• Energy Research

The reduction of fossil CO2 emissions from key relevant industrial processes represents an important environmental challenge to be considered. To enable large-scale deployment of low carbon technologies, a significant research and development effort is required to optimize the CO2 capture systems. This work assesses various hybrid solvent-membrane configurations for post-combustion decarbonization of coal-based super-critical power plants. As an illustrative chemical solvent, Methyl-Di-Ethanol-Amine was assessed. Various membrane unit locations were assessed (e.g., top absorber, before absorber using either compressor or vacuum pump). All investigated designs have a 1000 MW net power output with a 90% decarbonization ratio. Benchmark concepts with and without carbon capture using either reactive gas-liquid absorption or membrane separation technology were also evaluated to have a comparative assessment. Relevant evaluation tools (e.g., modeling, simulation, validation, thermal integration, etc.) were employed to assess the plant performance indicators. The integrated evaluation shows that one hybrid solvent-membrane configuration (membrane unit located at the top of absorption column) performs better in terms of increasing the overall net plant efficiency than the membrane-only case (by about 1.8 net percentage points). In addition, the purity of captured CO2 stream is higher for hybrid concepts than for membranes (99.9% vs. 96.3%). On the other hand, the chemical scrubbing concept has superior net energy efficiency than investigated hybrid configurations (by about 1.5–3.7 net percentage points).

AbstractIntegrated Gasification Combined Cycle (IGCC) is a technology for power generation in which the feedstock is partially oxidized with oxygen and steam to produce syngas. In a conventional IGCC design without carbon capture, the syngas is purified for dust and hydrogen sulphide removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power production. The hot GT flue gases are sent to Heat Recovery Steam Generator (HRSG) for steam generation. Additional power is produces by expanding the steam generated in a steam turbine.Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for reducing the greenhouse gas emissions. Integrated Gasification Combined Cycle is one of the power generation technologies having the highest potential to capture carbon dioxide with the low penalties in term of plant energy efficiency and cost. The modification of the IGCC design for carbon capture can be done in various plant concepts considering the carbon capture method to be used (e.g. pre- and post-combustion capture, syngas chemical looping etc.).This paper investigates various carbon capture methods suitable to be applied for an IGCC plant for power generation. The coal blended with biomass (sawdust) based IGCC case study investigated in the paper produces around 400–500 MW net electricity with more than 90% carbon capture rate. An important focus of the paper is concentrated on overall energy efficiency optimization of the IGCC plant concepts with various carbon capture options by better heat and power integration of the main plant sub-systems (e.g. steam integration between gasification island, syngas conditioning line and the steam cycle, influence of heat and power demand for Acid Gas Removal unit etc.). A particular attention of the paper is focused on the quality specification for the captured carbon dioxide stream considering various capture options but also the storage options (enhanced oil recovery, storage in depleted oil and gas fields, saline aquifers etc.).

Abstract Gasification is a promising conversion technology to deliver high energy efficiency simultaneously with low energy and cost penalties for carbon capture. This paper is devoted to in-depth economic evaluations of pre- and post-combustion Calcium Looping (CaL) configurations for Integrated Gasification Combined Cycle (IGCC) power plants. The poly-generation capability, e.g. hydrogen and power co-generation, is also discussed. The post-combustion CaL option is a gasification power plant in which the flue gases from the gas turbine are treated for CO2 capture in a carbonation–calcination cycle. In pre-combustion CaL option, the Sorbent Enhanced Water Gas Shift (SEWGS) feature is used to produce hydrogen which is used for power generation. As benchmark case, a conventional gasification power plant without carbon capture was considered. Net power output of evaluated cases is in the range of 550–600 MW with more than 95% carbon capture rate. The pre-combustion capture configuration was evaluated also in hydrogen and power co-generation scenario. The evaluations are concentrated for estimation of capital costs, specific investment cost, operational & maintenance (O&M) costs, CO2 removal and avoidance costs, electricity costs, sensitivity analysis of technical and economic assumptions on key economic indicators etc.

Even though the energy penalties and solvent regeneration costs associated with amine-based absorption/stripping systems are important challenges, this technology remains highly recommended for post-combustion decarbonization systems given its proven capture efficacy and technical maturity. This study introduces a novel centralized and decentralized hybrid control strategy for the post-combustion carbon capture plant, aimed at mitigating main disturbances and sustaining high system performance. The strategy is rooted in a comprehensive mathematical model encompassing absorption and desorption columns, heat exchangers and a buffer tank, ensuring smooth operation and energy efficiency. The buffer tank is equipped with three control loops to finely regulate absorber inlet solvent solution parameters, preventing disturbance recirculation from the desorber. Additionally, a model-based controller, utilizing the model predictive control (MPC) algorithm, maintains a carbon capture yield of 90% and stabilizes the reboiler liquid temperature at 394.5 K by manipulating the influent flue gas to the lean solvent flowrates ratio and the heat duty of the reboiler. The hybrid MPC approach reveals efficiency in simultaneously managing targeted variables and handling complex input–output interactions. It consistently maintains the controlled variables at desired setpoints despite CO2 flue gas flow disturbances, achieving reduced settling time and low overshoot results. The hybrid control strategy, benefitting from the constraint handling ability of MPC, succeeds in keeping the carbon capture yield above the preset minimum value of 86% at all times, while the energy performance index remains below the favorable value of 3.1 MJ/kgCO2.

AbstractPower generation is one of the industrial sectors with major contribution to greenhouse gas emissions (especially CO2). For climate change mitigation, a special attention is given to the reduction of CO2 emissions by applying capture and storage techniques in which CO2 is captured from energy-intensive processes and then stored in suitable safe geologic locations. Carbon capture and storage (CCS) technologies are expected to play a significant role in the coming decades for curbing the greenhouse gas emissions and to ensure a sustainable development of power generation and other energy-intensive industrial sectors (e.g. cement, metallurgy, petro-chemical etc.). Among various carbon capture options, chemical looping systems are very promising options for intrinsically capture CO2 with lower cost and energy penalties.This paper evaluates calcium looping process as a promising carbon capture option to be applied in the most important coal- based power generation technologies. Combustion technology (Pulverized Fuel - PF) operated in both sub-critical and super- critical steam conditions were evaluated. Also, the gasification technology using an oxygen-blown entrained-flow gasifier was evaluated. As benchmark options, the same power generation technologies were evaluated without CCS. The power plant case studies investigated in the paper produces around 545 – 560 MW net power with at least 90% carbon capture rate. The modeling and simulation of the whole power generation schemes produced the input data for quantitative technical and environmental evaluations of power plants with carbon capture (similar power plant concept without CCS was used as reference for comparison). Mass and energy integration tools were used to assess the integration aspects of calcium looping unit into the whole power plant design, to optimize the overall efficiency and to evaluate the main sources of energy penalty for carbon capture.

This paper investigates the impact of capture of carbon dioxide (CO2) from fossil fuel power plants on the emissions of nitrogen oxides (NOX) and sulphur oxides (SOX), which are acid gas pollutants. This was done by estimating the emissions of these chemical compounds from natural gas combined cycle and pulverized coal plants, equipped with post-combustion carbon capture technology for the removal of CO2 from their flue gases, and comparing them with the emissions of similar plants without CO2 capture. The capture of CO2 is not likely to increase the emissions of acid gas pollutants from individual power plants; on the contrary, some NOX and SOX will also be removed during the capture of CO2. The large-scale implementation of carbon capture is however likely to increase the emission levels of NOX from the power sector due to the reduced efficiency of power plants equipped with capture technologies. Furthermore, SOX emissions from coal plants should be decreased to avoid significant losses of the chemicals that are used to capture CO2. The increase in the quantity of NOX emissions will be however low, estimated at 5% for the natural gas power plant park and 24% for the coal plants, while the emissions of SOX from coal fired plants will be reduced by as much as 99% when at least 80% of the CO2 generated will be captured.

Abstract 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.