The growing demand for renewable energy has increased interest in the use of lignocellulosic residues for energy applications. Mallow (Urena lobata Linn.) stem residue is an underutilized Amazonian byproduct generated after fiber extraction, whose thermal degradation behavior remains poorly explored. This study evaluated the energy-related potential of mallow stem residue through thermogravimetric analysis, TG-MS, isoconversional kinetic modeling, thermodynamic assessment, and reaction mechanism analysis. The biomass was characterized by proximate and lignocellulosic analyses and subjected to non-isothermal thermogravimetric experiments under N2 atmosphere at heating rates of 2.5, 5, 10, 15, and 20 °C min-1. The use of FWO, Kissinger-Akahira-Sunose, Starink, and Vyazovkin methods allowed the consistency of activation energy estimates to be evaluated and enabled the conversion-dependent reactivity of the biomass to be described without assuming a single reaction model. TG/DTG results revealed a multistage degradation process, with the main devolatilization occurring between 200°C and 400 °C. TG-MS indicated the release of H2O, CO2, and light organic fragments, while minor m/z assignments were treated as tentative due to possible fragment overlap. The apparent activation energy decreased with conversion, ranging from approximately 133 to 104 kJ mol-1, with average values between 122.95 and 126.39 kJ mol-1. Thermodynamic parameters indicated a thermally activated and energy-demanding decomposition process, while reaction mechanism analysis suggested changes in the dominant mechanism throughout conversion. Overall, mallow stem residue showed thermal and kinetic characteristics comparable to other lignocellulosic feedstocks, indicating potential for energy-related applications. However, further product characterization, ash composition analysis, and reactor-scale studies are required to confirm its practical applicability in bioenergy conversion systems.
This study investigates a heterogeneous catalyst derived from calcined and NaOH-treated Madhuca indica (M. indica) shell ash for the transesterification of M. indica seed oil. Process parameters were optimized using a central composite design (CCD) within response surface methodology (RSM), resulting in a maximum biodiesel yield of 92.3% (GC-MS area-based ester content). The optimal conditions were a methanol:crude oil molar ratio of 22.5:1, a reaction temperature of 70 °C, a catalyst loading of 2.5 wt%, and a reaction time fixed at 6 h. Engine performance was evaluated on a single-cylinder diesel engine operating at 1,500 rpm, utilizing B10 and B20 biodiesel blends. Under full load conditions, B10 reduced hydrocarbon (HC), carbon monoxide (CO), and smoke emissions by 21.43%, 12.78%, and 5.97%, respectively. B20 reduced HC, CO, and smoke emissions by 27.55%, 20.3%, and 12.23%, respectively, relative to diesel. Nitrogen oxides (NOx) emissions increased by 8.37% for B10% and 17.1% for B20 relative to conventional diesel. A techno-economic analysis (TEA) was performed using an Aspen Plus economic analysis process model; results and underlying assumptions are detailed in the TEA section.
IntroductionMunicipal solid waste is an abundant feedstock with established collection infrastructure and negative or near-zero acquisition costs. This study quantifies the techno-economic and environmental performance of a gasification and alcohol-to-jet pathway that converts 2,000 tonnes per day of municipal solid waste into sustainable aviation fuel.MethodsProcess modeling was conducted in BioSTEAM v2.44.3. Techno-economic analysis and life cycle assessment were performed, including Monte Carlo uncertainty analysis incorporating syngas H2/CO variability, catalyst lifetime, MSW moisture, plastic fraction, and financial parameters.ResultsThe process yields 9.3 gallons of fuel per tonne of incoming waste, with aluminum, iron, and propanol recovered as co-products. The minimum fuel-selling price (MFSP) ranges from $1.25 to $3.68 per gallon depending on tipping-fee credits and co-product revenues, with the lower bound within the 2019–2024 petroleum jet fuel range of $2.00–$3.50 per gallon. Cradle-to-gate global warming potential is 33.67 g CO2-eq/MJ, representing a 63% reduction relative to conventional jet fuel. Natural gas and electricity account for 54% of total emissions, while avoided landfill methane and metal recovery provide 5.8 g CO2-eq/MJ in credits. Monte Carlo analysis yields a 90% confidence interval of –$0.12 to $2.61/gal for MFSP and 28.4–42.8 g CO2-eq/MJ for GWP.ImplicationsEconomic performance is most sensitive to internal rate of return and aluminum price, while environmental performance is primarily driven by electricity sourcing and plastic composition. Overall, the pathway demonstrates robust climate benefits and competitive cost potential across uncertainty ranges.
The valorization of waste biomass into tailored adsorbents presents a sustainable strategy for combating industrial water pollution. This study highlights the critical role of precursor morphology in determining the textural properties and function of bio-adsorbents derived from wheat straw (WS) and the organic fraction of municipal solid waste known as biopulp (BP). Through carbonization and KOH activation, the fibrous WS was transformed into a microporous, high-surface-area activated wheat straw (AWS) bio-adsorbent, while the compact BP yielded a mesoporous network in activated biopulp (ABP). This structural difference affects adsorption performance: AWS demonstrated superior efficacy in batch removal of phenols (93.2%) and total organic carbon (85%) from the complex hydrothermal liquefaction aqueous phase (HTL-AP), whereas ABP excelled in treating produced water (PW), achieving >95% removal of organic pollutants. Continuous fixed-bed column studies confirmed the scalability of AWS for HTL-AP treatment, revealing distinct breakthrough dynamics between bulk parameters and specific contaminants. This work provides evidence supporting precursor-dependent tailoring of pore structure for targeted wastewater treatment, providing a possibility for a circular and sustainable solution for the treatment of complex industrial wastewaters.
Microalgae have significant economic importance due to their fast growth and diverse biomass composition. However, achieving cost-effective large-scale production while maintaining the high yields of the desired metabolite remains a major challenge. Conventional cultivation strategies face an inherent trade-off: conditions that promote microalgae development often suppress metabolite synthesis, whereas stress conditions that induce the desired metabolite synthesis inhibit growth and overall biomass production. In recent years, there has been increasing interest in a two-step cultivation, in which microalgae are first grown under optimal conditions for maximal biomass, followed by exposure to stress to trigger targeted metabolite synthesis. Despite its advantages, this approach also faces limitations in precisely controlling metabolite induction and in avoiding undesirable stress responses. To overcome this issue, integrating inducible genetic switches in the second cultivation phase, particularly stress-responsive promoters linked to the gene of interest, offers a promising strategy to enhance metabolite production in a controlled manner. However, until now, there are no published studies on the utilization of inducible promoters along with a two-stage cultivation system for microalgae. The inducible systems are activated by specific stress factors or substrates, enabling targeted activation of desired pathways while limiting off-target effects. This review provides an overview of the mechanistic framework of the two-step cultivation system, types and mechanisms of inducible promoters, and switch-based metabolic regulation in microalgae. Finally, we will highlight the challenges and opportunities for integrating synthetic biology tools with cultivation engineering to enhance and sustain targeted metabolite production in microalgal biorefineries.
IntroductionDimethyl ether (DME) has potential to be used both blended with or as an alternative to Liquefied Petroleum Gas (LPG) to reduce the carbon emissions of a fuel used globally for cooking and heating. Standards to enable the adoption of this require flame speed measurements of the blends of these fuels.MethodsMeasurements of counterflow premixed flame speeds for blends of DME, propane, butane, and propylene at fuel-air equivalence ratios (φ) from 0.75 to 1.6 have been made. These measurements were taken to fill a gap in the current published datasets that primarily have focussed on pure fuels and blends of LPGs constituent gases. These measurements have been produced through a mixture of empirical and simulation work.ResultsWe found the flame speeds of the blends overall increase from 0.25 m/s at φ = 0.75 to between 0.4 m/s and 0.45 m/s at φ = 1.0 peaking around φ = 1.0 to 1.1 before decreasing as φ increases further.DiscussionThese data will be useful to support the production of industrial standards that allow for greater adoption of renewable DME as an alternative low carbon fuel to fossil LPG.
This paper aims to evaluate whether cofiring hydrogen and natural gas mixtures are suitable as industrial furnace fuels and to identify further characteristics that need more detailed understanding to enable successful implementation of fuel switching. The outcome of this research and further investigations will ensure that the full capability of fuel switching becomes available to energy-intensive process operators. Co-firing natural gas and hydrogen leading to dedicated hydrogen combustion are pathways to decarbonise industrial processes and can enable future hydrogen utilisation and interoperability with fossil fuels. The key observations from pilot-scale industrial furnace trials at the University of Sheffield Energy Innovation Centre included: (1) Radiant heat flux depended primarily upon furnace temperature with no relationship measured with varying fuel composition. (2) The chamber geometry, radiant heat flux from solid surfaces and control temperature achieved were more significant to the furnace heat exchange than the fuel mixture. (3) Firing with natural gas and hydrogen mixtures did not affect furnace temperature or uniformity beyond variations attributable to other process conditions. (4) Gas temperatures and species were distributed uniformly within the fully mixed atmosphere, which represented 2/3 of the chamber volume. (5) Gas temperature and species distributions were not affected by fuel composition, therefore measurements from the centre of the chamber were representative of the mean conditions in the fully mixed atmosphere. (6) CFD modelling of the gas and temperature distributions within the furnace enabled thermodynamic and fluid dynamic characteristics to be understood and afforded confidence in experimental and model outcomes. Co-firing hydrogen with natural gas and dedicated hydrogen firing as an interoperable fuel to substitute for natural gas could be a key means to decarbonise hard to abate foundation industries, whilst making continued use of existing capital assets. This investigation demonstrated that understanding hydrogen firing and co-firing will enable the mitigation of perceived risks arising from decarbonisation of energy-intensive industries with low and zero carbon fuels.
The decarbonization of heavy-duty transport, marine shipping, and aviation require sustainable liquid fuels that are compatible with existing infrastructure and derived from renewable carbon sources without competing with food or land resources. Cyclic acetals, particularly 1,3-dioxolane and 1,3-dioxane derivatives, have recently emerged as promising oxygenated fuel candidates capable of integrating multiple bio-hybrid carbon streams. These compounds can be synthesized from lignocellulose biomass-derived diols and higher aldehydes, captured CO2 valorized with green hydrogen, and C1 intermediates obtained from plastic waste. Compared with traditional formaldehyde-based routes, the use of higher aldehydes and catalytic CO2/H2 conversion pathways helps overcome thermodynamic limitations and phase-separation challenges in acetal synthesis. Process intensification strategies, such as reactive extraction and reactive distillation in integrated catalytic columns, further enable simultaneous synthesis and purification, simplifying process design and improving scalability. Cyclic acetals exhibit favorable fuel properties, including full miscibility with conventional diesel and jet fuels, high cetane numbers, excellent cold-flow characteristics, and stable oxygenated structures resistant to corrosion and degradation during storage and combustion. These attributes make them attractive molecular platforms for advanced bio-hybrid fuels, enabling pathways toward carbon-neutral and potentially carbon-negative diesel and aviation fuels derived from biomass, CO2, and recycled plastics. Remaining challenges include catalyst durability, impurity tolerance, pilot-scale validation, and techno-economic feasibility.
The increase in global demand for sustainable and eco-friendly energy has intensified research on biofuels derived from renewable biomass. Among various feedstocks, algal biomass has attracted more attention due to its high photosynthetic efficiency, rapid growth rate, and ability to grow on non-arable land using saline or wastewater, thus avoiding competition with food crops. Bioethanol and biobutanol, in particular, have emerged as promising alternatives to fossil fuels because of their cleaner combustion, higher energy content, and compatibility with existing fuel infrastructure. This review provides a comprehensive overview of converting algal carbohydrates into fermentable sugars and then fermentation using microbial or genetically engineered organisms for bioethanol and biobutanol production. Various pretreatment and hydrolysis methods, including mechanical disruption, chemical treatments, thermal and biological processes, are discussed for their effectiveness in breaking down the complex algal cell walls and releasing fermentable sugars. Bioethanol is mainly synthesized through the glycolytic pathway and subsequent alcoholic fermentation, whereas biobutanol is produced through the Acetone-Butanol-Ethanol fermentation process. The review also discusses a comparative analysis of algal bioethanol and biobutanol in terms of their industrial applications and market potential. It addresses key challenges, including feedstock availability, process scalability, and production costs, while evaluating opportunities for integration within biorefinery frameworks to enhance overall economic feasibility. Overall, algal biomass represents a sustainable, versatile, and scalable resource for bioethanol and biobutanol production, offering significant potential to support the global transition toward renewable energy. Advancements in research, technological optimization, and supportive policy frameworks will be essential for utilizing the full industrial potential of algal-based biofuels.
Access to energy is essential for the modern world, yet at the same time, anthropogenic greenhouse gas emissions are caused by energy-related activities across all sectors due to the predominance of fossil fuels. Today, most of the primary energy is still being provided by fossil fuels, with combustion being a key technology. In order to combat climate change, energy has to be decoupled from greenhouse gas emissions, with electricity and electrification being important pathways towards a net-zero energy system. However, electricity also has drawbacks as an energy carrier, especially in the context of large-scale energy storage, but also for applications requiring high energy densities. This, in addition to providing dispatchable power generation capacities for grid balancing and covering longer periods of reduced renewable power generation, is expected to result in significant contributions of synthetic and biogenic fuels to the energy landscape. The main purpose of combustion-based technologies will change from providing most of the primary energy to the energy system to complementing variable renewable energies when and where needed. This change of purpose has consequences for the directions of combustion research and development: while traditional topics such as equipment efficiency and pollutant emissions such as NOX will still be important, other topics such as more flexible and dynamic operation modes, hybrid applications and system integration will play a much bigger role in the future, along with the use of new fuels such as hydrogen or ammonia.
IntroductionOne of the main environmental problems is air pollution due to high CO2 emissions, a greenhouse gas that contributes to climate change because of the excessive use of fossil fuels. For this reason, CO2 reduction emerges as a promising solution by converting it into renewable fuels using sunlight and advanced semiconductor materials. Recently, hybrid systems based on artificial leaves composed of lead-free halide perovskites and porous support materials have been demonstrated to be highly efficient for CO2 reduction. In addition, the recycling and utilization of natural sources such as the brown algae, considered a plague in the Caribbean, represents an additional advantage for the pollution reduction, carbon sequestration, and social and economic impacts.MethodsThis research proposes an innovative solution to address this environmental problem by demonstrating that hybrid systems based on bismuth halide perovskites (K3Bi2I9) and brown algae-functionalized clay biosupports are promising for the reduction of CO2 with high efficiencies for formic acid production (2.5 mmol h-1) under visible light. The content of the brown algae was investigated to find the best load that promotes higher and stable CO2 reduction efficiencies.ResultsThe presence of the brown algae enhanced light absorption by its chlorophyll, provided free electrons to the semiconductor and highly reactive species (•OH), that favored the formation of C1-C3 products, e.g., HCOOH, CH3COOH, and CH3(CH2)2OH, with efficiencies in the order of >1 mmol. In addition, the stability of the hybrid systems was demonstrated after five hours of continuous visible light irradiation in liquid phase, which analysis of the medium showed a minimal leaching of potassium.DiscussionThe addition of 5 wt.% brown algae in the clays promoted both high efficiency and stability of the hybrid system by preventing cracking, while promoting a porous framework that maintained effective CO2 adsorption. This enhanced effect was attributed to efficient perovskite encapsulation and the presence of chlorophyll (from algae) acting as an electron donor, enhancing light absorption and charge transfer. This synergistic effect enabled efficient CO2 conversions to C1–C3 value-added products. In conclusion, this work demonstrated that the utilization of abundant natural materials such as clays and sargassum supports an ecological and scalable approach while addressing global and local environmental problems.
IntroductionBiomass pretreatment outcomes are heterogeneous across routes and severities, and condition-centered empirical models often fail to generalize beyond the settings on which they were trained, limiting early-stage decisions about where to focus costly wet-lab effort. This study evaluates a composition-centered surrogate that treats the post-pretreatment solid composition—cellulose, hemicellulose, lignin—as the input space and predicts enzymatic glucose yield as the response for kenaf core.MethodsKenaf core solids subjected to water, dilute-acid, and alkaline pretreatments were characterized for post-pretreatment cellulose, hemicellulose, and lignin contents and hydrolyzed under a fixed enzymatic protocol to obtain glucose yield at 24 h. The curated dataset (n = 35) was used to train Random-Forest regressors tuned by six hyperparameter optimizers (grid search, random search, Bayesian optimization, genetic algorithm, particle swarm optimization, and simulated annealing). Generalization performance was assessed using nested cross-validation and a held-out test split, with feature contributions examined via permutation importance and accumulated local effects.ResultsAcross optimizers, held-out performance clustered tightly (test R2 ≈ 0.49–0.55; RMSE 4.42–4.69 GY%), indicating that attainable accuracy is governed more by model capacity and data coverage than by optimizer choice. Feature diagnostics converged on a cellulose-led mechanism, with cellulose showing a positive monotonic effect on yield, lignin a negative effect, and hemicellulose a weaker, context-dependent influence. Iso-yield maps in the cellulose–lignin plane delineated feasible composition windows that prioritize high-cellulose/low-lignin regions under different hemicellulose levels.DiscussionWithin this accuracy band, the composition-centered surrogate is best suited for uncertainty-aware screening to prune unproductive regions of composition space before targeted design-of-experiments, rather than replacing detailed process optimization. The workflow provides a transferable template for small-sample, composition-based modeling of lignocellulosic feedstocks and can be extended to other varieties and integrated with mechanistic descriptors as data accumulate.
Biodiesels made from waste feedstock are viable sustainable fuels for compression-ignition engine use. However, biodiesels produced from single waste sources do not always comply with the European biodiesel standard. This study investigates fuel quality and engine performance when two biodiesels with different characteristics are blended at various proportions. Waste cooking oil biodiesel was blended with sheep fat biodiesel, which has a lower unsaturated fatty acid content. The engine performance, combustion, and exhaust emission characteristics of the neat biodiesels and their blends (at 60/40, 50/50, and 30/70 ratios) were analysed. The results showed that 60/40 and 50/50 blends met the core parameters of the BS EN 14214 biodiesel standard and improved combustion and emission characteristics compared to neat biodiesels and diesel. The 50/50 blends gave up to 5% and 14% improvements in the in-cylinder pressure and maximum heat release rate, respectively, compared to the same results for neat biodiesel operation. Reduction of up to 73% in CO, 96% in smoke and 3% in CO 2 emissions was observed. However, NOx emission was 2.5% higher than diesel. The results reveal that carefully selected biodiesel–biodiesel blending could meet fuel standards, improve engine performance, and reduce exhaust emissions.
Integrating green hydrogen production with existing oil and gas infrastructure is seen as viable step for the reutilization of oil and gas assets. Green hydrogen production through offshore wind has the potential to extend the lives of these systems, reduce decommissioning costs and provide a source of clean energy. This paper presents an outlook on wind license areas using existing oil and gas infrastructure. Three scenarios are proposed for the conversion of offshore assets into wind turbine sites, including the conversion of a platform into a substation. A methodology is provided to assess the suitability of offshore wind using exclusion criteria and the cessation of production dates for oil and gas infrastructure. This methodology is applied to the UK Exclusive Economic Zone (EEZ), and the results show that 7.4% of the UK EEZ is within the top suitability index for wind turbine development. The cost of green hydrogen production from different offshore locations is estimated to be in the range of 9.78–11.76 £/kgH 2 depending on the wind farm scale and the distance. The study highlights the potential for using existing infrastructure for wind turbine development and provides valuable insights for stakeholders in the energy industry.
Microalgae represent a promising solution for achieving greener and more sustainable applications, owing to their rapid growth rates, high photosynthetic efficiency, and capacity to produce valuable compounds such as lipids. Biofuels based on microalgae have emerged as a promising alternative to fossil fuels due to their sustainable and renewable nature. Moreover, the use of microalgae cultivated in wastewater not only contributes to biofuel production but also provides additional benefits such as wastewater treatment and CO2 sequestration to realize the carbon neutrality. However, the commercial viability of microalgae-based biofuels remains uncertain. This article reviews advancements in microalgae-based sustainable production while exploring its multi-objective applications beyond energy generation. Multi-objective applications, including multi-algal systems, species development, process optimization, and dust suppressant are necessary to improve cost-effectiveness and enhance overall feasibility.
In the context of global warming and the increasing demands for the application of sustainable fuels, measurements of a variety of experimental targets under a wide range of conditions are crucial to improving the fundamental understanding of real jet fuels and developing quality kinetic mechanisms for large hydrocarbons. Planar laser-induced fluorescence (PLIF) is an effective approach to investigate concentrations of important species of a given flame while quantifying the fluorescence image remains a great challenge with significant uncertainties. This investigation aims to improve the fundamental understanding of the oxidation of kerosene-based mixtures at two equivalence ratio conditions. Two gas fuels are utilized as the reference for the quantitative studies. For each flame condition, relative OH and NO quantities and temperature profiles were measured by applying the PLIF and coated fine wire type R Pt/Pt-Rh thermocouples, respectively. The converted OH and NO results were subsequently compared with the simulation by using ANSYS Chemkin Pro, and the results indicate that reliable temperature profiles are the key to accurately quantify the species concentration of a given flame.
The effects of dimethyl ether (DME) addition to methane and ethylene fuels on the combustion characteristics of heat release, soot emissions, and flame temperature were investigated experimentally and numerically in a non-premixed laminar flame configuration. The flame-heat release soot-volume fraction was measured experimentally using CH*, OH*, and C 2 * chemiluminescence and planar two-color soot pyrometry, respectively. The CH*, OH*, and C 2 * were used to locate flame-heat release regions as well as to investigate the soot signal’s effect on their measurements. The ratios of the chemiluminescence pairs (OH*/CH* and OH*/C 2 *) were studied for the feasibility of map local equivalence ratios. Numerical calculations across a full range of DME mixing ratios were performed through 1D laminar flame simulations implemented with a detailed mechanism to provide an indication of the flame structures and profiles of key species including OH*, OH, CH*, CH, CH 3 , C 3 H 3 , C 2 H 2 , heat release rate (HRR), and flame temperature. An existing developed soot model was used in a 2D computational study to investigate its validity for modeling soot for DME (oxygenated fuel)/C 2 H 4 /N 2 flames. Parametric studies have been carried out on some key parameters in the soot model to find optimum values that can be used in future studies. Although soot radiation intensities increased at a small amount (25%vol) of DME addition in the DME/methane flames, the soot pyrometry results showed a reduced soot volume fraction with an increased DME mixture ratio in both DME/methane and DME/ethylene flames studied, agreeing with the key conclusion of 1D numerical results. The flame HRR decreases with the increasing addition of DME to methane and ethylene flames and correlates with the trend of OH* and CH* profiles. The 1D simulation showed a non-monotonic correlation between OH*/CH* ratios and equivalence ratios, implying a limited use of OH*/CH* for the equivalence ratio measurement in non-premixed flames with DME additions.
The aviation industry, driven by evolving societal needs, faces rising demand post-Covid and increasing pressure to align with emission reduction targets, prompting the development of drop-in sustainable aviation fuels (SAF). Their compatibility with existing aircraft and infrastructure will help to implement these fuels with the urgency the global climate crisis requires. This review delves into the benefits and challenges of various feedstocks, addressing complexities in estimating feedstock availability by location. Identified research gaps include enhancing feedstock availability, yield, and diversity, investigating compositions, and implementing sustainable agricultural practices. A summary of ASTM-certified conversion processes and technical specifications is outlined, prompting further research into conversion efficiency, catalyst selectivity, blending limits, aromatic compounds, combustion instability, and numerical modeling. A summary of recent life cycle assessments (LCA) highlighted gaps in cradle-to-cradle assessments, location-specific analyses, temporal considerations, and broader environmental impact categories. Recommendations stress obtaining primary data for enhanced LCA accuracy, conducting more specialized and general LCA studies and combining LCA, techno-economic analysis, fuel requirements, and socio-political assessments in multi-criteria decision analysis. This paper underlines the pressing need for comprehensive research to inform SAF production alternatives in the context of global climate crisis mitigation.
Impending and increasingly stringent emissions regulations regarding natural gas compressor engines drive the research behind blending hydrogen with natural gas to make these internal combustion engines and their combustion process more efficient. This investigation seeks to answer two fundamental questions: will blending hydrogen with natural gas reduce overall engine fuel consumption, and can greenhouse gas emissions be reduced by blending hydrogen with natural gas? A 4-cylinder Cooper–Bessemer GMV engine, housed at Colorado State University’s Powerhouse facility, was investigated for hydrogen–natural gas blending using multiple engine configurations. A lean-burn engine uses an active pre-combustion chamber as its ignition source, along with electronically activated high pressure fuel injection in the main combustion chamber. One configuration tested utilized high-pressure fuel injection and blending in hydrogen, up to 40% by volume, in both the main chamber and pre-combustion chamber fuel supplies. A second configuration, where the main combustion chamber fuel was solely natural gas and only the pre-combustion chamber received hydrogen-blended natural gas, was also tested. The final configuration to be tested used low pressure fuel injection with mechanically actuated valves in the main chamber with a traditional spark plug ignition source. All engine configurations saw reductions in methane emissions of up to 30% using blended natural gas and hydrogen. Carbon dioxide emissions were also shown to be reduced for the two configurations. A reduction in brake-specific fuel consumption of up to 2% was also seen for two configurations. These results support the hypothesis that blending hydrogen into natural gas can reduce engine total fuel consumption and reduce greenhouse gas emissions.
