ensure of actual improvement of well-being. An example of such indicators is the proximity of public transport to social housing.

MUSE could make the most of the currently available data in order to give an insight on the future place of transport in urban dynamics, and thus help calculating these indicators further.

You can find out more about MUSE here.

BLOG: Building a cleaner natural gas supply chain

GasTech-560pxX300px-Twitter-LargeThe last few days in October saw the Gastech conference and exhibition carried out at the massive Singapore Expo. It was a large affair, with all the major gas companies discussing the most pressing issues for them, particularly emerging gas markets and the prospective rise of Liquefied Natural Gas (LNG). Helge Lund, the CEO of BG group, gave a keynote speech to kick off the conference. He gave his view on the challenges of incorporating gas in a lower carbon world: both a carbon price and a commitment from the industry to reduce methane and carbon dioxide emissions are vital.

It is indeed a challenge to incorporate a fossil fuel into a lower carbon world.  Natural gas is likely to play a crucial role on two fronts: reducing the dependency on the more carbon-intensive coal; and providing variable and peak electricity supply as a compliment to intermittent renewables. If we are going to carry on using gas for these services in the short and medium term, the environmental impacts must be minimised.

Our recent white paper at Sustainable Gas Institute published in September, assessed what we know about both methane and carbon dioxide emissions from the natural gas supply chain. The study found emissions to be highly variable, with some significant ‘hotspots’. Capture

In particular, very high methane emissions were found for liquids unloading processes, gas-driven pneumatic devices and compressors. For all of these sources, emissions were very variable and there are technologies and techniques that can minimise or even eliminate emissions. For example, gas-driven pneumatics could be replaced with instrument air drivers, compressors must be inspected regularly and dry-seals are much lower emitters than wet-seals for centrifugal compressors. The economic feasibility of these changes is likely to be variable but in many cases positive: i.e. a lower product loss more than pays for the increased capital or operating cost.

Another finding of the white paper on supply chain emissions was the appearance of ‘super emitters’ all across the supply chain.

Recent studies have found evidence of a small number of facilities or equipment that emit far more than the average, which significant skews the emissions distribution. These super emitters are likely to be due to the faulty or incorrect operation of equipment or ineffective inspection and maintenance procedures. Detecting the super emitters is the key challenge here, but once we do so, average emissions from the supply chain would be reduced significantly.

Paul Balcombe videoIn summary, no technological innovation is needed to reduce supply chain emissions significantly, only commitment to action from the gas industry. It is very promising to hear words of such commitment from world leading gas producers at Gastech and now is the time to act on this.

If you are interested in finding out more, please download the report, or a short summary note  or watch our short video.

To register for our monthly newsletter, email SGI@imperial.ac.uk or follow us on twitter @SGI_london.