Search Results (3)

Compressed natural gas (CNG) main stations are critical components of the urban energy infrastructure for CNG distribution. Due to its high electrification and significant power consumption, researching the economic operation of the CNG main station in demand response (DR)-based electricity pricing environments is crucial. In this paper, the dehydration process is considered in the CNG main station energy consumption model to enhance its participation in DR. A bilevel economic dispatch model for the CNG main station is proposed, considering critical peak pricing. The upper-level and lower-level models represent the energy cost minimization problems of the pre-system and rear-system, respectively, with safety operation constraints. The bilevel programming model is solved using a genetic algorithm combined with a bilevel programming method, which has better efficiency and convergence. The proposed optimization scheme has better control performance and stability, reduces the daily electricity cost by approximately 21.04%, and decreases the compressor switching frequency by 50.00% without changing the CNG filling demand, thus significantly extending the compressor’s service life. Moreover, the average comprehensive power cost of processing one unit of CNG reduces 20.62%. Full article

The hydrogen economy refers to an economic and industrial structure that uses hydrogen as its main energy source, replacing traditional fossil-fuel-based energy systems. In particular, the widespread adoption of hydrogen fuel cell vehicles (HFCVs) is one of the key factors enabling a hydrogen economy, and aggressive investment in hydrogen refuelling infrastructure is essential to make large-scale adoption of HFCVs possible. In this study, we address the problem of effectively designing a hydrogen supply network for refuelling HFCVs in urban areas relatively far from a large hydrogen production site, such as a petrochemical complex. In these urban areas where mass supply of hydrogen is not possible, hydrogen can be supplied by reforming city gas. In this case, building distributed hydrogen production bases that extract large amounts of hydrogen from liquefied petroleum gas (LPG) or compressed natural gas (CNG) and then supply hydrogen to nearby hydrogen stations may be a cost-effective option for establishing a hydrogen refuelling infrastructure in the early stage of the hydrogen economy. Therefore, an optimization model is proposed for effectively deciding when and where to build hydrogen production bases and hydrogen refuelling stations in an urban area. Then, a case study of the southeastern area of Seoul, known as a commercial and residential center, is discussed. A variety of scenarios for the design parameters of the hydrogen supply network are analyzed based on the target of the adoption of HFCVs in Seoul by 2030. The proposed optimization model can be effectively used for determining the time and sites for building hydrogen production bases and hydrogen refuelling stations. Full article

Building a competitive and resource-efficient transportation system involves the achievement of a number of ambitious goals. Two of the main instruments in the European transportation policy in this field address the significant reduction of GHG emissions and oil dependency in transportation. Alternative fuels and compressed natural gas (CNG) in particular have huge potential for achieving these goals. The main problem that limits its wide utilization is related to the insufficient number of CNG refueling stations, especially along highways and routes from the core TEN-T network where no gas pipelines are available. Therefore, the aim of this research is to study a possible solution to building daughter CNG refueling stations which can be used as basis for formulating some recommendations for their accelerated construction along TEN-T core network as well as providing some initial knowledge to be used later for more comprehensive research. The research is based on the case-study method, which allows the presentation of the described best practice. The process of data collection is based on semi-structured interviews, study of normative documents, observation of daily sales and direct observations which were processed with the help of qualitative and quantitative methods for time series analysis—trend and seasonal component as well as descriptive statistics tools. Scientific literature and research as well as secondary data provided by international institutions are also used. Full article