Renewable Gas Research Articles

Study on Hydrogen Direct Injection in RNG Combustion under Various Ignition Timings for Power Generation in a Retrofitted Gas Engine

Renewable natural gas (RNG) is attractive for energy policy goals in the world. Therefore, a regional system is designed to explore RNG combustion for power generation in localities. This study investigates a direct injection (DI) engine fueled with hydrogen (H2) blended into the simulated renewable natural gas, which consists of 50% methane (CH4) and 50% carbon dioxide (CO2) in volume. In order to obtain higher efficiency, comparisons between DI and port fuel injection (PFI) of H2 addition were made. Then, the volume percentage of H2 was changed from 20% to 100% by keeping the volume ratio of CH4 and CO2 at 1:1. Finally, results of power output, brake mean effective pressure (BMEP), brake thermal efficiency (BTE) and brake specific fuel consumption (BSFC) were discussed. Results showed that in contrast to PFI, H2 DI injection could increase efficiency by 4%. Additionally, H2 DI could retard the MBT ignition timing at 5 °CA. Compared with CH4/CH4 + CO2 combustion, under stoichiometric combustion, BMEP increases with H2 addition but BTE decreases significantly. However, by enlarging the excess air ratio (λ) to 1.24, both BMEP and BTE increase obviously with H2 addition. Moreover, when λ < 1.3, the MBT ignition timing should be advanced from −10 to 15 °CA top dead center (TDC). But the MBT ignition timing is fixed at −25 °CA TDC when λ is larger than 1.3. Furthermore, if efficiency is the priority, 30% H2 addition with λ at 1.24 (−15 °CA TDC) should be selected. If higher BMEP is preferred, 20% H2 addition with λ at 0.99 (−10 °CA TDC) should be selected.

Quantifying the Financial and Climate Impacts of Greenhouse Gas Abatement Pathways in Residential Space Heating

New York State (NYS) has set strict greenhouse gas (GHG) emission reduction targets across all sectors of its economy, including the heating sector. This study examines the financial value and environmental impacts of the residential space heating sector in NYS under different GHG abatement options by comparing the existing natural gas heating pathway with three potential GHG abatement pathways: renewable natural gas (RNG), hydrogen blended into RNG, and air-source heat pumps (ASHPs). These pathways are analyzed via a comparative net present value (NPV) framework from 2022 to 2042 with the emission reduction represented as a revenue stream that serves as a function of the social cost of GHGs. The investment timing of each of these pathways is also accounted for to reflect the pathways’ varying deployment timelines. The ASHP pathway with a 10% financial discount rate and a 2% social cost of the GHG discount rate achieves the lowest NPV. The RNG pathway achieves the highest NPV. A sensitivity analysis determines the impact of key factors on the NPV results. This study aims to inform policymakers, homeowners, and stakeholders of the potential benefits and costs of each of the four pathways to aid them in their decision-making process.

Auckland Council Food Scraps Project

This research project delves into the complexities of Auckland City Council's food scraps collection rollout, spanning from kerbside collection to the Anaerobic Digestion Facility in Reporoa, Rotorua; where collected food scraps are transformed into environmentally friendly fertilisers and renewable gases. The project comprises two key components: assisting in the creation of a dashboard to display weekly and monthly collection and disposal data to monitor ongoing participation rates and collected tonnage requirements are met; and assisting with the continuation of the food scraps rollout initiative in wider Auckland regions and help increase consumer knowledge and involvement. This is in conjunction of aligning with Auckland Council's aim for zero waste by 2040. The initiative aims to keep food scraps out of landfills, minimising harmful greenhouse gas emissions and return valuable nutrients to the land through biofertiliser production. This project required me to learn about Auckland's circular economy solution which emphasises prevention of food waste, supporting redistribution initiatives, and promoting home and community composting. As part of helping with the rollout and helping create an easy way for residents to separate their food scraps from general rubbish, individuals have gained a raised awareness of wastage, leading to considered meal planning and cost savings. The government's commitment to nationwide food scraps services by 2030 underscores the urgency of sustainable waste management practices which it why it was crucial for me to be familiar with the whole process and sectors within the rollout to assist Auckland Council to meet this commitment. This project has also meant that I was able to understand the whole process of the Anaerobic Digestion Facility's innovative technology which processes organic material into biogas and nutrient-liquid fertiliser, contributing to New Zealand's sustainability goals. Through comprehensive monitoring and filtration systems, the facilities uphold environmental standards while pioneering large-scale food scraps processing in the country.
 Supervised by: Sarah Nicholls
 Scholarship Project Funded by: Auckland City Council

Gas power — How much is needed on the road to carbon neutrality?

The national and international expansion of renewable energy and the retirement of conventional capacity are increasing the challenge of ensuring generation adequacy in the European power system. New gas-fired power plants have been perceived as a promising option to secure supply. However, recent geopolitical developments have raised concerns about the high dependence on natural gas. This paper explores how different scenarios of power consumption and renewable energy targets in Germany determine the reliance on gas-fired power generation capacity in 2030, 2040, and 2050. Using the electricity market model ELTRAMOD it examines the effects of the different scenario assumptions on gas-fired capacity and generation, renewable capacity, electricity trade, and greenhouse gas emissions in Germany and abroad. The results demonstrate a clear need for reliable capacity in the future, with gas-fired capacity accounting for the largest share. In all scenarios analyzed, Europe’s dependence on natural gas increases from historical levels until 2030 and then falls only slightly below historical levels until 2040. Stricter German renewable energy targets shift natural gas use from Germany to other European countries. Phasing out coal in Germany before 2030 instead of in 2038 makes Germany dependent on reliable capacity from abroad and increases its reliance on natural gas.

‘Greening’ an Oil Exporting Country: A Hydrogen, Wind and Gas Turbine Case Study

In the quest for achieving decarbonisation, it is essential for different sectors of the economy to collaborate and invest significantly. This study presents an innovative approach that merges technological insights with philosophical considerations at a national scale, with the intention of shaping the national policy and practice. The aim of this research is to assist in formulating decarbonisation strategies for intricate economies. Libya, a major oil exporter that can diversify its energy revenue sources, is used as the case study. However, the principles can be applied to develop decarbonisation strategies across the globe. The decarbonisation framework evaluated in this study encompasses wind-based renewable electricity, hydrogen, and gas turbine combined cycles. A comprehensive set of both official and unofficial national data was assembled, integrated, and analysed to conduct this study. The developed analytical model considers a variety of factors, including consumption in different sectors, geographical data, weather patterns, wind potential, and consumption trends, amongst others. When gaps and inconsistencies were encountered, reasonable assumptions and projections were used to bridge them. This model is seen as a valuable foundation for developing replacement scenarios that can realistically guide production and user engagement towards decarbonisation. The aim of this model is to maintain the advantages of the current energy consumption level, assuming a 2% growth rate, and to assess changes in energy consumption in a fully green economy. While some level of speculation is present in the results, important qualitative and quantitative insights emerge, with the key takeaway being the use of hydrogen and the anticipated considerable increase in electricity demand. Two scenarios were evaluated: achieving energy self-sufficiency and replacing current oil exports with hydrogen exports on an energy content basis. This study offers, for the first time, a quantitative perspective on the wind-based infrastructure needs resulting from the evaluation of the two scenarios. In the first scenario, energy requirements were based on replacing fossil fuels with renewable sources. In contrast, the second scenario included maintaining energy exports at levels like the past, substituting oil with hydrogen. The findings clearly demonstrate that this transition will demand great changes and substantial investments. The primary requirements identified are 20,529 or 34,199 km2 of land for wind turbine installations (for self-sufficiency and exports), and 44 single-shaft 600 MW combined-cycle hydrogen-fired gas turbines. This foundational analysis represents the commencement of the research, investment, and political agenda regarding the journey to achieving decarbonisation for a country.

Renewable gases production coupled to synthetic wastewater treatment through a microbial electrolysis cell

This study describes the use of a microbial electrolysis cells for the production of gaseous biofuels sustained by the oxidation of a synthetic wastewater. During the overall experimental investigation, the MEC’s bioanode removed on average 855 ± 57 mgCOD/d producing an average electric current of 66 ± 7 mA which was diverted into gaseous biofuels like biomethane, biohydrogen and biohythane. Three different MEC cathodic configurations were investigated selecting the electrodic materials (graphite granules GG, and mixed metal oxide MMO) and operating conditions (pH of the catholyte, additional sorption chamber). Biomethane production increased from 26 ± 4–102 ± 8 meq/d when the MMO electrode was used with respect to GG electrodic material. In contrast, the MMO electrode in combination with a CO2 sorption chamber was successfully utilized for simultaneous H2 production and CO2 sorption from a N2/CO2 mixture which simulates an anaerobic digestion biogas. The combination of H2 production and CO2 sorption allowed to obtain a gaseous mixture composed of 9% H2, 5% CO2, and 80% N2 that according to the assumption of replacing the N2/CO2 mixture with real biogas corresponded to a commercial-grade biohythane. Overall, the results highlight the potential of MECs as an efficient approach for biogas upgrading, allowing biohythane production increasing CH4 content and lowering CO2 concentration.

Topsoe and Standard Gas sign MoU to collaborate on UK-based renewable natural gas and methanol project

Topsoe and Standard Gas sign MoU to collaborate on UK-based renewable natural gas and methanol project

Integrated system for converting biomass to renewable natural gas to methanol and other value-added products

Integrated system for converting biomass to renewable natural gas to methanol and other value-added products

Life cycle cost and life cycle environmental analysis of the different waste-to-renewable natural gas pathways: An effort to identify an optimal pathway under different Multi-criteria decision-based scenarios

Currently, due to the insufficient resources of renewable natural gas, the development of renewable pathways to integrate into the natural gas-industry portfolio can reduce many concerns about the reserves depletion and the environmental crises. In the present article a structure-oriented framework for gas networks is developed to compare and prioritize different investment scenarios for renewable natural gas production projects. In this regard, different pathways to produce renewable natural gas through the waste-to-natural gas process were discussed and compared based on different waste feedstocks. To discuss and compare different pathways, a decision-making structure and framework under life cycle cost analysis (LCCA) and life cycle environmental analysis (LCEA) is employed to choose the appropriate pathway for the waste-to-natural gas process. The optimal pathway is identified through different multi-variable decision-making scenarios (under different geographical conditions, access to different feedstocks, and different interests of stakeholders). From the outcomes, under the neutral and Pro-economic scenarios, the renewable natural gas production pathway driven by landfill gas integrated with the pressure swing adsorption- biogas upgrading unit is the optimal and desirable option. While under an Eco-friendly scenario, the pathway driven by animal manure integrated with the pressure swing adsorption-upgrading unit is an optimal and desirable pathway.

Life cycle analysis (cost and environmental) of different renewable natural gas from waste procedures based on a multivariate decision-making approach: a comprehensive comparative analysis

Abstract This article presents a framework that focuses on structural considerations within gas networks to evaluate and rank various feasibility options for renewable natural gas (RNG) cases. Specifically, the analysis examines and compares a range of methods for producing RNG using natural gas from waste (NGFW), considering different types of waste as feedstock. To analyze and evaluate the different methodologies, the article uses a decision architecture based on life cycle analysis (cost and environmental). These tools are used to determine the most favorable path for the NGFW process. The preferred pathway is identified by considering a range of decision scenarios that take into account variables such as geographical conditions, the availability of various feedstocks and the different stakeholders’ priorities. The results show that according to the economically neutral scenarios and those that favor economic considerations, the pathway involving RNG generation from landfill gas coupled with a pressure swing adsorption (PSA) upgrading technology emerges as the optimum choice. Conversely, in a scenario where environmental sustainability is a priority, the process that emerges as most advantageous is the use of animal manure with the addition of a PSA upgrading unit. The designed structure can be adapted to different regions, each with its own unique geographical features and feedstock resources, and can be customized to meet the varying interests of stakeholders. Based on both parametric assessments and analytical interpretations, this article not only identifies optimal pathways but also provides a set of recommendations and strategies aimed at improving economic behavior.

Multi-scale assessment of global warming mitigation potential of anaerobic digestion for food waste management in the United States: A comparison of Life Cycle Assessment approaches

This study provides a holistic Life Cycle Assessment (LCA) for evaluating the decarbonization potential of using Anaerobic Digestion (AD) in food waste treatment. The LCA is based on the development of a new flexible tool that allows the integration of the LCA at the process level with geospatial data and therefore includes a wide range of factors such as multiple feedstocks, technologies for end-use applications, and facility locations. This tool estimates a potential for reducing 21.8 MMtons CO2eq/y (345 gCO2eq/kgwaste) and generating 161 TBTU/y of renewable natural gas for the whole United States by managing food waste based on waste-hierarchy. This study also identifies those states with a more efficient AD implementation potential regarding CO2eq avoidance. It highlights the importance of including region-specific conditions since feedstock diversion depends on the state and is the main contributor to the decarbonization potential, up to 60 % of the avoided emissions.

The Path to a Sustainable Energy Europe: An Analysis of the Transition from Fossil Fuels to Renewable Energy

The main purpose of this study is to investigate the application of predictive analytics techniques in the energy field and to identify strategies to stimulate renewable energy production. The analysis begins by examining four key indicators: renewable energy, gas price, gas consumption and renewable energy consumption through a detailed descriptive analysis. Visual graphs are built to get an overview of the evolution of the energy sector in the period 2011-2020 with the help of Tableau software. The analysis is supported by the use of the Random Forest algorithm as a prediction model, considering critical indicators such as gas price, gas consumption and renewable energy consumption. The prediction results provide insight into anticipating changes in renewable energy production in the European countries studied. At the same time, the study highlights the current situation of renewable energy in Europe and identifies the necessary measures for its sustainable development through the analysis of specialized literature. It also examines the way in which big data management, facilitated by technologies such as smart meters and drone sensors, can help improve the energy sector. This research offers valuable results, providing insights into the evolution of renewable and fossil energy, as well as a detailed comparison of renewable energy, gas prices, gas consumption and trends in renewable energy consumption. By integrating predictive analytics techniques, data management and renewable energy-specific indicators, this study makes an innovative contribution to energy systems analysis. Its focus on European countries contributes to the understanding of the growth potential of renewable energy generation in this region.

Modeling insights from the Austrian national gas grid under declining natural gas demand and increasing domestic renewable gas generation by 2040

This paper studies the development of the Austrian gas grid by 2040 under different decarbonization scenarios, ranging from electrifying most energy services to importing large amounts of renewable methane. The Austrian gas grid serves as a case study representative for those gas grids confronted with a drop in natural gas demand and an increase in domestic renewable gas generation in the future. A mixed-integer optimization model with a focus on the detailed representation of the existing grid (gas grid levels, pipeline capacity, route, and age) is used to determine the cost-optimal trade-off decision between expected low-utilized gas pipelines and an off-grid supply alternative (e.g., trucking and on-site gas storage) in a decarbonized Austrian and European energy system. Optimality determines whether to operate, decommission, or make replacement investments in the grid’s pipelines. Based on the required gas grid 2040 and its annual grid costs, estimates for tariffs of end customers are given. The paper’s main conclusion is that the domestic distributed renewable gas generation uptake will be associated with the need for an area-wide gas grid, but one that will be significantly less utilized. Future work could address, among other things, the exploration of the spatial interplay of local production and demand by forming regional clusters of renewable gas.

Multi-stage planning of integrated electricity-gas-heating system in the context of carbon emission reduction

In order to facilitate the carbon emission reduction to mitigate climate change, this paper proposes a coordinated multi-stage planning strategy for the transmission-level integrated electricity-gas-heating system. The strategy coordinates installations of gas-fired generation plants, renewable energy plants, gas wells, power-to-gas plants, transmission lines and pipelines, considering retirements of coal-fired generation plants. It can help facilitate carbon emission reduction of the electricity system as well as the integrated energy system. The objective is to minimize the total present value of the investment and the operation economic cost, with consideration of constraints from each sub-system and carbon emission restriction. In the case studies, the proposed planning strategy is verified to be able to obtain the installation plan of the related facilities. With which the system can reduce the proportion of fossil fuel energy utilization and increase renewable energy utilization. Hence, carbon emission reduction is achieved. In addition, it has demonstrated that integrating the multi-energy systems can help reduce the economic cost in the planning result.

Representative Modeling of MXene-based Hybrid Nanocomposites toward Catalytic Hydrogen Evolution Reactions: Comprehensive Review

Hydrogen can be seen not only as a renewable gas but also as an eco-friendly energy source in the future, and the demand tends to be increasing more and more....

Biological upgrading of biogas assisted with membrane supplied hydrogen gas in a three-phase upflow reactor

Biogas upgrading via CO2 conversion to CH4 is an emerging technology for renewable natural gas production and carbon management, but its development is limited by the low H2 gas to liquid phase transfer. Herein, an innovative biogas upgrading system employing a three-phase design was studied for CO2 conversion with H2 supply via gas-permeable membrane. The system produced biogas consisted of 74.1 ± 7.1 % CH4 and 25.9 ± 7.1 % CO2 with intermittent injection of H2. When H2 supply was continuous, the CH4 content increased to 91.6 ± 2.2 % at a H2:CO2 ratio of 4.4. Although a higher ratio of 5.5 could result in a higher CH4 percentage of 95.2 ± 2.5 %, biogas production rate started to decrease. The removal efficiency of organic contents remained above 90 % throughout the experiment. Microbial community analysis corroborated the findings, showing that hydrogenotrophic Methanobacteriaceae was more prevalent in the biofilm (71.9 %) compared to that in anaerobic digestion (15.8 %) and effluent (14.1 %).

DESIGN AND NUMERICAL INVESTIGATIONS OF AN AFTERBURNER SYSTEM USING METHANE-HYDROGEN BLENDS

The gas turbine industry strongly committed to develop gas turbines operating with 100% hydrogen till 2030, such fully supporting the transformation of the European natural gas grid into a renewable-based energy system by overcoming technical challenges and ensuring that this transformation takes place swiftly. By extending the fuel capabilities of gas turbines to hydrogen, their role can become predominant in the energy transition period but also in long-term energy strategies. In combined cycle configuration (CCGT), gas turbines are already the cleanest form of thermal power generation. For the same amount of electricity generated, gas turbines running on natural gas emit 50% less CO2 emissions than coal-fired power plants. Mixing renewable gas (e.g., green hydrogen, biogas) with natural gas enables further reduction in net CO2 emissions. In this paper pure hydrogen and blends of hydrogen methane will be studied as fuel in order to predict the behavior of afterburner system with a new designed geometry.

Life‐cycle analysis of sustainable aviation fuel production through catalytic hydrothermolysis

AbstractCatalytic hydrothermolysis (CH) is a sustainable aviation fuel (SAF) pathway that has been recently approved for use in aircraft fuel production. In alignment with broader sustainable aviation goals, SAF production through CH requires a quantitative assessment of carbon intensity (CI) impacts. In this study, a current‐day life‐cycle analysis (LCA) was performed on SAF produced via CH to determine the CI. Various oily feedstocks were considered, including vegetable oils (soybean, carinata, camelina and canola) and low‐burden oils and greases (corn oil, yellow grease and brown grease). Life‐cycle inventory data were collected on all processes within the CH LCA boundary: feedstock cultivation and/or collection, preprocessing, hydrothermal cleanup and CH, biocrude refining, fuel transportation and end use through combustion. Baseline results show that the CH‐produced SAF can be generated with CI reductions ranging from 48 to 82% compared with conventional jet fuel. Modest improvements to CI can be achieved through incremental changes to the brown grease CH process, such as relaxing the dewatering specification and implementing renewable natural gas and electricity, which could decrease the CI from 22.9 to 7.9 g CO2e/MJ. Total CH fuel production potential was also assessed on the basis of current or near‐future feedstock availability and CI. The total biofuel production potential of CH (SAF and renewable fuel co‐products) in the US sums to approximately 3487 million gallons per year, with 97% of these volumes having a CI below 50% of that for petroleum jet fuel. The study shows that from an LCA perspective, CH offers a viable SAF pathway that is comparable with existing SAF pathways like hydroprocessed esters and fatty acids.

A Review on Biodiesel and Effect of Oxygenize

Biodiesel is a renewable like solar energy, coal, oil and natural gases. It is eco-friendly and energy-accomplice fuel that is becoming a more prominent alternative to Petro-diesel. However, biodiesel's limitations can be overcome by optimizing its quality and properties. Oxygenize supplements have been shown to play an important role in this optimization. In this research work, biodiesel was produced from cow dung, which is a readily available and abundant resource in villages and farms. The competency of the produced biodiesel was studied and compared to various criterion. Oxygenates additives, including methanol (CH3OH), ethanol (C2H5OH), and diethyl ether (C2H5OC2H5), were added to this biodiesel at various ratios (10%, 20%, and 30%) to study their effects on the merits of the biodiesel produced. The efficiency of the biodiesel was also evaluated.

Gas Distribution System of Latvia and its Transitional Challenges

Abstract The future of the European Union’s (EU) gas sector and gas distribution systems in particular is under review as a necessity to move away from conventional natural gas is strictly outlined in its strategical energy framework. The main questions of future gas sector layout are largely related to gas decarbonization paths – whether they will include simultaneous transportation, distribution and storage of methane-based and non-methane based renewable gases or not. In general, this question is left for different Member States to decide, because as alternatives to it there are two options – decommissioning of all gas distribution and partially gas transportation and storage systems on the one hand and total replacement of existing gas transportation system with brand new hydrogen transportation and distribution system on the other. The first option leaves only liquified renewable gases (including, hydrogen) that are transported via truck and the second – pipeline transportation and distribution only for hydrogen, limiting methane-based renewable gases to road transportation solutions only. The Latvian gas distribution system is also facing imminent transformation in foreseeable future; thus, at the moment its sustainability priority is the maintenance of the existing system in a safe and secure manner by improving it in accordance with technical necessities and immediate customer requests. The current research shows two sides of gas distribution system priorities in Latvia – its maintenance and development trends prior to fundamental transformations of gaseous fuel transition and general transitional challenges laying ahead.