RESUMEN
Fossil fuel use drives greenhouse gas emissions and climate change, highlighting the need for alternatives like biomass-derived syngas. Syngas, mainly H2 and CO, is produced via biomass gasification and offers a solution to environmental challenges. Syngas fermentation through the Wood-Ljungdahl pathway yields valuable chemicals under mild conditions. However, challenges in scaling up persist due to issues like unpredictable syngas composition and microbial fermentation contamination. This review covers advancements in genetic tools and metabolic engineering to expand product range, highlighting crucial enabling technologies that expedite strain development for acetogens and other non-model organisms. This review paper provides an in-depth exploration of syngas fermentation, covering microorganisms, gas composition effects, separation techniques, techno economic analysis, and commercialization efforts.
RESUMEN
In the context of global carbon neutrality, the internal combustion engines aim to further reduce the carbon emission and improve the fuel economy for the transportation sector. Methanol is treated as a renewable, reliability, and applicability energy, which also shows some superior physicochemical properties compared to the traditional fossil fuels. However, some challenges such as cold start issue, low fuel economy, high unregulated emissions need to address before the methanol widely applies in the engines. This article comprehensively reviews the physicochemical properties and production processes of the methanol, the cold start issue of the methanol engine, and emission and combustion characteristics of the methanol engine for evaluating its potential effect of emission reduction and energy saving in the transportation sector. In addition, different optimization strategies and advanced technologies are proposed and comprehensively discussed in this paper for addressing the issues of the cold start, combustion and emissions of the methanol engines in the real application. Finally, the conclusions and prospects of the methanol engine are presented for promoting its application in the transportation sector and further reducing the carbon emission in the near future, thereby achieving the carbon peak and carbon neutrality in the China.
RESUMEN
This study quantified fugitive methane (CH4) losses from multiple sources (open digestate storages, digesters and flare) at two biogas facilities over one year, providing a much needed dataset integrating all major loss pathways and changes over time. Losses of CH4 from Facility A were primarily from digestate storage (5.8% of biogas CH4), followed by leakage/venting (5.5%) and flaring (0.2%). At Facility B, losses from digestate storage were higher (10.7%) due to shorter hydraulic retention time and lack of a screwpress. Fugitive emissions from leakage were initially 3.8% but were reduced to 0.6% after the dome membrane was repaired at Facility B. For biogas to have a positive impact on greenhouse gas emissions and provide a low-carbon fuel, it is important to minimize fugitive losses from digestate storage and avoid leakage during abnormal operation (leakage, roof failure).
Asunto(s)
Biocombustibles , Metano , AgriculturaRESUMEN
This work is all about utilization of more than two low carbon fuels in a diesel engine with a main objective of reducing harmful emissions. Initially, test engine was tested with a non-petroleum-based fuel namely mahua oil, under different load conditions. In the second phase of the work, test engine was modified into dual fuel mode with slight modification in the intake manifold for the admission of a low carbon high octane primary fuel namely ethanol. The engine was tested by varying the ethanol energy share (EES) from 5% to the point at which engine tends to knock at 100% and 40% of the maximum engine power output. Finally, an attempt was made to induct a zero carbon high octane fuel (i.e., hydrogen) in the intake manifold of the dual fuel engine operated with mahua and ethanol and tested for the behavior. Experimental results claimed that inclusion of ethanol improved the brake thermal efficiency (BTE) only at the higher loads. Optimized EES at 100% load conditions was identified as 15%. It is found that injection of ethanol significantly reduced the harmful emissions like smoke and oxides of nitrogen at the price of increased hydrocarbon and carbon monoxide emissions. It is also inferenced that BTE was improved further with the increases of hydrogen flow rate at peak load. Interestingly all the carbon-based emissions were drastically reduced with the inclusion of hydrogen. However, the oxides of nitrogen emission were found to be increased with increase of hydrogen flow rate.