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Environmental impact assessment of energy generation processes is essential to evaluate their contributions toward the global carbon footprint. Even though hydrogen is a non-carbonaceous energy source, the pathways undertaken for its production can have harmful environmental implications. Thus, this study focuses on investigating the exergoenvironmental performances of the copper-chlorine, iron-chlorine, and magnesium-chlorine thermochemical hydrogen generation processes. This study also performs a comparative exergoenvironmental analysis of the three processes. The performances of the various processes are examined based on of the environmental impact rates of exergy destruction, component-related environmental impact rates, cumulative environmental impact rates, and exergoenvironmental factors. The global warming potentials of the thermochemical cycles are also evaluated and compared for various electricity sources to obtain hydrogen. The modeling and simulation of each process are performed using Aspen-plus by considering various heat recovery approaches for thermal management. The results suggest that the environmental impact rates of exergy destruction are relatively much higher compared to the environmental impact rates associated with the components for all processes. Furthermore, the hydrolysis step yields the highest component-associated environment impact rate for all thermochemical cycles considered (Fe–Cl: 3497 mPts/h, Cu–Cl: 1997 mPt/h, and Mg–Cl: 910 mPts/h). Moreover, the magnesium-chlorine cycle results in the highest environmental impact rate of exergy destruction (650,328 mPts/h) while the iron-chlorine cycle has the highest component-related environmental impact rate (5219 mPts/h) among the three cycles. In addition, the global warming potential of the magnesium-chlorine cycle is relatively higher compared to the copper-chlorine cycle for several electricity sources. [Display omitted] • An exergoenvironmental analyses of three thermochemical cycles is performed. • Each cycle is incorporated with thermal management schemes for higher efficiencies. • Industrial waste flue gases are considered as a heat source for hydrolysis reaction. • A hydrogen production capacity of 668 kg/h is considered for each cycle. • A comparison of global warming potential for various electricity sources is made. [ABSTRACT FROM AUTHOR]

Exploitation of fossil fuel sources in the power generation and transportation sector has been a major source of carbon dioxide emissions that contributes to global warming. Replacement of hydrocarbon-based fuel sources with cleaner fuels is imperative for environmental preservation at the global level. In this regard, hydrogen can be used as an effective non-carbonaceous fuel option as well as an energy carrier. Canada is currently one of the economically advanced countries in the world and aims at achieving a net-zero economy by 2050. However, fossil fuels are still largely utilized for both transportation and power generation purposes. Slightly less than a quarter of the total grid power in Canada is supplied through fossil fuel combustion including natural gas, coal, and petroleum. As a matter of fact, Canada, as one of the top ten global producers of hydrogen, exhibits a great potential of achieving the goal of sustainable development. Thus, this paper discusses the current status, challenges, and opportunities offered by the hydrogen sector and its development in the near- and long-term future in Canada. The potential methods of hydrogen production in Canada are described by categorizing them according to the energy and feedstock sources required for their realization. In addition, the status of hydrogen storage and distribution in Canada is also discussed. Various sectors consuming hydrogen as the end-users in Canada are categorized based on hydrogen use as a fuel, a heating source, and an industrial feedstock and are comprehensively discussed. Several challenges and the necessary line-of-actions to establish a hydrogen economy in Canada in the long-term future are also discussed, and a road map for accomplishing the net-zero economy by 2050 is further explained based on achieving certain near-term, mid-term, and long-term goals. Moreover, the job creation opportunities in Canada are discussed by considering numerous critical sectors. [Display omitted] • Overview of Canada's global position with regards to hydrogen production. • Overview of Canada's natural resources and infrastructural potential. • Comprehensive discussion on hydrogen production pathways and end-use in Canada. • Identification of several key challenges to achieve net-zero economy by 2050. [ABSTRACT FROM AUTHOR]

This paper develops a four-step copper-chlorine cycle for hydrogen production with conceptual modification through flash vaporization and evaluates its economic and environmental performances through exergy approach. The flash vaporization method is employed as a new approach for realizing the anolyte separation under vacuum conditions for reducing the thermal requirement of the anolyte separation step and consequently of the overall cycle. A flash vaporization is usually employed commercially for seawater desalination purposes. However, its utilization in a thermochemical hydrogen production process has not been considered previously which is really one of primary novelties of this investigation. The obtained results for the exergoeconomic and exergoenvironmental analyses of the conceptually modified cycle are also compared with those of the existing integrated cycle at the Ontario Tech University. The exergoeconomic analysis of the cycle has also been carried out for the cycle operating with and without waste heat recovery. In this regard, waste heat recovery from a steel furnace has been considered for supplying the required thermal energy for the hydrolysis step. The cost assessment of the cycle is carried out in the Aspen-plus. Compared with the existing cycle, the cycle with the proposed modification results in a lower unit cost of hydrogen. Moreover, a significant reduction in the unit cost of hydrogen is observed when waste heat recovery is considered for the modified cycle. The average unit hydrogen cost for the modified version of the cycle is evaluated to be 4.7 $/kg which reduces to 2 $/kg with incorporation of waste heat recovery. Furthermore, the overall environmental impact of the existing cycle can be potentially minimized by considering the proposed modification through flash vaporization. • Exergoeconomic and exergoenvironmental assessement of copper-chlorine cycle. • Comparative evaluation of cycle operating with and without waste heat recovery. • Comparative evaluation of the modified and existing integrated cycles. • Evaluation of exergy and unit exergy cost at each state point of the cycle. [ABSTRACT FROM AUTHOR]

Transportation is an economic sector that contributes significantly to global warming due to its high consumption of fossil fuels, and sustainably produced hydrogen is a major contender for an alternative clean energy source. Public transit is vital for environmental sustainability via reducing individual vehicle usage and traffic congestion, and the prospect of powering buses using hydrogen fuel has been extensively studied lately. This paper seeks to comprehensively review the current status of research on hydrogen-powered buses considering triple bottom line sustainability perspectives. A brief technical overview of prospective environmentally benign hydrogen production processes has been presented. Technological, economic, and environmental findings and research trends seen in recent analyses on hydrogen-powered buses have been summarized, along with the status quo of global hydrogen refuelling stations. Identified focal points for future studies include performance enhancements, refuelling infrastructure propagation, and policy formulation. The conclusions derived from this review will benefit the accelerated deployment of hydrogen-fuelled public transit fleets. • Environmentally benign hydrogen production is reviewed techno-economically. • The prospects of using hydrogen for public bus transport are discussed thoroughly. • Blue and green hydrogen production are likely to coexist in the hydrogen economy. • Costs and energy consumption of hydrogen-powered buses need improvement. • Refuelling facility deployment and public awareness of safety should be enhanced. [ABSTRACT FROM AUTHOR]

In this study the specific exergy costing (SPECO) approach is employed on a four-step integrated thermochemical copper-chlorine (Cu Cl) cycle for hydrogen production for a second-law based assessment purposes. The Cu–Cl cycle is considered as one of the most environmentally benign and sustainable options of producing hydrogen and is thus investigated in this study due to its potential of ensuring zero greenhouse gas (GHG) emissions. Several conceptual Cu–Cl cycles have been exergoeconomically examined previously, however this study aims at investigating the four-step integrated Cu–Cl cycle developed at the Clean Energy Research Laboratory (CERL) at the Ontario Tech University thereby contributing to the thermo/exergoeconomic assessments of the thermochemical hydrogen production. In this study, the cycle is first thermodynamically modeled and simulated in a process simulation software (Aspen Plus) through exergy and energy approaches. The basic principles of the SPECO methodology are applied to the system and exergetic cost balances are performed for each cycle component. The exergetic costing of each cycle stream is then performed based on the cost balance equations. The purchased equipment cost and the hourly levelized capital cost rates for each cycle component is also obtained. The exergoeconomic factor, relative cost difference and exergy destruction cost rate for various cycle components are also evaluated. Moreover, the effect of several parameters on the total and hourly levelized capital cost rates is analyzed by performing a comprehensive sensitivity analysis. Based on the analysis, the exergy cost, the unit or specific exergy cost, and the unit costs of hydrogen are evaluated to be 6407.55 $/h, 0.042 $/MJ, and 4.94 $/kg respectively. • Exergoeconomic analysis of an integrated copper-chlorine thermochemical cycle. • Application of the specific exergy costing (SPECO) approach. • Unit cost of hydrogen estimated to be 4.94 $/kg. • Hydrogen production capacity of 1296 kg/h. [ABSTRACT FROM AUTHOR]

In this study, an exergoeconomic analysis is performed on an integrated four-step thermochemical copper-chlorine cycle developed at the Ontario Tech. University through exergy, cost, energy, and mass (EXCEM) method. A thermodynamic model is first constructed in Aspen-plus (a process simulation software) to simulate and investigate the integrated cycle through exergy and energy analyses. The capital costs, thermodynamic loss rates, and the ratio of the thermodynamic loss rate to the capital cost of various system's components are also determined. Moreover, the average unit cost of hydrogen is evaluated and the influence of several system's parameters on the unit cost of hydrogen is analyzed. The results show that the cost of hydrogen is strongly dependent on the production capacity of the plant. Based on the analysis, our system generates hydrogen at an average unit cost of 5.54 $/kg with a plant capacity of 1619.3 kg/h considering both internal (operating and maintenance costs, etc.) and external (costs of various inputs, etc.) parameters. • Exergoeconomic analysis of a new thermochemical copper-chlorine cycle. • Application of the exergy, cost, energy, and mass (EXCEM) method. • The average unit cost of hydrogen estimated to be 5.54 $/kg. • Hydrogen production capacity of 1619.3 kg/h. [ABSTRACT FROM AUTHOR]