Perspectives of pre-combustion CCS systems for central Europe

Carbon Capture and Storage (CCS) has a potential to play a significant role in the future of power generation in Europe, at least in a short to intermediate term. Among the reasons are necessity and also growing political willingness to limit the CO2 emissions while it appears that fossil fuels are to remain an important source for fuel and electricity production. CCS technologies however mean inevitable technical, energy and economic penalty, especially since most common fossil fuel for power generation in the Central Europe is lignite. We are presenting the focus and first results of a recently initiated Norway Grants project Study of CCS Pilot Technologies for Coal Fired Power Plants in the Czech Republic . In this project, different capture technology alternatives and various options for the transport of the captured CO2 are investigated. With the data for post combustion and oxyfuel combustion taken from previous project here the main emphasis is put onto various options for pre-combustion Integrated Gasification Combined Cycle (IGCC) systems. The investigated pre-combustion CCS IGCC systems are based on gasification of central European lignite which has LHV around 16.5 MJ/kg and ash content up to 20%. There is considered a Shell gasification technology with gas quench, utilizing heat from syngas cooling also as superheater and reheater. Nominal power output in this case study is approximately 250 MW and the gas turbine is thus based on current industrial turbine with nominal output 187 MWe (Siemens SGT5-2000E). Different capture technologies are being investigated and they include different modifications of solvent capture (based mainly on Rectisol system using chilled methanol). This is being compared with a low temperature capture method and a capture using various CO2 permeable or H2 permeable membranes. Last but not least different alternatives for CO2 transport and storage or utilization into both local and international sites are considered

Minimizing the energy and economic penalty of CCS power plants through waste heat recovery systems

Implementation of currently considered and available CCS technologies into fossil power plants brings inevitable technical, energy and economic penalty. This is getting even larger when fossil fuels such as low rank coal are being utilized. All three generally considered CCS technologies were modelled – oxyfuel combustion and ammonia based post-combustion (subcritical power plant with fuel drying) and pre-combustion (IGCC with Rectisol method for CO2 separation). After traditional methods of system optimization there was considered another way for increasing system efficiency. CCS technologies produce waste heat streams, which can be converted to electricity by small modular units with unit cost comparable to the whole plant, some of which are already commercially available. Here we consider technologies based on steam microturbine, Organic Rankine Cycle (ORC) and absorption power cycle. CCS technologies generally produce significant amounts of waste heat from CO2 compressor intercooling which pressurize the CO2 for state for the transport and storage. Post-combustion method provides possibility for waste heat recovery partly on cooling down of flue gas before entering absorber and from cooling down of desorbed CO2 stream. Oxyfuel combustion and IGCC with oxygen gasification provide also large amounts of waste heat from intercooling of air, eventually oxygen and nitrogen compressors of air separation unit. Fluidized bed fuel dryer exhaust also contains some potential for work. Pre-combustion IGCC plant provides other possibilities for waste heat recovery from low temperature syngas cooling and from very clean flue gas at low temperatures, which are already impossible to be utilized by regular steam part of combined cycles. In order to utilize the waste heat streams and increase plant efficiency, there are often designed sophisticated but complicated systems, especially for feed water preheating. Although they slightly increase the plant efficiency, the resulting system has low flexibility. It is presented here that by decoupling waste heat streams from main steam cycle and by low cost in modular waste heat recovery units there can be at the same time increased both plant efficiency and flexibility, while the negative effects associated with these measures are minimal. Detailed results (technical and economic) are presented for a case scenarios of 250 MWe coal fired power plants, applied to specific conditions of central Europe. The considered fuel for subcritical oxyfuel plant is a low rank coal, lignite, with heating value (LHV) down to 8.5 MJ/kg, water content up to 35% and ash content up to 40% and for the IGCC plant is used coal of LHV about 16.5 MJ/kg, water content over 30% and ash content around 9%

Environmental aspects of the implementation of MSWI fly ash treatment methods in the Czech Republic

Today about 80 million tonnes of municipal solid waste (MSW) is annually incinerated in Europe. One of the solid residues from the municipal waste incineration (MSWI) plant is fly ash (FA). FA is classified as hazardous waste due to the high content of soluble salts, potentially toxic elements (Zn, Pb, Cd, Cr, Cu, Hg, Ni, As, and Sb), and trace organic pollutants (e.g. dioxins, furans, etc.) and, therefore, must be disposed of in special landfills [1]. On the other hand, the high content of valuable components (Zn, Pb, Cu, and salts) makes FA a potential anthropogenic source for resource recovery. In addition, the production of FA usually accounts for 10-30 kg/t of incinerated waste. Nowadays, 0.75 million tonnes of waste in the Czech Republic is incinerated annually and about 0.02 mil. tonnes of FA produced. With the future limits of landfilling in the EU, the volume of FA will increase. Finding environmentally friendly pathways to promise the use of FA concerning the Green Deal, Circular Economy, and Sustainability goals of EU are critical to future developments in this sector. The study aims to identify and evaluate the potential environmental impacts (EI) or benefits of the viable pathways of MSWI FA treatment in the Czech Republic. EI are evaluated using the Life cycle Assessment (LCA) approach based on Product Environmental Footprint (PEF 3.0) methodology. The 5 cases of MSWI FA treatment pathways will be comparatively assessed for FA taken from 3 different Czech MSWI plants. The first case represents cement-based S/S of FA with landfilling of solidificates as non-hazardous waste. The second case describes the water washing of FA for removal and recovery of soluble salts and landfilling of residues as non-hazardous waste after cement-based S/S. The last three cases illustrate three different options of recovery of valuable metals (Zn, Pb, and Cu): acid extraction of metals followed by their chemical precipitation as a filter cake, acid extraction followed by electrochemical recovery of pure metals, the combination of water washing for recovery of salts followed by acid extraction of metals with their chemical precipitation. The remaining solid residues from these three cases are landfilled as non-hazardous waste after cement-based S/S, similarly to the first two cases. The evaluation is performed using GABI and OPenLCA software with specific databases (Sphera – 2021, Ecoinvent, ILCD, EF, Exiobase, etc.). The results of selected impacts (such as climate change, acidification, photochemical ozone formation, water consumption, ecotoxicity, etc.) are presented and compared with published data from international studies and databases. In addition, the potential circular economy indicators of by-products will be evaluated. The analysis is focused primarily on the operation phase. The life cycle inventory (LCI) includes the transportation of MSWI FA by truck from the MSWI plant to its disposal on an above-ground landfill. For all cases, the impacts of the transport of the necessary operating media (cement, acids, etc.) are included. The functional unit is defined as 1 tonne of MSWI FA for the treatment and disposal. For the cases, the recommendation from the study [2] is considered for possible transfer into the environments (more specific to air, soil, and aquatic) and validated with data obtained from databases. Input and output process flows are defined with the conclusions obtained from experimental verification of MSWI FA treatment supplemented by balances and data from international published studies, journals, and reports. In the end, two approaches of distributions of EI into by-products will be analyzed and compared. The first is the form of credits as a replacement for identical products from raw materials. In the second approach, the PEF 3.0 of the MSWI, including FA treatment, will be divided into each product based on allocation, i. e., techno (mass, exergy), economic (market price/cost), or circular indicators. [1] Yuying Zhang, et al., Treatment of municipal solid waste incineration fly ash: State-of-the-art technologies and future perspectives, Journal of Hazardous Materials, Volume 411, 2021, 125132, ISSN 0304-3894, https://doi.org/10.1016/j.jhazmat.2021.12 [2] Huber F, et al., Comparative life cycle assessment of MSWI fly ash treatment and disposal. Waste Manag. 2018 Mar;73:392-403. doi: 10.1016/j.wasman.2017.06.004. Epub 2017 Jun 9. PMID: 28602425 Please click Download on the upper right corner to see the presentation

Intermediate pressure reboiling in geothermal flash plant for increased power production and more effective non-condensable gas abatement

Non-condensable gases (NCG) in condensing geothermal flash plants have negative effects as they reduce heat transfer and thus deteriorate vacuum in condenser. Therefore, it is necessary to evacuate the condenser by vacuum pumps which substantially increases the parasitic load of the plant. Furthermore, NCG consist mostly of CO2 and H2S, gases for which methods of abatement are being searched for. In such case, further compressors or blowers are usually required to push the gas through absorption systems. Alternative methods of NCG separation consider a reboiler upstream of a turbine. This process is however connected with significant loss of steam enthalpy, moreover the NCG in high content have also certain work potential. Therefore, this method is often not considered as very perspective. We are proposing a novel solution where the turbine is split in two parts at high and low pressure. The splitting point is at a pressure right above an ambient pressure, wherein a reboiler is placed. By doing so the NCG stream is easily obtained without energy penalty of vacuum pumps, without decreasing turbine admission parameters, and also utilizes its pressure potential. This stream is thus easily ready for processing and subsequent CO2 separation and conditioning. Condensed water is from large part turned back to steam in the cold side of reboiler which gives further work in low pressure turbine with achievable lower backpressure and therefore potential for higher power production. Another advantage of this method is liquid phase elimination from the turbine thus achieving higher turbine efficiency

Techno-economic comparison of three technologies for precombustion CO2 capture from a lignite-fired IGCC

This paper compares the techno-economic performances of three technologies for CO2 capture from a lignite-based IGCC power plant located in the Czech Republic: (1) Physical absorption with a Rectisol-based process; (2) Polymeric CO2-selective membrane-based capture; (3) Low-temperature capture. The evaluations show that the IGCC plant with CO2 capture leads to costs of electricity between 91 and 120 €$MWh–1, depending on the capture technology employed, compared to 65 €$MWh–1 for the power plant without capture. This results in CO2 avoidance costs ranging from 42 to 84 €$tCO2,avoided –1 , mainly linked to the losses in net power output. From both energy and cost points of view, the low-temperature and Rectisol based CO2 capture processes are the most efficient capture technologies. Furthermore, partial CO2 capture appears as a good mean to ensure early implementation due to the limited increase in CO2 avoidance cost when considering partial capture. To go beyond the two specific CO2-selective membranes considered, a cost/membrane property map for CO2-selective membranes was developed. This map emphasise the need to develop high performance membrane to compete with solvent technology. Finally, the cost of the whole CCS chain was estimated at 54 €$tCO2,avoided –1 once pipeline transport and storage are taken into consideration. © Higher Education Press and Springer-Verlag GmbH Germany, part of Springer Nature 2019acceptedVersio

Techno-Economic Assessment of Carbon Mitigation Technologies (TRANSMIT)

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