A conventional exergy analysis can highlight the main components having high thermodynamic inefficiencies, but cannot consider the interactions among components or the true potential for the improvement of each component. By splitting the exergy destruction into endogenous/exogenous and avoidable/unavoidable parts, the advanced exergy analysis is capable of providing additional information to conventional exergy analysis for improving the design and operation of energy conversion systems. This paper presents the application of both a conventional and an advanced exergy analysis to a supercritical coal-fired power plant. The results show that the ratio of exogenous exergy destruction differs quite a lot from component to component. In general, almost 90% of the total exergy destruction within turbines comes from their endogenous parts, while that of feedwater preheaters contributes more or less 70% to their total exergy destruction. Moreover, the boiler subsystem is proven to have a large amount of exergy destruction caused by the irreversibilities within the remaining components of the overall system. It is also found that the boiler subsystem still has the largest avoidable exergy destruction; however, the enhancement efforts should focus not only on its inherent irreversibilities but also on the inefficiencies within the remaining components. A large part of the avoidable exergy destruction within feedwater preheaters is exogenous; while that of the remaining components is mostly endogenous indicating that the improvements mainly depend on advances in design and operation of the component itself.

Liquefied natural gas (LNG) will contribute more in the future than in the past to the overall energy supply in the world. The paper discusses the application of advanced exergy-based analyses to a recently developed LNG-based cogeneration system. These analyses include advanced exergetic, advanced exergoeconomic, and advanced exergoenvironmental analyses in which thermodynamic inefficiencies (exergy destruction), costs, and environmental impacts have been split into avoidable and unavoidable parts. With the aid of these analyses, the potentials for improving the thermodynamic efficiency and for reducing the overall cost and the overall environmental impact are revealed. The objectives of this paper are to demonstrate (a) the potential for generating electricity while regasifying LNG and (b) some of the capabilities associated with advanced exergy-based methods. The most important subsystems and components are identified, and suggestions for improving them are made.

Cryogenics-based energy storage (CES) is a thermo-electric bulk-energy storage technology, which stores electricity in the form of a liquefied gas at cryogenic temperatures. The charging process is an energy-intensive gas liquefaction process and the limiting factor to CES round trip efficiency (RTE). During discharge, the liquefied gas is pressurized, evaporated and then super-heated to drive a gas turbine. The cold released during evaporation can be stored and supplied to the subsequent charging process. In this research, exergy-based methods are applied to quantify the effect of cold storage on the thermodynamic performance of six liquefaction processes and to identify the most cost-efficient process. For all liquefaction processes assessed, the integration of cold storage was shown to multiply the liquid yield, reduce the specific power requirement by 50–70% and increase the exergetic efficiency by 30–100%. The Claude-based liquefaction processes reached the highest exergetic efficiencies (76–82%). The processes reached their maximum efficiency at different liquefaction pressures. The Heylandt process reaches the highest RTE (50%) and the lowest specific power requirement (1021 kJ/kg). The lowest production cost of liquid air (18.4 €/ton) and the lowest specific investment cost (<700 €/kW_char) were achieved by the Kapitza process.

Methanol is one of the most important feedstocks for the chemical, petrochemical, and energy industries. Abundant and widely distributed resources as well as a relative low price level make natural gas the predominant feedstock for methanol production. Indirect synthesis routes via reforming of methane suppress production from bio resources and other renewable alternatives. However, the conventional technology for the conversion of natural gas to methanol is energy intensive and costly in investment and operation. Three design cases with different reforming technologies in conjunction with an isothermal methanol reactor are investigated. Case I is equipped with steam methane reforming for a capacity of 2200 metric tons per day (MTPD). For a higher production capacity, a serial combination of steam reforming and autothermal reforming is used in Case II, while Case III deals with a parallel configuration of CO₂ and steam reforming. A sensitivity analysis shows that the syngas composition significantly affects the thermodynamic performance of the plant. The design cases have exergetic efficiencies of 28.2%, 55.6% and 41.0%, respectively. The plants for higher capacity can produce at a competitive price, while the design in Case I is hardly economically feasible. An exergoeconomic analysis reveals a high cost impact of the reforming unit, air and syngas compressors.

The transport of CO₂, as a part of the carbon capture and storage chain, has received increased attention in the last decade. This paper aims to evaluate the most promising CO₂ liquefaction processes that can be used for port-to-port and port–offshore CO₂ ship transportation. The energetic, exergetic, and economic analyses are applied. The liquefaction pressure has been set to 15 bar (liquefaction temperature −30 °C), which corresponds to the design of the existing CO₂ carriers. The three-stage vapor-compression process has been selected among closed systems (with propane-R290, ammonia-R717, and R134a as the working fluid) and the precooled Linde–Hampson process—as the open system (with R717). The three-stage vapor-compression process R290 shows the lowest energy consumption, and the CO₂ liquefaction cost 21.3 USD/tCO₂. Although the power consumption of precooled Linde–Hampson process is 3.1% higher than the vapor-compression process with R209, the lowest total capital expenditures are notable. The CO₂ liquefaction cost of precooled Linde–Hampson process is 21.13 USD/tCO₂. The exergetic efficiency of the three-stage vapor-compression process with R290 is 66.6%, while the precooled Linde–Hampson process is 64.8%.