Showing papers on "Compressed natural gas published in 2022"

Renewable hydrogen economy outlook in Africa

Abstract: Hydrogen presents an opportunity for Africa to not only decarbonise its own energy use and enable clean energy access for all, but also to export renewable energy. This paper developed a framework for assessing renewable resources for hydrogen production and provides a new critical analysis as to how and what role hydrogen can play in the complex African energy landscape. The regional solar, wind, CSP, and bio hydrogen potential ranges from 366 to 1311 Gt/year, 162 to 1782 Gt/year, 463 to 2738 Gt/year, and 0.03 to 0.06 Gt/year respectively. The water availability and sensitivity results showed that the water shortages in some countries can be abated by importing water from regions with high renewable water resources. A techno-economic comparative analysis indicated that a high voltage direct current (HVDC) system presents the most cost-effective transportation system with overall costs per kg hydrogen of 0.038 $/kg, followed by water pipeline with 0.084 $/kg, seawater desalination 0.1 $/kg, liquified hydrogen tank truck 0.12 $/kg, compressed hydrogen pipeline 0.16 $/kg, liquefied ammonia pipeline 0.38 $/kg, liquefied ammonia tank truck 0.60 $/kg, and compressed hydrogen tank truck with 0.77 $/kg. The results quantified the significance of economies of scale due to cost effectiveness of systems such as compressed hydrogen pipeline and liquefied hydrogen tank truck systems when hydrogen production is scaled up. Decentralization is favorable under some constraints, e.g., compressed hydrogen and liquefied ammonia tank truck systems will be more cost effective below 800 km and 1400 km due to lower investment and operation costs. • Africa has solar PV, wind, CSP and biomass potential for hydrogen production. • Renewable water resources and electricity access key in hydrogen production. • Long-distance export of green hydrogen key in propelling hydrogen economy. • Ammonia (fertilizer) market crucial in hydrogen adoption, and hydrogen for cooking. • Regional hydrogen partnerships key in driving down costs and investment risks.

Biomethane plants based on municipal solid waste and wastewater and its impact on vehicle sector in India – An Environmental-economic-resource assessment

Abstract: Advantages of biomethane production from large-scale biogas plants include savings of fossil fuels, better waste handling, job creation, odor, and greenhouse gas reduction. For these reasons, the government has launched and promoted various waste-to-energy schemes to install large-scale biogas plants in India. However, methane leaks from various plant sources are problematic as they contribute to global warming and compromise the environmental benefits. This paper assessed the significance of bio-compressed natural gas (bio-CNG) from large-scale biogas plants as a transportation fuel from an environmental and economic perspective. The results show that GHGs emissions of bio-CNG along its value chain (i.e., generation to utilization) are lower than other fuel options. If harnessed correctly, municipal solid waste and wastewater energy can replace 4053.47 tonnes of India’s diesel consumption per day. However, less than 2.5% of net bio-CNG potential is utilized in the current scenario. Uncertainty and sensitivity analysis shows a 0.32 and 0.08 probability that emissions from bio-CNG are greater than diesel and petrol, respectively. Furthermore, there is an 83.15% chance that the bio-CNG business will make a profit. Also, a 0.83 correlation coefficient was found between compressed biogas (CBG) price and net present value (NPV). This study indicates the massive scope of biogas in the transportation sector. Thus, to achieve the goal, setting up large-scale biogas plants is much needed.

Underwater Compressed Gas Energy Storage (UWCGES): Current Status, Challenges, and Future Perspectives

Abstract: Underwater compressed air energy storage was developed from its terrestrial counterpart. It has also evolved to underwater compressed natural gas and hydrogen energy storage in recent years. UWCGES is a promising energy storage technology for the marine environment and subsequently of recent significant interest attention. However, it is still immature. In this study, the latest progress in both academic and industrial fields is summarized. Additionally, challenges facing this emerging technology are analyzed. The pros and cons of UWCGES are provided and are differentiated from the terrestrial variant. Technical, economic, environmental, and policy challenges are examined. In particular, the critical issues for developing artificial large and ultra-large underwater gas storage accumulators and effective underwater gas transportation are comprehensively analyzed. Finally, the demand for marine energy storage technology is briefly summarized, and the potential application scenarios and application modes of underwater compressed gas energy storage technology are prospected. This study aims to highlight the current state of the UWCGES sector and provide some guidance and reference for theoretical research and industrial development.

Influencing factors of trucking companies willingness to shift to alternative fuel vehicles

Abstract: Freight transportation is a manifestation of a vibrant economy, but it is also associated with negative externalities such as greenhouse gas emissions. To mitigate these impacts, freight vehicles using alternative fuels have been developed, but they are not widely adopted. Moreover, there is not much information on the factors that could incentivize trucking companies to adopt such vehicles, especially in emerging economies where diesel engines dominate the market. Using Colombia as a case study, this paper aims to evaluate the factors that influence businesses to shift towards acquiring trucks powered by alternative fuels, applying an econometric approach based on discrete choice models. Results suggest that demand for alternative fuel vehicles (AFVs) is highly sensitive to purchase costs, operational range, and environmental awareness. Hybrid fuel alternatives seem to be preferred over electric and compressed natural gas vehicles. The analysis is supplemented with the estimation of marginal substitution rates, elasticities, and the simulation of scenarios considering subsidies and tax exemptions, from which we identify implications and draw policy recommendations to promote the use of AFVs.

Enviro-Economic Assessment of HHO–CNG Mixture Utilization in Spark Ignition Engine for Performance and Environmental Sustainability

Abstract: Road transportation has received the attention of researchers due to its higher carbon footprint. Alternative fuels present major advantages in terms of environmental sustainability. For this reason, an enviro-economic analysis of alternative fuels carries great significance. However, scarce attempts have been rendered in order to ascertain the impact of a hydroxy gas (HHO) and compressed natural gas (CNG) mixture on sustainable environmental development. The current study addresses this issue by employing an HHO–CNG mixture and gasoline in spark ignition (SI) engines for the purposes of performance and environmental pollutants measurement. Then, engine emission data were substituted for Weibull distribution in order to establish suitability for 50 and 95% confidence intervals (CIs). The mixture outperformed gasoline in terms of brake-specific fuel consumption (BSFC) and emission contents. On average, hydroxy gas with CNG produced 10.59% lower oxides of nitrogen (NOX) comparative to gasoline. Finally, the enviro-economic analysis also turned out to be in favor of the hydroxy gas mixture owing to a saving of 36.14% in USD/year due to 27.87% lower production of carbon dioxide (CO2) emission.

Impact of hydrogen substitution for stable lean operation on spark ignition engines fueled by compressed natural gas

Abstract: Compressed Natural Gas (CNG) appears as a midterm solution to conventional fuels, such as gasoline and diesel. The low carbon content and the possibility of being obtained from renewable sources (animal or agriculture waste, landfills, waste of the industry food or aquatic biomass) make CNG an attractive option to reduce Greenhouse Gases (GHG) emission. Applying lean combustion strategies on CNG improves efficiency levels while reducing pollutant emissions. In these conditions, heat transfer losses are reduced, and the thermal efficiency increased, especially at partial loads where increasing air dilution is one of the main strategies to reduce pumping losses. Hydrogen (H2) addition helps to enhance combustion in these diluted conditions and to reduce the combustion instability. This combustion concept has been widely studied over the last years, however further research is still needed. This investigation focuses on how hydrogen substitution affects the performance and emissions (both CO2 and pollutant) of a port fuel injection (PFI) spark ignition (SI) engine fueled by CNG. Thus, the main objective of this investigation is to contribute to the existent knowledge about dual-fuel combustion strategies based on CNG and H2 blends. Results demonstrated that hydrogen substitution helps to reduce the CO2 emissions by two ways: improving the engine efficiency and substituting part of the main carbon-based fuel. Despite of this advantage, NOx emissions are not reduced, and they will require after-treatment systems to deal with current pollutant regulations.

Emissions of Euro 6 Mono- and Bi-Fuel Gas Vehicles

Abstract: Compressed natural gas (CNG) and liquefied petroleum gas (LPG) are included in the group of promoted transport fuel alternatives in Europe. Most studies on emissions factors are based on old technology CNG and LPG fueled vehicles. Furthermore, there are not many data at low ambient temperatures, on-road driving, or unregulated pollutants, such as ammonia (NH3). In this study we measured the emissions of one Euro 6b CNG light commercial vehicle, one Euro 6b and one Euro 6d-Temp bi-fuel LPG passenger car, one Euro 6d-Temp bi-fuel CNG passenger car, and four Euro 6d-Temp CNG passenger cars. Tests included on-road testing and worldwide harmonized light vehicles test cycles (WLTC) in the laboratory with cold and hot engine, at 23 °C and −7 °C. The results showed 10–23% CO2 savings in gas modality compared to gasoline, lower CO and particle number emissions, and relatively similar total and non-methane hydrocarbons and NOx emissions. The ammonia emissions were high for all vehicles and fuels; higher than gasoline and diesel vehicles. The results also showed that, following the introduction of the real-driving emissions regulation, even though not applicable to the examined vehicles, Euro 6d-Temp vehicles had lower emissions compared to the Euro 6b vehicles.

Towards tailpipe sub-23 nm solid particle number measurements for heavy-duty vehicles regulations

Abstract: A heavy-duty engine is type-approved in engine dynamometers, while its in-service conformity is controlled on the road. In the first case, laboratory particle number systems (LABS) sample from a full dilution tunnel or a proportional partial flow dilution system (PFDS). In the second case portable emissions measurements systems (PEMS) measure directly from the tailpipe. Permitting in the regulation LABS sampling directly from the tailpipe would simplify testing and would improve their comparability with PEMS. In this study PEMS and LABS, both sampling from the tailpipe and measuring solid particles >10 nm, were compared with references systems (i.e. LABS from PFDS). One compressed natural gas (CNG) engine, and three diesel engines, all Euro VI step E, with or without urea injection, and with or without crankcase ventilation connected to the tailpipe, challenged the systems with different emission levels and particle sizes and properties. The results showed that the differences of the LABS to the references were in most cases within ±25%, with a few exceptions. The PEMS were within ±50%. There was no or small effect on the differences from engine technology, urea injection or crankcase ventilation. The inclusion of sub-23 nm particles increased 100% to 250% the particle number emissions. The urea injection increased the >10 nm emissions 300–600% (2–5 × 1010 p/kWh). Connecting the crankcase ventilation to the tailpipe further increased the >10 nm particle number emissions 340–560% (1.4–2.5 × 1011 p/kWh), bringing the >10 nm levels of the engines to approximately half of the current particle number limit, applicable to particles >23 nm.

Plug-in hybrid electric refuse vehicle routing problem for waste collection

Abstract: • Waste Collection Vehicle Routing Problem with Time Windows is studied. • Compressed natural gas plug-in hybrid electric vehicles are investigated. • A new Hybrid Threshold Acceptance algorithm is presented. • Extensive computational experiments are carried out. Commercial waste collection is an essential service requiring efficient and reliable provision for customers. At the operational level, one of the most challenging problems is to design a set of refuse vehicle routes to collect waste from a set of bins. To be used multiple times, these vehicles must be emptied regularly throughout the day. This paper investigates a waste collection problem with a homogeneous fleet of plug-in hybrid electric refuse vehicles powered by two different power sources, i.e., electricity and compressed natural gas (CNG). In addition, realistic fuel consumption functions are used to estimate total energy requirements for each type of fuel, including refueling and recharging, and the detailed energy consumption along the path between two nodes of interest. We propose a Hybrid Threshold Acceptance (HTA) algorithm for this problem and denote it as the Hybrid Waste Collection Problem (HWCP). Extensive computational experiments confirm that the proposed HTA algorithm provides good results against current state-of-the-art algorithms designed for the electric vehicle routing problem. Out detailed computational results demonstrate the performance of our method considering either full or partial recharging, as well as the effect of different battery/tank capacities. Compared to the standard CNG or electric vehicles, we also show the benefits of using a fleet of hybrid electric refuse vehicles in terms of operational costs and total distance traveled.

Benefits of electrifying app-taxi fleet – A simulation on trip data from New Delhi

Abstract: Battery electric vehicles (BEVs) appear integral to improving urban air quality, especially in less-wealthier countries whose cities rank amongst the most polluted and fastest growing. But despite steep declines in battery prices and generous subsidies, BEV adoption in such countries is weak. Here, the tremendous growth of app-taxi and retail delivery vehicles presents a massive new opportunity. Since they register several-fold greater utilization relative to the average pure private-use vehicle, electrifying such vehicles could deliver rapid financial payback and much greater economic and pollution benefits. A general framework for spatially-detailed estimation of charging infrastructure, and the economic and environmental benefits of commercial fleet electrification was developed and applied to a dataset comprising ∼ 730,000 app-taxi trips spanning ∼ 15 million kilometers (km) in Delhi, India, which shows: i) ∼ 23000 BEVs with 200 km range and a network of 3000 50 kilo-Watt chargers could satisfy 100% of Delhi’s daily app-taxi demand, and relative to a compressed natural gas (diesel) fleet eliminate 180 (7 0 0) and 0.14 (70) metric tonnes of vehicle tail-pipe NOX and particulate matter emissions respectively annually and reduce lifecycle greenhouse gas emissions by 15% (27%) per km. Cost savings are sensitive to retail BEV price and government subsidies, which are not indicative of future prices given the infancy of BEV industry. Under current prices and subsidies in India, BEVs reduce levelized cost per km 21% and 37% relative to CNG and Diesel vehicles respectively. Electrification of taxi fleets increases aggregate electricity consumption 2% with insignificant increase during daily peak demand hours. Therefore, ambitious zero emissions vehicle targets for commercial light duty vehicle fleets appear environmentally, economically and socially sound.