Browse Topic: Greenhouse gas emissions

Items (1,217)
Recent studies highlight the urgent need to reduce greenhouse gas (GHG) emissions to mitigate the impacts of global warming and climate change. As a major contributor, the transport sector plays a vital role in these efforts. Ethanol emerges as a promising fuel for decarbonising hard-to-electrify propulsion sectors, thanks to its sustainable production pathways and favourable physical and combustion properties, such as energy density, rapid burning velocity, and high knock resistance. This work proposes a methodology to enable the possibility of replicating the combustion behaviour of ethanol in a 1D CFD simulation environment representative of a single-cylinder research engine. Spark-ignition combustion is simulated through the Eddy Burn-Up combustion model previously calibrated for standard fossil gasoline. The combustion model features a laminar flame speed neural network, trained and tested through reference chemical kinetics simulations. The combustion model showed great accuracy
Ferrari, LorenzoSammito, GiuseppeFischer, MarcusCavina, Nicolò
The maritime industry is among the most energy-intensive sectors, and achieving fleet decarbonization is crucial to significantly reduce greenhouse gas emissions. As a transitional fuel, natural gas (NG) presents a viable short-to-midterm solution. Compared to conventional marine fuels, NG has the potential to lower carbon dioxide emissions by approximately 20–30%. However, to fully leverage this potential on carbon footprint reduction, substantial advancements in combustion technologies are required. One promising approach to enhance the efficiency of SI NG engines is the implementation of Passive Pre-Chamber (PPC) technology. This strategy enables leaner combustion, improving thermal efficiency, mitigating the occurrence of knocking, and reducing NOx emissions. This study presents both experimental and numerical investigations to analyze the impact of charge dilution and ignition timing on the performance and emissions of a single-cylinder prototype NG PPC SI engine for marine
Marchitto, LucaPesce, FrancescoAccurso, FrancescoTornatore, CinziaGorietti, ValentinaBuzzi, LucaGrosso, AlessandroLuci, MatteoNapolitano, PierpaoloPennino, VincenzoBeatrice, CARLODi Domenico, DavideGiardino, Angelo
Reducing greenhouse gas (GHG) emissions in the transportation sector is a significant challenge. A multi-technology approach is the most practical and sustainable solution for minimizing the environmental impact of road transport. Alternative gaseous fuels derivable from bio sources have the potential to significantly cut equivalent carbon dioxide (CO2eq) emissions from a Well-to-Wheel (WtW) perspective, and the development of technologies that allow to improve the efficiency of natural gas-powered Heavy Duty (HD) Spark Ignition (SI) engines is of strategic importance. In such applications, charge dilution strategies might have the potential to increase engine efficiency at a relatively low implementation cost. Diluting the in-cylinder charge can reduce fuel consumption by decreasing wall and pumping losses, and increasing the Heat Capacity Ratio (γ). The coupling with innovative technologies aimed at enhancing ignition energy, influencing combustion development, could be a promising
Di Domenico, DavideNapolitano, PierpaoloPapi, StefanoRicci, FedericoGolini, StefanoRapetto, NicolaGiordana, SergioBeatrice, Carlo
In the context of greenhouse gas emissions (GHG) reduction the most viable short-term solution in the maritime sector is the use of renewable carbon-free fuels. Among these, ammonia represents a possible alternative in compression ignition (CI) engines operating in dual fuel (DF) mode. Although, such fuel features low chemical reactivity, especially in lean mixtures, resulting in poor combustion efficiency, exhaust ammonia slip and low engine performance, DF combustion can be an interesting strategy to overcome such limitations. In this work a wide numerical examination of diesel injection strategies is presented, while ammonia acts as the primary fuel with energy supply around 80%. Since the original marine engine, fuelled with natural gas (NG), presents a single diesel injection, firstly, a pilot injection is added and different diesel mass shares between pilot and main are investigated, by varying the injection rate shape and the pilot start of injection (SOI). Calculations are
Cameretti, Maria CristinaDe Robbio, RobertaPalomba, Marco
This study presents a CFD-based evaluation of ignition strategies for enabling ammonia combustion in a light-duty internal combustion engine. The model was first validated against experimental data for both pure ammonia spark ignition and dual-fuel ammonia-diesel compression ignition cases. Upon validation, three ignition strategies were investigated: dual-fuel compression ignition with sixty percent ammonia energy fraction, and multi-spark and passive pre-chamber ignition under stoichiometric conditions. Simulations were used to assess combustion phasing, efficiency, and emissions characteristics. The dual-fuel mode enabled stable ignition but resulted in incomplete combustion, with three-dimensional contours revealing that central regions of the chamber remained largely unburned, contributing to high ammonia slip and highlighting the need for further optimization of spray targeting and combustion chamber design. The multi-spark strategy achieved the highest efficiency through rapid
Shafiq, OmarMenaca, RafaelLiu, XinleiUddeen, KalimTang, QinglongTurner, JamesIm, Hong G.
Ammonia (NH3) use as fuel poses technical challenges such as increased nitrogen-based and unburned NH3 emissions. This study used a 0D model coupled with detailed NH3 kinetics to evaluate the effect of equivalence ratio (ϕ) from 0.7 to 1.0 in a heavy-duty compression ignition engine converted to spark ignition operation. The goal was to evaluate how ϕ affected NOx and N2O formation and/or destruction at constant fuel energy per cycle, engine speed, and CA50. Simulated NOx emissions (i.e., NO + NO2) followed a trend similar to the one typically observed for hydrocarbon fuels in a SI engine, but that was different from the experiment. In addition, it underpredicted NOx emissions for ϕ = 0.7 by 79% and overpredicted NOx emissions for ϕ = 1 by 576%. The simulation showed that thermal NO production was more than 80% from the total NO production, but the effect of ϕ on this percentage was negligible. Then, predicted N2O emissions had an opposite trend and were three orders of magnitude lower
Saenz Prado, StefanyAlvarez, Luis F.Trujillo Grisales, Juan M.Akkerman, VyacheslavDumitrescu, Cosmin E.
Light-duty vehicles (LDV) are scaling up electrification technologies from battery to dedicated hybrid engines (DHEs). The success from electrification of LDVs can be a starting point to look into a similar trending development of commercial vehicles (CV), which are bigger and heavier with more demanding work cycles. “Greenhouse Gas Emissions Standards for Heavy-Duty Vehicles (HDV)—Phase 3” establishes new CO2 emission standards for MY 2032 (Model Year) and later HD vehicles with more stringent CO2 standards phasing in as early as MY 2027 for certain vehicle categories. In this article, the focus is about improving the operational efficiency of MDHD (medium-duty and heavy-duty) vehicles through a selected electrification technology in this study rather than pure BET (battery electric truck). Extended-range electric vehicle (EREVs) systems are studied here to address sustainability regarding charging infrastructure and by using the renewable fuels (hydrogen, ammonia, methanol, and
Wang, HailongMa, TiancaiShuai, ShijinWang, ZihuiSong, Xubin
The United States Environmental Protection Agency (US EPA) Greenhouse Gas (GHG) Phase 3 regulation targets a substantial reduction in GHG emissions across model year (MY) 2027–2032 class 2b-8 vehicles. This article explores the implementation of alternative fuels, such as compressed natural gas (CNG) and liquefied petroleum gas (LPG), along with powertrain hybridization as viable pathways for achieving these stringent standards in a cost-effective manner. A detailed analysis is performed on a Class-7 medium–heavy-duty (MHD) truck configuration, featuring an inline 4-cylinder 5.2-L spark-ignited (SI) engine, modeled with both CNG and LPG fuels. The vehicle’s powertrain is simulated to evaluate GHG emissions and fuel efficiency. The study further examines the impact of low rolling resistance (LRR) tires and varying tire rolling resistance coefficients (Crr) on vehicle performance. For further lowering the GHG emissions, a hybrid powertrain sizing study was performed. The simulation
Patil, Shubham V.Smith, Edward M.Bachu, Pruthvi R.Ross, Michael G.
Twenty-nine percent of the greenhouse gas emissions in the US are produced by the transportation sector according to the US Environmental Protection Agency. The combination of increasingly stringent regulations on emissions and fuel economy, along with the current practical limitations of electrification motivate continued development efforts for improving internal combustion engine efficiency and emissions. Ethanol, an extensive fuel additive or drop-in replacement for gasoline, is already recognized as a promising transition fuel in decarbonization efforts. Furthermore, lean combustion in spark-ignited (SI) engines has been pursued extensively for engine efficiency and emissions improvements. Lean combustion, however, faces the challenges of decreased combustion stability and strong increases to engine-out NOx at conditions where conventional SI engines are stable (ϕ > 0.7). Water dilution, historically used as a knock inhibitor in performance engines, has shown potential for
Voris, AlexLundberg, MattPuzinauskas, Paulius
Battery electric vehicles have gained popularity in the transport sector of late and are considered to emit lower greenhouse gas emissions than their internal combustion engine-powered counterparts. This study conducted a “cradle-to-grave” lifecycle assessment for two sets of battery electric, hybrid electric, and internal combustion engine vehicles sold in India to assess which powertrain emits lower greenhouse gas emissions during their lifetime. The system boundaries of the “cradle-to-grave” analysis consist of vehicle manufacturing, usage, maintenance, recycling of components, and finally, disposal. The “well-to-wheel” analysis includes oil extraction, feedstock cultivation, transportation, refining, fuel production, blending, and supply. This study considered India’s electricity generation mix from thermal, nuclear, solar, wind, and hydropower plants in different regions for 2020–2021. Greenhouse gas emissions from all three categories of vehicles were calculated for a lifespan of
Agarwal, Avinash KumarSingh, Rahul KumarBiswas, Srijit
The automotive sector in India is undergoing a transformation, driven by government policies and regulations aimed at achieving net-zero carbon emissions. In alignment with global climate goals, the Indian government has set ambitious targets to reduce greenhouse gas emissions, with a focus on promoting Electric Vehicles (EVs) and Hydrogen Fuel Cell Vehicles (FCVs). Initiatives like the Faster Adoption and Manufacturing of Hybrid and Electric Vehicles (FAME) Scheme, along with tax incentives, subsidies, and charging infrastructure development, are designed to accelerate the adoption of cleaner vehicles. The introduction of stricter emission standards and the National Electric Mobility Mission Plan (NEMMP) further underscores the push toward sustainable mobility. In response, Indian automotive companies are shifting strategies to align with these government directives. Major players are significantly increasing investments in EV technology, focusing on enhancing battery performance
Patil, Nikhil NivruttiSaurabh, SaurabhBhardwaj, RohitGawhade, RavikantGadve, DhananjayAmancharla, Naga Chaithanya
Recently, as regulations on greenhouse gas emissions have become stricter, driven by global warming, there is increasing interest in engines utilizing environmentally friendly fuels. In this context, ammonia is attracting attention as a potential alternative to fossil fuels in the future. However, due to its distinct fuel properties compared to conventional fuels, research is being conducted on utilizing diesel as an ignition source for ammonia. In this study, the effects of diesel injector fuel flow rate, and micro-pilot (MP) diesel injection timing on combustion and exhaust emission characteristics were analyzed in a single cylinder 12L marine ammonia-diesel dual-fuel engine. Two types of diesel micro-pilot injectors were tested. The first one was high flow rate micro-pilot injector (HMPI) and the second one was low flow rate micro-pilot injector (LMPI). HMPI injector had 66% more number of fuel injector nozzle hole and 250% larger fuel flow rate. Therefore, HMPI injector could
Jang, IlpumPark, CheolwoongKim, MinkiPark, ChansooKim, YongraePark, GyeongtaeLee, Jeongwoo
Ammonia-diesel dual-fuel engines can effectively reduce greenhouse gas (GHG) emissions. Aiming at the real-time control requirements of ammonia/diesel dual-fuel engines, this study proposes a segmented real-time modeling method and a heat release rate model simplification strategy by linearized heat release rate curves. First, the engine working cycle is divided into three parts: intake and exhaust stage, compression and expansion stage, and combustion process. Different simulation steps and modeling strategies are designed to optimize computational efficiency while maintaining the necessary level of accuracy at each stage. Secondly, based on the calibrated heat release rate (HRR) curves, feature points are extracted to construct a simplified linear heat release model. In the absence of calibration data, the characteristic points of the HRR curves are obtained through interpolation. Compared with the commonly used combustion model, the Wiebe model, the proposed simplified model can
Li, GuangyuanChen, RunWang, XinranLi, TieZheng, KexiongLiu, ShaolingLiu, YanzhaoLyu, Xiaodong
India aims to achieve 20% ethanol blending (E20) in petrol by 2025 under its National Biofuels Policy to reduce carbon emissions, enhance energy security, and support the agricultural economy. Building on this, E27 (27% ethanol in gasoline) is being evaluated as an advanced mid-level blend to further lower greenhouse gas emissions and reduce reliance on fossil fuels. This study investigates the performance, emissions, and combustion characteristics of a turbocharged gasoline direct injection (TGDI) engine using E27 fuel over 20,000 km in real-world driving conditions, as part of a broader research program accumulating over 100,000 km across multiple vehicle categories. Key findings indicate that E27 achieves an optimal balance of emissions reduction and performance, with NOx and THC emissions decreasing by 12% and 5%, respectively, compared to E10, while CO and CO₂ levels remained stable, reflecting ethanol’s oxygenation effect and lower carbon intensity. Power output and acceleration
D R, VigneshwarBhakthavachalu, VijayabaskarMuralidharan, M.
This research presents a numerical analysis of the environmental impacts associated with using hot steam as a co-product in hydrogen production through Steam Methane Reforming (SMR) of renewable gas sources. As hydrogen production technology advances rapidly, reducing emissions and addressing environmental concerns, particularly greenhouse gas (GHG) emissions, have become essential. This study examines the SMR process with a focus on the environmental effects of utilizing hot steam as a co-product for electricity generation or facility heating. The analysis evaluates renewable feedstocks, including landfill gas, animal waste, food waste, and wastewater sludge, to determine their viability for sustainable hydrogen production. Key pollutants, such as carbon monoxide and nitrogen oxides, along with GHGs, are assessed to identify the most environmentally advantageous feedstock options. This work aims to provide insights to promote sustainable hydrogen production practices.
Rosyadi, Ahmad AdibLim, Ocktaeck
In engine development, it is needed to investigate engine performance under a lot of conditions. This is called the adaptability test, and it takes a lot of times, money, and manpower. Therefore, decreasing the test is aspired and constructing models that estimate the engine performance is effective for early adoption of ammonia engines. In this research, factors determining the thermal efficiency of a spark ignition engine fueled with ammonia/hydrogen mixtures were investigated and two simple models to estimate the performance were constructed. A diesel based four-stroke single-cylinder spark ignition engine with a displacement volume of 412 cm3 was used. Different compression ratios ε and two pistons with different squish areas were used. Experiments were conducted for total equivalence ratio of 1.0, while changing the LHV (lower heating value) ratio of ammonia and hydrogen. It is shown that higher compression ratio and larger squish velocity expanded the stable operation range of
Ichikawa, AyaOgura, YutoYanaoka, KazukiGonzalez Palencia, JuanKambara, ShinjiAraki, Mikiya
The effects of diesel and the ammonia ratio on the emissions and combustion characteristics of ammonia utilized in AMMONIA direct injection (AMMONIA-Di) engines were investigated through experimental and numerical investigations. A rapid compression expansion machine (RCEM) modified to facilitate the dual direct injection fuel (diesel-ammonia) - compression ignition (CI) method was used to conduct the experiment. A compression ratio (CR) of 19 and an ammonia energy percentage ranging from 10% to 90% were used in the experiment. Changes were made to the start of injection (SOI) from 0o to 40o before top dead center (BTDC) in order to find the best auto-ignition properties of ammonia. In order to facilitate auto-ignition, the diesel’s SOI was maintained at 10o BTDC. Computational fluid dynamics (CFD) modeling was used to establish the detailed emission propagation during the combustion process. During the expansion step, ammonia goes through a second stage of combustion, demonstrating
Setiawan, ArdhikaLim, Ocktaeck
In this study, a strategy for MCCI combustion of a novel alcohol fuel is demonstrated. The novel fuel, “GrenOl”, is the result of the catalytic upgrade of sustainable ethanol into alcohols of higher molecular weight. The composition of GrenOl includes approximately 70% 1-butanol, 15% 1-hexanol, and 5% 1-octanol by mass, resulting in a cetane number around 18. In order to achieve mixing-controlled compression ignition with GrenOl, an exhaust rebreathing strategy is employed. In this strategy, the exhaust valve reopens for a part of the intake stroke, inducting hot exhaust into the cylinder and preheating the fresh air. This study investigates the feasibility of operating with such a valve strategy from idle to peak torque. At idle, the primary challenge is ensuring stable combustion by inducting adequate exhaust to achieve ignition. Under load, when cylinder temperatures are higher, the primary challenge is ensuring sufficient air is inducted to achieve the target torque. It was found
Trzaska, JosephXu, ZhihaoBoehman, André L.
The future potential of an opposed-piston two-stroke (OP2S) engine has attracted the attention of researchers worldwide as it offers a high thermal efficiency and power-to-weight ratio with a simple engine configuration. This engine can be used with low-carbon fuels and hydrogen to reduce greenhouse gas emissions. However, the two-stroke operation has always been limited by its low scavenging efficiency and short-circuit of fresh charge. The current work is focused on optimizing scavenging efficiency and short-circuit in a small 200 cc single-cylinder OP2S SI engine using 3-D computational fluid dynamic (CFD) simulations. The effect of four parameters, namely, area of intake ports, area of exhaust ports, and angular orientations of intake ports (swirl and tilt) on scavenging efficiency and short-circuit, has been assessed and optimized. A Latin-hypercube based Design of Experiments (DoE) methodology is used to sample the design space spanning over a range of four parameters. A response
Singh, SaurabhBoggavarapu, PrasadHimabindu, M.Ravikrishna, R.V.
To achieve carbon neutrality, manufacturers need to estimate Greenhouse Gas (GHG) emissions generated throughout the life cycle of motorcycles, namely the Carbon Footprint of Product (CFP). We developed a method that allows calculation of the per-unit CFP and the total CFP of sales volume of motorcycles with a common formula, and also enables the estimation of their future values. First, we made it possible to calculate the per-unit CFP of each individual model by setting factors that we quantified the characteristics of motorcycles such as material composition and replacement parts and incorporating them into the calculation formula. Next, we enabled the calculation of the total CFP of sales volume from the present to the future by standardizing the specs of individual models and calculating the CFP by product category and multiplying the sales volume. Furthermore, we made it possible to simulate future CFP according to scenarios of expansion of environmental protection actions such
Mori, YuichiKawatsu, HirotakaYamaguchi, TakumiTanaka, KazuhikoAoki, ToshikiNiimura, Ryuta
Shear-polarized ultrasonic sensors have been instrumented onto the outer liner surface of an RTX-6 large marine diesel engine. The sensors were aligned with the first piston ring at top dead center and shear ultrasonic reflectometry (comparing the variation in the reflected ultrasonic waves) was used to infer metal–metal contact between the piston ring and cylinder liner. This is possible as shear waves are not supported by fluids and will only transmit across solid-to-solid interfaces. Therefore, a sharp change in the reflected wave is an indicator of oil film breakdown. Two lubricant injection systems have been evaluated—pulse jet and needle lift-type injectors. The needle lift type is a prototype injector design with a reduced rate of lubricant atomization relative to pulse jet injectors. This is manifested as a smaller reduction in the reflected ultrasonic wave, showing less metal–metal contact had occurred. During steady-state testing, the oil feed rate was varied; the high flow
Rooke, JackLi, XiangweiDwyer-Joyce, Robert S.
Off-highway vehicles, with their unique requirements of durability, high power, and torque density, are typically powered by diesel ignition internal combustion engines (ICEs). This reliance on ICEs significantly contributes to greenhouse gases (GHGs) emissions. For this reason, there is an urge to develop an energy-efficient powertrain architecture that produces fewer GHGs emissions while meeting the variable torque levels and variable speeds and performing various duty cycles with high efficiency. In order to select the energy-efficient powertrain architecture for the off-highway vehicle, different existing powertrain architectures (i.e., series hybrid, parallel hybrid, series-parallel hybrid, conventional) for off-highway applications have been studied to highlight their pros and cons. This is done considering the different duty cycles and applications along with Life Cycle Analysis (LCA). Off-highway vehicles operate under different road/surface conditions than on-road vehicles
Abououf, HendHanif, AtharDickson, JonChandramouli, NitishAhmed, Qadeer
The transportation sector is responsible for a significant portion of greenhouse gas emissions. Within the sector, truck freight is responsible for a third of the associated emissions. Alternative powertrains are seen as a viable approach to significantly reduce these emissions. Prior to making a large-scale transition, it is important to consider the following questions: will the power grid support a transition to alternative powertrains?; will the transition truly reduce carbon emissions?; and will the transition impose an unnecessary economic burden on companies within the industry? The answer to these questions, however, can vary by geography, maturity/capacity of the energy distribution network or predicted vehicle load. We focus on the latter two questions, investigating the variation in estimated total cost of ownership and carbon emissions across the United States at the zip code level for both heavy-duty battery electric vehicles and heavy-duty fuel cell electric vehicles. As
Goulet, NathanSun, RuixiaoFan, JunchuanSujan, VivekMiller, Brandon
The use of internal combustion engine vehicles (ICEVs) and hybrid electric vehicles (HEVs) powered by biofuels produced by photosynthetic fixation of CO2 and synthetic fuels produced by industrial synthetic reactions can be an effective way to reduce well-to-wheel (WtW) greenhouse gas (GHG) emissions intensity from vehicles, including both new and legacy fleet. In this study, several lower-carbon intensity fuels that contain at least 50% of renewable components, have at least 40% lower carbon intensity compared to commercially available E10 gasoline, and meet applicable US fuel standards were evaluated in a naturally aspirated (NA) engine in the legacy fleet, a turbocharged engine in the legacy fleet, and a prototype turbocharged super lean-burn engine, to identify their effects on thermal efficiency and exhaust emissions. As a result, it was confirmed that the lower-carbon intensity fuel can provide almost equivalent engine power and thermal efficiency as conventional fuel, and good
Takada, KeishiSugata, KenjiMatsubara, NaoyoshiTakahashi, DaishiVuilleumier, DavidMorlan, BrianLorenz, RobertOhta, Satoshi
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