Steam Blowing Techniques for Large Solar Thermal Power Plants

Due to the growing world population and its increasing energy demand, the construction of new power plants is inevitable. At the same time, it is necessary to keep the rise of the global average temperature well below 2 °C compared to pre-industrial level in order to significantly reduce the impacts and risks of climate change. Therefore, an environmental friendly energy infrastructure is required to reduce greenhouse gas emissions. Solar thermal power plants are a promising technology, as they provide the possibility to buffer solar energy in a thermal storage. Thus, it can produce electricity according to the demand and is independent of meteorological fluctuations. A life cycle assessment is necessary to assess the environmental impact of a solar thermal power plant and its individual components. This work analyses the extent of the environmental effects of solar thermal tower power plants in the following selected impact categories according to the CML-method: Global Warming Potential (GWP 100 years), Abiotic Depletion potential (ADP elements), Eutrophication potential (EP) and Acidification Potential (AP). The most ecologically relevant components are identified and modelled with different specifications in order to compare the influence of different building types. Furthermore, the life cycle assessment model is applied to different geographical locations in order to enable site-specific considerations. The selected locations are Upington in South Africa, Evora in Portugal and Calama in Chile. The life cycle inventory is generated based on an extensive literature research and forms the foundation for the modelling of solar thermal tower power plants in the LCA software GaBi ts. As a result, the most ecologically relevant components are determined. A comparison of the different locations allows statements on the ecological potential of solar thermal tower power plants at a specific site. The heliostats and the molten salt (MS) as heat transfer fluid and storage medium dominate the impact on the GWP 100 years. The heliostats consist mainly of steel and glass and are needed in large numbers. The molten salt is used in a high amount and consists of a mixture from sodium nitrate and potassium nitrate which both have a high impact on GWP. Moreover, the transport and the construction on site have relevant contributions to GWP. The impact of the transport results from the large mass of all shipped components. The impact of the construction on site has copper cables as the main contributor. The end-of-life scenarios have a significant effect on the total impact. Depending on the recovery of the metals and especially the further use of the molten salt, the environmental impact is decisively influenced.

An adaptive control application in a large thermal combined power plant

This paper discusses about one of the possible solutions to overcome the influence of dust on the surface of solar PV panel. A decrease in power output with the increase in particle deposition has been identified in large scale solar PV power generation where there were many numbers of solar panels connected in the form of arrays and each array requires a robot to carry out efficient cleaning with in stipulated time. Autonomous automatic cleaning operation along with self-control and monitoring of accumulated dust with proper coordination through networking between robots is prerequisite option to attain efficient cleaning system in large scale solar power plants. To accomplish the same, selection of appropriate communication technology for real time wireless networking of solar cleaning robots with low power consumption and data delay to operate over wide area is required. Here an attempt had been made to bring in an automated robot cleaning system using low power wide area network (LPWAN) based on a network of ESP 8266 Node MCU’s associated with a set of sensors under different configurations which showed successful results for implementation in industrial scale large solar PV power plants.

With the view to minimize the energy crisis due to the ever depleting non-renewable energy resources, this research aimed to apply nanotechnology to enhance the efficacy of solar energy power plant – a renewable energy resource. According to literature Concentrated Solar Power Plant system requires heat transfer fluid (HTF) for proficient working. This research reports the synthesis of novel, efficient heat transfer fluid doped with nano sized particle including carbon nanotubes and metal oxide i-e copper oxide. This nano heat transfer fluid (NHTF) has very low melting point in comparison to conventionally prepared molten salt mixture for heat transfer purpose which typically have high melting point characteristically 140°C or higher. Most prominently this NHTF has enhanced thermo-physical properties including high thermal stability and high specific heat capacity. These properties ensures effective increase in thermal energy storage (TES) which is a key factor in solar thermal power plant and make it broad range operating heat transfer fluid.

Repowering of an existing steam power plant by means of solar concentrating collectors is examined as a viable option to decrease CO2 emissions and increase electric power production during daytime peak load energy demanding hours. In the proposed scheme, the regenerative bleeds from the steam turbine are partially intercepted while boiler feed-water is heated by means of parabolic solar trough concentrating collectors. It is considered that fossil boiler, steam turbine and condenser are the same of the original plant, without modifications. After choosing a steam cycle reproducing an existing power plant, the scheme of solar repowering is examined and the efficiency of conversion of the solar energy is optimized in relation to the characteristics of the solar collector. The paper shows that the modified scheme produces very little effects on the working conditions of the existing components, either at full load or partial load, and does not reduce the conversion efficiency of the fossil fuel. In comparison with solar thermal power plants with heat storage and only solar energy as thermal input, the proposed scheme is expected to have comparable efficiency but lower costs per kWh produced, as a consequence of the fact that there is no need for steam turbine, condenser, cooling tower and auxiliary boiler. Moreover it is expected that personnel and maintenance costs will be lower.

At the request of USA sponsors Spencer Management Associates (SMA) and Sun✦Lab, China's Center for Renewable Energy Development and former Ministry of Electric Power conducted an initial appraisal of the issues involved with developing China's first solar thermal electric power plant in the sunbelt regions of Tibet or Xinjiang provinces. The appraisal concerns development of a large-scale, grid-connected solar trough or tower project capable of producing 30 or more megawatts of electricity. Several of the findings suggest that Tibet could be a niche market for solar thermal power because a solar plant may be the low-cost option relative to other methods of generating electricity. China has studied the concept of a solar thermal power plant for quite some time. In 1992, it completed a pre-feasibility study for a SEGS-type parabolic trough plant with the aid of Israel's United Development Limited; Because the findings were positive, both parties agreed to conduct a full-scale feasibly study. However, due to funding constraints, the study was postponed. Most recently, Sun✦Lab and SMA asked China to broaden the analysis to include tower as well as trough concepts. The findings of this most recent investigation, completed in November of 1997, are the subject of this paper. The main conclusions of all studies conducted to date suggest that a region in the proximity of Lhasa, Tibet, offers the best near-term opportunity within China. The opportunities for solar thermal power plants in other regions of China were also investigated.

Performance evaluation of large solar photovoltaic power plants in Spain

During last, many years the electrical energy is generated in large Thermal Power Plants (TPP) and Nuclear Power Plants (NPP). Thermal Power Plants are the main electricity generating stations that are functioning based on the principle of thermal energy conversion into mechanical and finally into electrical energy. The noted conversion is accomplished by the condensation type of thermodynamic cycle that is called “Rankin” cycle. There are in use Co - generation heat and power plants too, which are functioning based on “Bryton” thermodynamic combined cycle. These plants are assigned for simultaneous generation and distribution of thermal and electrical energy. For this reason, they are more efficient. However, all mentioned cycles and conforming to them power plants serving for generation and distribution of large quantity of electricity from energy generating centralized stations to large number of consumers, which are located in significantly long distance from generating stations. The analysis of existing practice of use of mentioned types of electricity generating powerful centralized stations because of large losses of energy are not enough efficient and cost effective. For instance, the COP of electricity generating station, working by well-known Rankin cycle, makes only 30%, because about 70% of produced thermal energy should be lost to the surrounding environment for providing required conditions of electricity production. It is obvious that such big energy loses extremely pollute the environment, provoke global climate change and forces Governments adopting more forceful approaches to reduce carbon and other harmful gases rejections, increase efficiency of energy generation and improve environmental situation. For this reason, after having studied the potential possibilities of reduction of harmful gases rejections and increase of energy efficiency of electricity generation conventional mods the authors of this article became convinced in impossibility of assigned task and have decided to suggest novel and higher efficiency technology for electric energy generation. From this, point of view this article may become a guideline that can help to improve the present environmental and economic situations.

Third international conference on photochemical conversion and storage of solar energy

The tendency of renewable energies is one of the consequences of changing attitudes towards global energy issues. As a result, solar energy, which is the leader among renewable energies based on availability and potential, plays a crucial role in thoroughly filing global needs. Significant problems with the solar thermal power plants (STPP) are the operation time, which is limited by daylight and is approximately half of the power plants with fossil fuels, and the capital cost. In the present study, a new suggested sketch of adding latent heat storage (LHS) filled with commercial phase change material (PCM) to a 500-kW STPP case study has been investigated. Solar system details and irradiation amounts for a case study, including total and beam radiation have been determined. Also, the theoretical energetic and exergetic analysis of adding PCM storage to STTP is conducted, which showed a 19% improvement in the exergetic efficiency of the power plant to reach 30%. Besides, an optimized storage tank and appropriate PCM material have been investigated and selected concerning the practical limitations of the case study. By designing a new cycle, the LHS will be charged during daylight and will be discharged at night, doubling power plant operation time up to 2500[Formula: see text]h. Finally, exergoeconomic survey of STPP hybrid with PCM storage was carried out using Engineering Equation Solver (EES) program with genetic algorithm (GA) for three different scenarios, based on eight decision variables, which led us to decrease final product cost (electricity) in optimized scenario up to 30% compared to base case scenario from 28.99 to 20.27 $/kWh for the case study. Also, a comparison is made to demonstrate the effectiveness of the proposed new cycle on 250, 500, 1000, and 2000 kW STTPs.

Thanks to the solid standards and principles of design and restoration planning after a blackout, power systems in developed economies generally show a high level of resiliency. Nevertheless, this power system restoration practice strongly relies on conventional power plants, e.g. large thermal power plants. As future global goals aim at reducing the use of fossil fuels and lowering carbon-dioxide emissions, conventional power plants are often taken out of operation. These are characterised by slow start-up times and considerable use of fossil fuels. In this context, large offshore wind farms (OWFs) show potential as renewable-based black start (BS) service providers. These can be equipped with a self-starter, e.g. synchronous generators or innovative power-electronic-based converters, such as battery energy storage systems (BESSs) and/or grid-forming wind turbines in order to BS the system. Additionally, state-of-the-art complementary devices such as STATCOMs or synchronous condensers can help with dynamic regulation and support the OWF both in island operation and BS. In this paper, an overview of different system configurations for OWF BS is presented. Firstly, the requirements for BS from non-conventional power plants are outlined. Afterwards, the challenges faced by OWFs to fulfil these requirements are identified. Finally, different solutions for system configuration to equip OWFs for BS are proposed.

With the background of energy conservation and environmental protection,some application achievements of type selection and design optimization for heat engine equipments in large thermal power plant were analyzed,including steam turbine, boiler and main auxiliary equipments. The characteristics and shortcomings of equipment selection optimization of thermal power engine were pointed out,as well as some measures and suggestions were proposed,which have provided reference for the heat engine equipment selection in 600 MW and above large thermal power units.

Parabolic trough solar technology is the most proven and lowest cost large-scale solar power technology available today, primarily because of the nine large commercial-scale solar power plants that are operating in the California Mojave Desert. These plants, developed by Luz International Limited and referred to as Solar Electric Generating Systems (SEGS), range in size from 14–80 MW and represent 354 MW of installed electric generating capacity. More than 2,000,000m2 of parabolic trough collector technology has been operating daily for up to 18 years, and as the year 2001 ended, these plants had accumulated 127 years of operational experience. The Luz collector technology has demonstrated its ability to operate in a commercial power plant environment like no other solar technology in the world. Although no new plants have been built since 1990, significant advancements in collector and plant design have been made possible by the efforts of the SEGS plants operators, the parabolic trough industry, and solar research laboratories around the world. This paper reviews the current state of the art of parabolic trough solar power technology and describes the R&D efforts that are in progress to enhance this technology. The paper also shows how the economics of future parabolic trough solar power plants are expected to improve.

A systematic literature review on the economic performance of solar thermal power plants including integrated solar combined cycle (ISCC) plants was conducted. A number of solar thermal technologies like parabolic trough (PT), solar tower (ST), linear Fresnel reflector (LFR) and solar dish (SD) were evaluated. The evaluation revealed that solar tower plants typically had the highest capital costs, followed by parabolic-trough and linear Fresnel plants. The results of the studies showed that at smaller capacities of 10–50 MW, PT plants achieved lower LCOE than ST plants, while at larger capacities of 100 MW and above, ST tend to have lower LCOE than PT. There was limited comparative studies on the economic performance of LFR and SD plants. Hence, future studies should focus on the economic impact of different solar thermal technologies including LFR and SD of various capacities using homogeneous modelling conditions. The economic performance of direct steam generation (DSG)-ISCC plants was compared to ISCC, combined cycle gas turbine (CCGT) and conventional solar thermal plants and the results showed that DSG-ISCC plants achieved the lowest LCOE values. Studies also showed that in general, hybrid plants achieved lower LCOE than standalone solar thermal plants. LCOE and capital costs were the dominant financial metrics used in the literature, with very few studies using total life cycle cost, revenues, payback time and internal rate of return. Future studies should include these metrics in order to provide a comprehensive financial assessment of solar thermal power plants, enabling their economic performance to be compared with other renewable and non-renewable energy systems.

Currently, intensive work is underway in Poland to increase the share of renewable energy sources in the overall energy balance. Therefore, this paper presents the possibilities of using concentrated solar power in zones with a temperate climate. A simplified model based on the energy balance in the solar collectors considering the main operating parameters of the typical solar power plant was developed. It should be noted here that the model does not take into account issues related to heat accumulation and electricity generation in a Solar Thermal Power Station. The simulation of forced convection inside the solar collector absorber was additionally included in the calculations to improve its accuracy. The model was verified using actual heat measurements at the outlet of the parabolic collector installation at a Solar Thermal Power Station located in the south of Spain. The heat generated by a similar solar collector system in a selected region with a temperate climate, the city of Bialystok (north-eastern Poland, geographic coordinates: 53°08′07″ N 23°08′44″ E) was determined by the developed simplified model for different months of the year. Based on the results of the analysis, it was found that the energy obtained from the same area of concentrated solar collectors located near Bialystok is eight times lower compared to the location in Cordoba depending on the variant of the power plant operation.