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A novel solar-hybrid gas turbine combined cycle was proposed. The cycle integrates methanol-fueled chemical-looping combustion and solar thermal energy at around 200[degrees]C, and it was investigated with the aid of the energy-utilization diagram (EUD). Solar thermal energy, at approximately 150[degrees]C-300[degrees]C, is utilized to drive the reduction in [Fe.sub.2][O.sub.3] with methanol in the reduction reactor, and is converted into chemical energy associated with the solid fuel FeO. Then it is released as high-temperature thermal energy during the oxidation of FeO in the oxidation reactor to generate electricity through the combined cycle. As a result, the exergy efficiency of the proposed solar thermal cycle may reach 58.4% at a turbine inlet temperature of 1400[degrees]C, and the net solar-to-electric efficiency would be expected to be 22.3%. The promising results obtained here indicate that this solar-hybrid combined cycle not only offers a new approach for highly efficient use of middle-and-low temperature solar thermal energy to generate electricity, but also provides the possibility of simultaneously utilizing renewable energy and alternative fuel for C[O.sub.2] capture with low energy penalty. [DOI: 10.1115/1.4001467] Keywords: solar thermochemical, methanol-fueled chemical-looping combustion, inherent C[O.sub.2] capture

This paper proposes a new kind of multifunctional energy system (MES) using natural gas and coal to more efficiently and more economically produce methanol and power. Traditional chemical processes pursue high conversion ratios of chemical energy o f fuels. The new MES focuses on the moderate conversion of the chemical energy of fuels. To do this, about 50% of the coal is partially gasified with pure oxygen and steam as oxidant, and then the unconverted residuals (char) and natural gas are utilized synthetically by char-fired reforming to generate syngas. The combustion of char drives the methane/ steam-reforming reaction. Here, the reforming reaction is also moderately converted, and the reforming temperature is decreased 100-150[degrees]C compared with that of the conventional method. The carbon-rich syngas from the partial gasifier of coal and hydrogen-rich syngas from char-fired reformer are mixed together and converted into methanol at a proper conversion ratio (lower than that of the conventional chemical process). Finally, the unconverted syngas is used in a combined cycle as fuel for power generation. As a result, the total exergy efficiency of the new system is 55-60%. Comparing to individual systems, including the integrated gasification combined cycle and the natural gas-based methanol synthesis plants, this new system can generate 10-20% more electricity with the same quantity of fossil fuel input and methanol output. In addition, the possibility of reducing the size of gasifier, reformer, and methanol synthesis reactor may reduce investment costs accordingly. These results may provide a new way to use coal and natural gas more efficiently and economically. [DOI: 10.1115/1.3205025]

In this paper, we have proposed a novel coal-based hydrogen production system with low C[O.sub.2] emission. In this novel system, a pressure swing adsorption [H.sub.2] production process and a C[O.sub.2] cryogenic capture process are well integrated to gain comprehensive performance. In particular, through sequential connection between the pressure swing absorption (PSA) [H.sub.2] production process and the C[O.sub.2] capture unit, the C[O.sub.2] concentration of PSA purge gas that enters the C[O.sub.2] capture unit can reach as high as 70%, which results in as much as 90% of C[O.sub.2] to be separated from mixed gas as liquid at a temperature of -55[degrees]C. This will reduce the quantity and quality of cold energy required for cryogenic separation method, and the solidification of C[O.sub.2] is avoided. The adoption of cryogenic energy to capture C[O.sub.2] enables direct production of liquid C[O.sub.2] at low pressure and thereby saves a lot of compression energy. Besides, partial recycle of the tail gas from C[O.sub.2] recovery unit to PSA inlet can help enhance the amount of hydrogen product and lower the energy consumption for [H.sub.2] production. As a result, the energy consumption for the new system's hydrogen production is only 196.8 GJ/t[H.sub.2] with 94% of C[O.sub.2] captured, which is 9.2% lower than that of the coal-based hydrogen production system with Selexol C[O.sub.2] removal process and is only 2.6% more than that of the coal-based hydrogen production system without C[O.sub.2] recovery. More so, the energy consumption of C[O.sub.2] recovery is expected to be reduced by 20-60% compared with that of traditional C[O.sub.2] separation processes. Further analysis on the novel system indicates that synergetic integration of the [H.sub.2] production process and cryogenic C[O.sub.2] recovery unit, along with the synthetic utilization of energy, plays a significant role in lowering energy penalty for C[O.sub.2] separation and liquefaction. The promising results obtained here provide a new approach for C[O.sub.2] removal with low energy penalty. [DOI: 10.1115/1.3159369]

In this paper, a novel gas turbine cycle integrating methanol decomposition and the chemical-looping combustion (CLC) is proposed. Two types of methanol-fueled power plants, including the new gas turbine cycle with CLC combustion and a chemically intercooled gas turbine cycle, have been investigated with the aid of the T-Q diagram. In the proposed system, methanol fuel is decomposed into syngas mainly containing [H.sub.2] and CO by recovering low-temperature thermal energy from an intercooler of the air compressor. After the decomposition of methanol, the resulting product of syngas is divided into two parts: the part reacting with [Fe.sub.2][O.sub.3] is sent into the CLC subsystem, and the other part is introduced into a supplement combustor to enhance the inlet temperatures of the gas turbine to 1100-1500[degrees]C. As a result, the new methanol-fueled gas turbine cycle with CLC had a breakthrough in thermodynamic and environmental performance. The thermal efficiency of the new system can achieve 60.6% with 70% of C[O.sub.2] recovery at a gas turbine inlet temperature of 1300[degrees]C. It would be expected to be at least about 10.7 percentage points higher than that of the chemically intercooled gas turbine cycle with the same recovery of C[O.sub.2] and is environmentally superior due to the recovery of C[O.sub.2]. The promising results obtained here indicated that this novel gas turbine cycle with methanol-fueled chemical-looping combustion could provide a promising approach of both effective use of alternative fuel and recovering low-temperature waste heat and offer a technical probability of blending a combination of the chemical-looping combustion and the advanced gas turbine for carbon capture and storage. [DOI: 10.1115/1.3098418]

In this paper, a novel approach of middle-temperature solar hydrogen production using methanol steam reforming is proposed. It can be carried out at around 200-300[degrees]C, much lower than the temperatures of other solar thermochemical hydrogen production. For the realization of the proposed solar hydrogen production, solar experiments are investigated in a modified 5 kW solar receiver/reactor with one-tracking parabolic trough concentrators. The feature of significantly upgrading the energy level from lower-grade solar thermal energy to higher-grade chemical energy is experimentally identified. The interaction between the hydrogen yield and the energy-level upgrade of solar thermal energy is clarified. Also, this kind of solar hydrogen production is experimentally compared with methanol decomposition. The preliminarily economic evaluation of the hydrogen production is identified. As a result, in the solar-driven steam reforming, the thermochemical efficiency of solar thermal energy converted into chemical energy reached up to 40-50% under a mean solar flux of 550-700 W/[m.sup.2], and exceeding 90% of hydrogen production is achieved, with about 70% higher than that of methanol decomposition. The thermochemical performance of solar-driven methanol steam reforming experimentally examined at around 200-300[degrees]C for hydrogen production may be competitive with conventional methane reforming. The promising results obtained here indicate that the proposed solar hydrogen production may provide the possibility of a synergetic process of both high production of hydrogen and effective utilization of solar thermal energy at around 200-300[degrees]C. [DOI: 10.1115/1.3068336] Keywords: solar thermochemical hydrogen production, middle- and low-temperature solar thermal energies, methanol steam reforming

A partial gasification combined cycle with C[O.sub.2] recovery is proposed in this paper. Partial gasification adopts cascade conversion of the composition of coal. Active composition of coal is simply gasified, while inactive composition, that is char, is burnt in a boiler. Oxy-fuel combustion of syngas produces only C[O.sub.2] and [H.sub.2]O, so the C[O.sub.2] can be separated through cooling the working fluid. This decreases the amount of energy consumption to separate C[O.sub.2] compared with conventional methods. The novel system integrates the above two key technologies by injecting steam from a steam turbine into the combustion chamber of a gas turbine to combine the Rankine cycle with the Brayton cycle. The thermal efficiency of this system will be higher based on the cascade utilization of energy level. Compared with the conventional integrated gasification combined cycle (IGCC), the compressor of the gas turbine, heat recovery steam generator (HRSG) and gasifier are substituted for a pump, reheater, and partial gasifier, so the system is simplified obviously. Furthermore, the novel system is investigated by means of energy-utilization diagram methodology and provides a simple analysis of their economic and environmental performance. As a result, the thermal efficiency of this system may be expected to be 45%, with C[O.sub.2] recovery of 41.2%, which is 1.5-3.5% higher than that of an IGCC system. At the same time, the total investment cost of the new system is about 16% lower than that of an IGCC. The comparison between the partial gasification technology and the IGCC technology is based on the two representative cases to identify the specific feature of the proposed system. The promising results obtained here with higher thermal efficiency, lower cost, and less environmental impact provide an attractive option for clean-coal utilization technology. [DOI: 10.1115/1.2938273]

Solar thermochemical processes inherently included the conversion of solar thermal energy into chemical energy. In this paper, a new mechanism of upgrading the energy level of solar thermal energy at around 200[degrees]C was revealed based on the second law thermodynamics and was then experimentally proven. An expression was derived to describe the upgrading of the energy level from low-grade solar thermal energy to high-grade chemical energy. The resulting equation explicitly reveals the interrelations of energy levels between middle-temperature solar thermal energy and methanol fuel, and identifies the interactions of mean solar flux and the reactivity of methanol decomposition. The proposed mechanism was experimentally verified by using the fabricated 5 kW prototype of the receiver/reactor. The agreement between the theoretical and the experimental results proves the validity of the mechanism for upgrading the energy level of low-grade solar thermal energy by integrating clean synthetic fuel. Moreover, the application of this new middle-temperature solar/methanol hybrid thermochemical process into a combined cycle is expected to have a net solar-to-electric efficiency of about 27.8%, which is competitive with other solar-hybrid thermal power plants using high-temperature solar thermal energy. The results obtained here indicate the possibility of utilizing solar thermal energy at around 200[degrees]C for electricity generation with high efficiency by upgrading the energy level of solar thermal energy, and provide an enhancement to solar thermal power plants with the development of this low-grade solar thermochemical technology in the near future. [DOI: 10.1115/1.2840609]

This paper proposes a novel multifunctional energy system (MES), in which hydrogen and electricity are cogenerated and about 90% of C[O.sub.2] is removed. By integrating the methane/steam reforming reaction and combustion of coal, the natural gas and coal are utilized synthetically, and coal is burned to provide high-temperature thermal energy to the methane/steam reforming reaction. Afterwards, the resulting syngas enters a pressure swing adsorption (PSA) unit to separate about 70% of hydrogen, thereby significantly increasing the concentration of carbon dioxide from nearly 20% to 43% in the PSA tail gas. As a result, the overall efficiency of the new system becomes 63.2%. Compared to a conventional natural gas-based hydrogen plant and a coal-firing steam power plant without C[O.sub.2] removal (the overall efficiency of the two systems is 63.0%), the energy penalty for C[O.sub.2] removal in the new system is almost totally avoided. Based on the graphical exergy analysis, we propose that the integration of synthetic utilization of fossil fuel (natural gas and coal) and the C[O.sub.2] removal process plays a significant role in zero energy penalty for C[O.sub.2] removal and its liquefaction in the MES. The result obtained here provides a new approach for C[O.sub.2] removal with zero or low thermal efficiency reduction (energy penalty) within an energy system. [DOI: 10.1115/1.2799532]

This paper manufactured an original middle-temperature solar receiver/reactor prototype, positioned along the focal line of one-axis parabolic trough concentrator, representing the development of a new kind of solar thermochemical technology. A 5 kW prototype solar reactor at around 200-300[degrees]C, which is combined with a linear receiver, was originally manufactured. A basic principle of the design of the middle-temperature solar reactor is identified and described. A representative experiment of solar-driven methanol decomposition was carried out. Experimental tests were conducted from 200[degrees]C to 300[degrees]C under mean solar flux of 300--800 W/[m.sup.2] and at a given methanol feeding rate of 2.1 L/h. The conversion of methanol decomposition yielded up to 50-95%, and the efficiency of solar thermal energy conversion to chemical energy reached 30-60%. The experimental results obtained here prove that the novel solar receiver/reactor prototype introduced in this paper can provide a promising approach to effectively utilize middletemperature solar thermal energy by means of solar thermochemical processes. [DOI: 10.1115/1.2769698]

A new kind of multifunctional energy system (MES) with multifossil fuels and multiproducts is proposed in this paper. This new system consumes coal and natural gas as fuel simultaneously, and cogenerates methanol and power Coal and natural gas are utilized synthetically based on the method of dual-fuel reforming, which integrates the methane/steam reforming and the combustion of coal. During the dual-fuel reforming process, combustion of coal provides high-temperature thermal energy to methane/steam reforming reaction to product syngas. Then, the chemical energy of syngas is used efficiently since the new system integrates the chemical process and power plant. In this manner, the energy including both chemical energy of fuels and thermal energy can be used more effectively from the viewpoint of the whole system. As a result, the total energy efficiency of this new system was about 60-66%. Compared with the conventional systems, the new system provides an energy savings of about 8-15%. The results obtained here indicate that this new system may provide a new way to utilize coal and natural gas more efficiently and economically. [DOI: 10.1115/1.2432895]

In this paper we propose a novel C[O.sub.2]-recovering hybrid solar-fossil combined cycle with the integration of methane-fueled chemical-looping combustion, and investigate the system with the aid of the Energy-Utilization Diagram (EUD). Chemical-looping combustion (CLC) consists of two successive reactions: first, methane fuel is oxidized by metal oxide(NiO)as an oxygen carrier (reduction of metal oxide); and second, the reduced metal (Ni) is successively oxidized by combustion air (the oxidation of metal). The oxidation of methane with NiO requires a relative low-grade thermal energy at 300[degrees]C-500[degrees]C. Then concentrated solar thermal energy at approximately 450[degrees]C-550[degrees]C can be utilized to provide the process heat for this reaction. By coupling solar thermal energy with methane-fueled chemical-looping combustion, the energy level of solar thermal energy at around 450[degrees]C-550[degrees]C can be upgraded to the chemical energy of solid fuel Ni for better utilization of solar energy to generate electricity. The synergistic integration of solar thermal energy and chemical-looping combustion could make the exergy efficiency and the net solar-to-electric efficiency of the solar hybrid system more than 60% and 30%, respectively, at a turbine inlet temperature (TIT) of 1200[degrees]C. At the same time, this new system has an extremely important advantage of directly suppressing the environmental impact due to lack of energy penalty for C[O.sub.2] recovery. Approximately 9-15 percentage points higher efficiency can be achieved compared to the conventional natural gas-fired combined cycle with C[O.sub.2] separation. The results obtained here are promising and indicate that this novel solar hybrid combined cycle offers the new possibility of C[O.sub.2] mitigation using both green energy and fossil fuels. These results also provide a new approach for highly efficient use of solar thermal energy to generate electricity. [DOI: 10.1115/1.2212443]

It is important and necessary to develop a new technology for [CO.sub.2] capture with less or even no energy penalty to make a breakthrough in greenhouse gas abatement. Towards this objective, we have proposed a novel gas turbine power plant, which is not only to capture [CO.sub.2] in the stage of combustion, but also to increase thermal efficiency of the power plant. The chemical-looping combustor in the proposed system consists of a fuel reactor (fuel reacts with metal oxide) and an air reactor (the resulting metal reacts with oxygen in air). This new system requires no additional energy consumption for [CO.sub.2] separation (i.e., no energy penalty) and no [CO.sub.2] separation equipment. Here, we have identified several breakthrough points in the proposed system and summarized promising results from experimental investigation on the chemical-looping combustion. [DOI: 10.1115/1.1345891]

In this paper, a novel multifunctional energy system (MES) fueled by natural gas and solar radiation is proposed. In this MES, hydrogen and electricity are cogenerated and approximately 92% of CO2 derived from natural gas is removed. The solar concentrated process provides high-temperature thermal energy to the methane/steam reforming reaction. The resulting syngas enters a pressure swing adsorption unit to separate approximately 80% of hydrogen. This process significantly increases the concentration of carbon dioxide in syngas from nearly 19% to 49%, which decreases energy consumption in CO2 removal. As a result, the overall power efficiency of the new system becomes about 39.2%. Compared to a conventional natural gas-based hydrogen plant with CO2 removal and a concentrated solar power tower plant, the overall power efficiency of the new system is increased by 7.9 percentage points. Based on the graphical exergy analysis, the integration of synthetic utilization of natural gas and solar radiation, combination of the hydrogen production plant and power plant, and integration of the energy utilization processes and CO2 separation were found to play significant roles to improve thermodynamic performance. The result obtained here provides a new approach for highly efficient use of solar radiation by hybrid natural gas. [ABSTRACT FROM AUTHOR]

In this paper; we have proposed a novel coal-based hydrogen production system with low CO2 emission. In this novel system, a pressure swing adsorption H2 production process and a CO2 cryogenic capture process are well integrated to gain comprehensive peiformance. In particular, through sequential connection between the pressure swing absorption (PSA) H2 production process and the CO2 capture unit, the CO2 concentration of PSA purge gas that enters the CO2 capture unit can reach as high as 70%, which results in as much as 90% of CO2 to be separated from mixed gas as liquid at a temperature of -55°C. This will reduce the quantity and quality of cold energy required for cryogenic separation method, and the solidification of CO2 is avoided. The adoption of cryogenic energy to capture CO2 enables direct production of liquid CO2 at low pressure and thereby saves a lot of compression energy. Besides, partial recycle of the tail gas from CO2 recovery unit to PSA inlet can help enhance the amount of hydrogen product and lower the energy consumption for H2 production. As a result, the energy consumption for the new system's hydrogen production is only 196.8 GJ/tH2 with 94% of CO2 captured, which is 9.2% lower than that of the coal-based hydrogenproduction system with Selexol CO2 removal process and is only 2.6% more than that of the coal-based hydrogen production system without CO2 recovery. More so, the energy consumption of CO2 recovery is expected to be reduced by 20-60% compared with that of traditional CO2 separation processes. Further analysis on the novel system indicates that synergetic integration of the H2 production process and cryogenic CO2 recovery unit, along with the synthetic utilization of energy, plays a significant role in lowering, energy penalty for CO2 separation and liquefaction. The promising results obtained here provide a new approach for CO2 removal with low energy penalty. [ABSTRACT FROM AUTHOR]