Pyong Sik Pak

Economic evaluation of solar thermal hybrid H2O turbine power generation systems

The economics of two proposed solar thermal hybrid power generation systems (STHSs) have been evaluated. Each system consists of direct-steam-generation solar collectors, a steam accumulator and a gas turbine power generation system which uses steam as its working fluid. One (STHS-A) of the proposed systems emits CO2 generated by burning fuel, whereas the other (STHS-B) captures the CO2. Assuming that the systems are located in San Francisco, USA, where solar radiation energy is approximately the same as the global average, the levelized electricity costs (LECs) of the STHSs have been estimated considering future uncertainty of fuel cost and the capital cost of the solar collector. The LECs of combined cycle plants, which are considered to be one of the major thermal power generation systems in the near future, have also been estimated to evaluate the economics of the proposed systems. When fuel (methane) cost is 4.5

A CO2-capturing hybrid power-generation system with highly efficient use of solar thermal energy

/GJ, for example, the STHS-A has been estimated to be the most economical among the evaluated systems where the carbon tax is higher than a value in the range of 106–244

Comprehensive evaluation of new urban transportation systems by AHP

/t-C, whereas the STHS-B is the most economical where the carbon tax is higher than a value between 368 and 475

A hybrid power generation system utilizing solar thermal energy with CO2 recovery based on oxygen combustion method

/t-C.

Closed Dual Fluid Gas Turbine Power Plant without Emission of CO 2 into the Atmosphere

Characteristics have been investigated for the proposed system. Saturated steam is produced at a relatively low temperature and is used as the working fluid for a methane-fired gas-turbine system. The solar thermal utilization efficiency is considerably higher than that for conventional solar thermal power plants in which superheated steam near 670 K is used. The proposed hybrid system recovers generated CO2 during combustion with oxygen. Characteristics of the system with 10,000 m2 collector area were estimated on the basis of a computer simulation model. The net generated power was 1.55 MW, the capacity factor 21.5% and the total exergetic efficiency 20.9% when the temperature of the saturated steam is 496 K. Based on the consumed fuel, the net thermal system efficiency is 63.7%.

Exergetic evaluation of methods for improving power generation efficiency of a gas turbine cogeneration system

Many different kinds of transportation systems such as ‘group rapid transit’, etc., have recently been presented as ideal urban public transportation systems. When planning to introduce such a new transportation system into a city, it is necessary to select the most desirable system for that city from those that have been proposed. The comprehensive evaluation of transportation systems must reflect various aspects such as the costs of construction and maintenance and the viewpoints or both the system users and the local inhabitants. This makes it one of the most difficult and yet vitally important problems in public transportation planning. The analytic hierarchy process (AHP) developed by T. L Saaty is straightforward and has the feature that it can deal with both qualitative and quantitative factors at the same time, and it is suitable for applying to complex evaluation problems, In this paper, three transportation systems are proposed for one of the newly planned towns in Kansai Cultural and Academic R...

CO 2 -Recovering Power Generation System in a CO 2 -Recycling Global Energy System Based on Solar Energy

Abstract A CO2-recovering power generation system utilizing solar thermal energy was proposed. In the system, relatively low temperature saturated steam around 200 °C is produced by using solar thermal energy and is utilized as the working fluid of a gas turbine in which generated CO2 is recovered based on the method of oxygen combustion. Solar thermal utilization efficiency becomes considerably high compared with that of conventional solar thermal power plants in which high temperature steam near 400 °C has to be produced for steam turbines, and the requirement for solar radiation in the location in which the system is constructed can be significantly relaxed. The proposed system is a hybrid-type system using both the fossil fuel and solar thermal energy, and thus its capacity factor becomes very high. The fuel is utilized in an exergetically excellent way in the system, that is, is used for raising the steam temperature higher than 1000 °C. The generated CO2 is recovered by using oxygen combustion method, so that high CO2 capturing ratio near 100% as well as no thermal NOx emission characteristics can be attained. It has been shown through simulation study that the proposed system has net power generation efficiency of 64.5% on the base of consumed fuel energy by using saturated steam with temperature 230 °C, being higher than 48.3% compared with that of the conventional power plant with 43.5% efficiency.

Automated CT-based 3D surgical planning for total hip replacement: a pilot study

Abstract This paper describes a construction and characteristics of a coal-gas-burned high efficiency power plant which emits no carbon dioxide (CO 2 ) into the atmosphere. In the plant, CO 2 gas and superheated steam are used as the main and sub working fluid, respectively, of a closed dual fluid gas turbine power generation system. It is assumed that a coal gas whose principal compositions are CO, H 2 , CO 2 and CH 4 is burnt in a combustor using oxygen, and that CO 2 gas and superheated steam are used as the main and sub working fluid of a turbine, respectively. Consequently, the constituent gases of the combustion gas become CO 2 and H 2 O. Thus, CO 2 gas included in the exhaust gas can be easily separated at the condenser outlet from the condensate (H 2 O). Most of recovered CO 2 is recycled as the main working fluid of the turbine. In the plant, high-temperature turbine exhaust gas is utilized in a waste heat boiler to produce superheated steam which is injected into the combustor in order to improve power generation efficiency. It has been estimated that an electeic power of 208MW can be generated with gross thrmal efficiency of 51.3%. Power generating efficiency has been estimated to be 43.7% since the electric power of 31.1MW is required for producing the oxygen for combustion. The problem of liquefying CO 2 recovered has also been dealt with in the paper. It has been shown that the resultant power generating efficiency is estimated to be 39.0% if the power for liquefaction of recovered CO 2 is taken into account.

Characteristics of a CO2‐recovering combined cycle power generation system when its CO2 recovery rate is changed

A cogeneration system generating both heat and power for district heating and cooling is required to be more efficient to improve its economy. In this paper, three typical methods for improving the power generation efficiency of a gas turbine cogeneration system are evaluated by examining exergy flow at various points of the system. The three methods investigated are: (a) to raise turbine inlet temperatrue, (b) to incorporate a regenerative cycle, and (c) to introduce a dual-fluid cycle. Exergy flows at various points of each cogeneration system have been evaluated. It has been shown through quantitative analyses of exergy flows (1) what kind of exergy loss of the system can be reduced by introducing each efficiency-improving method, (2) that the method of incorporating a regenerative cycle is highly useful in improving exergy efficiency of the cogeneration system.

EXERGETIC EVALUATION OF GAS TURBINE COGENERATION SYSTEMS FOR DISTRICT HEATING AND COOLING

Abstract This paper first describes briefly the concept of a CO2-recycling global energy system utilizing solar energy. Second, a construction and characteristics of a CO2recovering high efficiency power generation system is described in detail which constitutes one of the most important subsystems of a CO2-recycling global energy system utilizing solar energy in the future. In the power generation system, CO2 gas is used as the working fluid of a closed-cycle gas turbine power generation system, and it is assumed that methanol is burnt in a combustor using oxygen. Hence the constituent gases of the Combustion gas become CO2 and H2O. Thus, CO2 gas included in the exhaust. gas can be easily separated at the condenser outlet from the condensate. The recovered CO2 gas is liquefied, transported by a CO2 tanker and reused to synthesize methanol. Gross thermal efficiency has been estimated to be 54.6%. Net power generation efficiency have been estimated to be 50.8%, by considering the electric power required for liquefying recovered CO2.