Co-firing In Power Plants Research Articles

Investigation of Palm Oil Wastes Characteristics for Co-Firing with Coal

Nowadays, renewable energy is a reliable solution for addressing global warming and fossil fuel depletion issues. Malaysia has an abundance of biomass resources currently underutilized to generate electricity, such as palm oil waste. Wastes from a palm oil mill plant, such as empty fruit bunch (EFB), palm mesocarp fibre (PMF), and palm kernel shell (PKS), are worth to be investigated as a possible raw material for co-firing with coal. The co-firing technique is the low-cost risk approach for the utilization of biomass in electricity generation. This paper aims to review and perform a comparative study on the existing co-firing biomass processes worldwide in order to explore the potential of using palm oil wastes with coal. To achieve successful co-firing of biomass with coal, the feedstock characteristics need to be understood before undergoing several pre-treatment options. It is recommended to implement co-firing palm oil waste with coal in Malaysia because palm oil wastes can reduce greenhouse gas, NOX, and SOX. Co-firing of palm oil wastes in existing coal-fired power plants is one of the practical ways to be implemented as it helps to reduce the over-consumption of fossil fuels. Based on the findings, Malaysia seems to be on the right track to maximize the use of palm oil wastes either in a standalone biomass power plant or in a co-firing power plant. The improved utilization will further minimize the negative impact of the greenhouse gas emission from the untreated palm oil mill wastes.

Development of environment-friendly dual fuel pulverized coal-natural gas combustion technology for the co-firing power plant boiler: Experimental and numerical analysis

The objective of this study was to develop and design an effective state-of-the-art dual-fuel pulverized coal (PC)-natural gas (NG) burner that incorporates fuel-air staging, flow swirling, preheating, and co-firing technologies to increase performance and minimize emissions. Experimental and numerical modeling were performed to study the effect of different operating conditions, excess air ratio, fuel staging, and NG blending. An optimal experimental design using a response surface methodology was adopted to examine the significance of the operating parameters. Analysis of variance indicates that the regression equation can correctly represent the responses (p-value < 0.0001). It is also indicated that the excess air ratio and percentage of preheated PC have significant effects on NOx emissions (p < 0.005). The optimal conditions were determined to include an excess air ratio of 1.2 and 50% PC injection into the preheating stream. Meeting these conditions, the predicted average NOx emission was 430 ± 3.1 ppm and the average measured NOx emission 436 ± 11.2 ppm, with 6% O2. Moreover, further reduction of NOx emission by up to 50% highlights the beneficial approach of NG co-firing. This design allows intensifying of recirculation and a mixture of fuels and oxidizers appropriate for improving the combustion characteristics significantly.

Life cycle cost assessment of biomass co-firing power plants with CO2 capture and storage considering multiple incentives

Realizing the 1.5 °C target of the Paris Agreement and reaching China's carbon neutrality by 2060 will most likely rely on the deployment of negative emissions technologies, especially biomass energy with CO2 capture and storage (BECCS). Co-firing biomass and coal in power plants with CCS is an efficient measure for deep decarbonization in the energy sector. Various incentives are currently implemented to compensate for the heavy economic burden of this technology portfolio, which has severely limited its large-scale application. We account for the levelized costs of electricity of ten co-firing plants from a life cycle perspective and optimize the best combination of three incentives (e.g., carbon price, tax credit, and feed-in tariff) to achieve cost-competitiveness under a goal of minimum policy burden. The results obtained reveal that power plants that use biomass energy with CCS are not currently economically viable in the absence of incentive measures. Biomass co-firing plants both with and without CCS should preferably select feed-in tariffs and tax credits, respectively, to improve their overall cost-competitiveness. However, the current policy constraints are not sufficient to meet the break-even levels required. Rational planning incentives have become a key option to improve the economic viability of BECCS technology and promote its development under existing conditions. Our results provide critical insights for designing a mitigation strategy in China's energy sector while laying out an important reference for achieving economically negative carbon emissions in other industry sectors.

Optimal timing for carbon capture retrofitting in biomass-coal combined heat and power plants in China

Industrial decision-makers may wonder about the optimal timing for investing in carbon capture retrofitting in co-firing power plants, faced with uncertain benefits from upcoming China’s carbon trading market and potential cost reductions derived from technology innovation. The decision on investment timing relates to the so-called waiting value, considering multiple uncertainties and trade-offs. This article applies a real options-based framework, adapted to deal with the waiting value in the context of multiple uncertainties of carbon market, technical improvements and biomass availability. The problem is solved through an efficient simulation method. The results suggest that the optimal retrofit timing for CCS (carbon capture and storage) in a co-firing CHP will be the year 2033 considering a basic scenario, in which the carbon price is 98 CNY/tonCO2 (14.5 US$/tonCO2) in 2025, the growth rate and volatility are 5% and 7% respectively, and technical improvements are expected every six years and result in a cost reduction of 50%. In addition, we examine the effects of different sub-dimensions in the carbon market and technical improvement on anticipating the retrofit timing. The conclusions of this article provide decision-makers with strategies of adjusting the investment timing in response to their different expectations of market and technology developments. Further practical applications require judgments of future trends made by decision-makers and extensive data of specific cases.

Techno-economic assessment of a biomass torrefaction plant for pelletized agro-residues with flue gas as a main heat source

Torrefaction combined with densification for upgrading biomass to torrefied biomass pellets is increasingly of great interest since torrefied biomass pellets are considered as a major renewable energy source. Especially in the application of co-firing with coal, torrefaction may be easily integrated into an existing co-firing power plant, whose flue gases from the power plant could be used to torrefy biomass pellets. This could also help to improve the overall carbon efficiency of the power plant and reduce emissions of greenhouse gases. In the present work, a torrefaction plant for corn residue pellets to produce torrefied solid fuels using flue gases as a main heat source was simulated in Aspen Plus® software. Torrefaction module was successfully modelled by an RYield reactor, which was programmed with the two-steps-in-series kinetic for the decomposition of biomass pellets as well as the volatile formation for by-products. The model can, therefore, provide the distribution and yield of both torrefied biomass pellets and volatile by-products. From the validation, the simulation results appeared to show good agreement with available experimental data in the literature. At the suggested conditions of 260 °C wet flue gas and 20 min residence time, thermal energy of 460 J/g and 380 J/g were required for the drying and the torrefaction modules, respectively. At these conditions, the performance of the whole process was found to be almost 95%. This plant produced 75% w/w torrefied biomass pellets yield with HHV of 21.9 MJ/kg. The by-products mainly included 10.7% w/w water, 7.4% w/w CO2, and 1.7% w/w CO. Our findings provide a feasible outlook for integrating a torrefaction process of biomass pellets into a co-firing power plant, utilizing a realistic heat of waste flue gases for the process.

Fuzzy Optimization of Direct and Indirect Biomass Co-Firing in Power Plants

Co-firing of biomass in fossil fuel-fired power plants is a mature technology option for reducing greenhouse gas emissions. Up to 10 % of fossil fuel energy input can be displaced by biomass without the need for major retrofits. Co-firing may be done directly or indirectly. However, direct co-firing has the disadvantage of being less flexible with the use of different types of biomass. Indirect co-firing, on the other hand, overcomes this limitation by using a gasifier which converts the biomass into syngas and biochar. The syngas can then be used for co-firing, while biochar can be applied to soil as a form of carbon sequestration. This process stores the carbon initially fixed by biomass through photosynthesis in the soil, and results in the net transfer of part of the carbon in biomass from the atmosphere to the soil. Biochar thus acts as a negative emissions technology with potential for scale-up in the near future. The utilization of biomass for co-firing in a fleet of thermal power plants can be optimized as a carbon management network, subject to biomass availability and the presence of suitable biochar sinks. In this work, a fuzzy mixed integer linear programming model is developed to minimize net carbon emissions in such a system, taking into account parametric uncertainties in the storage capacities of the biochar sinks. It is assumed that there is the option to use direct, indirect or no co-firing in each power plant in the system. The model is illustrated using a case study.

Life cycle environmental impact assessment of fuel mix-based biomass co-firing plants with CO2 capture and storage

As a carbon-neutral renewable energy source, biomass co-firing with coal contributes to reducing the carbon intensity of pulverized coal power plants with CO2 capture and storage; thus, this process significantly reduces the greenhouse gas emissions of the power industry. However, various types of environmental impacts caused by co-firing have hindered the large-scale deployment of this technology. In this study, ten life cycle assessment models were developed based on the Integrated Environmental Control Model and GaBi software to quantify the performance parameters of different power plants and the influence of the co-firing ratio on various environmental impact categories. The system boundaries included raw material acquisition, raw material transport, energy conversion of power plants, CCS and brine treatment. The results indicated that a pulverized biomass/coal co-firing power plant with CCS can achieve near-zero emissions at a co-firing ratio of 25% and negative emissions of 877 kg CO2-e/MWh from a life-cycle perspective when coal is totally replaced. Co-firing biomass and coal in power plants has a passive impact on seven environmental categories, such as the eutrophication potential and toxicity potential, rather than on the global warming potential, abiotic resource depletion potential and acidification potential. The major causes of environmental burden shifting are energy penalties and indirect emissions from high-energy-consumption processes, especially emissions of N2O, NH3 and ethylene oxide released during biomass extraction and solvent preparation. The conclusions and recommendations presented in this paper may have implications for deep decarbonization in other industrial sectors.

Understanding the impact of FGD technologies on the emissions of key pollutants in a Co-Firing power plant

The transition from limestone to lime-based flue gas desulphurisation system (FGD) was tested in a power station fired with high sulphur (S)-petroleum coke to better control the emissions of key pollutants. To this end, as a request of the power station owner to IDÆA-CSIC, we surveyed the power station fired with 70% S-petroleum coke and equipped with a slaked lime-based FGD, and compared the results with data from our previous works conducted at the same power station but operated with lower co-firing rates and a limestone FGD, the purpose being to improve the understanding on the impact that different FGD technologies may have on the fate, speciation and, ultimately, the emissions of key pollutants from the power station. Our observations suggest that the reaction pathways and speciation of key trace pollutants in the gypsum slurry including Cl, Mo, Hg and Se remained largely unchanged with the transition from limestone to lime-based FGD. By contrast, As, Cr, B, U and V speciation in the gypsum slurry was sensitive not only to the FGD sorbent, likely in response to differences in the pH, but also to the absence of ligands such as F−.The highly alkaline lime slurry neutralised the H+ released by the formation of metal-complexes. This favoured the stability of trace elements in their oxy-anionic forms or forming hydroxyl complexes, as opposed to the acidic conditions in limestone-FGD gypsum from previous works. Enrichment in Mo, V and Ni in the fly ash was primarily associated with the combustion of a petroleum coke. Other elements such as Pb, As, Zn, Cu and Se were also enriched in the fly ash relative to the boiler slag.

A Study on the Process Improvement of FGD Waste Water Treatment Facilities in Large Scale Biomass and Coal Co-Fired Power Plants

A Study on the Process Improvement of FGD Waste Water Treatment Facilities in Large Scale Biomass and Coal Co-Fired Power Plants

Enhanced CO2 sorption capacity of amine-tethered fly ash residues derived from co-firing of coal and biomass blends

Co-firing of coal and biomass blends provides a promising route for clean energy utilization with high efficiency and mitigated pollutants emission. However, the technology meets an important challenge in effective utilization of the co-firing fly ashes. Efforts have been made to valorize the co-firing fly ash residues as potential CO2 sorbents. To achieve enhanced CO2 sorption performance, the samples were modified with tetraethylenepentamine (TEPA). Effects of amine loading, CO2 sorption temperature, initial CO2 concentration and gas flow rate on CO2 sorption behaviors of the amine-tethered sorbents were investigated. The desired sorbent with 25% TEPA loading presented the highest CO2 sorption capacity of 1.19 mmol CO2/g when tested under 60 °C and 15%CO2 with a total gas flow rate of 1200 ml min−1. The effects of regeneration temperature and ramping rate on sorbent regeneration performance were demonstrated. The maximum sorbent regeneration efficiency of 97.2% was achieved under the regeneration condition of 110 °C and 5 °C min−1. CO2 sorption capacity of the amine-tethered sorbent kept stable within 5 repeated cycles. These findings indicate that the amine-tethered sorbent could be a good candidate for on-site CO2 capture from flue gas in co-firing power plants.

Advanced Woody Biomass Logistics for Co-Firing in Existing Coal Power Plant: Case Study of the Great Lakes States

One of the core decisions on securing the supply of biomass to co-firing power plants is the design of a proper logistics system. Though technologies have been developed to improve the characteristics of feedstock, their effects in the logistics systems have received less attention. This paper compares the conventional woody biomass logistics system with the advanced woody biomass logistics system that includes the torrefaction process to upgrade the feedstock. More specifically, this study uses a mixed integer linear program to integrate conventional and advanced biomass logistics and applies them to a case study of 26 coal power plants in the Great Lakes states to determine the most feasible logistics system for each plant. The results revealed that the amount of cost savings from the advanced woody biomass logistics depends on the capacity and location of the power plant. To categorize the cost savings of individual plants, it was found that plants can be divided into seven groups based on three parameters: 1) annual coal tonnage shipped (total capacity), 2) availability of biomass in the vicinity, and 3) average distance from biomass collecting sites. Overall savings from advanced logistics were small, but plants within each of the groups demonstrated similar cost reductions. The sensitivity analysis showed that trucking costs and feedstock purchasing costs were most sensitive to variation. From torrefaction effects, energy content after torrefaction had more significance than mass reduction.

An integrated sustainability model for a bioenergy system: Forest residues for electricity generation

In the U.S., bioenergy accounts for about 50% of the total renewable energy that is generated. Biomass may be used as a source of energy in a variety of ways. Using forest residues, which would normally be treated as waste, in a co-firing power plant application is one strategy for utilizing biomass. Every stage in the life cycle of using forest residues (e.g., growing biomass, harvesting biomass, transporting biomass, and co-firing with coal) has consequences in terms of the three dimensions of sustainability: economy, environment, and society. An integrated sustainability model (ISM) using system dynamics is developed for a bioenergy system to understand how changes in the bioenergy system influence environmental measures, economic development, and social impacts. Exogenous factors such as population growth, land-use change (LUC) patterns, and renewable energy policy are considered by the ISM. Predictions, such as soil carbon sequestration, greenhouse gas savings, monetary gain, and employment, can be made for a given temporal and spatial scale. Different policy scenarios varying the bioenergy share of the total electricity generation were identified and examined via the ISM. The results of the scenario analysis indicate that an increase in the bioenergy share of the total electricity generation will stimulate the bioenergy market for bio-power. Model projections provide comprehensive insights to key stakeholders and policy makers for supporting decision-making regarding bioenergy development.

Evaluation of wood pellet handling in import terminals

Wood pellet imports are expected to increase in the European Union and Southeast Asia by 2030, considering pellets are the main feedstock used for co-firing in power plants throughout these regions. Due to the material's physical and biological properties, the equipment at an import terminal need to be different than what is used for other bulk material. Thus, most of the common problems associated with handling can be avoided. Dust emission and explosions, degradation in storage, self-heating and ignition are important criteria when designing a wood pellet port terminal, and can greatly affect associated logistics. Despite some availability of data concerning the handling of pellets, there is a lack of insight into the equipment and operations of actual handling facilities. A detailed literature research was performed in order to ascertain the level of the scientific background on the subject. Subsequently, visits in pellet facilities in the Netherlands and in-depth interviews with representatives were conducted and serve as a means of gaining an overview of current industry practices and equipment used for the handling of wood pellets. The main objective of this work is to evaluate the state-of-the-art in wood pellet handling in import terminals. This way, future bottlenecks can be identified and actions needed to overcome them can be determined. The analysis performed shows that while wood pellet terminals might be able to cope with the low amounts being traded currently, a reexamination and redesign of terminal facilities to accommodate the increased volumes will probably be required by 2030.

Ambivalence, naturalness and normality in public perceptions of carbon capture and storage in biomass, fossil energy, and industrial applications in the United Kingdom

Carbon dioxide capture and storage (CCS) is a promising yet controversial climate change mitigation technology. While numerous studies have addressed perceptions of CCS in fossil energy applications, less attention has been paid to how other applications of the technology may be viewed by lay groups. This article reports on findings from a twoday deliberative focus group held near Drax power station; a coal-biomass co-firing power plant in the north of England. In so doing we adopt a broad, psycho-socially inspired conception of perceived naturalness in order to explore how perceptions of CCS in biomass, fossil fuel, and industrial applications are formed in the context of a range of potential technologies for supporting low carbon energy system transitions. In particular, we explore how perceptions of naturalness and interdependency shaped perceptions of different CCS applications. Our analysis illustrates how perceptions of CCS as threatening, uncanny disruptions to natural systems may shift when re-contextualised to include concerns relating to the intermittency of renewable energy, or be ameliorated through perceptions of industrial and bioenergy applications as supporting natural and economic interdependencies.

Burning wood pellets for US electricity generation? A regime switching analysis

Applying a regime switching model under the theoretic framework of real options, we inspect the optimal timing boundaries for coal and coal mixed wood pellets as two alternative fuels for a power plant in Georgia, United States. Results indicate that cofiring wood pellets with coal is generally not a commercially viable option. However, lower-level (with wood pellets<15%) cofiring could have been feasible during the infancy period (2009–2011) when wood pellet price was declining. Sensitivity analysis shows that our conclusions are robust and the most important factors are relative prices of coal and mixed fuel. Therefore, we reject the null hypothesis that cofiring is economically feasible and suggest using policy vehicles to stimulate the bioenergy market and meet the greenhouse gas emission reduction target. In particular, a subsidy of $1.40/mmbtu to the 10% mixed fuel or a tax of $1.50/mmbtu on coal would prompt the conversions of coal-only power plants to cofiring ones, and a subsidy of $0.45/mmbtu to the 10% mixed fuel or a tax of $0.50/mmbtu on coal would maintain existing cofiring power plants in the status quo.

Woody Biomass Characterization for 100 Megawatt-hours (MW) Power Generation

Abstract This paper characterized the wood pellet and torrefied wood pellet fuel as compared to coal for 100 MW co-firing power generation plant. There were five experiments to characterise the chemical and physical properties of coal, wood pellet and torrefied wood pellet namely moisture analysis, Thermo gravimetric Analyser (TGA), Bomb Calorimeter, Organic Elemental Analyser and Scanning Electron Microscope (SEM). The moisture analysis result from moisture analyser and TGA shows that the moisture content of torrefied wood pellet is lower than wood pellet at 6.760% and 3.629%. Moreover, the volatile matter, hydrogen and nitrogen content of torrefied wood pellet is lower than wood pellet at 65.20%, 5.993% and 0.4078% correspondingly. The calorific value, fixed carbon content, ash and sulphur also increase in torrefied wood pellet at 20.68 MJ/kg, 28.85%, 2.321% and 0.1656% respectively. In general, torrefaction improve the fuel properties of wood pellet similar to coal. The 100 MW direct co-firing power plant provides less capital investment, operation and maintenance cost for low rate co-firing ratio. However, there is economic challenges for high rate co-firing substation of torrefied wood pellets.

Corrosion Testing of Thermal Spray Coatings in a Biomass Co-Firing Power Plant

Large-scale use of biomass and recycled fuel is increasing in energy production due to climate and energy targets. A 40% cut in greenhouse gas emission compared to 1990 levels and at least a 27% share of renewable energy consumption are set in EU Energy Strategy 2030. Burning fuels with high content of corrosive species such as chlorine and heavy metals causes deterioration of boiler components, shortened lifetime, limited availability of a plant and hence higher maintenance and investment costs and lower thermal and economic efficiency. Coatings can be applied to protect the critical boiler components against high temperature corrosion. In this study, five thermal spray coatings were tested in an actual biomass co-firing boiler for 1300 h with a measurement probe. The coatings were analyzed after the exposure by metallographic means and scanning electron microscope/energy-dispersive X-ray spectroscope (SEM/EDX). The deposits formed on the specimens were analyzed by X-ray fluorescence. At 550 °C, the coatings showed excellent corrosion performance compared to reference material ferritic steel T92. At 750 °C, tube material A263 together with NiCr and NiCrTi had the highest corrosion resistance. To conclude, thermal spray coatings can offer substantial corrosion protection in biomass and recycled fuel burning power plants.

Pelletization of brown coal and rice bran in Indonesia: Characteristics of the mixture pellets including safety during transportation

With the aim of utilizing brown coal as fuel in co-firing power plants, a technique for the pelletization of brown coal and rice bran has been developed. By mixing rice bran with brown coal, the calorific value of brown coal was improved and its safety during transportation increased. The calorific value of the mixed pellets with 50% brown coal and 50% rice bran reached 15MJ/kg, and their durability was sufficiently high at 98%. This technique of pelletization decreases the manufacturing costs because thermal energy for dewatering and drying is not required. In addition, it is beneficial because it uses agricultural residues. Further, if the ratio of brown coal was reduced to below 50%, the mixed pellets did not act as a pyrophoric material (a self-heating substance).

ICOPE-15-1119 Biomass-coal Co-firing Power Plant System with a High Biomass Ratio

ICOPE-15-1119 Biomass-coal Co-firing Power Plant System with a High Biomass Ratio

Technico-economic assessment of coal and sawdust co-firing power generation with CO2 capture

Biomass, in contrast with different type of fossil fuels, is considered a renewable energy source (RES), having a neutral carbon impact in burning processes. As a result, biomass co-firing offers a good potential solution for reducing greenhouse gas emissions in conventional coal fired power plants. This paper evaluates the technical and economic aspects of biomass co-firing electricity production with and without CO2 capture (CC) using different mixtures of coal and sawdust. The impact of biomass co-firing on power plant performances were evaluated in terms of energy efficiency, auxiliary power consumption, capital costs, operational & maintenance (O&M) costs, specific CO2 emissions, electricity cost and CO2 avoidance costs. Depending on the feedstock composition, the biomass co-firing power plant generates 750–800 MW electricity in the case of carbon capture and 980–1027 MW electricity without capture. The results indicate a continuous decrease in both technical and economical performances with the increase of biomass content in the feedstock.