Liquefied Natural Gas Power Research Articles

Carbon Neutral Design of Waste Energy Recovery System for LNG Power Plant Using Organic Rankine Cycle

In liquefied natural gas (LNG) power plants, a significant amount of heat and cold energy is consumed to capture and store carbon dioxide (CO2) emitted during the combustion of fossil fuels. The proposed system addresses this problem by utilizing the temperature difference between waste heat and cold energy as a power source to generate electricity. In this study, a novel waste heat and cold energy recovery system for a postcombustion LNG power plant was developed using an organic Rankine cycle (ORC). To design the proposed system, a process model was developed with the following five parts: (i) LNG vaporization, (ii) natural gas combined cycle (NGCC), (iii) amine scrubbing, (iv) CO2 liquefaction, and (v) CO2 injection. In the proposed system, waste LNG cold energy is used for lean amine cooling and CO2 liquefaction. The liquefied CO2 was pressurized to meet the injection pressure requirements. The ORC uses high-temperature exhaust gas from the NGCC as the heat source and high-pressure liquefied CO2 as the heat sink. The economic feasibility of the proposed system was demonstrated by an economic assessment, with the net profit evaluated by a sensitivity analysis considering variations in water, electricity, and equipment costs. Consequently, the proposed system exhibited an 18.6% increase in net power production compared to the conventional system. In addition, the net profit of the proposed system exhibited a 76.7% increase compared to the conventional system, confirming its economic feasibility.

Analysis on the Development of LNG Clean Energy Technology for Inland Ships in China

Liquefied natural gas (LNG) is recognized as the most mature and feasible low-carbon clean alternative energy for ships in the world. Liquefied natural gas is widely favored by ship owners. This paper systematically summarizes the development status of promoting the application of LNG in ships at home and abroad. This paper deeply studies the key technologies of ship LNG power system, and focuses on the comparison of the characteristics of power technology at home and abroad. This paper comprehensively summarizes and analyzes the supporting system for the development of LNG powered ships in China. This paper explores the problems existing in the application of LNG in ships. The paper puts forward a power development path of LNG ships in China in the future. The proposed development path can provide strong support for China to achieve green shipping and dual carbon goals.

Novel process design for waste energy recovery of LNG power plants for CO2 capture and storage

In an liquefied natural gas (LNG) power plant, the amine scrubbing and CO2 liquefaction process are generally employed for CO2 capture and storage (CCS) because it is suitable for large-scale plants. However, a large amount of hot and cold energy is required for CO2 absorption, regeneration and liquefaction. As a solution, the waste LNG cold energy from the LNG regasification process and waste hot energy from natural gas combined cycle (NGCC), which are generally disposed into the seawater, can be recovered and utilized for the abovementioned purposes. Hence, this study suggested a novel process for waste hot and cold energy recovery of the LNG power plants for CCS. The suggested process model consists of the following four steps: LNG regasification, natural gas combined cycle, CO2 capture and regeneration and CO2 liquefaction. In the process model, the waste LNG cold energy is recovered at the lean amine cooler in the CO2 capture process and each heat exchanger in the CO2 liquefaction process. Furthermore, for CO2 regeneration, the waste hot energy from NGCC is recovered at the stripper reboiler. The exergy and economic analyses were addressed to evaluate the economic feasibility of energy conversion of the proposed process. As a result, compared to the base process, the net power generation and exergy efficiency of the proposed process increased by 16% and 8%, respectively. In addition, the net profit of the proposed process increased by 75%, indicating high economic feasibility. The overall energy efficiency and economic feasibility using waste cold and hot energy were observed to increase, which resulted in decreased fuel usage. Therefore, we believe that the proposed approach can contribute significantly to the economic improvements and environmental protection efforts.

Technical and Economic Evaluation and Development Policy Suggestions of LNG Power Plants

The return on investment (RIO) of a Liquefied natural gas (LNG) power plant is lower than that of conventional power plants with high pollution due to the “take or pay” supply mode of natural gas and the two-shift peak shaving operation mode in the LNG power plants. . In this paper, firstly, based on the characteristics of the gas turbine combined cycle (GTCC) unit for peak shaving and standby application, it is proposed to calculate the generation cost of LNG power plants according to the depreciation of operation life. Secondly, through the sensitivity analysis of power generation cost, it is found that fuel price and average efficiency are the first influencing factors. Next, to reflect the environmental protection characteristics of LNG power plants, the on-grid price included in the environmental value is put forward innovatively based on the calculation of the environmental cost and environmental value of natural gas power generation.

Tax Reform for the Energy Transition in Korea’s Power Generation Sector

The tax structure capable of achieving an energy transition in the power sector was analyzed by applying the Pigouvian tax on generation fuels. Under the 2018 Tax Act Amendment, the tax rate criteria for the excise tax on power generation fuels changed from the calorific value to environmental externalities of the fuel. However, to reverse the merit order of bituminous coal generation with liquefied natural gas (LNG) generation, reflecting only some external costs of the environment as a tax is not enough. In this paper, we established four tax reform scenarios for bituminous coal and LNG considering environmental externalities, and we analyzed the reversal of dispatch priority using the electricity system unit commitment and M-Core economic dispatch model. According to the analysis results, the share of bituminous coal generation will be reduced to 10–20% depending on the scenario, reflecting the relative tax rate equalizing the fuel costs of bituminous coal and LNG power. To achieve an energy transition by reversing the merit order of bituminous coal and LNG generation, the tax rate of bituminous coal must be more than twice that of LNG. Moreover, to achieve an eco-friendly generation mix through tax reform, the external costs of the environment by fuel source should be accurately estimated and efficient taxation that can adequately reflect these external costs of the environment while considering tax fairness, neutrality and simplicity should be established.

Ammonia Emission Sources Characteristics and Emission Factor Uncertainty at Liquefied Natural Gas Power Plants.

This study developed the NH3 emission factor for Liquefied Natural Gas (LNG) power facilities in Korea by analyzing the emission characteristics from two LNG power plants using methods such as uncertainty analysis. Also, comparing the differences in NH3 emission levels between the developed emission factors, which reflect the characteristics in Korea, and the U.S. Environmental Protection Agency (EPA) values currently applied in Korea. The estimation showed that the NH3 emission factor for the LNG power plants was 0.0054 ton NH3/106Nm3, which is approximately nine times less than the EPA NH3 emission factor of 0.051 ton NH3/106Nm3 for LNG fuels of the industrial energy combustion sector currently applied in national statistics in Korea. The Selective Catalytic Reduction (SCR) emission factor for LNG power plants was 0.0010 ton NH3/106Nm3, which is considerably lower than the EPA NH3 emission factor of 0.146 ton NH3/106Nm3 currently applied in national statistics in Korea for the LNG fuels of the industrial process sector. This indicated the need for developing an emission factor that incorporates the unique characteristics in Korea. The uncertainty range of the LNG stack NH3 emission factor developed in this study was ±10.91% at a 95% confidence level, while that of the SCR NH3 emission factor was –10% to +20% at a 95% confidence level, indicating a slightly higher uncertainty range than the LNG stack. At present, quantitative analysis of air pollutants is difficult because numerical values of the uncertainty are not available. However, quantitative analysis might be possible using the methods applied in this study to estimate uncertainty.

Thermodynamic analysis of a novel combined cooling and power system utilizing liquefied natural gas (LNG) cryogenic energy and low-temperature waste heat

A novel combined cooling and power (CCP) system utilizing liquefied natural gas (LNG) cryogenic energy and low-temperature waste heat was presented. The proposed system consists of two subsystems, absorption refrigeration/power cycle (ARP) subsystem and LNG refrigeration/power cycle (LRP) subsystem. The Rankine cycle and absorption refrigeration cycle were connected in series to form the ARP and they showed mutual enhancement in the integration. The operating performance of the system was calculated and analyzed. And the effects of generator pressure and circulation ratio on the performance were analyzed. Furthermore, a typical application case, in which the proposed system is integrated into the gas-steam combined cycle system as an LNG pre-processing and power enhancement unit, had been studied. The results showed that the net power generation efficiency, comprehensive energy utilization ratio, and exergy efficiency of the proposed CCP system reached 32.70%, 81.63%, and 35.14%, respectively. The feasibility and performance of the integrated system with combined cycle gas turbine were proved. And suggestions for the parameter design were presented.

The Arctic: Ecology and Hydrogen Electrical Power Engineering

The social and environmental aspects, climatic and glaciological features of the Arctic development in terms of energy supply are considered. The most expedient ways of complex development of the Arctic are shown. On the example of the large and unique stationary projects, paper marks some shortcomings: high cost, long-term construction, incomplete autonomy, insufficient solution of problems of ecology and waste processing. Incomplete autonomy is due to the need for transportation of materials, products, replacement crews and personnel, as well as insufficient logistics and transportation difficulties in summer on the mainland and in winter by sea. Problems of ecology and waste processing are associated with the use of traditional methods of burning solid and liquid fuels using coal or fuel oil polluting the environment. Switching to liquefied natural gas (LNG) for electric propulsion and power supply will significantly improve the environmental situation. The research performed on the mathematical model of the multifunctional energy complex of IEC shows the possibility of uninterrupted power supply of local load from both the centralized network, and from the diesel generator (DG) and the electric power storage; DG is used to save fuel as a backup source. The proposed technologies of power generation based on hydrogen or low-power nuclear power plants allow increasing the energy efficiency of the direct fuel conversion plant and provide integrated waste processing along with improving the environment. The small population of the Arctic, its mobility when using the rotational method requires the integrated development of mobile energy and life support systems of low power up to 30 MW using LNG or low-power nuclear power plants supplemented with RES. If the installation on hydrogen is both source and storage of electricity, the use of low-power nuclear power plants and especially RES require the use of energy storage devices. These hydrogen or electrochemical cycle storage devices are the most progressive in the world energy sector, and their applicability significantly depends on the development of the service infrastructure. Typing and replication of power supply sources can solve the problem of development of remote and isolated regions of the Arctic through the integrated use of innovative technologies for generation, storage, transmission and distribution of electricity, life support, recycling and recycling of waste, environmental conservation using hydrogen energy and digital control and monitoring systems.

Proposal and assessment of a new geothermal-based multigeneration system for cooling, heating, power, and hydrogen production, using LNG cold energy recovery

Multigeneration systems (MGSs) driven by renewable sources are proved as cutting-edge technologies for multiple productions purposes to curb greenhouse gas emissions. With this regard, a novel geothermal-based MGS is proposed to produce multiple commodities of cooling, heating, power, and hydrogen, simultaneously, using liquefied natural gas (LNG) as cold energy recovery. The system is composed of an organic Rankine cycle (ORC), an ejector refrigeration cycle (ERC), an LNG power generation system, and a proton exchange membrane (PEM) electrolyzer system. To demonstrate the feasibility of the proposed MGS, energy, exergy, and exergoeconomic analysis are employed as the most effective tools for the performance assessment of the system. It is found that the proposed MGS can produce cooling capacity, heating capacity, net output power, and hydrogen of 1020 kW, 334.8 kW, 1060 kW, and 5.43 kg/h, respectively. In this case, the thermal efficiency, exergy efficiency and total SUCP (sum unit cost of the product) of the MGS are calculated 38.33%, 28.91%, and 347.9 $/GJ, respectively. Furthermore, condenser 2 is introduced as the main source of irreversibility of the proposed MGS by exergy destruction ratio of 58.98%. Moreover, a comprehensive parametric study is carried out and it is concluded that the SUCP of the system can be optimized based on the geothermal inlet temperature. In addition, it is demonstrated that a higher thermal efficiency can be obtained by increasing the turbine 2 expansion ratio, evaporator temperature, and geothermal temperature or decreasing of the generator terminal temperature difference, turbine 1 expansion ratio, pump 3 pressure ratio, and condenser temperature. In the same vein, a higher exergy efficiency can be attained at high turbine 1 expansion ratio, turbine 2 expansion ratio, evaporator temperature, and pump 3 pressure ratio or low generator terminal temperature difference, geothermal inlet temperature, and condenser temperature.

Thermo-economic analysis and optimization of combined PERC - ORC - LNG power system for diesel engine waste heat recovery

In order to recover diesel engine exhaust gas waste heat, a new configuration consisting of screw expander based Partial Evaporation Rankine Cycle (PERC) combined with Organic Rankine Cycle (ORC) and Liquefied Natural Gas (LNG) power system is proposed and its performance is investigated from thermo-economic viewpoint. In studied system, a heat exchanger preparing domestic hot water is considered to recover the residual waste heat after PERC evaporator and thermo-economic performance of the system is investigated for 6 various organic fluids in ORC. Also, parametric analysis is performed to assess the effects of PERC evaporation temperature, PERC expander inlet steam quality and ORC condensation temperature on system performance. Finally, multi objective optimization is used to find the favorable performance point of system. LNG and PERC systems have a proper operation respectively from energy and exergoeconomic viewpoints. Also, ORC condenser has the highest total cost rate. System optimization results show that using isopentane fluid leads to the highest net power output and total cost rate respectively equal to 178.6 kW and 19.3 $/h and using toluene fluid leads to the lowest net power output and total cost rate that are respectively equal to 154.7 kw and 17.36 $/h.

Exergetic Analysis, Optimization and Comparison of LNG Cold Exergy Recovery Systems for Transportation.

LNG (Liquefied Natural Gas) shares in the global energy market is steadily increasing. One possible application of LNG is as a fuel for transportation. Stricter air pollution regulations and emission controls have made the natural gas a promising alternative to liquid petroleum fuels, especially in the case of heavy transport. However, in most LNG-fueled vehicles, the physical exergy of LNG is destroyed in the regasification process. This paper investigates possible LNG exergy recovery systems for transportation. The analyses focus on “cold energy” recovery systems as the enthalpy of LNG, which may be used as cooling power in air conditioning or refrigeration. Moreover, four exergy recovery systems that use LNG as a low temperature heat sink to produce electric power are analyzed. This includes single-stage and two-stage direct expansion systems, an ORC (Organic Rankine Cycle) system, and a combined system (ORC + direct expansion). The optimization of the above-mentioned LNG power cycles and exergy analyses are also discussed, with the identification of exergy loss in all components. The analyzed systems achieved exergetic efficiencies in the range of to , which corresponds to a net work in the range of 214 to 380 kJ/kg.

Thermoacoustic Stirling power generation from LNG cold energy and low-temperature waste heat

Recovering cold energy generated in the regasification process of liquefied natural gas (LNG) can help to improve the energy efficiency of LNG power generation systems, meanwhile, abundant low-grade waste heat can also be exploited from the exhaust gas of gas turbines. This study proposes to apply the thermoacoustic Stirling electric generator to recover LNG cold energy and waste heat simultaneously. A pair of linear alternators is directly coupled with the thermoacoustic loop by replacing the long and bulky resonator completely. Numerical simulation is conducted on the basis of the thermoacoustic theory to characterize and optimize the operations of the system. The effects of the back volumes of linear alternators, feedback tube length and regenerator length on the output performances are investigated. The distributions of key parameters, including pressure, volume flow rate, phase difference, acoustic power and exergy flow, are further studied. One design of the thermoacoustic Stirling electric generator operated with 4 MPa helium gas is capable of generating 2.3 kW electric power with the highest exergy efficiency of 0.253 when the cold and hot ends are maintained at 110 K and 500 K. Performances can be further improved if the conversion efficiency of the linear alternators is further increased.

Walking the Wall

Walking the Wall

LNG 냉열을 이용하는 암모니아-물 복합 재생 동력 사이클의 성능 특성

The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

Corrosion of Tail Heated Surface Tube under Flue Gas Medium in LNG Power Station HRSG

Corrosion type, reasons and influential factors of the tail heated surface tube of the low carbon steel under the flue gas medium in LNG(Liquefied Natural Gas) power station HRSG(Heat Recovery Steam Generator) were researched through cracks morphology observation, corrosion products analysis, corrosion elements measurement and tube wall temperature field FEM calculation. Results showed that the crack initiated from the outer wall of the tube and propagated toward the inner wall with the arborescent morphology. Intergranular embrittlement ruptured. Rock type feature and secondary crack were observed on the fracture. Mud pattern and polygonal figure of the corrosion products were present. According to these morphology characteristics, the crack was identified as stress corrosion crack, and corrosion type was SCC(Stress Corrosion Cracking). Reasons of SCC were that low feed water or flue gas temperature during a certain period of the unit startup and shutdown for peaking operation brought about the temperature of the outer wall of tube below the flue gas dew point, and the flue gas became dew and corrosion solution emerged on the outer wall of tube. The SCC component was CO2 solution according to the corrosion products. S and Cl elements were found in the outer wall of tube, but their effects on SCC are still needed more researches.

Economic and environmental analysis of power generation expansion in Japan considering Fukushima nuclear accident using a multi-objective optimization model

Nuclear power has long been a cornerstone of energy policy in Japan, a country with few natural resources of its own. However, following on from the Fukushima Daiichi accident, the Japanese government is now in the throes of reviewing its nuclear power policy. On the other hand, under continuing policies of greenhouse gas reduction, it is crucial to consider scenarios for the country to realize an economic, safe and low-carbon power generation system in the future. Therefore, in the present study, economic and environmental analysis was conducted on the power generation system in Japan up to 2030 using a multi-objective optimization methodology. Four nuclear power scenarios were proposed in light of the nuclear accident: (1) actively anti-nuclear; (2) passively negative towards nuclear; (3) conservative towards nuclear; and (4) active expansion of nuclear power. The obtained capacity mix, generation mix, generation cost, CO2 emissions and fuel consumption of the scenarios were compared and analysed. The obtained results show that the large scale penetration of PV (photovoltaic), wind and LNG (Liquefied Natural Gas) power can partly replace nuclear power, however, removing nuclear power entirely was not suggested from economic, environmental and energy security perspectives.

From the Heart of the Middle East, the Energy of the Future: North Adriatic LNG Terminal

Petroleum is still our most important energy source and it will certainly remain that way for a long time to come. Moreover, an end of oil use is not foreseeable at the present. However, reserves are declining. Liquefied natural gas (LNG), on the other hand, is available in abundant quantities. Nevertheless, the use of LNG is useful to solve a significant problem: the LNG power stations produce much lower CO2 emissions than petroleum. In fact, an 80% carbon dioxide reduction should be possible, as several companies are currently working on cleaner power stations, such as the LNG ones. Alternative energies are often not used enough as sources of energy. It is therefore all the more important that energy companies put a great deal of effort into supporting sustainable energy and developing cleaner technology, in order to make people less dependent on power from petroleum.

A combined power cycle utilizing low-temperature waste heat and LNG cold energy

This paper has proposed a combined power system, in which low-temperature waste heat can be efficiently recovered and cold energy of liquefied natural gas (LNG) can be fully utilized as well. This system consists of an ammonia–water mixture Rankine cycle and an LNG power generation cycle, and it is modelled by considering mass, energy and species balances for every component and thermodynamic analyses are conducted. The results show that the proposed combined cycle has good performance, with net electrical efficiency and exergy efficiency of 33% and 48%, respectively, for a typical operating condition. The power output is equal to 1.25 MWh per kg of ammonia–water mixture. About 0.2 MW of electrical power for operating sea water pumps can be saved. Parametric analyses are performed for the proposed combined cycle to evaluate the effects of key factors on the performance of the proposed combined cycle through simulation calculations. Results show that a maximum net electrical efficiency can be obtained as the inlet pressure of ammonia turbine increases and the peak value increases as the ammonia mass fraction increases. Exergy efficiency goes up with the increased ammonia turbine inlet pressure. With the ammonia mass fraction increases, the net electrical efficiency increases, whereas exergy efficiency decreases. For increasing LNG turbine inlet pressure or heat source temperature, there is also a peak of net electrical efficiency and exergy efficiency. With the increase of LNG gas turbine outlet pressure, exergy efficiency increases while net electrical efficiency drops.

新 LNG 冷熱発電方式の開発

Studies are underway to develop technologies for improving the output and efficiency of the gas turbine combined cycle (GTCC) by means of the cold energy of liquefied natural gas (LNG). This paper discusses the present situation of LNG power generation in Japan and the evaluation of the efficiency of intake cooling GTCC, MGT and SOFC/GT as well as the result of the development of cooling air to -100℃ or below with the test unit.

Green House Effects and Liquid Natural Gas Generation. Modern Technologies for Liquefied Natural Gas Power Plant.

Green House Effects and Liquid Natural Gas Generation. Modern Technologies for Liquefied Natural Gas Power Plant.