Structural change and inequality in a general equilibrium model of a transition economy

The paper studies the role of economic transition in the evolution of wealth inequality. We build a novel overlapping generations model that features heterogeneous workers and exogenous changes: (i) a structural change shifting employment from manufacturing to services and increasing educational attainment, (ii) TFP growth along the path of macroeconomic convergence and (iii) gains in longevity. Using this model, we quantify the role of structural change in the evolution of wealth inequality in Poland as of 1990. We show that a rise in wealth inequality because of growing longevity is lower in an economy undergoing structural change. Thus, structural change per se lowers wealth inequality, at least initially. We also provide an evaluation of a policy-relevant redistribution instrument

Hydromechanical modelling of shaft sealing for CO2 storage

The geological sequestration of CO2 in abandoned coal mines is a promising option to mitigate climate changes while providing sustainable use of the underground cavities. In order to certify the efficiency of the storage, it is essential to understand the behaviour of the shaft sealing system. The paper presents a numerical analysis of CO2 transfer mechanisms through a mine shaft and its sealing system. Different mechanisms for CO2 leakage are considered, namely multiphase flow through the different materials and flow along the interfaces between the lining and the host rock. The study focuses on the abandoned coal mine of Anderlues, Belgium, which was used for seasonal storage of natural gas. A two-dimensional hydromechanical modelling of the storage site is performed and CO2 injection into the coal mine is simulated. Model predictions for a period of 500 years are presented and discussed with attention. The role and influence of the interface between the host rock and the concrete lining are examined. In addition the impact of some uncertain model parameters on the overall performance of the sealing system is analysed through a sensitivity analysis

Coal waste slurries as a fuel for integrated gasification combined cycle plants

The article summarizes recent development in integrated gasification combined cycle technology and lists existing and planned IGCC plants. A brief outlook on the IGCC gasification technology is given with focus on entrained-flow gasifiers where the low-quality coal waste slurry fuel can be used. Desired properties of coal and ash for entrained-flow gasifiers are listed. The coal waste slurries, which were deposited at impoundments in Upper Silesian Coal Basin, were considered as a direct feed for such gasifiers. The average ash content, moisture content and lower heating value were analysed and presented as an average values. Entrained-flow commercial gasifiers can be considered as suitable for the coal slurry feed, however the ash content of coal slurries deposited in impoundments is too high for the direct use as the feed for the gasifiers. The moisture content of slurries calculated on as received basis meets the requirements of entrained-flow slurry feed gasifiers. The content of fines is relatively high which allow to use the slurries in entrained-flow gasifiers

Assessment of coal slurry deposits energetic potential and possible utilization paths

Coal-slurries and post-flotation mud have the highest carbon content among other mine waste produced during coal mining and preparation. Therefore, coal slurries deposited in impoundments can be regarded as potential fuel. In the article methods of energetic potential assessments of raw and beneficiated coal slurry deposits were discussed. Results of such assessment for 21 impoundments were presented and the loss of energetic potential due to the imperfection of beneficiation method was discussed. The lowest losses were observed for beneficiation by froth flotation where the loss of energetic potential was on average 15%. The highest loss was observed for beneficiation in centrifugal separators where on average it was 68%. Possible paths of utilization of such slurries in Polish national fuel balance were studied using the SWOT analysis. The results of the SWOT analysis indicate that the internal factors, i.e. the ones related to the coal slurry processing technology have much lower impact on the possibility of using coal slurry deposits in the national fuel balance. Instead, according to the experts, external factors have much greater impact

Investigation of coal slurry properties deposited in impoundments located in the upper silesian coal basin

Results of investigation of physical, chemical and energetic properties of steam and coking coal slurries deposited in twenty Polish impoundments are presented in the paper. Coal slurry was sam-pled in accordance with a certain procedure from different locations and depths at each impoundment whereas laboratory investigation was performed on averaged samples. The performed investigation in-clude determination of chemical composition, moisture content, volatile matter, sulfur and calorific value at various states. Additionally, properties of coal slurry of particle size below 0.1 mm are presented. The average content of this fraction is approximately 62% and ranges at individual impoundments from 28 to 79%. An average calorific value in analytical state of coal slurries deposited in impoundments in the fraction below 0.1 mm is rather high (12.01 MJ/kg on average) in comparison to the average calorific value of impoundments in analytical state i.e. 16.4 MJ/kg. Average ash and sulfur contents of the coal slurries in analytical state is on average: 42.5% and 1.0% respectively. Transient moisture content of coal slurries in the analytical state is on average 22%, whereas the average volatile matter content is 20.0% Chemical composition is typical for coal tailings with low Al2O3 and TiO2 content. The results indicate considerable variations in the quality of coal slurries deposited in different impoundments due to different geology of coal deposits of the mines. For individual impoundment these differences are smaller which is demonstrated by a lower variation in the standard deviation

A method of proppant pack permeability assessment

Hydraulic fracturing methods used for low permeability reservoirs such as shale gas or tight gas require the use of proppants. The current standard used for proppant assessment does not take into account its interaction with the rock and the embedment effect. In this paper a new method of proppant pack permeability assessment is proposed where proppant is placed into a rock sample with induced fracture. Three types of proppant were assessed to verify the method i.e. offshore sand, onshore sand and ceramic proppant. The rock sample was a Tumlin sandstone. As the flowing medium supercritical carbon dioxide was used. Tests were performed with 300-500 μm size proppants at flowing pressure of 3 MPa and confining pressure of 5 MPa. Additional test was conducted with 1–2 mm sand proppant at two confining pressure, i.e. 5 MPa and 16 MPa. Proppant were characterized in accordance with the Krumbein/Sloss diagram. Similar values of permeability for the proppant concentration of 0.5 kg/m2 were obtained ranging from 2.3 to 3.3 D although the highest permeability was achieved with Baltic sand proppant and ceramic proppant. For the larger size of proppant (1 – 2 mm) the initial permeability with confining pressure of 5 MPa was initially larger but when the confining pressure was increased it declined by 37%. This proves that in the proposed method we can observe changes in the permeability of the fracture with change in confining pressure apply subjected to the sample