The ongoing depletion of conventional fossil fuel reserves, coupled with escalating environmental concerns and the volatility of global oil markets, has intensified the search for cleaner and more sustainable energy alternatives for transportation. Among various low-emission fuels—such as biodiesel, ethanol, methanol, ammonia, hydrogen, and Compressed Natural Gas (CNG)—Liquefied Natural Gas (LNG) has emerged as a particularly viable option for Medium- and Heavy- Duty Vehicles (M&HDVs). LNG offers several advantages, including higher volumetric energy density, reduced tailpipe emissions, and compatibility with high-efficiency engine technologies. Its adoption is of strategic relevance to countries such as India, where transportation remains one of the largest contributors to Greenhouse Gas (GHG) emissions and is predominantly dependent on imported crude oil. The utilisation of LNG in M&HDVs has been identified as a means to simultaneously reduce GHG emissions and enhance national energy security. In this context, a comprehensive assessment is presented, encompassing LNG production pathways, distribution logistics, cryogenic storage technologies, and economic feasibility, as well as supportive government policies and international best practices. Key challenges, such as Boil-off gas (BOG) management, refuelling infrastructure gaps, cost parity with diesel, and engine retrofitting, have also been critically evaluated. Particular attention has been given to recent technological advancements and their potential to improve lifecycle emissions performance and cost-effectiveness. It is suggested that the integration of LNG into national energy and transportation strategies may yield substantial environmental and economic benefits, especially when supported by policy instruments, public–private investment models, and standardised regulatory frameworks. The findings indicate that LNG is poised to play a pivotal role in the decarbonisation of the freight and commercial transport sector, both in India and globally, thereby contributing to long-term sustainability objectives.

Efficient water management in agriculture increasingly depends on the ability to deliver uniform irrigation while minimizing energy consumption. Low-pressure irrigation systems have emerged as a sustainable alternative to traditional high-pressure networks, offering significant potential for small-scale and greenhouse applications. This study investigates the hydraulic and energy performance of low-pressure irrigation manifolds through a combined Computational Fluid Dynamics (CFD) analysis and performance assessment framework. The computational model simulates steady-state, incompressible flow within manifolds of two diameters (12 mm and 25 mm) and two emitter configurations (6 and 12 outlets), under inlet pressures of 50 kPa and 100 kPa. Detailed flow fields were analyzed in terms of pressure distribution, velocity contours, helicity, and wall shear stress, while outlet pressures and mass flow rates were used to evaluate distribution uniformity (DU). Mesh independence tests ensured numerical reliability, and hydraulic performance was quantified using standard indices such as the Coefficient of Variation (CV) and Christiansen’s uniformity coefficient (CU). The results demonstrate a consistent pressure and discharge decline from the inlet to the downstream outlets, with localized hotspots of velocity, shear, and rotational flow near emitter junctions. The manifolds with smaller diameters and higher inlet pressures led to greater non-uniformity (CV up to 14.8%, CU $\approx$ 87%), while the manifolds with larger diameters significantly improved uniformity (CV < 6%, CU > 95%) at lower inlet pressures. Energy analysis showed a strong link between hydraulic performance and pumping demand: designs with better uniformity required significantly less energy, with total pumping energy dropping from 4470 kWh in the least efficient case to just 1072 kWh in the optimal one. These findings highlight that manifold diameter, emitter spacing, and operating pressure are critical determinants of system efficiency. Optimized designs featuring larger diameters and moderate pressures offer a dual benefit of enhanced water-use efficiency and reduced energy consumption. The results provide actionable guidelines for the design of sustainable low-pressure irrigation systems, particularly in small-scale and greenhouse applications, where uniform distribution and energy savings are essential.

The growing reliance on air conditioning (AC) systems in residential and commercial buildings has led to significant increases in energy consumption and associated greenhouse gas emissions, underscoring the need for cost-effective and sustainable cooling technologies. In this study, the feasibility and performance of a 1-horsepower (1 HP) non-inverter split-unit AC system assembled entirely from locally sourced components were evaluated under controlled residential conditions. Essential parts, including copper tubing, aluminum fins, compressor units, and refrigerant gases, were procured from regional suppliers and integrated following standard Heating, Ventilation, and Air Conditioning (HVAC) design protocols. Performance tests were conducted across five rooms in a residential apartment-comprising a lounge (largest), masters bedroom, and three additional bedrooms of decreasing size-to assess cooling effectiveness. Using an infrared thermometer (IR8895), temperature metrics including saturation temperature, cooling rate, and peak cooling temperature were recorded. Initial room temperatures ranged from 23.5${ }^{\circ} \mathrm{C}$ to 26.2${ }^{\circ} \mathrm{C}$, while final cooling temperatures ranged from 16.1${ }^{\circ} \mathrm{C}$ to 16.9${ }^{\circ} \mathrm{C}$. Cooling time increased progressively with room size, extending from 10 to 100 minutes. Corresponding saturation temperatures were observed at 24.9${ }^{\circ} \mathrm{C}$ to 26.6${ }^{\circ} \mathrm{C}$, with saturation times between 3.24 and 5.43 minutes, and peak temperatures consistent with the final cooling levels. Calculated cooling loads were 28.8 W (small rooms), 47.0 W (medium rooms), and 65.93 W (large rooms), with respective power consumption values of 85.5 W, 142.6 W, and 199.6 W. The Energy Efficiency Ratio (EER) and Coefficient of Performance (COP) were determined to be 9.25 and 2.7, respectively, across room types. The results indicated that the locally assembled split-unit AC system delivered competitive cooling performance relative to commercial equivalents, particularly in terms of thermal regulation, response time, and energy efficiency. The use of indigenous materials and components did not compromise operational reliability or compliance with HVAC standards. These findings support the viability of locally fabricated AC systems as a sustainable alternative for effective residential cooling in resource-constrained settings.

The degradation of ambient air quality in urban regions of India has been exacerbated by the expansion of automobile fleets and stationary engines. In response, the Central Pollution Control Board (CPCB), under directives from the Ministry of Environment, Forest, and Climate Change (MoEF&CC) and the National Green Tribunal (NGT), has implemented stricter emission norms, including CPCB IV+ standards for power generators. Concurrently, the escalating costs of diesel gensets, driven by the integration of advanced air-fuel systems and emissions control technologies, have necessitated the exploration of alternative fuels. Hydrogen-enriched compressed natural gas (HCNG), a blend of hydrogen and natural gas, has emerged as a promising solution for achieving low emissions while maintaining power performance. This study evaluates the application of an 18% HCNG blend in a genset engine initially compliant with CPCB II standards, achieving compliance with CPCB IV+ emission norms without requiring hardware modifications. Key calibration parameters, including injection timing, ignition timing, injection duration, and desired lambda, were optimized to ensure enhanced performance and emissions control. The in-cylinder combustion characteristics, including combustion pressure, temperature, rate of heat release (RoHR), and brake mean effective pressure (BMEP), were thoroughly analysed for both Piped Natural Gas (PNG) and the HCNG blend. The results indicate that the HCNG blend significantly reduces emissions, with reductions of 66% in carbon monoxide (CO) and 74% in methane (CH₄) compared to PNG. These findings underscore the potential of HCNG to serve as a transitional fuel, bridging the gap towards the adoption of pure hydrogen technologies. This study demonstrates that HCNG can achieve substantial reductions in regulated emissions while supporting cleaner and more sustainable energy systems, positioning it as a viable alternative for stationary power generation applications.