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Ash deposition-related issues adversely affect the thermal transfer and cause corrosion to biomass fired utility boilers. Various models have been proposed to estimate the slagging propensities for firing biomass fuels of different origins. However, there is no reliable general applicable method that is available for assessing biomass fuel slagging propensities without carrying out extensive experimental testing. In addition, empirical correlations developed for coal produce large inaccuracies when applied to biomass. In this paper, a predictive slagging index, I n , has been built by analysing the slagging formations of a range of woody biomass fuels, using the thermodynamic equilibrium modelling tool FactSage, together with the partial least squares regression (PLSR) coupled with cross-validation. The new index has been validated and supported by experimental observations from various literatures. The results obtained with the new index showed a substantially greater success rate in predicting the woody biomass ash slagging propensity when compared with the experimental observations from the literature than the other five conventional slagging indices. The predictive index, I n , also successfully predicts the slagging propensities with high accuracy when extended to the application of herbaceous biomass and blended fuel between woody biomass and peat. • Prediction of the woody biomass ash slagging propensity on high temperature region in utility boilers. • New semi-empirical index based on chemical equilibrium calculation, ash composition and ash content. • Wood-based biomass with high SiO 2 and CaO contents. • Partial least square regression (PLSR) coupled with cross-validation has been used in slagging index development. • FactSage thermochemical equilibrium calculation software has been widely applied in solid fuel firing analysis. [ABSTRACT FROM AUTHOR]

The application of carbon capture and storage (CCS) and carbon neutral techniques should be adopted to reduce the CO 2 emissions from power generation systems. These environmental concerns have renewed interest towards the use of biomass as an alternative to fossil fuels. This study investigates the comparative potential of different power generation systems, including NGCC with and without exhaust gas recirculation (EGR), pulverised supercritical coal and biomass fired power plants for constant heat input and constant fuel flowrate cases. The modelling of all the power plant cases is realized in Aspen Plus at the gross power output of 800 MW e and integrated with a MEA-based CO 2 capture plant and a CO 2 compression unit. Full-scale detailed modelling of integrated power plant with a CO 2 capture and compression system for biomass fuel for two different cases is reported and compared with the conventional ones. The process performance, in terms of efficiency, emissions and potential losses for all the cases, is analysed. In conclusion, NGCC and NGCC with EGR integrated with CO 2 capture and compression results in higher net efficiency and least efficiency penalty reduction. Further, coal and biomass fired power plants integrated with CO 2 capture and compression results in higher specific CO 2 capture and the least specific losses per unit of the CO 2 captured. Furthermore, biomass with CO 2 capture and compression results in negative emissions. [ABSTRACT FROM AUTHOR]

A techno-economic assessment of options for large scale combustion based power generation in the United Kingdom is presented. Three of the main technologies for large-scale power generation are examined: Pulverised Fuel (PF), Integrated Gasification Combined Cycle (IGCC), and Natural Gas Combined Cycle (NGCC), with and without CO2 capture. The effect of three different CO2 capture technologies is studied: Post-Combustion Capture (PCC) is applied to PF and NGCC plants, Oxyfuel Combustion Capture (OCC) is applied to PF plants, while precombustion capture is for IGCC. Different suboptions for PCC are applied to PF and NGCC plants, namely: amine scrubbing, ammonia scrubbing and membrane physical absorption, with the latter technology applied only to PF plants. Alternatives to coal are studied by using mixtures of 75% coal and 25% biomass by weight in PF and IGCC plants. Fifteen combustion technology, fuel and CO2 capture combinations are tested, including five base cases without CO2 capture with different combustion technologies and fuels, four PF-PCC cases with different solid fuels and capture suboptions, 2 PF-OCC cases with different solid fuels, two NGCC-PCC cases with different capture suboptions, and two IGCC cases with precombustion capture and different solid fuels. The Integrated Environmental Control Model (IECM) for calculating the performance, emission and cost of fossil-fuelled power plants is used to perform the techno-economic comparison. The results highlight the economic preference for PCC. NGCC is the most efficient and economically attractive choice and although IGCC plants are more expensive than PF plants, the introduction of CO2 capture makes IGCC competitive. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 1425-1431, 2014 [ABSTRACT FROM AUTHOR]

Abstract: Mold biomass pellets have been utilized on a 300MW pulverized coal-fired furnace in China for the first time. Biomass was ground using the existing mill system, and without using any additional equipment. The maximum ratio of the biomass used in the experiments is 16.1% by energy input. The feasibility of grinding biomass and the safety of mill operation have been analyzed. In addition, the effects of co-firing biomass on the flame, temperature, pollutant emission, and unburned carbon in ash have been investigated. Also the characteristics of fly ash and its utilization in the concrete have been tested. The results show that existing roller mills and direct-blowing pulverizing systems can be used to grind mold biomass and to transport pulverized biomass within the limit in the flow rate of the biomass that can be processed. During the processes of biomass co-firing, the flame on the biomass injector is stable, but the outlet temperature of the furnace decreases, and the unburned carbon in the fly ash increases, when compared with the condition when firing coal only. NO x emission decreases with an increase in the biomass input. When the rate of biomass feed reaches 24t/h in the test, the NO x emission is reduced by about 10%, but there is only a small reduction in the SO2 emission. Investigations on the characteristics of the fly ash shows that the content of potassium and chlorine in the ash increases with an increase in the biomass feed, but co-firing biomass does not affect the quality of the fly ash to be used in the cement industry. The results presented in this paper can provide guidance for direct biomass co-firing in existing high-capacity pulverized coal-fired furnaces in China. [ABSTRACT FROM AUTHOR]

Biomass energy with CO2 capture could achieve net negative emissions, vital for meeting carbon budgets and emission targets. However, biomass often has significant quantities of light metals/inorganics that cause issues for boiler operation and downstream processes; including deposition, corrosion, and solvent degradation. This study investigated the pilot-scale combustion of a typical biomass used for power generation (white wood) and assessed the variations in metal aerosol release compared to bituminous coal. Using inductively coupled plasma optical emission spectrometry, it was found that K aerosol levels were significantly greater for biomass than coal, on average 6.5 times, with peaks up to 10 times higher; deposition could thus be more problematic, although Na emissions were only 20% of those for coal. Transition metals were notably less prevalent in the biomass flue gas; with Fe and V release in particular much lower (3–4% of those for coal). Solvent degradation may therefore be less severe for biomass-generated flue gases. Furthermore, aerosol emissions of toxic/heavy metals (As/Cd/Hg) were absent from biomass combustion, with As/Cd also not detected in the coal flue gas. Negligible Cr aerosol concentrations were found for both. Overall, except for K, metal aerosol release from biomass combustion was considerably reduced compared to coal. [ABSTRACT FROM AUTHOR]

Abstract Gasification is one of the most promising technologies for conversion of biomass into power generation due to its tremendous potential for improving the efficiency of energy conversion and reducing the cost of electricity (COE). In this study, the techno-economic feasibility of distributed power plants via wheat/corn straw gasification in China was investigated, and an economic model was established using a basic discounted cash flow analysis to estimate economic performance of the power plants. The effects of key variables (such as scales, feedstock cost, electricity prices and run time etc.) on economic performance were analyzed, and the results showed that plant scale and straw cost are the most influential parameters on the plant economic performance. It is estimated that a plant with a capacity of 5 MWe can be the optimal option for agricultural straw gasification for distributed power generation, the COE is 0.402 CNY/kWh, and SO 2 , NOx and dust emission are 2.5, 2.0 and 0.038 g/kWh, respectively. The net present value (NPV) and the annual average of return on investment (ROI) of the plant are 85.9 million CNY and 49.7%, respectively, with a high discount of 0.12 at a current feed-in tariff (0.75 CNY/kWh) for biomass to power in China, suggesting a good economic feasibility and market competitiveness. The deployment of agricultural residues resources gasification to distributed power generation displacing coal-fired power to supply electricity with rural area shows a significant potential in pollutants emission reduction and coal saving. Biomass gasification for distributed power generation serves as a sustainable technique for utilization of agricultural resources in practice, and would be widely applied in the near future supported by renewable energy strategies of Chinese government. Graphical abstract Image 1 Highlights • Techno-economic feasibility of distributed crop straw gasification to power plants was analyzed • Agricultural residues cost associated with power plant scale was investigated • Wheat/rice straw gasification to power plant with 5 MWe is more suitable for distributed power generation • A sustainability analysis was performed on wheat/rice straw gasification to power plant • The models and methods on feasibility evaluation of biomass utilization can be applied for other biomass resources and in different areas [ABSTRACT FROM AUTHOR]

Biomass to power generation is an alternative for fossil fuel to power pathways and plays a significant role in electricity supply and CO 2 emissions reduction of the United Kingdom (UK). Additionally, the UK government plans to phase out coal to power in the near future (2025), implying that all coal power plants in the future must be deployed with CO 2 capture and storage (CCS). In this study, life cycle evaluation of energy use, CO 2 emissions and cost requirements for pulverized fuel combustion power plants using white wood pellets and bituminous coal, a typical coal widely consumed in coal power station in the UK, as feedstocks, with and without (w/o) post-combustion CCS are investigated for deep understanding application and challenges of these technologies. The life cycle evaluation covers the whole power generation process including wood pellets/coal supply chain and electricity generation at the power plant. The analysis demonstrates that biomass or biomass/coal co-fired plants w/o CCS has no advantage in comparison to coal fired plant w/o CCS regarding the energy use due to the high energy consumption during the biomass supply chain process. From a life cycle viewpoint, CO 2 released when combusting biomass will be consumed during plant growth, resulting in an approximate carbon neutral combustion process with additional CO 2 emissions from the supply chain process. The biggest handicap for biomass power plants is the high operational cost of the feedstock supply chain process, with the additional high capital cost of the carbon capture plant, if considered. These results are a comprehensive guide which can help decision makers perform suitable measures to push forward development and application of coal/biomass power generation with CCS. [ABSTRACT FROM AUTHOR]

Bioenergy with Carbon Capture and Storage (BECCS) is recognised as a key technology to mitigate CO 2 emissions and achieve stringent climate targets due to its potential for negative emissions. However, the cost for its deployment is expected to be higher than for fossil-based power plants with CCS. To help in the transition to fully replace fossil fuels, co-firing of coal and biomass provide a less expensive means. Therefore, this work examines the co-firing at various levels in a pulverised supercritical power plant with post-combustion CO 2 capture, using a fully integrated model developed in Aspen Plus. Co-firing offers flexibility in terms of the biomass resources needed. This work also investigates flexibility within operation. As a result, the performance of the power plant at various part-loads (40%, 60% and 80%) is studied and compared to the baseline at 100%, using a constant fuel flowrate. It was found that the net power output and net efficiency decrease when the biomass fraction increases for constant heat input and constant fuel flow rate cases. At constant heat input, more fuel is required as the biomass fraction is increased; whilst at constant fuel input, derating occurs, e.g. 30% derating of the power output capacity at firing 100% biomass compared to 100% coal. Co-firing of coal and biomass resulted in substantial power derating at each part-load operation. [ABSTRACT FROM AUTHOR]