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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
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    <language>en-us</language>
    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Dynamic risk assessment for methanol ship-to-ship bunkering operations</title>
      <link>https://trid.trb.org/View/2728693</link>
      <description><![CDATA[Methanol is a promising alternative marine fuel that can contribute to greenhouse gas emission reductions. Despite its significant environmental potential, the inherent toxicity and high flammability pose substantial safety challenges during ship-to-ship (STS) bunkering operations. Effective risk management is essential to enhance operational safety in methanol bunkering and promote its adoption. To address this, a Dynamic Bayesian Network (DBN) combining physical and statistical models is proposed for methanol STS bunkering. This approach improves dynamic probabilistic assessment of hazardous consequence by integrating weather, operational, and port conditions that change over time. It builds a fault tree from investigation reports and methanol properties, and maps it to a DBN with time-dependent properties. Conditional probability tables are derived from weighted scoring, fluid mechanics, and diffusion models. The method was applied to three sites in Hong Kong to assess dynamic probabilities of hazardous consequences. The analysis identified Cheung Chau South Anchorage as the most suitable location for methanol STS bunkering due to its lower mean threat probabilities during the bunkering process across toxic dispersion, vapor cloud explosion, and flash/pool fire. Sensitivity analysis identified key influencing factors, revealing that although methanol and oil fuel share common key factors, they also exhibit significant differences. Methanol requires particular attention to bunkering pressure, bunkering rate, and corrosion degree. The validated and adaptable model offers actionable guidance for ports and regulators to enhance methanol STS bunkering safety. It can also be extended to other ports for dynamic probabilistic safety assessment of methanol STS bunkering.]]></description>
      <pubDate>Mon, 28 Sep 2026 08:36:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2728693</guid>
    </item>
    <item>
      <title>Simulation-driven aftertreatment optimization and emissions characterization of a high-efficiency methanol DI engine</title>
      <link>https://trid.trb.org/View/2724597</link>
      <description><![CDATA[This study presents an integrated calibration and aftertreatment optimization framework for a 1.5L direct-injection methanol-fueled spark-ignition engine targeting compliance with China 6b emission regulations. Methanol’s unique physicochemical properties, high latent heat of vaporization, fast flame speed, and elevated octane rating, enabled advanced ignition phasing at high loads and significantly reduced CO, HC, NOₓ, and PM/PN emissions relative to gasoline. Furthermore, the methanol engine displays unique emission behaviors in response to the aftertreatment system, in contrast to those observed in the gasoline engine. A simulation-driven approach was applied to develop a tailored aftertreatment system, leveraging a validated catalyst performance model to define platinum group metal (PGM) loadings and washcoat architecture. Experimental validation under WLTC conditions demonstrated strong agreement with simulated midbed temperatures and tailpipe emissions, confirming predictive model fidelity. Although calibrated under fresh conditions, a thermal aging sub-model incorporating Arrhenius-based degradation was used to extrapolate full useful life (FUL) catalyst performance over 240,000 km. The results highlight methanol’s heightened sensitivity to catalyst aging due to its oxygen-rich and chemically reactive exhaust composition. To address this, a Design of Experiments (DOE) methodology was employed to optimize catalyst volume and PGM distribution across close-coupled and underfloor positions. The finalized configuration, consisting of dual TWC bricks and an underfloor uGPF, achieved regulatory compliance with reduced PGM usage and packaging feasibility, offering a cost-effective solution for low-emission methanol engine applications.]]></description>
      <pubDate>Wed, 23 Sep 2026 15:56:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2724597</guid>
    </item>
    <item>
      <title>Study of engine combustion in cold start in use of rich methanol blended fuel</title>
      <link>https://trid.trb.org/View/2706127</link>
      <description><![CDATA[Methanol is being studied as a carbon-neutral fuel for internal combustion engines. However, its physical properties, high latent heat of vaporization, boiling point and low specific calorific value, can present challenges for combustion during cold starts. In this study, using a spark ignited engine from a production motorcycle, we investigated fuel vaporization in the intake port, temperature distribution across engine components, and emissions from both the exhaust and crankcase, alongside combustion stability during cold starts. The results indicate that significant temperature drops and poor fuel vaporization in the intake port cause degraded combustion stability following the start-up.]]></description>
      <pubDate>Tue, 18 Aug 2026 14:11:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2706127</guid>
    </item>
    <item>
      <title>Transition Towards Fossil-Free Energy Sources in the Shipping Sector: A Sustainability Index Analysis of Methanol and Liquefied Biogas</title>
      <link>https://trid.trb.org/View/2581438</link>
      <description><![CDATA[Around 80% of global trade volumes are transported by ships. The shipping sector is responsible for approximately 2.89% of anthropogenic greenhouse gas emissions due to its prevailing dependency on fossil fuels. However, the tightening of environmental regulations urges shipping to shift to fossil-free energy sources, such as biofuels and synthetic fuels. In this paper, we analyze the sustainability of methanol, produced either from natural gas or biomass, and liquefied biogas. For this, we utilize a sustainability index combining environmental and economic indices. The environmental index demonstrates the environmental harms from emissions derived from producing and consuming the fuels. The economic index includes the fuels’ life-cycle costs. Our results reveal that biofuels’ environmental sustainability depends on how CO2 emissions are calculated during their life cycle. Burning biofuels produces CO2 emissions, but the emissions from biofuel production depend on the biomass source. Environmental regulations are not unanimous about treating CO2 emissions from biofuels: In the EU Emissions Trading System, if the biomass is from sustainable sources, CO2 emissions from biofuel consumption are considered zero, in contrast to IMO regulation. Moreover, the economic index is highly influenced by fuel prices, which are difficult to predict. With alternative fuels, the life-cycle perspective is especially important since emissions from production dominate more than with fossil fuels. Therefore, the importance of the holistic analysis of shipping fuels, which we conducted here, will increase.]]></description>
      <pubDate>Thu, 13 Aug 2026 17:00:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2581438</guid>
    </item>
    <item>
      <title>Methanol sprays in marine engines: CFD modelling of port fuel injection systems</title>
      <link>https://trid.trb.org/View/2701215</link>
      <description><![CDATA[The maritime sector aims to achieve short and medium-term sustainability targets through the conversion of Internal Combustion Engines to methanol operation. For small to medium sized engines, Port Fuel Injection (PFI) is the most viable injection method to achieve this conversion. However, the knowledge of the behaviour of methanol in combustion engines, particularly its spray characteristics under PFI conditions, is limited. To better understand liquid methanol sprays, this paper studies the injection of methanol in marine PFI conditions through Computational Fluid Dynamics (CFD) modelling. The CFD models use the Lagrangian-Eulerian (LE) coupling method within the Reynolds Averaged Navier Stokes (RANS) turbulence framework. Numerical results were validated using dedicated methanol experiments from the literature for both high and low injection pressures. Subsequently, this predictive CFD framework was used in a number of different injection pressures with scaled injection quantities that represent marine applications. Moreover, we demonstrated that high injection pressure improves atomisation and, thus, evaporation prior to wall impingement. This work strongly contributes to our understanding of marine PFI methanol engines by modelling fuel quantities relevant for ship applications. Our approach can be implemented in full engine simulations to solve evaporation challenges often found in small-bore methanol marine engines.]]></description>
      <pubDate>Tue, 04 Aug 2026 09:34:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/2701215</guid>
    </item>
    <item>
      <title>Experimental Investigation on Unburned Methanol and Formaldehyde Emissions from a Direct-Injection Diesel / Methanol Dual-Fuel Engine</title>
      <link>https://trid.trb.org/View/2742445</link>
      <description><![CDATA[For large-bore marine methanol / diesel dual-fuel engines, this study investigates the formation characteristics of unregulated emissions through experimental methods and explores the mechanisms by which engine load and injection timing influence the emissions of unburned methanol and formaldehyde. The study was carried out on a supercharged intercooled inline six-cylinder engine, and Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor the exhaust composition in real time. The study shows that methanol released in the exhaust is due to the incomplete combustion of the methanol fuel. In the combustion process of methanol fuel, formaldehyde mainly arises from two pathways, the first of which is the partial oxidation of methanol inside the cylinder; secondly, the unburned methanol in the exhaust gas oxidizes in the exhaust pipe to generate formaldehyde. As the load increased from 25% to 100%, the unburned methanol emissions decreased by 29%, and formaldehyde emissions decreased by 71%. This is mainly attributed to the enhanced oxidation reaction and reduced wall crevice effect due to the increased combustion temperature. Methanol injection timing optimization was effective in controlling unregulated emissions, with methanol emissions lower at -7° CA ATDC and formaldehyde emissions reaching larger values under this condition. Delaying the diesel injection to -16°CA ATDC led to a 38% increase in unburned methanol emissions, caused by fuel spray interactions and longer stagnation, whereas formaldehyde emissions showed minimal change.]]></description>
      <pubDate>Mon, 03 Aug 2026 15:57:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/2742445</guid>
    </item>
    <item>
      <title>An experimental and simulative study for transient performance and emissions analysis of a marine engine fed with flex-fuel as methanol and ammonia blends</title>
      <link>https://trid.trb.org/View/2689380</link>
      <description><![CDATA[Transportation, being a significant contributor to rising global emissions, underscores the need for alternative fuels like ammonia, methanol, hydrogen, and others. Transient scenarios are crucial to study because they reflect real-world driving conditions where engines frequently transition between different loads and speeds, significantly impacting emissions and performance. There is a significant gap in research on using ammonia and methanol blended fuels in engines, particularly under transient conditions, due to the complexity and challenges in combustion control. This study aims to address this gap by conducting a comprehensive simulative investigation of ammonia-methanol flex-fuel blends for a transient marine engine. Utilizing an experimentally validated GT-Power model, the study evaluates three key characteristics: performance, combustion, and emissions, under various operating conditions involving parameters such as injection timing, spark timing, and different blend ratios of both fuels. The study reveals that increasing the ammonia content in methanol blends results in moderate changes to engine performance, with slight decreases in indicated mean effective pressure and indicated efficiency, despite maintaining constant energy input. These performance reductions are minor compared to pure methanol. However, the most significant advantages are seen in emissions, with carbon dioxide levels decreasing by up to 80% when comparing blends of 25% Methanol and 75% Ammonia to 100% Methanol, highlighting the potential of ammonia-methanol flex-fuels as environmentally friendly alternatives. Furthermore, the air-fuel ratio fluctuation was also observed to be reduced with methanol-ammonia blends, which can make the engine drivability smoother during transient operation with sudden load changes that will minimized the engine vibration during transition stage. This research positions ammonia-methanol blends as a 100% renewable fuel option for engines, offering significant potential for reducing emissions and improving environmental sustainability in the transportation sector.]]></description>
      <pubDate>Fri, 31 Jul 2026 09:23:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2689380</guid>
    </item>
    <item>
      <title>Experimental investigation on the effects of water blending on combustion and emission characteristics of diesel pilot high pressure direction injection methanol combustion</title>
      <link>https://trid.trb.org/View/2689379</link>
      <description><![CDATA[Water blending is a potential method to reduce NOₓ emissions for the diesel pilot high-pressure direct injection (HPDI) methanol combustion. In this study, experiments were conducted on a specially designed dual direct injection single - cylinder engine to explore the effects of water blending on the combustion and emission performance of diesel pilot HPDI methanol combustion under a high methanol substitution rate of over 90%. Results indicate that water blending increases the density, viscosity, and surface tension of methanol while significantly elevating specific heat capacity and latent heat. Combustion remains stable even under 30% water blending conditions, though water blending slightly delays ignition timing (CA10) and combustion phasing (CA50). As the water blending ratio increases, the peak in-cylinder pressure and heat release rates (HRR) decline, particularly at high loads, while combustion duration (CA90–CA10) shortens with 20–30% water ratio, effectively reducing exhaust losses. However, when the water blending ratio reaches 30%, it causes a significant increase in heat transfer loss, resulting in a decrease in thermal efficiency. Under all load conditions, increasing the water blending ratio can greatly reduce NOₓ emissions with slightly increased carbon monoxide and hydrocarbon emissions at low loads. When the water blending ratio reaches 30%, NOₓ emissions fully meet Tier III emission standards under all operating conditions, yet thermal efficiency is lower than that of pure methanol. By contrast, a 20% water blending ratio maintains thermal efficiency superior to pure methanol while still having the potential to meet Tier III NOₓ limits. Therefore, to balance emissions and efficiency in practical engine applications, a compromise ratio within the 20%–30% range is recommended.]]></description>
      <pubDate>Fri, 31 Jul 2026 09:23:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2689379</guid>
    </item>
    <item>
      <title>Study on chemical kinetic mechanism of methanol/diesel surrogate fuel</title>
      <link>https://trid.trb.org/View/2689375</link>
      <description><![CDATA[In order to study the combustion process of diesel/methanol dual-fuel (DMDF) in the engine cylinder, a methanol/diesel surrogate fuel reaction mechanism was constructed, which includes 101 species and 288 reactions. This study optimized the diesel/methanol combustion mechanism by adjusting the rate constants of key reactions based on ignition delay sensitivity analysis. A zero-dimensional model was used to validate the ignition delay time (IDT), laminar flame speed (LFS), and concentration of key species under various conditions for the dual-fuel mechanism. Furthermore, the methanol/diesel surrogate fuel mechanism was coupled with multidimensional computational fluid dynamics (CFD) to validate the combustion process within the engine cylinder under both pure diesel and DMDF modes. The results show that the combustion mechanism of methanol/diesel surrogate fuel is highly consistent with the experimental data in terms of IDT, LFS, and concentration of key species. In addition, by combining the combustion mechanism with CFD simulation, the simulation results of cylinder pressure, heat release rate, and formaldehyde, acetaldehyde, ethylene, and butadiene emissions are consistent with the experimental data, further verifying the reliability of the methanol/diesel surrogate fuel mechanism. The constructed DM mechanism can provide a theoretical basis for the development and application of clean, low-carbon alternative fuels in engines.]]></description>
      <pubDate>Fri, 31 Jul 2026 09:23:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/2689375</guid>
    </item>
    <item>
      <title>Influence of alternative pre-chamber fuels on engine performance</title>
      <link>https://trid.trb.org/View/2696111</link>
      <description><![CDATA[The application of active pre-chamber (PC) combustion systems offers potential increases of the indicated efficiency of spark-ignition (SI) engines by increasing the lean operating limit. In conventional SI operation, methanol revealed promising engine performance without substantial knock limitation. In PC operation with methanol under lean conditions, the PC jets can fail to ignite the charge in the main combustion chamber (MC) due to methanol’s high enthalpy of vaporization. The PC jet characteristics in turn depend on the applied PC fuel. In this study, it was assumed that the application of alternative liquid PC fuels might extend the lean operating limit of an engine that was operated with methanol as MC fuel. To this end, methanol, ethanol, 2-butanone, ethyl acetate, 1,3-dioxolane, and diethoxymethane were investigated as PC fuels in this study, while the MC was fueled with methanol. The fuels were experimentally investigated on a thermodynamic SI single-cylinder engine equipped with an active PC and a compression ratio of 16.4. Variations of the relative air/fuel ratio in the exhaust gas at net indicated mean effective pressures of 6?bar and 15?bar were performed. The observed differences in the engine performance between the investigated PC fuels were minor because a large fraction of the PC mixture consisted of the MC fuel methanol that was forced into the PC during the compression stroke. However, measured PC-driven HC emissions depended on the applied PC fuel and increased toward the engine’s lean operating limit at low engine load. At high engine load, this behavior was not observed. In PC operation, a maximum net indicated efficiency of 47.3% was observed, which was 0.8%-points higher than in conventional SI operation.]]></description>
      <pubDate>Fri, 31 Jul 2026 09:23:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2696111</guid>
    </item>
    <item>
      <title>Study on Diesel-Methanol Non-Premixed Combustion Characteristics of a Marine Dual-Fuel Engine at Different Methanol Substitution Rate</title>
      <link>https://trid.trb.org/View/2732223</link>
      <description><![CDATA[Methanol use in marine engines has the potential to reduce nitrogen oxide                     emissions, particulates, and greenhouse gas emissions. A turbocharged                     four-stroke marine diesel powerplant was converted to run as a double-DI (direct                     injection) diesel-methanol hybrid engine. Experimental studies using a                     non-premixed combustion scheme showed that higher methanol substitution ratios                     (MSR) led to increased peak heat release rates. The combustion process displayed                     distinctive two-phase behaviors. Increasing MSR caused retarded ignition timing,                     shortened combustion duration, and improved thermal efficiency. Combustion                     stability was significantly improved at higher MSR. Emissions results showed                         NOX and HC were increased in proportion to MSR, whilst                     particulate emissions and CO concentrations were inversely reduced. Methanol                     enrichment was found to enhance NOX and HC formation processes but                     also accelerate soot particulate decomposition and CO oxidation mechanisms.]]></description>
      <pubDate>Tue, 21 Jul 2026 11:36:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2732223</guid>
    </item>
    <item>
      <title>Alcohol-Based Energy Carriers in Transportation: Status, Standards, and Outlook</title>
      <link>https://trid.trb.org/View/2717261</link>
      <description><![CDATA[The global transport sector accounts for approximately 30 % of total final energy consumption and 15.9 % of worldwide greenhouse gas (GHG) emissions, with road transport alone accounting for the largest share at 11.8 %. Decarbonizing this sector requires energy sources that combine scalable generation from renewable sources with compatibility with various modes of transportation and existing infrastructure.Methanol and ethanol emerge as promising alternative energy carriers that can leverage existing logistics infrastructure while reducing dependence on fossil fuels. Global methanol production reached 112 million metric tons, and global ethanol production totaled approximately 93.5 million metric tons in 2024, compared to more than 2 billion metric tons of gasoline and diesel produced annually. The review assesses production pathways and cost trajectories for both alcohols, evaluates fuel requirements across multiple transport modes, including passenger vehicles, light- and heavy-duty vehicles, maritime shipping, aviation, and rail, and provides regulatory frameworks governing fuel standards in six major markets, the European Union, the USA, Brazil, China, Japan, and India. From a technical perspective, the internal combustion engine is examined in greater detail as the energy conversion system, synthesizing current combustion research on engine performance, emissions characteristics, and cold-start behavior.Current standards predominantly accommodate ethanol blending for spark-ignition (SI) engines in passenger vehicle applications, with permitted concentration limits ranging from 3 % in Japan to nearly pure ethanol in Brazil. Methanol applications remain more limited in road applications. In the maritime sector, recent ISO 8217:2024 specifications and International Maritime Organization (IMO) interim guidelines have established frameworks for the use of methanol and ethanol as marine fuels. Aviation remains the most restrictive sector, with alcohol fuels explicitly prohibited in certified aviation fuels due to material compatibility and safety concerns.To unlock the decarbonization potential of methanol and ethanol in the transport sector, coordinated policy support and continued technological innovation will be essential. As production scales and regulatory frameworks mature, both alcohol fuels may play an increasingly central role in the transition toward sustainable mobility.]]></description>
      <pubDate>Tue, 23 Jun 2026 10:34:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2717261</guid>
    </item>
    <item>
      <title>Lessons Learned from Designing, Constructing and Operating the Methanol-Powered Vessels in the FASTWATER Project</title>
      <link>https://trid.trb.org/View/2581612</link>
      <description><![CDATA[This paper reports on lessons learned during the design of the vessels, including the risk assessments; during the actual build/retrofit; and during the vessels’ operation. The focus is on the gained knowledge, to serve as proofs of concept and as a starting point for other methanol vessel conversions.]]></description>
      <pubDate>Thu, 18 Jun 2026 08:54:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/2581612</guid>
    </item>
    <item>
      <title>Methanol Mixing Controlled Combustion Process Enabled by Methanol Dehydration to Dimethyl Ether</title>
      <link>https://trid.trb.org/View/2692274</link>
      <description><![CDATA[This work demonstrates an initial proof-of-concept approach for operating a compression ignition off-road and marine relevant engine using neat methanol. The approach utilizes mixing controlled compression ignition (MCCI) of methanol that is enabled by a homogeneous charge compression ignition (HCCI) pre-burn of premixed dimethyl ether (DME). Although two fuels are used, this work explores and evaluates the opportunity and performance to generate the premixed fuel via methanol catalytic dehydration over an alumina catalyst at engine relevant temperatures, pressures, and space velocities. Conversion purity and species output results from catalytic dehydration bench flow reactor studies were coupled with single-cylinder experiments of the characterized output species for pre-burn HCCI performance. Subsequently, methanol MCCI performance is also evaluated and compared to conventional diesel combustion. The detailed flow reactor results show that the catalytic dehydration conversion efficiency of methanol to DME is a function of system pressure, temperature, and space velocity. The engine results demonstrate that a 100% conversion of methanol to DME is not required for successful pre-burn HCCI, and the water formed during the dehydration process does not need to be removed to achieve the desired HCCI event from this pre-burn mixture. Subsequent methanol MCCI combustion results show that the level of methanol slip in the dehydration process affects the pre-burn HCCI phasing, low temperature heat release process, and magnitude of energy release, all of which can dictate the available window for direct-injection of methanol for MCCI combustion. 1]]></description>
      <pubDate>Sat, 06 Jun 2026 12:01:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2692274</guid>
    </item>
    <item>
      <title>Challenges of Mixture Formation in Methanol Port Fuel Injection Engines</title>
      <link>https://trid.trb.org/View/2692227</link>
      <description><![CDATA[Port fuel injection (PFI) is an attractive strategy for methanol adoption in both spark-ignition and dual-fuel compression-ignition engines due to its lower cost and simpler hardware compared to direct-injection. However, methanol PFI mixture formation can be challenging due to methanol’s high heat of vaporization, low volatility at cold conditions and high tendency to wall wetting. Understanding and addressing these challenges is critical to ensure robust engine operation.In this study, the effects of injector geometry, coolant temperature, intake temperature and fueling rate on mixture formation of methanol PFI have been investigated for anhydrous methanol and for a blend of 90%vol methanol plus 10%vol water in an optical engine. Mie scattering and infrared imaging were applied to assess the liquid and vapor methanol distribution in the cylinder. For a high-flow injector compatible with methanol, significant amounts of liquid were detected in the cylinder at all conditions tested, leading to poor mixing and high fuel stratification during the compression stroke. This effect was mitigated by using a multi-hole injector that promoted better atomization, indicating that high atomization is preferred over high flow for methanol PFI. The probability of detecting liquid in the cylinder decreased as the coolant temperature or the intake temperature increased or if the fueling rate decreased, with coolant temperature being the dominant parameter to control methanol vaporization. Liquid probability increased with water addition mainly because of the high heat capacity of water. Liquid methanol accumulated in the intake port, decreasing the effective engine intake temperature and limiting fuel vaporization. This accumulation led to a delay of the system response to changes in the PFI settings, with injected fuel requiring one cycle to reach the cylinder and additional 50 cycles required to completely flush the fuel accumulated in the port. Finally, the operating envelope for liquid-free operation was defined.]]></description>
      <pubDate>Sat, 06 Jun 2026 12:01:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/2692227</guid>
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