Utility Power Generation Research Articles

Investigation of CuO-based oxygen carriers modified by three different ores in chemical looping combustion with solid fuels

This effort is to improve CuO’s chemical-looping characteristics by introducing iron ore, chrysolite and limestone to obtain high power efficiency in chemical looping combustion (CLC) power plants. The reactivity and oxygen uncoupling behavior were evaluated by thermogravimetric analysis (TGA) in N2 and CO2 atmosphere under different heating rate. CuO modified by chrysolite and limestone showed better performance than iron ore-added CuO oxygen carrier (OC) in a CLC system. CO2 could play an important role in the gasification of char only when the temperature is above 800 °C. Two peaks were found in the Differential thermal gravity (DTG) curve when modified CuO reacted with char. That could be the solid-solid reaction turned into gas-solid reaction with temperature increasing. Scanning electron microscopy (SEM)/energy-dispersive X-ray (EDX) technique analysis indicated an enhancement of high temperature tolerance of Cu-based OCs, while CuO occurred sever sinter and agglomeration. Higher temperature tolerance means higher temperature off-gas from the fuel reactor entering the heat utilization power generation system, which could obtain higher efficiency in CLC power plants.

Does a small difference make a difference? Impact of feed-in tariff on renewable power generation in China

This study investigates the effectiveness of regionally differentiated feed-in tariffs (FIT) for the development of renewable energy in China. By using a spatial regression discontinuity design, we estimate the impacts of regionally differentiated FITs on the outcome indicators of wind and solar power generation, such as utilization rate, installed capacity, power generation, and hours of operation. Our findings show that FIT implementation plays an important role in promoting renewable energy development. A small difference in the tariff rate leads to statistically significant differences in outcome indicators among regions. Our results suggest that regionally differentiated FITs might help mitigate the overproduction of wind electricity in regions with abundant wind resources but low electricity demand. In addition, we conclude that enlarged tariff gap among regions can lead to greater impact on increasing installations of renewable power generation facilities in resource-poor regions. • We explore the impact of feed-in tariffs policy in China. • We use a spatial regression discontinuity design to investigate the policy impact. • Results show that a small difference in the tariff rate makes a significant impact. • The regionally differentiated tariffs might help mitigate the curtailment issue.

Research on Releasing Plans of Power Generation and Power Utilization in China

Chinese government intends to fully liberalize the power generation and utilization plans for operating power users. This paper analyzes the problems faced when power generation and utilization plans fully liberalized, that is priority electricity unbalance problem and power grid enterprises’ income problem. Then three schemes for priority generation and purchase matching as well as two schemes for price adjustment are proposed. After comparing the advantages and disadvantages of each schemes, we recommend the partly decoupling mode for priority generation and purchase matching, that is allocating priority purchase power to clean energy first, and sharing the shortfall to conventional units in proportion. We also recommend cost sharing mode for price adjustment, that is determining priority generation plans in advance, and calculating related costs in transmission and distribution prices for market-oriented users.

Accurate Study and Evaluation of Small PV Power Generation System Based on Specific Geographical Location

As an important new energy, solar energy has been extensively used in the world and different types of solar energy systems have been used in different fields. The photovoltaic power generation system has obvious advantage and high stability compared with other energy systems. Furthermore, the small-scale photovoltaic power generation system has a wider application in the field of power generation due to the performance of high efficiency. In this paper, the optimization research and system evaluation of small-scale photovoltaic power system have been studied in different areas by simulation and experimental methods. Based on the determination of photovoltaic model system, four typical geographical locations are selected and PVsyst is applied to the simulation study. The annual power output is 4829 kWh, 3489 kWh, 4455 kWh, 2766 kWh and the solar energy utilization efficiency is 14.91%, 14.79%, 17.66%, 15.77% for Mexico City, Xinyang, Changchun and London respectively from the simulation results. The results show that the radiation conditions, the optimum tilt angle, the minimum spacing and different geographical locations are the main reasons for the difference of power generation and solar energy utilization efficiency. Subsequently, Changchun is selected as the experimental area to carry out experimental research and verify the conclusion of the simulation study. The volt ampere characteristic curve and power output curve show that the photovoltaic system has no defects, hot spots, partial shading and damage. The annual total power generation of Changchun is 4119 kWh. Hence, the simulation results are in good agreement with the experimental results. Consequently, the application of small photovoltaic power generation system requires to fully consider the regional conditions and key parameters (optimum tilt angle, minimum spacing, etc.) to obtain better power generation efficiency.

Dynamic measurement of gas volume fraction in a CO2 pipeline through capacitive sensing and data driven modelling

Gas volume fraction (GVF) measurement of gas-liquid two-phase CO2 flow is essential in the deployment of carbon capture and storage (CCS) technology. This paper presents a new method to measure the GVF of two-phase CO2 flow using a 12-electrode capacitive sensor. Three data driven models, based on back-propagation neural network (BPNN), radial basis function neural network (RBFNN) and least-squares support vector machine (LS-SVM), respectively, are established using the capacitance data. In the data pre-processing stage, copula functions are applied to select feature variables and generate training datasets for the data driven models. Experiments were conducted on a CO2 gas-liquid two-phase flow rig under steady-state flow conditions with the mass flowrate of liquid CO2 ranging from 200 kg/h to 3100 kg/h and the GVF from 0% to 84%. Due to the flexible operations of the power generation utility with CCS capabilities, dynamic experiments with rapid changes in the GVF were also carried out on the test rig to evaluate the real-time performance of the data driven models. Measurement results under steady-state flow conditions demonstrate that the RBFNN yields relative errors within ±7% and outperforms the other two models. The results under dynamic flow conditions illustrate that the RBFNN can follow the rapid changes in the GVF with an error within ±16%.

Techno-economic performance comparison of enhanced geothermal system with typical cycle configurations for combined heating and power

The hot dry rock contains abundant heat, which can be exploited by enhanced geothermal systems, being one of the most commonly used geothermal power generation solutions. To enhance the power generation efficiency and utilization of geothermal resource, four combined heating and power systems are presented for geothermal fluids temperature ranging from 120 °C to 220 °C and dryness between 0 and 0.9. The operating parameters of four enhanced geothermal systems are respectively optimized, and the system performances are analyzed and compared. The results showed that the system performances as well as the optimal operating conditions varied with the temperature and dryness of the geothermal fluid. The double-flash organic Rankine cycle based combined heating and power system exhibited the highest power generation efficiency under geothermal fluid temperature and dryness coupling. The double-flash organic Rankine cycle based combined heating and power system had the highest techno-economic performance in the practical application, which the levelized cost of electricity was 0.0831 $/kWh and the payback period was 9.43 years. The organic Rankine cycle subsystem using n-Octane showed preferable power generation performance, while using n-Decane showed preferable techno-economic performance. Moreover, the enhanced geothermal system configuration and its operating parameters should match with actual local geothermal fluid conditions and the double-flash organic Rankine cycle based combined heating and power system was recommended in most cases.

Matrix Converter Based Maximum Power Extraction through Wind Turbine and Induction Machine

Wind power extraction has found an expressive growth in the past few years. This work endeavors on maximum utility power generation from wind resource and fulfill the needs of the society. Power extraction is composed of wind turbine (WT), induction machine (IM) and matrix converter (MC) forms a system of wind energy conversion (WECS). The stator and rotor synchronous speed of the IM is controlled by adjusting the frequency using MC for different given wind speeds. As the power accessible from induction generator (IG) is a component of WT shaft speed, so that maximum power is extracted by changing frequency for different wind speeds. MC acts as bridge between the grid and induction generator to confirm purely active generated power injection to the grid and maintains power factor at unity (UPF) at the grid side. To track and extract the maximum power for different wind velocities based on constant voltage/frequency control strategy to regulate the shaft speed of IM accordingly is presented. The effective maximum power generation is supported by simulation results and analysis with respect to WT characteristics is proposed.

Wireless Network Smart Grids for Continuous Power Supply and Monitoring

Advent of electric power revolutionized the life of a civilized human. From the early dated discoveries of Nikola Tesla, Alessandro Volta to the latest applications of electricity has made it indispensable for our daily life. The wide-ranging applications of power have made ease of living. From greenland to brownland we are dealt with the utilization of the electricity. Power generation, transmission, distribution, and efficient utilization promote the progress of a nation. Power crisis which has been abating. India suffers large deficits which need to be overcome at the earliest. We see a lot of power outages and most of the time we never know the reason behind it. Even in the 21st century, the digital age, we should not be facing this problem. One of the reasons behind the shortfall of a proper power supply is the inefficient power monitoring ensued by breakdowns, repairs and maintenance work of power plants, transformers, and transmission lines. This project is designed as the one-time solution to monitor the outages in real time without the requirement of a meatware. A power monitoring system automatically analyzes and retrieves the power quality events. The monitoring system comprises of smart grids and a centralized workstation. Smart grids contribute towards sending data of power supply status to the workstation continuously. Based on the status drawn by the grids the workstations analyze the data and intimate the electricity boards about the power outages. Thus elimination of manual summoning the designated authorities by automatic monitoring acts as the core of the proposed project. The automatic switching to an alternative resource is done by the automatic phase selector. The smart grids also promote to increase efficiency and energy conservation. The gravity of the paper is power monitoring and shift to a secondary power resource in the absence of the primary. Power monitoring acts as a preventive measure to recover the huge deficits suffered by the power crisis.

Wireless Network Smart Grids for Continuous Power Supply and Monitoring

Advent of electric power revolutionized the life of a civilized human. From the early dated discoveries of Nikola Tesla, Alessandro Volta to the latest applications of electricity has made it indispensable for our daily life. The wide-ranging applications of power have made ease of living. From greenland to brownland we are dealt with the utilization of the electricity. Power generation, transmission, distribution, and efficient utilization promote the progress of a nation. Power crisis which has been abating. India suffers large deficits which need to be overcome at the earliest. We see a lot of power outages and most of the time we never know the reason behind it. Even in the 21st century, the digital age, we should not be facing this problem. One of the reasons behind the shortfall of a proper power supply is the inefficient power monitoring ensued by breakdowns, repairs and maintenance work of power plants, transformers, and transmission lines. This project is designed as the one-time solution to monitor the outages in real time without the requirement of a meatware. A power monitoring system automatically analyzes and retrieves the power quality events. The monitoring system comprises of smart grids and a centralized workstation. Smart grids contribute towards sending data of power supply status to the workstation continuously. Based on the status drawn by the grids the workstations analyze the data and intimate the electricity boards about the power outages. Thus elimination of manual summoning the designated authorities by automatic monitoring acts as the core of the proposed project. The automatic switching to an alternative resource is done by the automatic phase selector. The smart grids also promote to increase efficiency and energy conservation. The gravity of the paper is power monitoring and shift to a secondary power resource in the absence of the primary. Power monitoring acts as a preventive measure to recover the huge deficits suffered by the power crisis.

Design and Optimization of a Full-Generation System for Marine LNG Cold Energy Cascade Utilization

This paper took a 100,000 DWT LNG fuel powered ship as the research object. Based on the idea of “temperature matching, cascade utilization” and combined with the application conditions of the ship, a horizontal three-level nested Rankine cycle full-generation system which combined the high-temperature waste heat of the main engine flue gas with the low-temperature cold energy of LNG was proposed in this paper. Furthermore, based on the analysis and selection of the parameters which had high sensitivity to the system performance, the parameters of the proposed system were optimized by using the genetic algorithm. After optimization, the exergy efficiency of the marine LNG gasification cold energy cascade utilization power generation system can reach 48.06%, and the thermal efficiency can reach 35.56%. In addition, this paper took LNG net power generation as the performance index, and compared it with the typical LNG cold energy utilization power generation system in this field. The results showed that the unit mass flow LNG power generation of the system proposed in this paper was the largest, reaching 457.41 kW.

Deterioration of Porcelain Insulators Utilized in Overhead Transmission Lines: A Review

Reliability of a power system is generally designated as a measure of the ability of the system to provide customers with adequate and constant supply. Power system failure have adverse effects and become a great concern for important large scale industries in South Korea such as semiconductors, steel and chemicals which require a high quality, stable power supply. In South Korea, nearly 80% of transmission system failures are caused by either natural eventualities such as lightning strikes or failure of insulators. Ageing assets pose significant challenges for utilities. Moisture with high temperature, fluctuation in temperature, contamination and electric stress accelerates aging in suspension insulators. The primary goal for the utility is to utilize the full life of an asset, but ageing increases the probability of deterioration and failure of equipment. The average age of vital assets, is estimated to be more than 35 years. In South Korea near about 1,223,538 porcelain insulators are reported to be in functional state. Among them only 65.19% of insulators are reported to be in operative state over 35 years. Insulators demand only 5–8% of installation costs. However, it demands more than 50% of maintenance costs. Thus, deterioration of insulator enhances capital expenditure and decrease returns on the asset base. Therefore, insulators should possess excellent electrical aging resistance to prevent deterioration of insulators. Korea Electric Power Corporation (KEPCO), largest power generation and distribution utility in South Korea utilize porcelain for almost all suspension insulators employed in transmission lines. Porcelain insulators are usually employed in transmission system as they are cost-effective and possess near about 30 to 60 years of lifespan. Lifetime evaluation of porcelain insulators in overhead transmission line is absolutely challenging, owing to aging process. This work highlights investigation of various failures of suspension type porcelain insulators, influencing factors responsible for degradation in lifetime and deterioration of suspension type insulators, various laboratory test methods available for evaluation of insulators employed in overhead transmission lines.

Photovoltaic system energy yield monitoring

Abstract Photovoltaic is one of the most popular clean energy applications to provide electricity using the sun’s power. This technology is more rapidly developed worldwide for power generation utility and building integration. It has a very substantial role to play in the global energy landscape and in the environmental strategies. It’s commonly known that, the energy produced by PV panels differs from place to another. Several studies have investigated the performance of different PV technologies and systems according to atmospheric conditions like temperature, solar radiation, wind, rain and dust. In fact, realistic performance assessment in actual outdoor conditions is very central to evaluate cost effectiveness, reliability and environment durability of the PV system. This study aims to evaluate the performance of three different grid-connected power systems, operating in an institutional building in Agadir, Morocco. The focus is on the assessment of measured energy output under real operating conditions. The key contribution of this study is to provide useful information to local investors, researchers and interested individuals about small grid connected PV systems in Agadir and near regions.

Comprehensive Evaluation of the Combustion Kinetic Characteristics of Owukpa Coal

Coal is a cheap and widely abundant fossil fuel that currently accounts for a significant share (35–40%) of the global energy mix. As a result, coal-fired electricity has catalyzed rapid socioeconomic growth and sustainable development worldwide. With the rapidly growing global energy demands, emerging economies like Nigeria need to address their widespread energy crises. Coal utilization for power generation is proposed as a panacea for the persistent power shortages, blackouts, and load shedding typically experienced in Nigeria. However, coal-fired power generation in Nigeria requires a comprehensive examination of the fuel properties, energy recovery potential, and emissions profiles of coal feedstocks, which is currently lacking in the literature. Therefore, this paper presents the comprehensive physicochemical, microstructure, mineralogical and thermal fuel properties of Owukpa (WKP) coal to evaluate its potential for future energy recovery and industrial applications. The results demonstrated that it contains high combustible elements, heating value (26.7 MJ/kg), and low potential for NOx and SOx emissions. Microstructural and mineralogical analyses revealed a mix of coarse-grained particles indicating the occurrence of carbonaceous and aluminosilicate minerals such as quartz, and kaolinite. Thermal properties of WKP revealed its low-rank coal (LRC) properties such as high thermal reactivity, which resulted from high mass loss (93.69 to 95.87%) and low residual mass (6.31 to 4.13%) during multiple heating rate TGA combustion. Kinetic analysis revealed that WKP is considerably reactive due to its low activation energy (Ea) and frequency factor (A), which ranged from Ea = 28.86 to 57.29 kJ/mol, whereas the A = 5.97 to 9.86 min–1 computed at high correlation R2 values of 0.97 to 1.0. The results showed that Owukpa (WKP) is a low-rank coal (LRC) with potential for electricity generation and other industrial applications.

Modeling and simulation of a novel combined heat and power system with absorption heat pump based on solar thermal power tower plant

In this paper a novel solar combined heat and power (CHP) system incorporating absorption heat pump (AHP) driven by mid-temperature solar heat and exhaust heat is proposed to improve solar energy utilization and electricity power generation. To validate thermodynamic performance of the proposed system, a case study is carried out based on 1 MW solar tower power plant located in Beijing. Depending on the well-developed mathematical model in accordance with actual equipment, the relevant module is coded in TRNSYS application environment. Besides, control and operation strategy is deeply analyzed to efficiently utilize solar energy with principal of cascade utilization. The dynamic simulation effectively predicts thermodynamic performance under the different operation modes in a typical winter day. Results indicate that flexible heating supply of the proposed system can meet well with user-generated heating loads. The AHP system recovers the condensate heat of 914 MJ with the average COP of 1.52. The proposed system generates the additional power of 217 kWh due to the regenerative cycle. Accompanying with power generation of 6214 kWh and useable thermal energy of 14502 MJ of the proposed system, the overall utilization efficiency of solar energy is up to 15.96% with the increase of 4.55 percentages.

Abnormal Detection of Wind Turbine Operating Conditions Based on State Curves

Wind energy is a clean and renewable energy source and thus has promising future prospects. To increase the utilization rate and power generation of wind turbines and reduce their maintenance costs, it is necessary to monitor the operating conditions of wind turbines. This paper introduces a monitoring method based on state curves and includes a study that analyzes five types of state curves, namely, wind speed–power, wind speed–rotor speed, wind speed–pitch angle, rotor speed–power, and rotor speed–pitch angle. The results indicate that due to the external environment (e.g., atmospheric temperature, atmospheric pressure, wind turbulence, wind direction, topography), the wind turbine internal hardware performance, and the control strategy, the first three curves did not allow the wind turbine to distinguish the normal operation status from a fault status. However, the rotor speed–power and rotor speed–pitch angle curves were able to accurately monitor abnormal conditions of the wind turbine. This study aims to establish theoretical curves of a wind turbine and correct the state curves to calculate the distance from the actual operating point to the state curves. During operation, the wind turbine will be under several conditions, ranging from maximum power point tracking to constant speed to constant power conditions. Using the time window and a confusion matrix to determine the best deviation of the wind turbine under different operating conditions is more effective in reducing the false alarm rate. Based on the optimal offset distances and the relationship among rotor speed, power, and pitch angle during start-up and shut down, a corresponding evaluation system is established. Taking the operational data from a wind farm as an example, the research reveals that when a wind turbine is operating normally, the deviations in the state curves under different operating conditions fall within an appropriate range; once an abnormal condition occurs, if the number of abnormalities exceeds a specified value during a specified time window, then an alarm signal will sound. Compared with the supervisory control and data acquisition (SCADA) system, in this system the alarm time is advanced.

Life Cycle Assessment of Low-Rank Coal Utilization for Power Generation and Energy Transportation

In China, the electricity load is concentrated in the east, but low-rank coal resources are concentrated in the west. To solve this contradiction, in this study, three cases for energy transmission about power system with and without solar energy were studied by life cycle assessment (LCA). Case 1 directly combusts low-rank coal to generate electricity in western China and transmits it to eastern China by grid. Cases 2 and 3 upgrade low-rank coal and transport it to eastern China for power generation. With the evaluating indicators and various stages of LCA, the impact of each case on the environment was compared clearly. The results show that over 90% of the pollutant emission comes from coal combustion throughout the life cycle. The pollutant emission of upgraded coal transportation is less than 5%. With low-rank coal upgrading then combusting, the total emission is less than that of direct combustion. In particular, with solar energy added, the emission of combustion can be further reduced. On the bases of LCA, analytic hierarchy process (AHP) was used to establish the connection of these four evaluation indicators to comprehensively evaluate the performance of the three cases through the objective function of AHP, which provided guidance for the energy transmission and utilization in the eastern and western China. Finally, sensitive analysis shows the main major factors affecting system performance on the system. The results show that the Case 3, which integrates with solar energy, performs best in the whole life scale.

Production, combustion and emission impact of bio-mix methyl ester fuel on a stationary light duty diesel engine

NOx emissions are the major threat in biodiesel fuelled engines due to fuel bound oxygen and presence of double bonds in their molecular structure. An attempt has been made to reduce the biodiesel NOx emission by varying the saturation level with the help of an approach called “bio-mix”. In this study, bio-mix fuel has been prepared from the waste resources of raw mixture of pig fat and waste cooking oil. Five samples of raw bio-mix oil have been prepared from the different blend ratio of pig fat and waste cooking oil and converted into biomix methyl ester (BMME) samples through transesterification process such as BMME-1, BMME-2, BMME-3, BMME-4 and BMME-5 respectively. All the bio-mix samples have been tested on a single cylinder, light duty stationary diesel engine. Results show that the percentage of saturated fatty acids, cetane number, and calorific values have increased whereas viscosity and iodine values have decreased with an increase in blend ratio. Bio-mix methyl ester fuel shows better combustion, performance compared with waste cooking oil biodiesel (WCOB). Bio-mix methyl esters shows higher in-cylinder pressure and heat release rate which is lower than WCOB at all engine load condition. All the emissions such as NOx, Smoke, CO, and HC have been found lower for BMME compared to WCOB. The non-road diesel engines are also consuming the fossil diesel fuel and hence, this study suggest that bio-mix fuel can be a viable alternative fuel for stationary diesel engines widely used in utility power generation, agriculture and construction equipments.

Syngas conditioning by ceramic filter candles filled with catalyst pellets and placed inside the freeboard of a fluidized bed steam gasifier

Gasification is a very advantageous conversion process to obtain a fuel gas from organic wastes, however it also generates by-products, such as particulate and tar. These should be removed from the syngas for its smooth utilization in power generation devices and/or biofuels production. In this work, biomass gasification tests were carried out in a bench-scale fluidized bed gasifier with a ceramic filter candle filled with commercial Ni-catalyst pellets integrated in its freeboard, for the abatement of particulate and tar. The activity of catalyst was studied at different operating conditions (temperature and catalyst bed layout) and the results were analysed in terms of residual tar content and composition of the product gas. The catalyst resulted very effective, particularly in tests at higher temperature and with the partially filled candle configuration. Tars were reduced to 250 mg/Nm3 in the best case. The Ni-catalyst did not show deactivation during tests lasting 4 h.

Economic analysis of a 600 mwe ultra supercritical circulating fluidized bed power plant based on coal tax and biomass co-combustion plans

In recent years, circulating fluidized bed combustor (CFBC) has been regarded as a viable alternative to the conventional pulverized coal combustor (PCC) for utility-scale coal power generation owing to its superior technology for fuel flexibility and supercritical (SC)/ultra supercritical (USC) steam circuit adaptability. The objective of this study is to analyze the economic feasibility of a 600MWe USC CFB boiler, in which coal or a mixture of coal and biomass would be used as fuel. After the demonstration and commercialization of SC CFBC units had succeeded up to 600MWe, USC CFBCs have been widely developed throughout the world. Although high capital costs, high auxiliary power use, and technology maturity have hindered the adoption of USC CFBC for utility power generation, the demand of cleaner environments and energy conversion have driven communities to develop and adopt USC CFBC. Its economic feasibility was evaluated in terms of net present value (NPV), benefit/cost ratio (B/C ratio), and internal rate of return (IRR). In particular, the effect of coal tax and domestic biomass co-combustion on economic efficiency was analyzed.

Synthesis of Pure and High Surface Area Sodalite Catalyst from Waste Industrial Brine and Coal Fly Ash for Conversion of Waste Cooking Oil (WCO) to Biodiesel

The ravaging environmental menace of coal utilization in power generation and high cost of biodiesel production had recently resulted to global energy discourse. Non-waste-derived heterogeneous catalysts prepared from waste materials could reduce production cost of biodiesel and thus make it economical and environmentally sustainable. In this preliminary study, coal fly ash and industrial waste brine of South African origin were beneficiated for synthesis of waste-derived solid Hydroxy Sodalite (HSOD) catalyst. Non-waste-derived catalysts are not economical and environmentally sustainable. However, hydrothermal synthesis technique was employed to synthesize the catalysts used to produce biodiesel in a batch reactor. The physicochemical properties of the catalysts were studied using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), Scanning electron microscopy equipped with Energy-dispersive X-ray spectroscopy (SEM-EDS). Textural property of the catalyst was obtained via nitrogen physisorption at 77 K. The catalyst was tested for producing biodiesel from waste cooking oil using these conditions: methanol-to-waste cooking oil ratio of 15:1, 3 wt % of catalysts, and agitation speed of 300-500 rpm, 8 h reaction time and temperature of 60 o C. The biodiesel yield for waste-derived catalyst and non-waste-derived catalyst were 89.4 and 85.0 % respectively, at a maximum waste cooking oil conversion of 97.0 %. Results of the BET analysis reveal that the surface areas of waste-derived and non-waste derived catalysts were 33.05 m 2 g -1 and 0.1645 m 2 g -1 , respectively.