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A thorough analysis of a polymer electrolyte membrane (PEM) fuel cell system is presented. A generalized performance model of a single PEM fuel cell is developed and applied in a semi-empirical form for a Ballard Mark V 35-cell, 5kW PEM fuel cell. A thermodynamic and economic analysis of the components and of the whole system is performed. The purpose of this study is to explore the intrinsic relations...
The availability of wet biomass as waste from a lot of industrial processes, from agriculture and farms and the need to meet the environmental standards force to investigate all options in order to dispose this waste. The possible treatments usually strongly depend on biomass characteristics, namely water content, density, organic content, heating value, etc. In particular, some of these wastes can...
In countries where space heating demand is limited to a few months in the year, potentials for increasing the penetration of cogeneration (CHP) are strictly linked to sites where concentrated heat utilizations already exist. Hence the energy system will move towards a larger number of small-medium size CHP plants, which is herein named distributed cogeneration.Design criteria are analysed for plants...
Four approaches to the diagnosis of malfunctions in energy systems are presented and applied to the same test case plant. The paper is part of a project, started in 2001 and named thermoeconomic approach to the diagnosis of energy utility systems (TADEUS), aimed at integrating various experiences accumulated by a group of researchers operating in the thermoeconomic diagnostics, a field of research...
The Two-Stage Gasifier was operated for more than 2000h. This paper will focus on the first tests (465h). During these tests the gasifier was operated automatically unattended day and night, and only small adjustments of the feeding rate were necessary once or twice per day. The operation was successful, and the output as expected. The engine operated well on the produced gas, and no deposits were...
The Danish power stations have a long-standing tradition of building plants with high-efficiency. Elsam's two most recent power plants commissioned in 1997 and 1998 represented a turning point in Europe for high-efficiency conventional power plants with double reheat and steam temperatures of 580°C. The operational experiences have been good and the plants are just as flexible in operation as more...
Technical demonstration of an innovative small-scale gasification and power generation system for solid fuels such as wastes and biomass are described which is known as the STAR-MEET (steam/air reforming type multi-staged enthalpy extraction technology) system. In this system, a fixed-bed pyrolyzer combined with a high temperature reformer using a high temperature steam/air mixture is employed. From...
The introduction of deregulated markets requires correct operation strategies for the competitiveness of electricity utilities. Optimum strategies are determined in this paper for different groups of thermal power plants using a dynamic programming technique suggested by the authors in a previous paper. Attention focuses here on the ‘Day-Ahead market’ session, considering the viewpoint of a company...
Oxy-gasification, or oxygen-blown gasification, enables a clean and efficient use of coal and opens a promising way to CO 2 capture. Moreover, oxy-co-gasification with biomass implies the use of a renewable resource and additional CO 2 reduction. Proper gasifier operation is a key issue in both techniques. A model of an entrained flow gasifier, validated with nearby 3000 actual steady-state...
Due to the diminishing reserves of carbon based primary energy carriers and the need to reduce carbon dioxide (CO 2 ) emissions worldwide, an alternative energy concept was developed using elemental silicon as secondary energy carrier. Starting from sand, silicon can be accessible on a carbon/carbon dioxide free route in a process cycle using cost-effective—at best renewable—energy anywhere...
Ever since the release of the Kyoto protocol the demand for CO 2 -free processes have been increasing. One of the most expanding sources of electric power in the industrialised world today is the gas-fired combined cycle, combining high efficiency and low investment cost. In this paper, the integration of a post-combustion CO 2 -separation unit into a combined cycle is studied from...
This paper presents and evaluates different energy efficient options for integrating drying and pelletising of biofuel with a modern energy efficient pulp mill process. When drying biofuel, a large amount of the heat input can often be recovered. One option for heat recovery is to cover low-temperature heat demand in the pulping process. Alternatively available excess heat from the pulp mill can be...
This paper proposes a new thermal energy recovery process of hot gas exhausted from the steelmaking converter by utilizing not only latent heat but also endothermic heat of reaction. The intermittently emitted LD gas was first transferred into continuous, constant-temperature heat source in the form of latent heat in the Phase Change Material (PCM) of copper. Then, the stored heat was supplied to...
The cement and lime industries are major contributors to the anthropogenic CO 2 emissions to the atmosphere. By combining the CO 2 -releasing calcination of CaCO 3 with the CO 2 -consuming dry-reforming of CH 4 , and by further combining these endothermic reactions with the exothermic partial oxidation of CH 4 , a single thermo-neutral process can be...
This paper reports a performance analysis on CRGT power plants fuelled by DME, which is a potentially attractive fuel for gas turbines. The study also includes a performance comparison of simple cycle gas turbines fuelled by natural gas, DME and methanol. The study shows that, owing to the exhaust heat recovery carried out through DME pre-heating and vaporization before combustion, the efficiency...
This paper concerns a performance evaluation of a small scale (about 100kWe), externally fired gas turbine (EFGT) fuelled by residual biomass and integrated with a biomass dryer. In biomass fuelled EFGT power plants, compressed air is heated in the high temperature heat exchanger by using the hot gases produced by the biomass combustion process. The hot air expands in the turbine and then feeds the...
A novel liquefied natural gas (LNG) fueled power plant is proposed, which has virtually zero CO 2 and other emissions and a high efficiency. Natural gas is fired in highly enriched oxygen and recycled CO 2 flue gas. The plant operates in a quasi-combined cycle mode with a supercritical CO 2 Rankine-like cycle and a CO 2 Brayton cycle, interconnected by the heat transfer...
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