Comparative Techno-economic assessment of biomass and coal with CCS technologies in a pulverized combustion power plant in the United Kingdom

The technical performance and cost effectiveness of white wood pellets (WWP) combustion in comparison to three types of coal namely U.S., Russian and Colombian coals are investigated in this study. Post-combustion capture and storage (CCS) namely with amine FG+, and oxy-fuel with carbon capture and storage (oxy-fuel) are applied to a 650 MW pulverized combustion (PC) plant. The impacts of the Renewable Obligation Certificate (ROC) and carbon price (CP) policy in accelerating the CCS deployment in the framework of GHG emissions mitigation, are also evaluated. The operational factors affecting CCS costs and emissions in the power generation plants are taken into consideration, hence, the Integrated Environmental Control Model (IECM 8.0.2) is employed for a systematic estimation of plant performance, costs and emissions of different scenarios of fuel and CCS technologies. This study showed that the utilization of white wood pellets (WWP) in electricity generation can annually avoid about 3 M tonnes CO2 emissions from a 650 MW power plant. However, this mitigation process had impact on the plant efficiency and the cost of electricity. Further, the BECCS using white wood pellets has showed a better efficiency and lower cost of electricity with the oxy-fuel technology than the post-combustion CCS technology. However, in order to boost biomass energy CCS (BECCS) deployment with the WWP, an increase of the ROC for biomass power plants, or, an increase of the carbon price for the coal power plants is recommended. It was found that, the sensitivity of COE towards the ROC was higher than towards the carbon price variation. This result can be interpreted as the ROC has more positive impact than the carbon price, on the COE from the point of customers view without adding more burdens on the power generation companies

Effect of oxy-fuel combustion on ash deposition of pulverized wood pellets

Biomass is a clean alternative fuel to coal in terms of carbon, NOx, and SO2 emissions in the power generation sector. However, ash deposition problems have been a concern with biomass fuels due to the high alkali and residual sulphur contents in the ash forming particles. In this study, the influence of oxy-fuel firing conditions of wood pellets combustion on ash partitioning and deposit formation, were investigated experimentally on a 250-kW pilot scale pulverized furnace and theoretically through chemical equilibrium modelling using the FactSage program. Oxy-fuel combustion case was compared with air-fuel case in this assessment. The results of this study showed that wood pellets had a low tendency for radiation zone slagging, but, had a high fouling tendency in the convective passes. It is possible that oxy-fuel combustion inhibited the release of volatile elements to the gas phase in the initial stages of the combustion, thus reducing the alkali sulphates slagging, increasing however, the alkali sulphate fouling tendencies on the convective passes. Moreover, the effect of the oxy-fuel environment on the ash formation was significant. The chemical equilibrium modelling showed reasonable predictions of the ash behaviour of wood pellets in terms of alkali behaviour and explained to some extent the influence of the oxy environment on ash deposit formation

Kinetic parameters of the intrinsic combustion reactivity of woody biomass and coal chars via thermogravimetric analysis

The available data on intrinsic kinetic parameters of wood char combustion is limited in the literature. The intrinsic reactivity of porous char particles reflects the variance in the pore structure resulted from various compositions of parent biomass or coal fuels. In this study detailed kinetic models for calculating the intrinsic reaction rate and the Arrhenius parameters in two combustion zones are developed for the char combustion. The influence of the parent fuel composition and the thermal treatment on the char oxidative reactivity observed on the char surface area and particle density are explored through a mathematical model of the char service area and density. A higher reactivity of the wood pellets than coal and enhanced reactivity with the increasing pyrolysis temperature were observed as well