Category: biogas

Methane emissions from biogas facilities are underestimated

A blog by Dr Semra Bakkaloglu, a Research Associate at the Sustaianable Gas Institute. 

Biogas production could have an important role in renewable energy, reducing the adverse effects on the climate. However, biogas production’s contribution to emissions of the greenhouse gas, methane, is not fully understood. Methane (CH4) is the second most potent and abundant greenhouse gas after carbon dioxide (CO2) but because it only lasts in the atmosphere for short time (a decade) reducing methane emissions could have a more rapid impact on mitigating climate change. Unfortunately, there are significant discrepancies between official inventories of methane emissions and estimates derived from direct atmospheric measurement of biogas plants.  If biogas is to be a solution to climate change, we need to find effective emission methane reduction strategies, and sources also need to be properly quantified.

What is biogas?

According to the United Nations Framework Convention on Climate Change (UNFCCC), biogas is defined as gas generated from anaerobic digesters. Biogas plant feed may be any biodegradable material, such as dedicated energy crops, agricultural residues, organic waste and paper mill waste. The integrated process in biogas plants includes feedstock supply and pre-treatment, gas treatment and utilisation, and recovery, pre-treatment and use of digestate (Wellinger et al., 2013). This comprises 50 to 70% methane, 30 to 50% CO2 and traces (1 to 5%) of hydrogen suphide and ammonia (National Non-Food Crops Centre, 2021). Biogas is used for heating, electricity or both. If biogas is upgraded to biomethane by removing other gases, biomethane has similar properties to natural gas and can be injected into gas grid or used as a road fuel.

Emissions from biogas plants

Biogas production has an important place in renewable energy, reducing the adverse effects on the climate. However, high methane emissions from biogas plants can arise from fugitive emissions. Depending on engine construction, plant design and operation conditions, emissions can occur through venting from compressors, pipes, single large leaks or long-lasting pressure relief valves and incomplete combustions from combined heat and power units.

Biogas plant and field
Figure 1: One of the UK’s biogas plants

Biogas plants not accounted for

Waste practices in the EU and the UK have changed recently as more waste is being diverted from landfill to biogas plants and composting facilities. There are 579 biogas plants in the UK (National Non-Food Crops Centre, 2021) and their number of biogas plants has grown in the last decade (Figure 2). Unfortunately, most have not been included in the National Atmospheric Emission Inventory (NAEI).

The sustainability of biogas plants depends on the land requirement and greenhouse gas accounting (OFGEM, 2018). However, studies have shown that there is often a maximum loss of 9% of the total production rate of methane (Bakkaloglu et al., 2021; Scheutz and Fredenslud, 2019, and Samuelsson et al. 2018). Also, research conducted by my colleagues and I at Royal Holloway in 2021, demonstrated that biogas plants emissions may account for up to 3.8% of the total methane emissions in the UK. This does not include the sewage sludge biogas plants. We therefore need robust, consistent emission measurements in the UK. Legal requirements should also be implemented, not only UK Net Zero Commitment, but also for the sustainability of biogas plants.

Biogas in the UK’s Net-Zero Commitment

Figure 2. Biogas plant market in the UK (Source: Anaerobic Digestion and Bioresources Association, 2019)

On 27 June 2019, the UK government committed to achieving net-zero Carbon emissions by 2050, in line with the UN’s Paris Agreement (Climate Change Committee, 2019). This Agreement sets out many recommendations as to how to achieve net-zero targeted, including:

  • Diversion of all biodegradable waste from landfills to anaerobic digesters or composting facilities by 2025.
  • Measures to reduce emissions from livestock, soils and waste manure.
  • Elimination of food waste as far as possible, and separation of food waste collections
  • Full utilisation of the UK’s biogenic waste sources, including residues from agriculture and forestry.

According to a recent article on the UN website in December 2020, more than 110 countries have a carbon neutral strategy by 2050 but this aim can only be achieved with appropriate reduction methods. As a result of this zero-commitment, biogas plants have assumed a more significant role, not only in the renewable energy market but also in waste strategies.

Although emissions from biogas plants have not, as yet, attracted serious attention, they may jeopardise the net-zero commitment unless the necessary action is taken.

References

Insights into a Brazilian sustainable energy future

Dr Ivan Garcia Kerdan, a research associate at the Sustainable Gas Institute (SGI), at Imperial College, is developing a specialised energy systems model for Brazil which will help ensure the country has a low carbon economy in the future.

In this short blog post, Ivan tells us about how he is building a picture of the Brazilian energy economy and gathering data for a specialised MUSE-Brazil (funded by FAPESP/Newton Fund). 

Currently Brazil is in a post-World Cup/Olympic hangover, with the country’s economy shrinking for two years in a row. This has resulted in reduction of energy consumption in every sector of the economy. Between 2015 and 2016, the economic sector that suffered the most was Agriculture, where there was a reduction of 10.4% in energy use.  Energy use also has decreased across the energy (by 5.3%) and industrial sectors (1.1%). But on the other hand, the energy sector has increased its domestic supply. Fortunately, the Brazilian economy is already showing good signs of recovery. It is expected that there will be a 60% growth in the domestic energy demand in the next decade, and therefore careful energy planning is needed.

Currently Brazil  has clean energy mix, with 46% of its energy from renewables (hydropower and biofuels). MUSE-Brazil aims to generate plausible transitions to ensure a low carbon energy system remains. The framework for the model is based on a global energy systems model, MUSE , being developed at SGI.  MUSE-Brazil will help us understand what role natural gas (a transitional fuel) and biomethane will play in the energy system in 2050.

So how does Brazil’s developing gas market currently look? 10% of the country’s primary energy supply comes from gas. Brazil’s gas reserves are around 388-453 billion m³, with a daily production rate in 2016 of 103.8 million m³ and a reinjection rate of 35.0 million m³. Brazil also imports 32.1 million m³/day, mainly from the Bolivian pipeline and LNG imports. In the case of biogas and biomethane, despite a large production potential of between 63-100 million m³/day (mainly from agriculture and livestock residues and vinasse),  there are only 33 biogas power generation plants in operation. This accounts for 127 MW installed capacity.

In order to get a better understanding of the current Brazilian energy situation, I visited the largest two cities in Brazil, Rio de Janeiro and São Paulo. My first visit in May was to Rio and the EPE (Empresa de Pesquisa Energetica or Department Energy Research). This  department is linked to the Ministry of Mines and Energy, and supports studies and research in planning the national energy sector.

Interestingly, EPE was created in 2004 after blackouts occurred in the country at the beginning of the century, which was mainly attributed to lack of planning. It was also in this period that the majority of the current gas-based power plants installed capacity were put in place (currently this stands at 12.9 GW), and provides the much-needed energy security to the power system.  Ricardo Gorini’s team from the energy economic department arranged meetings with specialists at each one of these sectors. As part of my work on MUSE-Brazil, I need to fully comprehend the specific characteristics of every energy subsector in the economy and the various interactions between them.

While in Rio, I also visited UFRJ-COPPE Energy Planning department led by Prof Roberto Schaeffer. This department is the first energy planning programme in Brazil and is recognised worldwide for its contributions to the international reports on climate change.  Characterised by an interdisciplinary approach, it associates the technological dimension of energy with political, economic, social and environmental aspects. At COPPE, I learnt  more about their own energy system model (MESSAGE-Brazil) which aims to evaluate Brazil’s role in a low carbon global economy and has been used to produce outputs for government and academic reports.

As part of bigger FAPESP/NERC project, MUSE-Brazil is only a small part of a wider collaborative research with the University of São Paulo (USP), University College London (UCL), University of Cardiff and University of Leeds. Other projects are looking at optimising bio-refinery efficiency, and the socio-economic impacts of bioenergy production, as well as examining land use and ecosystems impact of bioenergy production.

During my first visit to Brazil, I also spent  time at USP which is also the home of the Research Centre for Gas Innovation (RCGI). This Institute works very closely with the Sustainable Gas Institute (SGI). RCGI aims to examine the sustainable use of natural gas, biogas, hydrogen and management, transport, storage and and usage of carbon dioxide on a global scale.

In late September, I returned again to São Paulo, and USP to present an update of MUSE-Brazil based on some of my findings from my first trip. Although the model is still in its early stages, this was also an opportunity to present at the joint SGI/RCGI conference, Sustainable Gas Research & Innovation 2017. 

Delegates at the Sustainable Gas Research & Innovation Conference 2017

RCGI projects are spread across three different disciplines: i) Engineering, ii) Physical-Chemistry and iii) Policies and Economics topics. At the conference, some of the most insightful presentations were, “Studies of the application of laser (LIDAR) for atmospheric pollution measurement” by Roberto Guardani, which focused on the application of remote sensing to measure fugitive emissions associated with the petroleum industry. I also enjoyed the presentation given by Renato Romio and Clayton Barcelos, “Development of a hybrid penta-fuel flex vehicle” which uses big data techniques to understand the use of a hybrid car in real traffic conditions with the aim of improving efficiency in the transport sector. It is planned that some of these outputs, directly or indirectly will be used in MUSE-Brazil to populate the model.

Ivan in São Paulo

Several contacts and collaborations have been put in place from this visit.  I am looking forward for the upcoming year and expecting great results from this collaboration. Most importantly, the insights gained from my experience at both at UFRJ/EPE in Rio de Janeiro and USP in São Paulo has been crucial for understanding the requirements, needs, and challenges of the energy sector in Brazil.

What I am taking away from my time working in Brazil is that although there is still plenty of research to do, we are following the right path to understand the potential of Brazil in a low carbon economy. More data and modelling efforts are still necessary to produce robust outputs with MUSE-Brazil. The model should be ready by April 2019; we will provide open access to the code and the majority of the data.

About the author: Ivan is currently based in the Department of Chemical Engineering at Imperial College. He has a degree and MSc from the National Autonomous University of Mexico (UNAM) and a PhD in the Energy Institute at University College London. His areas of interest are energy analysis, thermodynamics, low-carbon technologies, energy systems modelling and optimisation.

SGRI 2016 Conference: My reflections on natural gas innovation and sustainability in Brazil

Dr Julia Sachs, a Research Associate at the Sustainable Gas Institute shares some insights from this year’s Sustainable Gas Research and Innovation 2016 conference.Conference logo

Last month, I had the opportunity to attend the first annual conference in natural gas sustainability and innovation, which took place in São Paulo, Brazil. One of the main aims of the conference, co-organised by the Sustainable Gas Institute (SGI) and Research Centre for Gas Innovation (RCGI), was to bring together international stakeholders from academia and industry, and to explore the role of natural gas in the global energy landscape and a low carbon world.

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Deep offshore wave generator tank

São Paulo was an excellent location for the conference as it’s a key industrial hub in Brazil, and also responsible for 10.7% of Brazilian GDP.

Before the conference, we had the opportunity to tour around the University of São Paulo (USP) campus (where RCGI is based) and find out more about the research taking place at our sister institute, in the Laboratories of the Mechanical Engineering and Chemical Engineering departments.

It was really impressive to see the numerous experimental setups and how theoretical research was directly brought into practice. The highlight for me was the virtual reality simulator used for guiding boats into ports and also the deep offshore wave generator tank which serves as model for testing the durability of design for ships, renewable energy devices and offshore structures.

For the Olympics, the tank had even been programmed to generate an image of the Brazilian flag. You can see the video in this tweet.

The two day conference started with the directors from the co-hosting organisations, Prof  Nigel Brandon (SGI) and Prof Julio Meneghini (RCGI) introducing the keynote speakers, Dr Rob Littel (General Manager Gas Separation from Royal Dutch Shell) and Prof. Carlos Henrique de Brito Cruz (Scientific Director from FAPESP, the São Paulo Research Foundation).

RCGI / Conference 2016 - São Paulo - Sustainable Gas Research & Inovation Conference 2016, no Hotel Mercure. Rob Littel,General Manager Gas Separation, Shell Foto:Luiz Prado / LUZ
Dr Rob littel from Royal Dutch Shell

Dr Rob Littel emphasised the current challenges faced by the industry; CO2 regulations, a lower oil price, and rising energy demand which will require a diverse energy landscape and a combination of fossil fuels and renewables as well as new innovations. Dr Littel described two promising separation technologies; the next-generation post combustion capture of CO2 potentially using solid sorbents and carbon molecular sieve membranes for natural gas separation to achieve a reduction of the amount of space required and up to 60% cost savings.

He also emphasised the need for a strong collaboration between universities and industry to successfully face these challenges, and that the role universities such as Imperial College and University of  São Paulo (USP) will play in identifying the most promising technology pathways.

RCGI / Conference 2016 - São Paulo - Sustainable Gas Research & Inovation Conference 2016, no Hotel Mercure. Carlos Brito, FAPESP. Foto:Luiz Prado / LUZ
Prof Carlos Henrique de Brito Cruz from FAPESP

The second keynote was Prof. Carlos Henrique de Brito Cruz, who emphasised the role of Brazil in meeting these challenges, in particular São Paulo as an unique city/state with significant economic, research and academic importance.

In Brazil, nearly half (47%) of power is from renewables such as biofuels. He also mentioned how Brazil is the world’s second largest producer of ethanol fuel which uses an exclusive blend of ethanol and gasoline to run light vehicles. The question is how to integrate renewables with natural gas.

While travelling around São Paulo, we were aware of one of the major problems facing the city. Huge traffic jam build ups to 100km long are common. Prof. Carlos Henrique de Brito Cruz mentioned this congestion issue, and the resulting high CO2 emissions which requires technological innovations.

The core of the conference consisted of a series of talks about ongoing projects of the RCGI and SGI covering a wide range of topics in areas such as engineering, physics, chemistry, modelling, economics, policy, and energy efficiency all under the linked to drive the wider research field of sustainable gas innovations.

In total, RCGI has 29 projects in different phases of a technology’s life cycle.

As a member of the Energy System Modelling team, it was of particular interest to me to identify how energy models that could be applied to the different projects.

In particular, Energy Systems Models such as those being developed at SGI (MUSE) will play an increasingly influential role to identify trends in the energy market, the effects of policy regulations and the requirements needed and necessary actions to meet different environmental and economic objectives.

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A diagram of the MUSE model

MUSE is designed to generate plausible transitions of energy systems towards a low carbon economy with a specific focus on the role of gas in delivering a more sustainable future.

One of the highlights of the conference was the panel discussion “An international perspective: Innovation in natural gas”. The list of speakers included global experts from academia, government and industry to discuss the opportunities and challenges with natural gas as well as to give a perspective about the innovation technologies that might be required.

RCGI / Conference 2016 - São Paulo - Sustainable Gas Research & Inovation Conference 2016, no Hotel Mercure. Prof. Jim Watson. Foto:Luiz Prado / LUZ
Dr Jim Watson and the panel

Some key points were highlighted during the discussion:

  • Natural gas needs to be considered as an isolated solution but as part of the global energy mix.
  • New technologies (e.g. CCS) are needed to enable an efficient use of natural gas to meet the agreements of the COP-21
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Credit: The Economist

Although, there exists some common points about the future of natural gas across the world, the problems individual countries face and the role of natural gas is surprisingly different. For example, in the UK, the national gas consumption is already declining. While, in contrast, natural gas presents a promising solution to limit emissions in coal dominated markets such as China.

Research from the International Energy Agency (IEA) generally shows that natural gas is likely to play a crucial role in two main areas: in the transport and the power sectors. In particular, there is a trend for the use to substitute coal in the OECD counties and as an addition to the energy mix in non-OECD regions to meet the rising energy demand while simultaneously limit emissions. The US has a large amount of natural gas as ethane resources which raises the problem of how to cost efficiently export natural gas and also how best to use the ethane.

One of the take home messages for me was that there are different drivers in different parts of the world based on the availability of gas, the accessibility, the price and in particular the existing energy mix but all aim to limit emission and require innovations to reach these goals.

Julia is a Research Associate working on the MUSE energy systems model at the Sustainable Gas Institute.

The next Sustainable Gas Research Innovation conference will take place on September 17th and 18th in 2017. Please email SGI@imperial.ac.uk for further information.