Gas Distribution Infrastructure Research Articles

The Australian Hydrogen Centre – feasibility studies for achieving 10 and 100% renewable hydrogen in South Australia and Victoria

The Australian Hydrogen Centre (AHC) was established to deliver Australian-first feasibility studies into how existing natural gas distribution networks could be used in a system to produce, store, and transport renewable hydrogen, decarbonising gas supply while still meeting the needs of customers. The AHC Reports show that it is technically and economically feasible to use existing gas infrastructure for scaled hydrogen distribution, delivering: (1) net-zero carbon emissions gas; (2) minimised customer disruption while retaining security and diversity of supply; (3) services to the electricity grid through flexible electricity demand and frequency control; (4) 15 gigawatts (GW) of electrolysis supported by over 30 GW of new renewable electricity generation; (5) 30 petajoules (PJ) of hydrogen storage to harness the ability of gas to store vast amounts of energy, balancing renewable electricity supply and demand swings between colder and warmer months; and (6) over AU$1.5 billion in additional economic value a year including more than 12,500 jobs during construction and 6200 jobs during operation. Supported by a range of independent technical studies, the Reports provide a better understanding of the opportunity to access Australia’s world-class gas distribution infrastructure to unlock hydrogen opportunities while retaining energy security and affordability; identifying a range of low-regret enablers that could trigger coordinated action by government and industry. They also share learnings from Hydrogen Park South Australia (HyP SA), an Australian-first demonstration of hydrogen blending in a gas distribution network.

Hydrogen blending in Italian natural gas grid: Scenario analysis and LCA

In this paper, a detailed analysis of the impact of hydrogen blending in the natural gas grid in terms of potential increase of Intermittent Renewable Energy Source (IRES) penetration, increase of electrolyzer power installed, reduction of CO2 emission and environmental footprint, is provided formulating models in EnergyPLAN and OpenLCA software. The Italian energy system is taken as case-study. Three scenarios have been analysed: BASELINE scenario represents the current energy system; MID-SCENARIO foresees a total IRES capacity of 158.17 GW (x5 compared to 2019 capacity) derived from the capability to convert intermittent electricity surplus in hydrogen and inject it in the natural gas grid; in the END-SCENARIO, the IRES capacity is pushed up to 272.1 GW.The main outcomes of the study attest that blending of hydrogen in the natural gas grid leads to beneficial impacts in terms of environmental footprint. Considering the global energy system, hydrogen production and blending in the natural gas grid leads to a maximum decrease of 15% in CO2 emissions compared to 2019. The impact is significant but limited by a threshold in the maximum hydrogen amount that the gas distribution infrastructure can currently accept (hydrogen molar fraction <20%).Focusing the study on the electricity generation sector, the reduction of CO2 emissions reaches −66% in the END-SCENARIO. The LCA index “Fossil resource scarcity” is reduced by up to −77% due to the replacement of fossil fuels, starting from coal. On the other hand, the LCA category “Mineral scarcity” undergoes an increase (x3.03 in MID-SCENARIO, ×2.73 in END-SCENARIO) due to the large amounts of materials needed to manufacture the photovoltaic plants, wind farms and electrolyzers, such as copper, aluminum, platinum, nickel, titanium and silicon, exacerbating the critical materials issue.

Unconventional sources of gaseous energy in the Southern Region of Brazil: a comparative SWOT analysis

The southern region of Brazil is diverse when it comes to unconventional gaseous energy sources with high methane concentrations. Located above the Paraná Sedimentary Basin, the region has great potential to produce shale gas and coalbed methane, situated in the Ponta Grossa and Rio Bonito Formation, respectively. In addition, the generation of biomethane from pig farming effluents in the state of Paraná has been gaining national prominence. In this sense, this work aimed to carry out a comparative SWOT analysis of three potential methane sources in the southern region of Brazil: (1) shale gas, (2) coalbed methane, and (3) biogas from swine effluents. This qualitative study debated each option regarding its regional impacts, developed gas distribution infrastructure, and investments in R&amp;D for risk mitigation. A clearer consolidation of the federal government’s competence and states would bring more confidence and predictability to the market and promote better policy and legal security for investors.

Long-term factors and trends in the development of the fuel and energy complex of Ukraine

The objective of the paper is to define long-term trends and factors in the development of the world energy industry and their refraction to Ukrainian realities. The article consists of an introduction, three sections, namely: the main trends in the development of the global fuel and energy complex, analysis of the current state, long-term trends and factors in the development of the national fuel and energy complex of Ukraine. Conclusions end the paper. As for the world energy sector it is shown that its modern changes – Grand Transit – are due to the ideology of sustainable development and have the character of an extraordinary change in the technocenosis, the transition from the use of fossil fuels to energy from renewable sources, mainly – wind and photovoltaic nature. Along with the major tendencies of the Great Transition, there is also the trilemization and politicization of energy sector. Trilemization components are: Energy Security, Energy Equity and Environmental Sustainability. There are three scenarios for the development of the global energy – Unfinished Symphony, Modern Jazz and Hardrock, distinguished by the degree of greening and the availability of energy resources. Political motives are becoming more and more significant at all levels – from global to local. Major players are lobbying their interests, there is an activity of structures from the field of nuclear energy, powerful fuel companies, owners of gas transportation and gas distribution infrastructure. In Ukraine, transformation processes are taking place against the backdrop of low environmental acceptability and high depreciation of fuel and energy sector facilities and infrastructure, political and economic instability. The requirements of decarbonization create challenges to the very existence of coal energy, which is the main component of the energy generating fund of the country and the regions, where mines are located. Options for the development of hydrogen/ammonia energy in the form of vertically integrated energy-chemical systems with the nuclear power plants and reformed coal-fired thermal power plants are considered as promising; energy diversification of mining regions; the creation of virtual power plants based on hydrodynamic water heating installations.

A Comprehensive Review on the Prospects of Using Hydrogen–Methane Blends: Challenges and Opportunities

An analysis of the literature data indicates a wide front of research and development in the field of the use of methane–hydrogen mixtures as a promising environmentally friendly low-carbon fuel. The conclusion of most works shows that the use of methane–hydrogen mixtures in internal combustion engines improves their performance and emission characteristics. The most important aspect is the concentration of hydrogen in the fuel mixture, which affects the combustion process of the fuel and determines the optimal operating conditions of the engine. When using methane–hydrogen mixtures with low hydrogen content, the safety measures and risks are similar to those that exist when working with natural gas. Serious logistical problems are associated with the difficulties of using the existing gas distribution infrastructure for transporting methane–hydrogen mixtures. It is possible that, despite the need for huge investments, it will be necessary to create a new infrastructure for the production, storage and transportation of hydrogen and its mixtures with natural gas. Further research is needed on the compatibility of pipeline materials with hydrogen and methane–hydrogen mixtures, safety conditions for the operation of equipment operating with hydrogen or methane–hydrogen mixtures, as well as the economic and environmental feasibility of using these energy carriers.

Modelling the impact of the energy transition on gas distribution networks in Germany

The energy transition is leading to profound changes in all parts of the energy system, but the reduction of fossil fuels in the heating sector is a major challenge for the energy sector. The changing heat-generating structure also affects its supply infrastructures. The impact on the existing electricity infrastructure is evident and subject to a lot of research, but gas distribution networks are not considered in most studies. The ongoing defossilization brings the need to assess the impact on gas distribution networks. The assumption of gas as a bridge technology might lead to potential lock-ins or sunk cost. The central question reads: how will gas distribution networks change by 2050 as we move towards a greenhouse gas neutral energy system?This question is answered by using a model network analysis called DINO to compute the infrastructure development and associated cost for existing greenhouse gas-neutral scenarios from present day until the year 2050. The supply task and the necessary network elements with their physical parameters are included in the model, and the cost-optimal gas distribution network infrastructure is calculated for each county in Germany.In short, the infrastructure analysis shows a declining need for gas distribution networks for all given greenhouse gas-neutral scenarios. In all-electric scenarios, the network length of the required grid infrastructure decreases to zero by 2050. Even in moderate scenarios with high shares of synthetic gas in the heating system, less gas distribution infrastructure is needed. The results of the research presented in this paper can be used to support the necessary measures to ensure a development of gas distribution networks that support greenhouse gas neutrality.

Feature extraction and machine learning techniques for identifying historic urban environmental hazards: New methods to locate lost fossil fuel infrastructure in US cities.

U.S. cities contain unknown numbers of undocumented “manufactured gas” sites, legacies of an industry that dominated energy production during the late-19th and early-20th centuries. While many of these unidentified sites likely contain significant levels of highly toxic and biologically persistent contamination, locating them remains a significant challenge. We propose a new method to identify manufactured gas production, storage, and distribution infrastructure in bulk by applying feature extraction and machine learning techniques to digitized historic Sanborn fire insurance maps. Our approach, which relies on a two-part neural network to classify candidate map regions, increases the rate of site identification 20-fold compared to unaided visual coding.

Investigation of the Spatial Distribution of Methane Sources in the Greater Toronto Area Using Mobile Gas Monitoring Systems.

For methane emission reduction strategies in urban areas to be effective, large emitters must be identified. Recent studies in U.S. cities have highlighted the contribution of methane emissions from natural gas distribution networks and end use. We present a methane emission source identification and quantification method for the Greater Toronto Area (GTA), the largest metropolitan area in Canada, using mobile gas monitoring systems. From May 2018 to August 2019, we collected 77 surveys of methane mixing ratios, covering a distance of about 6400 km, and sampled emission plumes from sources such as closed landfills, natural gas compressor stations, and waterways. Our results indicate that inactive landfills emit less than inventory estimates. Despite this discrepancy, we confirm that the waste sector is the largest methane emitter in the GTA. We also report that the frequency of methane leaks from the local distribution system ranges between 4 and 22 leaks per 100 km of roadway in downtown Toronto, which is comparable to the range observed in U.S. cities, which have invested in modern natural gas distribution infrastructure. Last, we find that engineered waterways, whose emissions are currently not reported in inventories, may be a significant source of methane.

Coordinated management of organic waste and derived products

We propose a coordination framework for managing urban and rural organic waste in a scalable manner by orchestrating waste exchange, transportation, and transformation into value-added products. The framework is inspired by coordinated management systems that are currently used to operate power grids across the world and that have been instrumental in achieving high levels of efficiency and technological innovation. In the proposed framework, suppliers and consumers of waste and derived products as well as transportation and technology providers bid into a coordination system that is operated by an independent system operator. Allocations and prices for waste and derived products are obtained by the operator by solving a dispatch problem that maximizes the social welfare and that balances supply and demand across a given geographical region. Coordination enables handling of complex constraints and interdependencies that arise from transportation and bio-physico-chemical transformations of waste into products. We prove that the coordination system delivers prices and product allocations that satisfy economic and efficiency properties of a competitive market. The framework is scalable in that it can provide open access that fosters transactions between small and large players in urban and rural areas and over wide geographical regions. Moreover, the framework provides a systematic approach to enable coordinated responses to externalities such as droughts and extreme weather events, to monetize environmental impacts and remediation, to achieve complex social goals such as geographical nutrient balancing, and to justify technology investment and development efforts. Furthermore, the framework can facilitate coordination with electrical, natural gas, water, transportation, and food distribution infrastructures.

Risk Assessment of Incidents Response for Downstate New York Natural Gas Distribution Infrastructure

In the United States today, there are thousands of miles of an extended network of natural gas pipelines across the nation. Current pipeline explosions and leaks in several regions have challenged the natural gas industry to re-evaluate efforts and to pursue proactive strategies. Safety and the environmental threat has become a primary concern in the United States and around the world, but mostly in cases where natural gases, oil, and other hazardous wastes are intricate. Thus, a significant point in the natural gas pipeline industry that signifies both the economic and social issue is the unplanned pipeline risk. In this article, a quantitative data analysis was performed for Downstate New York companies, Con Edison and National Grid. There, the data from various natural gas pipelines was observed for the trend regarding failing material, failure cause, aging characteristics, and perform a risk assessment to come up with training and risk checklist that could be crucial for risk handling strategies. The statistical analyses of the natural gas pipeline-related incident data for distribution pipelines between 2012 and 2016, which were composed from Pipeline and Hazardous Material Safety Administration (PHMSA) of the United States Department of Transportation (DOT), are compiled. The total miles in the gas distribution pipelines in downstate New York is approximately 48,539 as of 2016. The equipment failure, other incident cause, other outside force, and excavation damages are the leading causes of the pipe-related incidents, which are responsible for over 20% of the total incidents between 2012 and 2016. As a result, a quantitative research methodology has been developed as the suitable approach to achieve risk assessment. Mainly, this approach aims towards risk management in natural gas industry projects using the maximum likelihood method on 70 rupture incidents between 2012 and 2016, which were collected from the PHMSA pipeline incident database. The hypothetical quantitative risk assessment of the gas distribution pipelines are illustrated by combining the statistics of the pipeline rupture incidents, as well as risk assessment performed in the present study.

The renaissance of the Sabatier reaction and its applications on Earth and in space

The Sabatier reaction (that is, CO2 methanation) is undergoing a revival for two main reasons. First, the power-to-gas concept offers the prospect of large-scale recycling of (point source) CO2 emissions, in combination with the use of large quantities of renewable energy to form methane. When this can be achieved in a cost-effective manner, it can use the gas distribution infrastructure that already exists. However, methanation is no simple panacea to the detrimental environmental effect of CO2 emissions, and reaction products other than methane should also be targeted. Second, methanation has been identified as an important reaction to facilitate long-term space exploration missions by space agencies, such as NASA. This Perspective discusses the current understanding of CO2 hydrogenation within these concepts, from fundamental mechanistic aspects to several parameters that will ultimately define its technical and economic feasibility on Earth and in space, as we transition into the era of small-molecule activation.

Contemporary trends in metropolitan gas distribution infrastructure construction

Scope of Study: Current development trends for all gas infrastructure systems utilizing natural gas and alternative fuels (most commonly, liquefied hydrocarbon gas) do not provide due justification for all criteria influencing the efficiency of such systems. Meanwhile, expediency of natural or liquefied gas supply shall be calculated by taking into account network configuration for settlements, their population density, type of gas equipment utilized by customers and other relevant factors. Very often, dismissal of such criteria leads to tremendous and unjustified investment into gas distribution systems, thus decreasing their economic viability and efficiency.The purpose of this study is development of an optimal structure for natural and liquefied hydrocarbon gas distribution system that taken into account individual characteristics of gas fuel consumption by metropolitan community.Materials and Methods: The study is based on generalization and systematization of gasification data provided by gas distribution companies operating in Russian Federation. System analysis and mathematical simulation have been used to find optimal values for relevant limitations.Results: Optimal operation parameters of gas distribution system utilizing natural and liquefied hydrocarbon gas and taking into account gas consumption rates have been found. System analysis of elements of distribution system under construction allowed estimating the number and specific features of gas fuel consumption in various settlements, number of said settlements and their annual gas consumption rates and number of distribution stations in terms of regional supply of natural and liquefied hydrocarbon gas.Conclusions: We have evaluated gas distribution systems parameters based on annual gas consumption rates. The scope of application for natural and liquefied hydrocarbon gas within specified gasified region has been established. We have also provided recommendations on practical application of obtained research data.

Joint Costs in Electricity and Natural Gas Distribution Infrastructures: The Role of Urban Factors

This paper analyzes the joint cost structure of electricity and natural gas distribution investments. Assessing the joint costs is critical for urban development and public policy regarding competition at the local level. The paper accounts for the urban and geographic factors at the local level, while the previous literature primarily used company-level data with a few or no site-specific variables in joint cost analyses. An empirical analysis of the multi-utility capital costs suggests that the local urban and geographic conditions affect such costs, with economies of scope present in electricity and natural gas both in terms of total costs and underground investment costs. Hence, the joint service provision makes economic and environmental sense for urban policy makers.

A greenhouse gas abatement framework for investment in district heating

Biomass resources could be used in the Northeastern U.S. in centralized district heating networks supplied by combined heat and power (CHP) plants to reduce consumption of petroleum resources (fuel oil), generate renewable electricity, and cost-effectively reduce greenhouse gas (GHG) emissions when supplying buildings with space and water heating. Alternatively, the CHP plants could be powered by natural gas, which would reduce GHG emissions relative to conventional, individual heating solutions owing to the improved efficiency of cogeneration. To assess the potential for investment in these technologies, hourly heat load demand in residential and commercial buildings in all New England and New York state towns (populations > 5000) was estimated and used to optimize the energy efficiency of district heating networks using MODEST software. All of the 116 studied locations without access to natural gas distribution infrastructure showed negative carbon abatement costs, the majority between −$250 and −$38 per Mg CO2 equivalents (eq.), when biomass-fed district heating was implemented due to significantly reduced operational costs and life cycle GHG emissions. Similarly, almost all (465 out of 467) locations connected to the natural gas grid were found to have negative GHG abatement costs, ranging from −$4500 to −$400 per Mg CO2 eq., demonstrating strong economic feasibility for district heating. Natural has an economic advantage over biomass in district heating due to its combined cycle CHP plants being able to generate more electricity per heat unit compared to biomass CHP plants and its lower O&M costs. District heating in all locations could abate 2.6 billion Mg of CO2 eq. at an economic surplus over 30 ears of continuous operation. Using a framework that integrated spatial tools, optimization, LCA, and cost evaluation, this study uniquely identified promising locations in the U.S. where district heating could be both environmentally and economically beneficial. This framework can be applied to other global regions that have significant space heating needs, for CHP implementation, and as a tool for identifying alternative building energy investments, such as improved insulation or individual space heating solutions, which in some cases could yield higher GHG reductions per dollar.

Design and optimization of a natural gas-fired thermoelectric generator by computational fluid dynamics modeling

The paper reports the results of the computational part of an ongoing research and development project aimed at designing and optimization of a thermoelectric generator fired with natural gas. The idea of the project is to provide an independent and reliable source of power in the power range of 50–100W for island-mode supply, tailored for remote objects of the natural gas distribution infrastructure which, for economic reason, are not connected to the electric grid. The device includes a burner as a heat source, flow channels for air and for exhaust gases and a set of thermoelectric modules generating electric current if subject to temperature difference. The pre-selected design configuration (type E) was subject to parametric optimization. A corresponding numerical model based on the Ansys/Fluent computational fluid dynamics code was built. The optimization procedure aims to maximize the temperature difference across the thermoelectric module in order to maximize the generated power output. Simultaneously, it is essential to maintain the hot-side temperature below the required technical limit of 320°C. First, thirteen design parameters (most of them concerning geometry) influencing the target function were identified. A central value and a possible range for each parameter have been set. Next, the partial impact of each parameter on the target function was found, and the set of the design parameters was limited to eight. Finally, only five parameters were estimated to be non-monotonically related to the generated power. The impact of the selected five parameters on the target function was investigated using a central composite design optimization plan. The set of points obtained in the multi-dimensional response surface was then limited to points meeting the imposed limitation of maximum temperature. Eventually, three candidate points (i.e. three sets of design parameters) have been proposed for the next stage of the project involving an experimental set-up for the design of the prototype.

Comparing Low- and High-Temperature Electrochemical Process Pathways for Converting H2o and CO2 into Synthetic Natural Ga

The conversion of water and carbon dioxide into useful products such as synthetic natural gas using renewably supplied electrical energy can offer several advantages for stabilizing the electric grid and increasing the security of energy supply chains. In addition to providing increased grid operational flexibility for dealing with intermittent renewable electrical energy supplies, infrastructure changes such as hydrogen pipelines could conceivably be avoided in situations where natural gas pipelines and CO2 sources coincide. The natural gas distribution infrastructure is well developed in many countries, enabling the fuel to be transported long distances and easily delivered throughout cities. Using the existing pipeline to transport renewably generated synthetic natural gas (SNG) can further enhance the value of the product via offering grid services such as load leveling. While the price of natural gas is near record lows in the United States, many other countries are working to develop SNG as an alternative fuel for transportation and residential/commercial heating markets, especially in Europe and for island nations. This study presents pathway studies of low- and high-temperature electrolysis integrated with an SNG plant design and evaluates their performance for producing SNG by reacting renewably generated hydrogen with carbon dioxide. The carbon dioxide feedstock is assumed to be captured and scrubbed from either an existing coal fired power plant at the city-gate or from sequestered CO2, where the SNG plant is co-located. In the first pathway, water is split using either low-temperature alkaline or proton exchange membrane technology. In a second path, the co-electrolysis of steam and CO2 is done in-situ using high temperature (600°C) solid oxide cell technology. Historically, methanation has been a common practice for eliminating carbon monoxide and carbon dioxide in various chemical processes such as ammonia production and natural gas purification; for these processes, only small amounts (1-3% molar basis) of carbon oxides need to be converted to methane. A “bulk” methanation process is unique due to the high concentration of carbon oxides and hydrogen. In addition, the carbon dioxide is the only carbon source, and the reaction characteristics of carbon dioxide are much different than carbon monoxide. In process paths involving low-temperature electrolyzers, a methanation plant is required. In this study, thermodynamic and kinetic considerations of the methanation reaction are explored to model and simulate a system of reactors for the conversion of hydrogen and carbon dioxide to SNG. Multiple reactor stages are used to increase temperature control of the reactor and drain water to promote the forward direction of the methanation reaction. Heat recuperation and recovery using organic Rankine cycle units for electricity generation utilizes the heat produced from the methanation reaction. Bulk recycle is used to increase the overall reactant conversion while allowing a satisfactorily high methane content SNG product. A hydrogen membrane separates hydrogen for recycle to increase the Wobbe index of the product SNG by increasing the methane content to nearly 93% by volume. In both pathways, the product SNG has a minimum Wobbe index of 47.5 MJ/m3 which is acceptable for natural gas pipeline transport and end-use appliances in existing infrastructures. The overall plant efficiencies of both pathways are compared as well as the expected price of the product SNG using the H2A tool.

System Analysis of Poly-Generation of SNG, Power and District Heating from Biomass Gasification System

A transition towards synthetic fuels such as synthetic natural gas (SNG) is a requirement that can contribute to future energy security and sustainable development. Conventional coal gasification could be replaced with biomass gasification to produce synthetic natural gas that can be used in existing natural gas distribution infrastructure, transport, domestic and industrial sectors with almost no or little modifications. This study evaluates the integration of synthetic natural gas production using biomass gasification with combined heat and power plant (CHP). Various system performance indicators are used for comparing different systems such as carbon conversion, energy efficiencies, economic feasibility and commercial viability of technologies. For the evaluation of studied system, 100 MW of dried biomass is used as input for synthetic natural gas production together with power and district heating. The results obtained by integration of process showed a substantial synthetic natural gas production potential i.e. about 74.3 MW based on 100 MW biomass input. The process heat requirement of the system is about 26.60 MW and 0.60 MW for electrification. The results indicate that 27.35 MW heat is available for district heating and about 3.4 MW net amount of heat is available for power production by organic Rankine cycle (ORC). The results also show that the system is 74.3 % efficient based on lower heating value. Poly generation concept of SNG production along with power and district heating system claims its economic viability.

The effect of distributed electricity generation using natural gas on the electric and natural gas grids

The efficient and economical design and operation of individual small-scale distributed generation (DG) units has received considerable attention. It is now plausible to envision a future scenario where a large number of such units, spanning capacities from the kW to the MW scale, are deployed in a region. As distributed electricity generation using natural gas becomes more widespread, the dependency of the electric grid on the natural gas grid will increase. This concerns multiple interaction points along the two networks, and reaches beyond the natural gas demand of large-scale load following or baseload gas-fired powerplants. More specifically, a better understanding is required of the potential changes in the dynamic behavior and interaction of the electricity and natural gas grids at or close to residential use sites (neighborhoods), where the small-scale DG infrastructure is likely to be located. In this paper, an optimization-based framework is developed for analyzing the operation of an ensemble of small-scale natural gas fueled DG units, and quantify their ability to flatten the electric grid load (i.e., reduce the peak demand) of the neighborhood that they serve. Our analysis relies on realistic energy use data and takes into account capacity limitations of the current natural gas distribution infrastructure, centralized vs. decentralized control of the DG unit operation, equipment durability considerations, heating preferences of home users, and seasonal effects. There is a substantial increase in natural gas consumption near consumers for all scenarios considered, which has implications for the control of the natural gas grid. We demonstrate the importance of having a centralized decision-making scheme when multiple distributed generation resources are present, and make recommendations for the optimal sizing of generators.

Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments

Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 – 2.3 × 104 g CH4•day−1. The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing ‘superemitter’ leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as ‘safely leaking.’ Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks.

Optimal sizing of an electrolytic hydrogen production system using an existing natural gas infrastructure

Power to Gas for energy storage is a novel concept that is considered to be a viable solution to manage the existing off-peak power grid surplus issue. This work proposes the utilization of surplus power in the Canadian province of Ontario to produce hydrogen via the water electrolysis process to be used for energy storage and distribution to enhance the efficiency of the overall energy system. The existing natural gas distribution and storage infrastructure is utilized to distribute and store the electrolytic hydrogen. Although the system as a whole has a number of potential energy recovery pathways, this work focuses on the power to gas energy recovery route using two multi-period mixed integer linear programming models of potential energy hubs. The first model focusses on the case without the use of buffer storage for hydrogen, and the second model employs storage. The preliminary results show that net power exports to neighboring jurisdictions can be reduced by 2.3% and 6.1%, respectively, by making use of the exports to produce hydrogen. Within this framework the hydrogen concentration in the natural gas system is limited to a maximum value of 5 vol. %. It was found that the monetary losses mitigated by reducing the power exports were close to $3.8 million and $10 million in the respective models. In addition to this, the use of hydrogen enriched natural gas in place of pure natural gas at the end user results in CO2 emission reductions close to 3504 metric tonnes and 9429 metric tonnes. The sized power to gas systems in the two cases can also earn potential revenues close to $52,555 and $141,427 from the emissions based on $15 per tonne of CO2 emission reduced. These positive results encourage the development of more rigorous optimization models that can size the system based on trade-off benefits between the different energy recovery pathways of the power to gas system.