42 research outputs found
Life cycle assessment of synthetic natural gas production from different CO2 sources: A cradleâto-gate study
Fuel production from hydrogen and carbon dioxide is considered an attractive solution as longâterm storage of electric energy and as temporary storage of carbon dioxide. A large variety of CO2 sources are suitable for Carbon Capture Utilization (CCU), and the process energy intensity depends on the separation technology and, ultimately, on the CO2 concentration in the flue gas. Since the carbon capture process emits more CO2 than the expected demand for CO2 utilization, the most sustainable CO2 sources must be selected. This work aimed at modeling a PowerâtoâGas (PtG) plant and assessing the most suitable carbon sources from a Life Cycle Assessment (LCA) perspective. The PtG plant was supplied by electricity from a 2030 scenario for Italian electricity generation. The plant impacts were assessed using data from the ecoinvent database version 3.5, for different CO2 sources (e.g., air, cement, iron, and steel plants). A detailed discussion on how to handle multiâfunctionality was also carried out. The results showed that capturing CO2 from hydrogen production plants and integrated pulp and paper mills led to the lowest impacts concerning all investigated indicators. The choice of how to handle multiâfunctional activities had a crucial impact on the assessment
Designing Service Level Contracts for Supply Chain Coordination
Supply contracts are used to coordinate the activities of the supply chain partners. In many industries, service level-based supply contracts are commonly used. Under such a contract, a company agrees to achieve a certain service level and to pay a financial penalty if it misses it. The service level used in our study refers to the fraction of a manufacturer's demand filled by the supplier. We analyze two types of service level-based supply contracts that are designed by a manufacturer and offered to a supplier. The first type of contract is a flat penalty contract, under which the supplier pays a fixed penalty to the manufacturer in each period in which the contract service level is not achieved. The second type of contract is a unit penalty contract, under which a penalty is due for each unit delivered fewer than specified by the parameters of the contract. We show how the supplier responds to the contracts and how the contract parameters can be chosen, such that the supply chain is coordinated. We also derive structural results about optimal values of the contract parameters, provide numerical results, and connect our service level measures to traditional service level measures. The results of our analyses can be used by decision makers to design optimal service level contracts and to provide them with a solid foundation for contract negotiations
Performance of Service Level Contracts in Two-Level Supply Chains with Decentralized Decision-Making
Life Cycle Assessment of synthetic fuel production from renewable hydrogen: Process contribution and impact assessment considering different 2030 energy mixes
Renewable energy source generation has been increasing drastically for the last decades. In order to avoid grid congestions or overloads and energy curtailments, it is necessary to envisage energy storage technologies. Converting surplus electricity into hydrogen or eventually other synthetic fuels through Powerto- X technologies is regarded as a promising solution for the mid and long-term storage and for its potential of providing sector interconnection. However, synthetic fuel production consists of energy-intensive conversion steps, for which it is of importance to assess its environmental impacts before large scale plant development. This work aims at modeling and assessing the impacts of different alternative fuel synthesis based on renewable hydrogen in a life cycle assessment perspective. The analyzed fuels are chosen among the ones that can rely on a reliable and extensive infrastructure and, likewise, feed emerging and innovative technologies (e.g., fuel cells); in particular, methane, methanol, ammonia are selected as promising hydrogen carriers. The plant models developed in previous works are assessed regarding several environmental impacts in the software SimaPro. The data used in the present study included both data from ecoinvent database version 3.5, data from literature, and assumptions based on engineering practice for electricity generation, electrolysis, and concerning carbon dioxide sources. From a process contribution analysis, the sub-optimal and critical steps are pointed out and an outlook is provided. Since electricity production proved to be one of the most critical parameters, a sensitivity analysis over different 2030 energy mixes and renewable energy sources is carried out