High Plant Efficiency Research Articles

Process development for integrated coal gasification solid oxide fuel cells hybrid power plants – Investigations on solid oxide fuel cells/gas turbine hybrid power plants run on clean coal gas

On the road to sustainable generation of electricity, the efficiency of fossil-fuel power plants and CO2 emissions must be increased and decreased respectively. Integrated coal gasification solid oxide fuel cell hybrid power plants have the potential to achieve high power plant efficiencies and enable opportunities for the efficient capture of CO2. The investigation of such power plants is the subject of this publication. The developed systems are based on conventional integrated coal gasification combined cycle technology and integrated with solid oxide fuel cells preceding the combined cycle process. The state of development of the selected solid oxide fuel cell technology is similar to that of integrated coal gasification combined cycles. Along with the base case, several other concepts with and without CO2 capture are developed using various process technologies. Fundamental system and sensitivity analyses are performed using simplified sub-processes to obtain general statements and trends as well as to calculate optimal boundary conditions for the overall systems. The simulations show that the preparation of process gas using a water gas shift reactor before entering the solid oxide fuel cells is beneficial for the overall efficiency. If a CO2 capture process is included, 11–16% lower net efficiencies are achieved. The level of specific CO2 emissions is significantly influenced by the net efficiency of the power plants and the portion of carbon bound as CO2 at the beginning of the CO2 capture process. Here, the combination of CO2 capture and water gas shift reactor upstream of the solid oxide fuel cells is the preferred concept regarding efficiency and CO2 emissions.

CRISPR/Cas-mediated gene targeting in plants: finally a turn for the better for homologous recombination.

We summarize recent progress of CRISPR/Cas9-mediated gene targeting in plants, provide recommendations for designing gene-targeting vectors and highlight the potential of new technologies applicable to plants. Gene targeting (GT) is a tool of urgent need for plant biotechnology and breeding. It is based on homologous recombination that is able to precisely introduce desired modifications within a target locus. However, its low efficiency in higher plants is a major barrier for its application. Using site-specific nucleases, such as the recent CRISPR/Cas system, GT has become applicable in plants, via the induction of double-strand breaks, although still at a too low efficiency for most practical applications in crops. Recently, a variety of promising new improvements regarding the efficiency of GT has been reported by several groups. It turns out that GT can be enhanced by cell-type-specific expression of Cas nucleases, by the use of self-amplified GT-vector DNA or by manipulation of DNA repair pathways. Here, we highlight the most recent progress of GT in plants. Moreover, we provide suggestions on how to use the technology efficiently, based on the mechanisms of DNA repair, and highlight several of the newest GT strategies in yeast or mammals that are potentially applicable to plants. Using the full potential of GT technology will definitely help us pave the way in enhancing crop yields and food safety for an ecologically friendly agriculture.

Performance enhancement and optimization of solar chimney power plant integrated with transparent photovoltaic cells and desalination method

This study proposed two novel configurations of Conventional Solar Chimney Power Plants (CSCP) integrated with transparent PV cells (PVSCP) and saline water desalination (PVDSCP) method to improve utilization of solar energy and land resource. Mathematical models were developed for each configuration and validation of CSCP was performed with experimental results. Results showed that majority of data points are within error band of ±15%. Comparative study of CSCP, PVSCP and PVDSCP exhibited that PVDSCP outperforms others with significantly larger collector and plant efficiencies. PVDSCP collector efficiency was 26.13% and 21.92% higher compared to CSCP and PVSCP respectively. Parametric studies of key inputs showed that all geometry parameters and operating conditions have significant effects on plant efficiency and should be considered in optimization. DIRECT optimization of plant efficiency demonstrated that PVDSCP efficiency was 37.15% and 36.1% higher than optimized CSCP and PVSCP respectively. Implementation of proposed optimized configurations as PVSCP and PVDSCP can enhance the plant efficiency of the original Manzanares pilot plant relatively by 55.97% and 71.8% respectively. These systems can be used for performance enhancement of CSCP with advantages of relatively high plant efficiency, endless capacity, simple structure, low cost and no pollution.

Evaluation of chromium phyto-toxicity, phyto-tolerance, and phyto-accumulation using biofuel plants for effective phytoremediation

Contamination of chromium signifies one of the major threats to soil system. Phytoremediation is a promising technique to reclaim metal-contaminated soil using plants which are capable to tolerate and accumulate heavy metals within in their tissues. The experiment reported in this article was carried out with six biofuel plant species, Cyamopsis tetragonoloba, Glycine max, Avena sativa, Abelmoschus esculentus, Sesamum indicum and Guizotia abyssinica, were subjected to eight Cr concentrations (0.5, 2.5, 5, 10, 25, 50, 75 and 100 mg kg−1 soil) to investigate Cr toxicity, tolerance and accumulation. After 12 weeks of experiment, Cr phytotoxicity on morphological and biochemical parameters were evaluated. For six plant species, seed germination and most of growth parameters were significantly (p < 0.05) reduced under high Cr stress. Chlorophyll contents were also decreased with increased Cr concentrations. Accumulation of Cr was higher in roots than shoot in all studied plants. Significant Cr accumulation was in the order of C. tetragonoloba > A. sativa > A. esculentus > S. indicum > G. max > G. abyssinica. Bioconcentration factor, bioaccumulation coefficient, translocation factor and phytoremdiation ratio suggested that C. tetragonoloba, A. sativa and A. esculentus being more tolerant; having higher Cr accumulation and could be a high efficient plants for reclamation of Cr-contaminated soils.

Bioclimatic assessments for tea cultivation in Western Nghe An

Bioclimatic assessments for tea cultivation in Western Nghe An

Affine nonlinear control for an ultra-supercritical coal fired once-through boiler-turbine unit

The ultra-supercritical once-through boiler (OTB) unit is an advanced power generation technology with high plant efficiency, high coal utilization, and low emission. However, it is difficult to realize a coordinate control for the ultra-supercritical OTB unit to achieve fast and stable dynamic response during load tracking and grid frequency disturbances, and its complexity and nonlinearity result in the ultra-supercritical OTB unit becoming a multiple-input and multiple-output system filled with severe coupling and interference. According to the affine nonlinear system theory, a nonlinear control method is developed to solve nonlinear decoupled optimal control problems of a nonlinear ultra-supercritical OTB unit. Firstly, the exact linearization technique is used to transform the nonlinear ultra-supercritical OTB system into a linear one and an optimal LQR is designed for the corresponding nominal system. The optimal nonlinear control law can be derived by coordinate conversion and condition feedback and the study can be conducted for reasonable experiments and analysis. Then, compared with the linear PID control and model predictive control, the effectiveness and superiority of the proposed nonlinear optimal control have been verified through different loads disturbances from 50% to 100% using the Matlab/Simulink Toolbox.

Bilevel and parallel programing‐based operability approaches for process intensification and modularity

Process operability emerged in the last decades as a powerful tool for the design and control of chemical processes. Recent efforts in operability have been focused on the calculation of the desired input set for process design and intensification of natural gas utilization applications described by nonlinear models. However, there is still a gap in terms of problem dimensionality that nonlinear operability methods can handle. To fill this gap, in this article, the incorporation of bilevel and parallel programing approaches into classical process operability concepts is discussed. Results on the implementation of the proposed method show a reduction in computational time up to two orders of magnitude, when compared to the original results without parallelization. These results could be extrapolated for use in a supercomputer as presented in the computational time analysis performed. In terms of intensification, the proposed approach can produce a natural gas combined cycle plant modular design with a dramatic reduction in size, from the original 400 to 0.11 MW, while still keeping the high net plant efficiency. This approach thus provides a computationally efficient framework for process intensification of high‐dimensional nonlinear energy systems toward modularity. The proposed approach also enables the verification of a modular design and conditions that can be obtained according to economic and physical constraints associated with a specific natural gas well production. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3042–3054, 2018

English

English

Dynamic Optimization and Control of Chemical Looping Combustion Combined Cycle Power Plants

Integration of combined cycle (CC) with chemical-looping combustion power plants (CLC) is studied for its potential for high power plant efficiency and low-cost CO2 capture. Dynamic modeling of the integrated process is used as a tool to analyze the extrema of CLC-CC power plant efficiency. Specifically, this work proposes control architectures for the CLC reactor and the integrated power plant. The time-averaged optimal CLC-CC power plant efficiency is estimated at 51.84% with CO2 capture efficiency at 96%. The main factor that limits the CLC-CC power plant efficiency is the reactor temperature, which is constrained by the oxygen carrier material. Plant-level sensitivity analysis shows that the inlet air temperature at the heat removal stage and gas compressor/gas turbine pressure ratio are the most important operating variables and if properly tuned the CLC-CC power plant can reach efficiencies sufficiently high for its economic deployment as a carbon neutral power generation option.

Performance evaluation of photovoltaic/thermal–HDH desalination system

The efficiency of photovoltaic (PV) panel drops with increase in cell temperature. The temperature of the PV panel can be controlled with various cooling techniques. In the proposed work the PV panel is cooled by circulating water and the recovered heat energy is used to run a humidification and dehumidification desalination to produce distilled water from sea water (or) brackish water. This work deals with a detailed analysis of performance of combined power and desalination (Photovoltaic/Thermal–Humidification and Dehumidification) system. A mathematical model of PV/thermal–humidification dehumidification plant was developed and simulations were carried out in MATLAB environment. The performance of photovoltaic/ thermal desalination (Photovoltaic/Thermal–Humidification and Dehumidification) system was investigated under various solar radiation levels (800–1000 W/m2). For each solar radiation level the effect of mass flow rate of coolant water (30–110 kg/h) on water outlet temperature, PV efficiency, PVT thermal efficiency, distilled water production, and plant efficiency was studied. Results show that under each solar radiation level increasing coolant flow rate increases efficiency of PV panel and reduces the plant efficiency. The highest PV efficiency (16.598%) was reached under 800 W/m2 at mass flow rate of 110 kg/h and the highest plant efficiency (43.15%) was reached under 800 W/m2 at a mass flow rate of 30 kg/h. The maximum amount of distilled water production rate (0.82 L/h) was reached under 1000 W/m2 at water mass flow rate of 30 kg/h.

Compliance choice analysis for India's thermal power sector in the market-based energy efficiency regime

India has recently introduced a market-based scheme―Perform, Achieve, and Trade―to realize emission reduction by enhancing energy efficiency. In the case of thermal power plants, investment in energy efficiency projects, using clean coal and buying energy saving certificates are the available compliance options for complying with the scheme. These options are associated with specific forms of cash flows that depend on the uncertain price of energy saving certificates and clean coal premium. This paper uses a Monte Carlo-based decision tree approach to find the optimal compliance options for an efficient and a less efficient thermal power plant. The decision tree evaluates different sequences of compliance options in three consecutive PAT cycles by using the discounted cash flows and their associated probabilities. The study shows that investment in energy efficiency is optimal in the first PAT cycle for the inefficient plant only. The threshold certificate price for the efficient plant is substantially higher than the inefficient plant, implying that the real efficiency improvement is likely to take place in the low-efficiency plants. The study also indicates that the investment in high-efficiency plants is not optimal over a wide range of certificate prices and the incremental cost of clean coal.

Driving forces and obstacles to nuclear cogeneration in Europe: Lessons learnt from Finland

Nuclear power plants generate electricity and a large amount of waste heat which is valuable for cogeneration. District heating (DH) is a suitable technology to decarbonize the European heat sector. By contrast with most of nuclear non-electric applications, nuclear district heating (NDH) has already been implemented in Europe, thus providing us with some valuable empirical insights. This paper investigates the forces and obstacles to nuclear cogeneration by looking at the Loviisa 3 NDH project in Finland. The key forces are energy efficiency, decarbonization of the heat sector, operational competitiveness of future nuclear technologies, and synergies with renewable energies. The key obstacles are split incentives, electricity prices volatility, inexpediency of business models and regulatory frameworks, electioneering of local authorities and pessimist expectations with regards to project financing. Policy makers should recognize nuclear plants alongside other utilities generating large amounts of wasted heat. International cooperation programs involving both nuclear and heat stakeholders should be encouraged. EU28 Member States wanting to promote nuclear cogeneration may consider providing support for the electricity generated by high-efficiency plants.

Experimental evaluations of solid-fueled pressurized chemical looping combustion – The effects of pressure, solid fuel and iron-based oxygen carriers

Coal-based Pressurized Chemical Looping Combustion Combined Cycle (PCLC-CC) is the second generation of coal-fueled CLC plant, which possesses much higher plant efficiency and lower-CO2 capture cost compared to the first generation - Coal-based CLC combined solely with steam cycle. PCLC-CC has a similar plant configuration to the Pressurized Fluidized Bed Combined Cycle (PFBC), and is composed of a PCLC Island, gas turbine, Heat Recovery Steam Generator (HRSG) and steam cycle. In the fuel reactor of PCLC Island, the metal-based oxygen carrier (OC) supplies oxygen for coal combustion and in-situ CO2 capture. The air reactor of PCLC Island, where the OC is re-oxidized by air, serves as a combustion reactor to produce oxygen-depleted air of high temperature and high pressure to drive the gas turbine and the following steam cycle for large-scale power generation. This research provides an initial understanding of the complex reactions in the fuel reactor of the solid-fueled PCLC Island in the pressures range of 1–6bars. Experiments conducted in the TGA apparatus and the fixed- and fluidized-bed reactors demonstrated the effects of operational pressure, coal char reactivity and different iron-based OCs behavior on the performance of PCLC.

Optimizing the CSP-Calcium Looping integration for Thermochemical Energy Storage

Thermochemical energy storage (TCES) is considered a promising technology to overcome the issues of intermittent energy generation in Concentrated Solar Power (CSP) plants and couple them with yearly electricity demand. The development of this technology could favor the commercial deployment of CSP, which is considered as a key factor for new challenges in reducing GHG emissions. Among other possibilities, using the Calcium Looping (CaL) process for TCES is an interesting choice mainly due to the low cost of natural CaO precursors such as limestone (below $10/ton) and the high energy density that can be achieved (around 3.2GJ/m3). This manuscript explores several configurations in order to maximize the performance of the CSP-CaL integration with the focus on power cycle integration in the carbonator zone. For this purpose, firstly, a discussion about the possibility of using open and closed power cycles is carried out, which leads to the conclusion that a CO2 closed cycle is more appropriate. Then, a closed regenerative CO2 Brayton cycle is analyzed in further detail and optimized by means of the pinch-analysis methodology. A main output is that high plant efficiencies (of about 45%) can be achieved using a simple closed CO2 Brayton power cycle. The optimized integration layout shows good performances at carbonator to turbine outlet pressure ratios around 3, thus allowing for a feasible integration of the power cycle in the CSP-CaL system.

Construction of high-efficiency transformation vector with multiple insect-resistant genes and expression in tobacco

A high-efficiency plant transgenic vector expressing multiple genes has been modified from expression vector pCAMBIA1302. Briefly, multiple cloning sites of a cloning vector pUCm-T were constructed into plant transgenic vector pCAMBIA1302 backbone using Bsp120 I and Spe I restriction digest site. Two Bt genes, cry1Ac and cry3A, were then constructed into the modified transgenic vector in different orders as p1870-35S::cry1Ac-Coy::cry3A and p1870-Coy::cry3A-35S::cry1Ac, respectively. Transgenic tobacco plants were generated using Agrobacterium-mediated transformation method. Polymerase chain reaction (PCR) results showed that both the exogenous genes were integrated into the genome of tobacco. Fluorescence qRT-PCR detected both transgenes and further ELISA assay validated the expressed Bt proteins. Transgenic lines showed enhanced resistance to larvae of Helicoverpa armigera Hubner in the further feeding assays. In conclusion, our modified transgenic vector was suitable for multiple gene expression and would greatly facilitate our future research.

냉각공기 예냉각을 통한 가스터빈 설계변수 변화에 의한 복합발전시스템 성능향상 분석

Turbine blade cooling is one of the major technologies to enhance the performance of gas turbine and combined cycle power plants. In this study, two cases of coolant pre-cooling schemes were applied in combined cycle power plant: decrease of coolant mass flow needed to cool turbine blade and increase of turbine inlet temperature (TIT). Both schemes are benefited by the decrease of coolant temperature through coolant pre-cooling. Under the same degree of pre-cooling, increasing TIT exhibits larger plant power boost and higher plant efficiency than reducing coolant flow. As a result, the former produces the same gas turbine power with a much smaller degree of pre-cooling than the latter. Another advantage of increasing TIT is a higher plant efficiency. Even with an assumption of partial achievement of the theoretically predicted TIT, the method of increasing TIT can provide considerably larger power output.

고효율 저공해 청정화력 발전동향

고효율 저공해 청정화력 발전동향

Technical and Economical Assessment of the Indirectly Heated Carbonate Looping Process

Carbonate looping promises low energy penalties for postcombustion CO2-capture and is particularly suited for retrofitting existing power plants. To further improve the process, a new concept with an indirectly heated calciner using heat pipes was developed, offering even higher plant efficiencies and lower CO2 avoidance costs than the oxy-fired standard carbonate looping process. The concept of the indirectly heated carbonate looping (IHCL) process was tested at sufficient scale in a 300 kWth pilot plant at Technische Universität Darmstadt. The paper presents a technical overview of the process and shows first test results of the pilot plant. Furthermore, the concept is economically evaluated and compared to other carbon capture processes.

An Effective Nonlinear Multivariable HMPC for USC Power Plant Incorporating NFN-Based Modeling

The ultra-supercritical (USC) unit is an advanced power generation technology with high plant efficiency, high coal utilization, and low emission. However, it is difficult to realize a coordinate control for the USC unit to achieve fast and stable dynamic response during load tracking and grid frequency disturbances, because it is complex, nonlinear, and large scale. This paper presents a nonlinear hierarchical model predictive control (HMPC) to incorporate both the plant-wide economic process optimization and the regulatory process control into a hierarchical control structure, in which the model predictive control (MPC) technology is utilized to solve the multilayer optimization problem. While the nonlinear HMPC optimization problems can be nonconvex, the neuro-fuzzy network (NFN) modeling on USC is incorporated to facilitate the convex quadratic program (QP) routine. Detailed analysis on load tracking and grid frequency disturbances via simulations has been addressed to demonstrate the effectiveness of the proposed nonlinear HMPC.

Photovoltaic and Micro-Hydroelectric Proposed Plant for Stand Alone Electric Generation in a Sixty-Floor Skyscraper (P60)

Abstract: The aim of this paper is the feasibility study of a micro-hydroelectric (Pelton turbine with a rated power lower than 50 kW) and a Photovoltaic plant integrated in a sixty floor skyscraper. In this proposal, the hydraulic plant is located in the foundation and it is designed to use the greywater from each apartment; the photovoltaic system is on the top of the building, to take advantage of the height and the wind. A multi-tank configuration has been analyzed, its periodical emptying, fixes and regulate the turbine working cycles, guaranteeing a steady power generation; at the bottom of this turbine, a high efficient ultra-filtration plant has been designed. The purified water is now ready to be pumped back to the users and used again. On the roof, there are 28 solar strings, each one of 25 serial panels made, facing south and installed at a tilt angle of 35°. The total power is 165 kW p .