Power Generation System In China Research Articles

Development and Research Status of Tidal Current Power Generation Systems in China

Considering the depletion of oil, coal, gas and other fossil energy, and the increasingly serious environmental pollution, all countries in the world are developing clean and renewable energy, such as wind energy, water energy, solar energy, etc., to alleviate the current energy crisis. Tidal current energy belongs to the marine renewable energy. It is clean, pollution-free, and abundant, with a good prospect of development due to its similarity with wind energy. This paper firstly analyses the reserves and distribution of tidal current energy in China. Then the early exploration of Tidal Current Power Generation System (TCPGS) in China is briefly introduced. Subsequently, it gives the details of the devices and experimental platforms of TCPGS that were researched and developed by various universities, research institutes and enterprises in China. The information mainly includes: the size and the capacity of the system, the support structure, turbine type, the selection of generator, and some river and offshore test information, etc. Finally, it discusses the similarities and differences between China and other countries in tidal current power generation technology, and summaries the current development status and gives the prospect of the TCPGS technology in China.

Status of an MWth integrated gasification fuel cell power-generation system in China

Here, we provide a status update of an integrated gasification fuel cell (IGFC) power-generation system being developed at the National Institute of Clean-and-Low-Carbon in China at the megawatt thermal (MWth) scale. This system is designed to use coal as fuel to produce syngas as a first step, similar to that employed for the integrated gasification combined cycle. Subsequently, the solid-oxide fuel-cell (SOFC) system is used to convert chemical energy to electricity directly through an electrochemical reaction without combustion. This system leads to higher efficiency as compared with that from a traditional coal-fired power plant. The unreacted fuel in the SOFC system is transported to an oxygen-combustor to be converted to steam and carbon dioxide (CO2). Through a heat-recovery system, the steam is condensed and removed, and CO2 is enriched and captured for sequestration or utilization. Comprehensive economic analyses for a typical IGFC system was performed and the results were compared with those for a supercritical pulverized coal-fired power plant. The SOFC stacks selected for IGFC development were tested and qualified under hydrogen and simulated coal syngas fuel. Experimental results using SOFC stacks and thermodynamic analyses indicated that the control of hydrogen/CO ratio of syngas and steam/CO ratio is important to avoid carbon deposition with the fuel pipe. A 20-kW SOFC unit is under development with design power output of 20 kW and DC efficiency of 50.41%. A 100 kW-level subsystem will consist of 6 × 20-kW power-generation units, and the MWth IGFC system will consist of 5 × 100 kW-level subsystems.

Is solar power renewable and carbon-neutral: Evidence from a pilot solar tower plant in China under a systems view

Solar power has been widely treated as renewable and carbon-neutral for being free of fossil resource inputs and causing no carbon emissions. Recent studies, however, qualitatively challenged the traditional thinking derived under a local-realism-based perspective. In response to the recent concerns, this study as a continuation of a previous work offers a systems view into comprehending the ‘renewable’ and ‘carbon-neutral’ characters of solar power by the case of a Chinese pilot solar power plant. Under the systems view, a solar power plant is positioned as an organic system fed by ‘nutrients’ from the macro economy that relies on exogenous non-renewable energy resources as environmental support. A quantitative framework for evaluating the renewability and carbon-neutrality of solar power systems is proposed. A package of indicators is also devised, together with a retrospect of the history of methodological development. The non-renewable energy cost is revealed to be in magnitude 1.6 times as much as the electricity produced and the carbon emissions induced are also shown to be remarkable, implying that solar power is not as renewable and carbon-neutral as generally perceived. In contrast to coal-based power, however, solar power still appears as a promising alternative: the non-renewable energy cost and carbon emission for per unit of electricity delivered are revealed as 55% and 64% of that by the reference coal-fired power generation system in China, respectively. The outcome of this work provides a well-adapted assessment framework and adds insights into the intuitive understanding of renewable-based electricity.

Analysis of CO2 Abatement Cost of Solar Energy Integration in a Solar-Aided Coal-Fired Power Generation System in China

Utilization of renewable energy, improvement of power generation efficiency, and reduction of fossil fuel consumption are important strategies for the Chinese power industry in response to climate change and environment challenges. Solar thermal energy can be integrated into a conventional coal-fired power unit to build a solar-aided coal-fired power generation (SACPG) system. Because solar heat can be used more efficiently in a SACPG system, the solar-coal hybrid power system can reduce coal consumption and CO2 emissions. The performance and costs of a SACPG system are affected by the respective characteristics of its coal-fired system and solar thermal power system, their coupling effects, the solar energy resource, the costs of the solar power system, and other economic factors of coal price and carbon price. According to the characteristics of energy saving and CO2 emission reductions of a SACPG system, a general methodology of CO2 abatement cost for the hybrid system is proposed to assess the solar thermal energy integration reasonably and comprehensively. The critical factors for carbon abatement cost are also analyzed. Taking a SACPG system of 600 MW in Jinan, Shandong and in Hohhot, Inner Mongolia in China as an example, the methodology is further illustrated. The results show that the efficiency of solar heat-to-electricity should be high and it is 0.391 in the scheme of SIH1 in Hohhot, and that the designed direct normal irradiation (DNI) should be greater than 800 W/m2 in order to make full use of solar energy resources. It is indicated that the abatement cost of a SACPG system depends significantly both on the cost of solar power system and its relevant costs, and also on the fuel price or the carbon prices, and that the carbon abatement cost can be greatly reduced as the coal prices or CO2 price increase. The methodology of carbon abatement cost can provide support for the comprehensive assessment of a SACPG system for its design and optimal performance.

Modeling for the bed temperature 2D-interval prediction of CFB boilers based on long-short term memory network

Circulating fluidized bed (CFB) units play an important role in thermal power generation system in China. Because of advantages of wide fuel flexibility and low pollutant emissions, the proportion of CFB units is increasing constantly. For an accurate bed temperature changing trend prediction in advance, sequence prediction is needed, and accurate bed temperature change interval prediction is also required, a sequence-interval prediction indicates the 2D-interval prediction. This paper presents a bed temperature sequence interval prediction model for typical 300 MW CFB unit using long-short term memory network (LSTM) based on actual operation unit, and the coal feed rate, primary air rate and secondary air rate are selected as input variables using grey relational analysis. Previous bed temperature and automatic generation control instruction are introduced to the prediction models, and the length of input variables sequences are optimized using genetic algorithm. Several model patterns are compared and discussed, and the effect of introducing of automatic generation control instruction is investigated. The results reveal that the model structure could effectively described the characteristic of bed temperature of CFB unit and the model could achieve an accurate 2D-interval trend prediction of bed temperature.

Water use of a biomass direct-combustion power generation system in China: A combination of life cycle assessment and water footprint analysis

Biomass combustion for power generation plays an important role in achieving 1.5 °C climate target and fulfilling global energy demand, while putting pressure on global water resources. Confronted with severe water shortage, it is imperative to understand its comprehensive impact on water resource. Recently remarkable advances of life cycle assessment and water footprint analysis have been witnessed in this field. Based on a review of the two methods' history, we propose a combination evaluation framework and define an associated indicators set to integrate both methods' advantages. By methods integration, direct and indirect water use are combined with the green, blue, and gray water footprint to describe the water use in detail. Furthermore, the life cycle water footprint of a typical biomass direct-combustion power generation system in China is evaluated based on the combined method. Results show the system life cycle water use is 11.71 L/MJ, while agricultural plantation accounts for the major part (84.61%). In addition, direct green water footprint is the largest component (46.54%), while direct and indirect blue water footprints account for 36.59% and 1.74%, respectively; indirect gray water footprint is 1.771 L/MJ. In terms of water use intensity, the direct-combustion power generation is lower than bio-oil power generation, but far more than solar photovoltaic and wind power. Sensitivity analysis suggests that improving power generation efficiency, straw collection coefficient and cultivating high water-efficient crops can evidently contribute to alleviating water stress conditions for bioenergy production.

Quantifying uncertainties in greenhouse gas accounting of biomass power generation in China: System boundary and parameters

Systematically quantifying the greenhouse gas (GHG) emissions of biomass power generation is a prerequisite for robust decision-makings associated with the technology's scale deployment. This study compared the planting-to-wire GHG emissions of a typical corn-stover-based power generation system in China, estimated using one process-based and two hybrid life-cycle assessment (LCA) models. Results showed that emissions calculated by process-based LCA were 11% lower than that of hybrid models because of the truncations on services and accessory equipment. The two tiered hybrid approaches yielded total-supply-chain GHG footprints of material and equipment with a negligible difference (0.7%). The parameter settings varied by time and regions/countries resulted in temporal and spatial uncertainties of process-based LCA at 4%–10% and 0.1%–16% respectively. We proposed adopting hybrid LCA models for footprint calculation because of their strength in comprehensive accounting coverage, less dependence on data acquisition, and reduced temporal and spatial uncertainties. As the GHG footprint of biomass energy utilization is region-specific and determined by multiple factors, such as supply-chain configurations and landscape of power generation technology, results of this study help to understand the uncertainties and trade-offs associated with different LCA model deployments in China, and thus, contribute to advancing the country's biomass power sector moving forward.

The striking amount of carbon emissions by the construction stage of coal-fired power generation system in China

Based on an extensive review of related studies, the striking amount of carbon emissions induced by the construction stage of a typical 2 × 660 MW coal-fired power generation system is revealed, by means of systems LCA as a concrete hybrid of process analysis and input-output analysis. Differing from previous works that simply treat the whole inputs in the construction stage as some primary materials, this study inclusively covers all input items as products of the economy, supported by input-output database. An integrated inventory that contains over seventy items is established, in which the materials, equipment, and services inputs throughout the construction stage are given full consideration. In magnitude, the greenhouse gas emissions embodied in the construction stage of the power plant are calculated in carbon dioxide equivalent as 1.54% of those from coal combustion, which are several times or even one order of magnitude higher than that estimated in some previous studies. The emissions induced by coal-fired power generation infrastructure in China are accordingly estimated, in magnitude up to 0.6%, one-eighth and one-sixth of the total national emissions in China, UK and France, respectively. The outcome provides a unique perspective for policy makers into apprehending carbon emissions by the power sector.

Energy and water nexus in power generation: The surprisingly high amount of industrial water use induced by solar power infrastructure in China

A crucial aspect of the energy and water nexus is reflected with the revelation of the surprisingly high amount of industrial water use induced by plant infrastructure of a pilot solar power generation system in China, by means of a concrete hybrid of process analysis and Input-Output analysis. With an inclusive collection of all the input items as products of the economy, this scoping distinguishes from existing accountings that either overlook the construction stage or simply cover the plant infrastructure of solar power system as some primary materials. Supported by embodied water database from input-output analysis, the industrial water use induced by each input item is fully addressed. The industrial water use induced by the solar power plant infrastructure is revealed to be over one order of magnitude higher than that in previous scoping: this magnitude approximately doubles the life cycle industrial freshwater withdrawal of typical coal-fired power generation system for per unit amount of electricity generated. Under the 2020 scenario raised in the newly issued 13th Five Year Plan for Renewable Energy Development, the annual industrial water use induced by solar thermal power infrastructure in China is accordingly estimated, in magnitude up to around 30% of the total industrial freshwater use in Beijing in the year 2014, one-fourth of that in Tianjin, and one-tenth of that in Shanxi, respectively. In the long term water-saving planning, the promotion of solar power installations is afforded further consideration.

Life Cycle Assessment of a Co-Firing Power Generation System in China

Life Cycle Assessment of a Co-Firing Power Generation System in China

Energy–water nexus of wind power generation systems

Energy and water are two interwoven elements of power generation systems. Because wind power is regarded as a promising renewable energy, how to increase its production and reduce energy and water costs has attracted many attentions. However, there is a lack of comprehension of the energy–water nexus in wind power generation systems. In this study, we developed a new energy–water nexus analysis framework for wind power generation systems, which includes both element and pathway nexus analyses. In element nexus analysis, energy used for water extraction and wastewater treatment and water consumed for electricity generation were investigated. The mutual interactions and control situations within the wind power generation system were also examined in pathway nexus analysis based on Network Environ Analysis (NEA). Taking a typical wind power generation system in China as the case, the element nexus analysis results show that water consumptions per unit of wind power generation are much lower than those of the other power generation systems. Energy consumption of the water system in the wind power generation system is 3.395×107MJ, of which water extraction process constitutes 90.22%. In pathway nexus analysis, network utility analysis and network control analysis are performed to investigate the dominant sectors and pathways for energy–water circulation and the mutual relationships between pairwise components of the wind power generation system. The results of network utility analysis show that compartment of surface water and groundwater (WA) is beneficiary from waste treatment (WT), which implies that although extra energy is devoted to WT, the benefit of water recycling is larger than energy cost. The results of network control analysis indicate that on-grid power (PG) not only depends on direct wind resource input (WI) (with a dependence coefficient of 0.20), but also indirectly supported by major compartments of fossil fuel input (FU) (0.16), construction material input (CO) (0.14), and wind turbines manufactory (MA) (0.12). Compartments of WA and MA have large dependences on WT. Therefore, increasing wastewater and material treatment and recycling in the wind power generation system could reduce water and energy demand from the external environmental. Dissipation (DIS) mainly relies on FU (0.19), wind power generation (WP) (0.16) and CO (0.2), which should be the focus of dissipation reduction. The presented energy–water nexus analysis may shed light on synergistic management of wind power generation systems.

Biomass direct-fired power generation system in China: An integrated energy, GHG emissions, and economic evaluation for Salix

To gain a better understanding of the options of biomass power generation in China, this study presented an integrated energy, environmental, and economic evaluation for Salix in China, and a typical Salix direct-fired power generation system (SDPGS) in Inner Mongolia was selected for case study. A tiered hybrid life cycle assessment (LCA) model was developed to calculate the “planting-to-wire” (PTW) energy consumption, greenhouse gas (GHG) emissions, and economic cost and profit of the SDPGS, including feedstock cultivation, power plant construction and operation, and on-grid price with/without government subsidies. The results show that the PTW energy consumption and GHG emissions of Salix are 0.8MJ/kWh and 114g CO2-eq/kWh, respectively, indicating an energy payback time (EPBT) of 3.2 years. The SDPGS is not economically feasible without government subsidies. The PTW costs are dominated by feedstock cultivation. The energy saving and GHG mitigation benefits are still robust, even when the power plant runs at only 60% design capacity. For future development of biomass power in China, scientific planning is necessary to guarantee a sufficient feedstock supply. In addition, technology progress, mature industrial chains, and reasonable price setting policy are required to enable potential energy and environmental advantages of biomass power moving forward.

Analysis of the Impact Caused by Residential Users Distributed Photovoltaic Grid-Connected on Distribution Network

With more and more wide application of distributed power generation system, it is necessary to explore its impact on the power grid. The first residential user of distributed photovoltaic power generation system in China has recently connected to the power grid. A series of experiments were carried out by State grid metering center to detect status of the residential users system. The testing method of distributed photovoltaic power generation system and the results of field test are briefly introduced in this paper. Through the analysis of the test results, the characteristics of photovoltaic power generation system are discussed, in order to carry out further research of measurement technology.

The Energy Consumption and Environmental Impacts of Biomass Power Generation System in China

Combined with practical operation of a biomass direct-fired power pant in South China, the whole life cycle of the process, including biomass growing, transportation, pretreatment, combustion power generation and power plant manufacturing are analyzed by means of LCA. The energy consumption and the impact on environment in each stage are also collected and calculated. The results show that 2182.32 MJ fossil energy is consumed to generate 104 kWh power. The total loading of the impact on environment is 13.45 PET2000 and the mainly impact on environment is soot and ashes. Compared with coal-fired power, biomass direct-fired power plant can reduce 5282.87 kg CO2 emissions during the process of generating 104 kWh power, which plays a positive part in mitigating greenhouse gases.