Natural Gas Power Research Articles

A Study on Primary Energy and Secondary Energy Price in Distributed Energy Projects

This paper constructed an energy configuration model with economic optimization in distributed energy system. On this basis, we carried out the sensitivity analysis of the price of large power grid, natural gas, cooling, heating and secondary power for the economic optimized results. And then, we have analyzed the critical value point of new energy conversion technologies appear or old disappear with the change of those energy price. In this paper, the secondary power price is same with the price of large power grid. In this study, an economic analysis of a distributed energy station project has been completed, which is a commercial complex in Shanghai. The results show that the power price have a biggest impact to -F value, and the influence of heating price is minimum, and supposing that self-generating electricity is grid-connected with no power injection. And at last, we find that the energy conversion technologies appear in different place of different scenario.

Forecasting Carbon Emissions Related to Energy Consumption in Beijing-Tianjin-Hebei Region Based on Grey Prediction Theory and Extreme Learning Machine Optimized by Support Vector Machine Algorithm

Carbon emissions and environmental protection issues have brought pressure from the international community during Chinese economic development. Recently, Chinese Government announced that carbon emissions per unit of GDP would fall by 60–65% compared with 2005 and non-fossil fuel energy would account for 20% of primary energy consumption by 2030. The Beijing-Tianjin-Hebei region is an important regional energy consumption center in China, and its energy structure is typically coal-based which is similar to the whole country. Therefore, forecasting energy consumption related carbon emissions is of great significance to emissions reduction and upgrading of energy supply in the Beijing-Tianjin-Hebei region. Thus, this study thoroughly analyzed the main energy sources of carbon emissions including coal, petrol, natural gas, and coal power in this region. Secondly, the kernel function of the support vector machine was applied to the extreme learning machine algorithm to optimize the connection weight matrix between the original hidden layer and the output layer. Thirdly, the grey prediction theory was used to predict major energy consumption in the region from 2017 to 2030. Then, the energy consumption and carbon emissions data for 2000–2016 were used as the training and test sets for the SVM-ELM (Support Vector Machine-Extreme Learning Machine) model. The result of SVM-ELM model was compared with the forecasting results of SVM (Support Vector Machine Algorithm) and ELM (Extreme Learning Machine) algorithm. The accuracy of SVM-ELM was shown to be higher. Finally, we used forecasting output of GM (Grey Prediction Theory) (1, 1) as the input of the SVM-ELM model to predict carbon emissions in the region from 2017 to 2030. The results showed that the proportion of energy consumption seriously affects the amount of carbon emissions. We found that the energy consumption of electricity and natural gas will reach 45% by 2030 and carbon emissions in the region can be controlled below 96.9 million tons. Therefore, accelerating the upgradation of industrial structure will be the key task for the government in controlling the amount of carbon emissions in the next step.

Equilibrium of Interdependent Gas and Electricity Markets With Marginal Price Based Bilateral Energy Trading

The increasing interdependencies between natural gas systems and power systems create new business opportunities in coupled energy distribution markets. This paper studies the marginal price based bilateral energy trading on the equilibrium of coupled natural gas and electricity distribution markets. Convex relaxation is employed to solve a multiperiod optimal power flow problem, which is used to clear the electricity market. A successive second-order cone programming approach is utilized to solve a multiperiod optimal gas flow problem, which is used to clear the gas market. In addition, the line pack effect in the gas network is considered, which can offer storage capacity and provide extra operation flexibility for both networks. In both problems, locational marginal energy prices are recovered from the Lagrangian multipliers associated with nodal balancing equations. Furthermore, a best-response decomposition algorithm is developed to identify the equilibrium of the coupled energy markets with bilateral gas and electricity trading, which leverages the computational superiority of SOCPs. Cases studies on two test systems validate the proposed methodology.

Influence of H2O phase state on system efficiency in O2/H2O combustion power plant

In this work, oxy-fuel combustion with H2O as diluent in natural gas power plant is proposed, and the effect of phases of H2O on the overall system efficiency is investigated. Three different phase states of H2O, liquid water, steam and liquid-steam mixture are investigated, and the corresponding systems GST-L, GT-S and GT-M system are simulated and compared. To overcome the problem that the steam Rankin cycle cannot fully utilize the latent heat of water, the transcritical CO2 (T-CO2) cycle is introduced. The thermal analysis results show that the GT-M system with steam-water mixture as diluent performs the best, and the energy and exergy efficiency is 60.86% and 49.29%, respectively. The GST-L system takes the second place, and the GT-S system shows the lowest efficiency. The results reveal that steam-water mixture is the best phase of H2O recycled to control the combustion temperature, and the integration of gas turbine and T-CO2 cycle can fully utilize the thermal energy of flue gas to generate electricity. Therefore, the high-efficiency power generation with near-zero carbon emissions is achieved.

Parametric, cyclic aging and characterization studies for CO2 capture from flue gas and catalytic conversion to synthetic natural gas using a dual functional material (DFM)

Abstract Solid sorbents have attracted extensive research attention for enhanced adsorption of effluent CO2. A Dual Functional Material (DFM), composed of a CO2 adsorbent (“Na2O” derived from hydrogenated Na2CO3) in combination with Ru both supported on the same Al2O3, overcome limitations of traditional sorbent technology. It captures CO2 from a simulated flue gas and catalytically converts it to synthetic natural gas (CH4) in the same reactor and temperature utilizing H2 generated from renewable sources. The methane produced is recycled to the plant inlet for repeated combustion maintaining a closed carbon loop. The process is envisioned to operate with parallel reactors, containing DFM, where one captures CO2 and the other methanates and vis versa for continuous operation. We report parametric, cyclic aging and characterization studies in a simulated natural gas power plant flue gas using 10 g of 5 mm × 5 mm tablet DFM. This material shows stable CO2 capture and conversion to CH4 performance for over 50 adsorption and conversion aging cycles (equivalent to 80 h of operation) with no loss in BET surface area, CO2 capture capacity nor Ru dispersion.

Cost optimal scenarios of a future highly renewable European electricity system: Exploring the influence of weather data, cost parameters and policy constraints

Cost optimal scenarios derived from models of a highly renewable electricity system depend on the specific input data, cost assumptions and system constraints. Here this influence is studied using a techno-economic optimisation model for a networked system of 30 European countries, taking into account the capacity investment and operation of wind, solar, hydroelectricity, natural gas power generation, transmission, and different storage options. A considerable robustness of total system costs to the input weather data and to moderate changes in the cost assumptions is observed. Flat directions in the optimisation landscape around cost-optimal configurations often allow system planners to choose between different technology options without a significant increase in total costs, for instance by replacing onshore with offshore wind power capacity in case of public acceptance issues. Exploring a range of carbon dioxide emission limits shows that for scenarios with moderate transmission expansion, a reduction of around 57% compared to 1990 levels is already cost optimal. For stricter carbon dioxide limits, power generated from gas turbines is at first replaced by generation from increasing renewable capacities. Non-hydro storage capacities are only built for low-emission scenarios, in order to provide the necessary flexibility to meet peaks in the residual load.

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.

Development and application of screw expander in natural gas pressure energy recovery at city gas station

There is a tremendous energy loss in the process of natural gas delivery by pipes. The energy lost in the pressure reduction process can be first transformed into mechanical energy and then further converted into electricity by a generator. In this study, an oil free twin screw expander was designed and applied for the nature gas energy recovery at a city gas station for the first time. And the critical speed of the rotors, the seals and bearings were discussed and presented in the design, which was proved that the system designed with the twin screw expander is much simpler without challenges of the sealing and bearing selection facing in the traditional turbine expander used in the CGS. Finally, the feasibility and simplicity of using the screw expander in natural gas energy recovery and power generation were proved through its stable running performance at site. The twin screw expander, therefore, could make up for the defects of the traditional turbine expander at a high rotation speed applied in the samilar area, and turned out to be an effective way to recover the pressure energy from the natural gas.

Hydro-Optimization-Based Medium-Term Price Forecasting Considering Demand and Supply Uncertainty

This paper proposes an electricity market model of Turkish electricity market for monthly and yearly electricity price forecasting in medium-term by means of supply and demand dynamics formed via a theoretical approach. The electricity market model created within this scope consists of three main components related to electricity demand, supply, and price segments along with hydro optimization submodel, which takes into account the nonlinear relation between supply and price. Electricity price is determined based on the intersection of demand curve and merit order curve that has dynamic behavior for dam-type hydrogeneration, import coal, and natural gas power plants. The paper aims to determine the range of possible electricity prices rather than a single price forecast by creating multiple scenarios based on the uncertainties in main variables affecting the electricity prices. Meanwhile, electricity generation portfolio with respect to market participants and primary energy resources as well as price forecasts can be obtained simultaneously. Ultimately, the model can identify how effective a variable of the market on the electricity price is. The developed method is validated via real data.

Spatio-temporal variations in SO2 and NO2 emissions caused by heating over the Beijing-Tianjin-Hebei Region constrained by an adaptive nudging method with OMI data

The Beijing-Tianjin-Hebei (BTH) region in China suffers from heavy air pollution, especially in heating period. SO2 and NO2 are two of the key primary gaseous pollutants emitted by coal burning. The increase in air pollution caused by heating in the south-central part of the BTH region is higher than that in the northern part. And the distribution of SO2 and NO2 increment has significant differences. In this work, SO2 and NO2 emissions over the BTH region are determined using an adaptive “nudging” constrained method and a variational processing technique based on Ozone Monitoring Instrument (OMI) satellite data and surface measurement data collected in 2015. The application of the method can provide reliable, up-to-date and high-resolution mapping of sources of SO2 and NO2 emissions. These SO2 and NO2 emissions reflect the spatial differences in point and area sources in urban agglomerations and rural areas under different meteorological conditions during the non-heating and heating seasons. The intensity and influence of SO2 and NO2 emissions, particularly those of SO2, are significantly greater during the heating season than those during the non-heating season. Winter increases in SO2 emissions in the northern areas of the BTH region are larger than those in the southern part. In addition, significant increases in SO2 emissions occur mainly in suburban and rural areas, while those of NO2 emissions mainly occur in urban agglomerations. In the major urban areas, where coal has been replaced by natural gas or electric power for heating, winter heating causes much smaller increases in SO2 emissions than in other areas. The large amounts of bulk coal consumption in the suburban and rural areas could cause significant regional air pollution. Clear increases in SO2 and NO2 emissions in winter occur along a belt from southern Beijing to Langfang, Baoding, Shijiazhuang and Xingtai, which is consistent with a special “quasi-steady” air pollutant transport belt in the region. All above results show that the adaptive “nudging” constrained emission method could be an effective tool for air pollution control during certain seasons.

Energy Price Reform in China

The Chinese leadership has determined to assign the market a decisive role in allocating resources. To have the market to play that role, getting the energy prices right is crucial because this sends clear signals to both producers and consumers of energy. While the overall trend of China’s energy pricing reform since 1984 has been moving away from the prices set by the central government in the centrally planned economy and towards a more market-oriented pricing mechanism, the pace and scale of the reform differ across energy types. This article discusses the evolution of price reforms for coal, petroleum products, natural gas, electricity and renewable power in China, and provides some analysis of these energy price reforms, in order to have the market to play a decisive role in allocating resources and help China’s transition to a low-carbon economy.

A multi-criteria and multi-expert decision aid approach to evaluate the future Turkish power plant portfolio

The study presents recent developments in the Turkish power market and introduces an Analytic Hierarchy Process model to evaluate and compare the relative overall attractiveness of power plant options for Turkey. The developed model incorporates technical characteristics, resource availability, socio-economic, environmental, cost, political, legal and organisational aspects, for evaluating and prioritising power plant types (biomass, coal, geothermal, hydro, natural gas, nuclear, petroleum, solar and wind). The study incorporates perspectives of different experts that represent various stakeholders of the Turkish power sector. The study reveals that supply reliability, investment costs and contribution to national economy are perceived as most important factors, whereas waste disposal and decommissioning costs are perceived as least important factors. Considering the overall weights, the most attractive power plant types for the Turkish power market are coal, hydro and natural gas power plants. The study indicates that Turkey should drastically decrease the installed capacity share of traditionally dominant power plants (to 58% from 89% in 2016) and fossil fuel power plants (to 40% from 56% in 2016), and increase the share of renewable power plants (to 52% from 44% in 2016), indigenous resource based power plants (to 67% from 56% in 2016) and nuclear power plants.

Coordinated Expansion Planning of Natural Gas and Electric Power Systems

The interdependence between natural gas and electric power systems is becoming increasingly tight, as the share of natural gas-fired units increases. Within this context, this paper addresses the coordinated expansion planning of natural gas and power systems. We analyze the tradeoff of building natural gas-related facilities (e.g., natural gas pipelines and natural gas-fired generation units) versus electric-power-related facilities (e.g., transmission lines and other generation units). We use a two-stage stochastic optimization model that provides an appropriate balance between accuracy and computational tractability and represents uncertainty pertaining to electricity and natural gas demands. We show the importance of representing uncertainty by computing the value of stochastic solution, which is significant. We analyze the functioning of the model through a small example and a case study based on the IEEE 118-bus system. Computational results confirm the need for detailed representation of both the natural gas and power systems to achieve investment decisions that are well coordinated and optimal.

Comparative life-cycle assessment of a novel osmotic heat engine and an organic Rankine cycle for energy production from low-grade heat

Abstract A comparative life-cycle assessment (LCA) was performed to evaluate the environmental impacts of an osmotic heat engine (OHE) and an organic Rankine cycle (ORC) for electrical energy generation from low-grade heat. The OHE is a novel membrane-based process that couples pressure retarded osmosis (an energy generating process) and membrane distillation (a working fluid regeneration process), whereas the ORC is an established power cycle. The LCA considered the material use for system construction and operation, and found that the environmental impacts for both the construction and operation stages of the OHE were higher than the ORC. The sensitivity analysis concluded that OHE environmental impacts could be reduced by 80% with future improvements to PRO membranes and membrane module performance. Additionally, with further improvements the OHE could be a viable energy production process that can increase energy efficiency and reduce CO2 emissions from coal and natural gas power plants by 20.5 and 11.9 million kg of CO2 per year, respectively.

Effects of technology assumptions on US power sector capacity, generation and emissions projections: Results from the EMF 32 Model Intercomparison Project

This paper is one of two syntheses in this special issue of the results of the EMF 32 power sector study. This paper focuses on the effects of technology and market assumptions with projections out to 2050. A total of 15 models contributed projections based on a set of standardized scenarios. The scenarios include a range of assumptions about the price of natural gas, costs of end-use energy efficiency, retirements of nuclear power, the cost of renewable electricity, and overall electricity demand. The range of models and scenarios represent similarities and differences across a broad spectrum of analytical methods.One similarity across almost all results from all models and scenarios is that the share of electricity generation and capacity fueled by coal shrinks over time, although the rate at which coal capacity is retired depends on the price of natural gas and the amount of electricity that is demanded. Another similarity is that the models project average increases in natural gas power generating capacity in every scenario over the 2020–2050 period, but at lower average annual rates than those that prevailed during the 2000–2015 period. The projections also include higher gas capacity utilization rates in the 2035–2050 period compared to the 2020–2050 period in every scenario, except the high gas price sensitivity. Renewables capacity is also projected to increase in every scenario, although the annual new capacity varies from modest rates below the observed 2000–2015 wind and solar average to rates more than 3 times that high. Model estimates of CO2 emissions largely follow from the trends in generation. Low renewables cost and low gas prices both result in lower overall CO2 emission rates relative to the 2020–2035 and 2035–2050 reference. Both limited nuclear lifetimes and higher demand result in increased CO2 emissions.

Operational Water Withdrawal and Consumption Factors for Electricity Generation Technology in China—A Literature Review

As two indispensable resources for human development, energy and water are closely related. China, as the world’s largest consumer of electricity, is also experiencing very serious water shortages. Understanding the water consumption intensity in various types of electric power production technologies according to China’s national conditions is a prerequisite for understanding the potential impact of electrical power production on water resources. Therefore, following the steps of a meta-analysis, this paper provides a literature review on operational water withdrawal and consumption factors for electricity generation technology in China. We observed that 50% of water consumption for electricity generation was for coal power, whereas there was no research on the water consumption intensity of natural gas power generation, and a shortage of studies on water intake during electrical power production. The average water consumption intensity of hydropower is the largest. The results indicate that compared with other fuel types, hydropower is not a sustainable energy with respect to water conservation, and the study of hydropower applications should be improved in China.

Why We Need Nuclear Power Plants

The major growth in the electricity production industry in the last 30 years has centered on the expansion of natural gas power plants based on gas turbine cycles. The most popular extension of the simple Brayton gas turbine has been the combined cycle power plant with the Air-Brayton cycle serving as the topping cycle and the Steam-Rankine cycle serving as the bottoming cycle for new generation of nuclear power plants that are known as GEN-IV. The Air-Brayton cycle is an open-air cycle and the Steam-Rankine cycle is a closed cycle. The air-Brayton cycle for a natural gas driven power plant must be an open cycle, where the air is drawn in from the environment and exhausted with the products of combustion to the environment. This technique is suggested as an innovative approach to GEN-IV nuclear power plants in form and type of Small Modular Reactors (SMRs). The hot exhaust from the AirBrayton cycle passes through a Heat Recovery Steam Generator (HSRG) prior to exhausting to the environment in a combined cycle. The HRSG serves the same purpose as a boiler for the conventional Steam-Rankine cycle [1].

Implications of diversification strategies in the European natural gas market for the German energy system

The energy system is facing changes across Europe, motivated by CO2 emission reduction targets and driven by the expansion of renewable energy sources (RES). Germany is carrying out efforts to reshape its future energy system to be mainly based on RES. Nonetheless, flexible generation capacities like natural gas (NG) power plants will still be needed in the coming decades. Recent developments in the NG market have been characterised by uncertainties on the supply side as plans have been put forth for new pipelines to facilitate Russian or Caspian NG towards Europe as well as increasing volumes of liquefied natural gas entering the market. This paper aims to show the interdependence between infrastructure developments and primary NG demand in the German energy system. The authors analyse impacts for the German ‘Energiewende’ on a time horizon from 2010 to 2050. Coupling a European NG model with a German energy system model, we develop six scenarios regarding climate policy in Germany and European diversification strategies in infrastructure expansion. The results show, that NG prices influence sectoral changes especially in the residential sector. Further strategies to reduce CO2 emissions in the entire energy system should also consider NG as part of the solution.

Molten Carbonate Fuel Cells for Retrofitting Postcombustion CO2 Capture in Coal and Natural Gas Power Plants

The state-of-the-art conventional technology for postcombustion capture of CO2 from fossil-fueled power plants is based on chemical solvents, which requires substantial energy consumption for regeneration. A promising alternative, available in the near future, is the application of molten carbonate fuel cells (MCFC) for CO2 separation from postcombustion flue gases. Previous studies related to this technology showed both high efficiency and high carbon capture rates, especially when the fuel cell is thermally integrated in the flue gas path of a natural gas-fired combined cycle or an integrated gasification combined cycle plant. This work compares the application of MCFC-based CO2 separation process to pulverized coal fired steam cycles (PCC) and natural gas combined cycles (NGCC) as a “retrofit” to the original power plant. Mass and energy balances are calculated through detailed models for both power plants, with fuel cell behavior simulated using a 0D model calibrated against manufacturers' specifications and based on experimental measurements, specifically carried out to support this study. The resulting analysis includes a comparison of the energy efficiency and CO2 separation efficiency as well as an economic comparison of the cost of CO2 avoided (CCA) under several economic scenarios. The proposed configurations reveal promising performance, exhibiting very competitive efficiency and economic metrics in comparison with conventional CO2 capture technologies. Application as a MCFC retrofit yields a very limited (<3%) decrease in efficiency for both power plants (PCC and NGCC), a strong reduction (>80%) in CO2 emission and a competitive cost for CO2 avoided (25–40 €/ton).

Trade-offs between integration and isolation in Switzerland's energy policy

In response to the Fukushima nuclear accident, Switzerland has targeted to phase out nuclear power by 2050. Two diametrically opposite pathways to accomplish Switzerland's nuclear phase-out are quantitatively investigated for the year 2035 using a novel high-resolution power systems simulation framework. The first pathway, “Island in Europe”, installs new natural gas power plants to ensure a self-sufficient Swiss energy system. The second pathway, “Battery of Europe”, increases Switzerland's engagement with central Europe with new pumped hydro storages and increased cross-border electricity trade of European renewable energy. The results show that the “Battery of Europe” scenario enables a threefold increase in financial surplus of cross-border electricity trade compared to the “Island in Europe” scenario. This surplus translates to 15–23% lower domestic Swiss electricity prices, thereby enhancing the competitiveness of the Swiss marketplace; however, Switzerland is then exposed to more technical and political engagement with its neighbours. Additionally, successful implementation of the “Battery of Europe” scenario requires reinforcing 5% of the Swiss transmission grid, which necessitates more streamlined legal processes for new transmission infrastructure. Along a different political dimension, electricity price reductions of up to 22% are possible if the targeted increase of efficiency in Switzerland's energy policy is accomplished.