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The European Union (EU) presented a uniform List of Waste (LoW) in 2000 and last updated the technical guidance in 2018. The respective local regulations for the classification of waste in Estonia were set in 2015. Due to the changes in the regulations, it was necessary to review the properties of solid wastes generated in Estonian oil shale industry in light of hazardous properties. Therefore, the properties of the produced ash streams were analysed and the obtained results were compared to those for coal for being in accordance with common practices. The main objective of the paper was to answer the question whether the properties of oil shale (OS) are comparable to those of coal as coal and its combustion residues were not considered hazardous waste in Europe, but the respective counterparts of oil shale were. The EU guidelines suggest the use of calculations based on trace element concentrations for the classification of hazardous property (HP) 14 - ecotoxic. Therefore, an extensive study was conducted to investigate the hazardous properties of all the solid residues from power plants operating on oil shale and shale oil production facilities. This paper describes one part of it - the trace element compositions of the major ash streams produced in the Estonian oil shale industry and focuses on their comparison with data available for coal ash samples. The findings of the study showed that, similarly to coal, oil shale ash (OSA) should not be considered as ecotoxic due to the low concentrations of trace elements. It was found that the investigated oil shale ash samples exhibited a very similar composition and properties to those of coal, and as a result of a larger study, from the beginning of 2020, oil shale ash and other oil shale thermal treatment residues are not classified as hazardous waste in Estonia, thereby initiating policy changes that affect most areas of the economy. [ABSTRACT FROM AUTHOR]

Naturally monopolistic network industries are subject to economic regulation to achieve an optimal use of infrastructure and avoid the abuse of monopolistic power. In theory, such intervention leads to a higher allocative and productive efficiency in the industry. Relatively little is known about the results the economic regulation gives in practice and whether it achieves the objectives set. Literature states that due to the context-specific nature of regulatory framework, ex post analysis and practical experiments are necessary to be performed to study the impact of economic regulation on the performance of industries. In this paper, analysis of the impact of economic regulation on the oil shale value chain in Estonia is performed and the results are provided. Based on relevant policy documents, regulatory objectives and targets are identified and indicators compiled to monitor the results. The discussion is presented and recommendations for further research are given. [ABSTRACT FROM AUTHOR]

The objective of the paper is to define CO2 intensity for Estonian oil shale used for energy generation. Life cycle analysis (LCA) is selected as a modelling tool to reach the objective. The model analysis energy requirements and CO2 emissions are associated with mining and transportation of shale rocks and production of shale oil. Since the oil shale retorting process works as a 100% self-compensation energy technology (heat and gas derived from retorting of oil shale are reused within the on-going and next retorting), the paper lays emphasis on analysis of the co-products life cycle in elimination of CO2 emissions. Preliminary results of the research show that life cycle CO2 emission factors of oil shale processing mainly depend on the technology used for production of final raw products as shale oil, semi-coke gas and generator gas. Also, boundaries of the researched system must be taken into account due to avoided emissions from co-products production instead of using universal CO2 emission factors and assumptions. Future work will be focused on J) material based life cycle analysis to investigate whether the energy produced from oil shale resources can compete with other fuels in terms of life cycle emissions, and 2) LCA impact assessment of the system. [ABSTRACT FROM AUTHOR]

This paper describes the requirements for the generator's excitation system. Different parts of the excitation system are also presented. Two totally different types of excitation systems are installed in generators of both Eesti and Balti power plants. The one -- fast static excitation system UNITROL5000 produced by ABB -- was installed in 2005. The other is a rather slow excitation system -- high-frequency AC machine -- produced in Russia in the middle of the 70s. The paper presents main structures of those excitation systems and their control systems and also proposes models of control systems for dynamic calculations of those systems. [ABSTRACT FROM AUTHOR]

This paper presents the results of determination of the total sulphur content of Estonian and Chinese oil shales (OS) by using different analytical methods - elemental analysis, quantitative chemical analysis and X-ray fluorescence spectroscopy (XRF). The different forms of sulphur and respective quantities were determined in order to offer a possible explanation to the discrepancy between the results. Thermogravimetric analysis coupled with mass spectrometry (TGA-MS) was used as an additional tool to verify the release of SO2 and confirm the existence of sulphur in the organic and mineral parts of oil shale. Different analysis methods established different sulphur contents for the samples, showing a strong relationship between the sample composition and the analysis result. For both Estonian and Chinese oil shales the highest total sulphur content values, 1.53 and 2.23%, respectively, were determined using elemental analysis. As expected, the values were highly dependent on analysis conditions: the mass of sample and amount of catalyst used. The total sulphur contents of Estonian and Chinese oil shale samples as determined by the quantitative chemical analysis were 1.2 and 2.01%, respectively. Surprisingly, for Chinese oil shale the total sulphur content found by the quantitative chemical analysis was lower than that established by XRF. XRF determined the total sulphur contents of Estonian and Chinese oil shales to be 1.2 and 2.19%, respectively. These results suggest that elemental analysis should be the preferred method for the determination of total sulphur content. [ABSTRACT FROM AUTHOR]

The problems and long-term prospects of energy supply in the world and in Estonia have been discussed in the paper. The problems treated in this paper are: environmental impacts, economical using of energy sources, electricity supply, optimization of power and interconnected power systems and electricity supply prospects in Estonia. The vector optimization of energy supply with the objective to minimize the consumption of energy sources, environmental impacts, operational and investment costs in the long-term perspectives is recommended in the paper. [ABSTRACT FROM AUTHOR]

The paper introduces the landscape assessment approach for the post-mining landscapes in the Estonian oil shale open-cast mines. Typologies of mining landscapes are based on landscape pattern, features and functions predetermined by mining technologies. The open-cast mines which have been predominantly subjected to monofunctional reforestation should direct to diversification of landscape and its functions to enrich biodiversity and public uses. Despite controversial approaches and image on mining landscapes reasons for higher appraisal and multifunctional use of mining areas are argued. Preserving heritage-valued mining landscapes could be applied using integrated physical planning. [ABSTRACT FROM AUTHOR]

Estonian national energy strategy since 1991 is analyzed in this paper. Estonia separated from the Soviet Union in 1991 and joined the EU in 2004. The first national energy strategy was worked out in 1938. Creation of contemporary energy strategy for re-independent Estonia started in 1988. Over 90% of electricity in Estonia is generated by oil shale thermal power plants. Estonian state is the owner of strategic power plants, electrical networks and mining enterprise. In this paper a short overview of national energy development programs and state's role in forming the energy strategy is presented. [ABSTRACT FROM AUTHOR]

This paper studies the effect of alkaline oil shale ash on oil shale thermal decomposition products during oil shale and ash co-retorting. Experiments with and without ash were carried out in a standard laboratory-scale retort (Fischer Assay) to determine relative yields of retorting products and sulfur distribution in them. Oil shales compared in this study were kukersite and Dictyonema shales from Estonia, Jordanian El-Lajjun oil shale and Saveljev oil shale from Russia. Oil shales were primarily selected due their difference in sulfur composition. Ash for co-retorting experiments was prepared from kukersite oil shale. The ash contains about 57.5 wt.% alkaline compounds CaO and MgO. [ABSTRACT FROM AUTHOR]

The paper gives an overview of changes in heating value of Estonian oil shale, when it is burned in fluidized bed (FB) boilers, and of the accompanying phenomena -- increase in boiler efficiency, fuel flow, and decrease in harmful atmospheric emissions. In the context of boiler efficiency, the paper also tackles the issue of the extent of the actual increase in efficiency and the importance of partial decomposition of carbonate in the mineral part of oil shale, and almost complete sulphur binding in FB boilers. [ABSTRACT FROM AUTHOR]

Presents an overview of the Symposium on Oil Shale held in November 2002 in Tallinn, Estonia. Symposium section on oil shale resources, geology and mining; Section on power generation from oil shale; Section on oil shale chemistry and technology.

Provides information on the Symposium on Oil Shale from November 18 to 21, 2002 in Tallin, Estonia. Discussion on oil shale resources of the world; Analysis of the oil shale energy system in the country; Advantages of the use of oil shale.

In this paper, the geopolymerization of the solid heat carrier (SHC) ash waste produced at Petroter shale oil plants, Viru Keemia Grupp (VKG), Estonia was studied. Different mixtures were prepared to study and evaluate the potential use of this SHC ash for geopolymer-type mortar and cement production and to compare alkali-activated black ash with the material having self-cemented upon hydration with plain water. Mixtures prepared with plain water and NaOH solution show comparable compressive strength development, but the mixture with NaOH affords significantly lower com­pressive strength values, which can be explained by the absence of an ettringite/monosulphate phase in the NaOH-activated samples. Hydro­calumite precipitated instead of ettringite in the NaOH-activated mixture does not provide the interlocking structure that is found in water mixtures, though the formation of an amorphous geopolymer phase is possibly observed in the NaOH-activated sample after 90 days of curing. Sodium silicate- and Na-silicate/NaOH-activated samples show a strong geopoly­meriza­tion and development of Ca-Na-Al-silicate gel formed in the pore space of the ash aggregate. However, due to strong shrinkage upon drying, the compressive strength obtained after 7 days of curing is lost in the pro­longed curing process, and further research into the causes and prevention of Ca-Na-Al-silicate gel shrinkage is needed. [ABSTRACT FROM AUTHOR]

About five years ago, in 2011, Prof. Volli Kalm wrote a short review of the bibliometrical analysis of Oil Shale, an Estonian journal covering all aspects of science and technology related to oil shale. Now, a few years later, it would be good to take another, more up-to-date look at Oil Shale and its bibliometrical data to see how the journal’s role and pertinent information have changed since 2011. In the last years, a lot has changed in bibliometrics and scientometrics. Bibliometrical analysis is still an everyday part of science and scientific analysis just as a peer review, but the range of bibliometrical indicators has widened from superficial indicators like citation count and h-index to more specific indicators like field-normalized citation rate and journal quartile score. These new indicators enable us to have a deeper insight into a journal’s impact within its own field. Strong competition between Thomson Reuters Web of Science and Elsevier Scopus has made them two of the largest, most reliable and prestigious databases in the world. There is little doubt about the quality of information in these databases. The data contained may sometimes be different but this does not affect their overall value. Although criticized by some users for being more useful for those fields of research whose numbers of citations are higher, both have followed a fair and equal policy towards all of them. This short review of the bibliometrical indicators of Oil Shale was made using data from the following databases: Web of Science Core Collection (WoS), Journal Citation Reports (JCP), Scopus and SCImago. Data was taken on the 2nd of November 2014. [ABSTRACT FROM AUTHOR]

The objective of this paper is to elucidate the sustainability of Estonian shale oil industry until the year 2030 in terms of the full cycle breakeven cost of oil. The full cycle cost is rapidly increasing due to increasing necessary capital expenditure, increased national taxation and the European Union (EU) carbon (C) emissions abatement policies. There is a fair amount of uncertainty about all three components, which makes scenario analysis an appropriate tool to estimate the survivability of Estonian shale oil industry scenarios in the next 15 years. Past economic performance alone is not a proper guide for future in case of Estonian oil shale industry. However, heavy investments have been made in the industry since 2011 and several hundred million euros are being invested or planned to invest in the replacement of old capacity and raising new oil production capacity. Analysis shows that, indeed, in certain scenarios the shale oil breakeven price is at the highest end of global crude oil production projects, thus raising questions of the industry’s survivability in case of multiyear sustained global oil prices below 90 USD/bbl. Conclusions of the study are relevant to analyzing the full cycle costs of other promising global shale oil projects. [ABSTRACT FROM AUTHOR]

The aim of this paper is to examine the role of the public perception of oil shale mining and industrial heritage in regional revival. Oil shale mining and chemical operations have left an imprint on both the people and the landscape of Ida-Viru County, NE Estonia. Along with increasing or decreasing production volumes of oil shale mining, heritage has been overlooked, left to naturally deteriorate or to be destroyed or recultivated. Heritage-awareness revival projects for similar natural resource postindustrial situations have proved to be successful in culture, sports and recreational tourism. The current view on oil shale mining heritage is investigated through focus group interviews and a questionnaire. Unemployment, language barriers and social problems are considered to be the most important issues, and the responsibility for solving these problems is primarily deemed to be the role of the national government. At the same time, in general, people are willing to participate in processes and regard coordinated planning as crucial to holistic development. Post-industrial areas should be utilized to support the development. [ABSTRACT FROM AUTHOR]

Oil shale is considered the most important natural resource of Estonia and its role in energy production and chemical industry has been pointed out in numerous papers. But there are no special publications about the history of the Estonian oil shale industry in English. This article tries to fulfil the gap relying on numerous archival documents and literature sources which have remained out of the attention of scientists up till now. It follows from the article that without the studies carried out by Russian researchers in 1916-1920 the Estonian oil shale industry may not have been born. Using the results of Russian investigators, the Estonians hoped to set up their own oil shale industry applying Scottish experience. This hope failed, however, and thus the Estonians had to elaborate their own methods for the development of oil shale chemistry. [ABSTRACT FROM AUTHOR]

Oil shale ash (OSA) as a binder has air, pozzolanic or latent hydraulic properties depending on the combustion temperature and type of ash collection equipment. This paper focuses on the use of OSA as the main binder for low strength concrete. Impact of hardening conditions on the strength development and soundness of various concrete mixes made with two main types of OSA and their mixes was tested. Crushed limestone was used as aggregate. Concrete mixes were designed at an OSA:aggregate ratio of 3:1 and 1:1, using fresh concretes with the same workability. The results revealed differences in the strength development, 28-day compressive strength and durability properties between hardened concretes made with various OSA binders. The compressive strength of concretes made with various OSA was tested in different curing conditions. The durability properties of OSA based hardened concrete such as water absorption and resistance were tested. The results of expansion and water resistance tests indicated that by increasing the content of CFB ash in OSA binders, water resistance was improved and expansion diminished. [ABSTRACT FROM AUTHOR]

The global importance of and demand for oil shale are currently rapidly growing. Deposits of oil shale are widespread around the world. All this necessitates assessment of the sustainability of existing open-pit and underground mining technologies to improve oil shale mining management The aim of the present study is to elaborate a method for assessment of the sustainability of oil shale mining to develop advanced mining technologies on this basis. Sustainability assessment has earlier been applied to two exploited Estonian carbonate rock deposits - dolostone and limestone. It was shown that a three-level matrix monitoring scale gives structured results. This paper considers the applicability of a sustainability assessment matrix to Estonian oil shale mining. [ABSTRACT FROM AUTHOR]

Estonia has two of the world's largest oil shale firing circulating fluidized bed (CFB) units with a designed electrical capacity of 215 MW each. The units are based on double boiler CFB technology provided by Foster Wheeler Energia OY. The units are located at Eesti and Balti power plants (EPP and BPP). The paper presents analyses of data obtained from tests of oil shale and biomass co-combustion in the full-scale CFB boiler located at BPP. The tests were conducted at nominal boiler load: 100% (314 t/h), with a biomass thermal input of 15%- During the experiments ash samples from the furnace chamber (bottom ash), INTREX, super-Zreheater (SH, RH), economizer (ECO), and air preheater (APH), and from all four fields of the electrostatic precipitator (ESP) were taken. Samples of fly ash for determining the mass division (total suspended particulates PM10 and PM2.5) were taken after the ESP. The gas analysis was performed at the ESP inlet. Analysis of the chemical composition of ash was carried out. The specific consumption of oil shale per useful heat and gross electricity were found and other techno-economic characteristics determined. It was found that oil shale and biomass co-combustion reduced CO2 emission by J4.6% and ash formation by 16% when, compared with conventional oil shale CFB combustion. The SO2 emissions remained in the limits of 20-30 mg/Nm3. Total suspended particulates PM10 and PM2.5 did not change compared to conventional oil shale CFB firing. The CFB boiler efficiency even increased slightly, when it is known that in case of coal and biomass co-combustion it decreases. Therefore, oil shale and biomass co-combustion can be considered as a viable option and near-term solution for reducing the environmental impact of oil shale-based power production. [ABSTRACT FROM AUTHOR]

Several extraction technologies have been used for mining oil shale in Estonia. The quality and properties of the raw material for fuel and oil depend directly on the initial geological properties of the mineral resource. In case of kukersite oil shale in Estonia the calorific value, oil yield and limestone content vary. The paper considers possibilities for selective mining of kukersite oil shale based on tests and theoretical studies. Analyses show that selective and high selective mining extraction methods have a potential for increasing oil shale yield and decreasing losses. [ABSTRACT FROM AUTHOR]

The growing demand for the world energy supply necessitates the employment of local low-grade fossil fuels like oil shale (OS). The use of such fuels is accompanied by the formation of large amounts of waste ash, which are usually disposed of in open-air deposits and may hence lead to serious environmental problems. The nature of environmental hazards depends on the composition and properties of the deposited ash, which in turn are derived from the composition of the initial fuel, as well as its processing parameters. The exploitation of Estonian OS deposits has a near centurylong history, including over 60 years of industrial production of heat and power, and the respective management of ash deposits. In the current paper, the results of the last decade's studies on the processes taking place in Estonian OS ash fields have been analysed. The complex composition of ash and its transformation reactions under ambient conditions have been considered. It is shown that the hydraulic ash removal and wet depositing system works as a natural CO2 trap. The algorithm for the calculation of the resulting effect has been evaluated. [ABSTRACT FROM AUTHOR]

Estonia had set a target to increase the share of renewable energy sources in the energy production up to 5.1% of total consumption by the end of 2010. There are no large rivers and solar activity is also low in Estonia. Therefore one of the biggest possibilities to achieve that target is to use bio fuels and wind power. Approximately 90% of total electricity is generated from oil shale, hereby oil shale power plants have to cover wind energy deficits. Wind speed is very variable and therefore electric power production by wind turbines varies from zero to nominal power. This is a problem for the power grid. The current paper analyses whether wind turbines and wind farms need 100% balanced power. Wind data of four weather stations around Estonia were investigated. Wind speeds were calculated to 100 meters above the ground level and Weibull distributions were composed. Distribution and duration of zero energy periods were analysed. In 2008 zero wind production periods varied from 1 to 7 hours (63 times) and their sum was 137 hours. In these periods wind turbines need 100% balance power. [ABSTRACT FROM AUTHOR]

Estonian electricity generation requires new investments due to limitations for emissions, deterioration of old power plants and growing electricity consumption. This could be the turning point for distributed generation (DG) in Estonia. DG would allow saving energy and reducing emissions due to more efficient fuel usage. Also the supply reliability and energy security would be increased through availability of local power generation. In this paper the definition and potential of DG in Estonia is estimated and the optimal operation criteria are examined. The possible effect of DG development on electricity price and emissions is assessed using LEAP software. [ABSTRACT FROM AUTHOR]

Characteristic numbers of Primary Control for a small control area of interconnected power systems, such as Estonian Power System, become a major consideration in perturbation's islanding (isolated operating), or in initiating black start situation. Against a background of independence of the transmission system and electricity production towards the recently opened electricity market in Estonia arise the actuality of reliability in the context of the quality of supply (frequency and voltage) and successful parallel operation. Characteristic numbers of Primary Control, such as the network power frequency characteristic, governor droop and load response influence to the frequency regulation process in case of significant frequency deviation. Because of solely dependence on Primary Control executed by IPS central regulator, the limited number of frequency affecting events can be obtained for the reasonable figures. The controlled system separation test is the only opportunity for Estonian Power System that investigates the capability of frequency regulation. Primary Control relates to the supply and load responses that stabilize frequency whenever there is a change in loadresource balance. Based on the methodology suggested by ENTSO-E and local measurements, the study state behavior of Primary Control of the isolated Estonian Power System is described in the case study. The paper presents the characteristic numbers of Primary Control in the isolated system under the system contingencies such as the artificially created failure produced by network or switch-offs of individual generating blocks and switch-offs of the HDVC link. [ABSTRACT FROM AUTHOR]

Estonia had obligation to EU to use 5.1% of renewable power (from the total consumption) by the end of 2010. This obligation could be reached mainly by introduction of new co-generation power plants on the basis of biomass (Tallinn, Tartu, Pärnu), with expanding power production from the wind, but also by co-firing Estonian oil shale (OS) and biomass (BM) at large oil shale power plants in Narva region. The essential precondition of co-firing of BM and OS in boilers of Baltic and Estonian power station is availability of sufficient quantities of bio fuels in the neighbourhood. In Estonian conditions the most promising biomass for co-firing is wood fuel, but due to availability of abandoned agricultural lands in the North-Eastern part of Estonia short-rotation forestry (willow, grey alder etc.) or plantations of energy crops and wetland plants may play considerable role, too. During 2009/2010 about 200000 tons of wood chips and about 10 million tons of OS were used for power production in Narva power plants already [1]. In the context of OS and BM cofiring at large OS boilers two aspects should be analysed. The first question is related to possible technical problems of co-firing, and the second one concerns BM resources available in the North-East region of Estonia. These two problems are analysed in the paper. It was concluded that co-firing of pulverized OS and BM (up to BM content in the blend of 15% by mass) does not have any considerable negative effect on the normal operation of boiler while reducing environmental emissions. Wood and other BM resources will cover relevant need for BM at the distance of 100 km from the power plants. [ABSTRACT FROM AUTHOR]

In this paper the country-specific carbon emission factors for the by-products from oil shale thermal processing (generator gas, semi-coke gas and semicoke) for different technologies are presented. Today these emission factors have still not been determined in Estonia. As the shale oil production will increase significantly in the future, major attention should be paid to the oil shale production-related emission factors. [ABSTRACT FROM AUTHOR]

Surface miners (further SM) can find their natural applications in projects where drilling and blasting is prohibited or where high-selective mining of mineral seams required. Selective mining improves the quality of oil shale. Through the cutting quality the mineral resource utilisation is more effective and environmental impact is lower. The present paper introduces a highly selective oil-shale mining technology and results of an analysis on cutting and quality parameters. Size distribution and calorific value of oil shale is in dependence on cutting thickness and cutting (advance) speed. It is possible to achieve required average size of mined oil-shale particles, which was confirmed by the present investigation data. The information obtained enables specialists to improve the quality of mining works by means of fuel consumption optimisation. [ABSTRACT FROM AUTHOR]

In this paper the changes of power demand, power generation of oil-shale thermal power plants, the changes of wind power and interchange power are analysed. The analysis is made on the basis of 2-second and 5-minute data acquired from Estonian power system. From the analysis it is concluded that using of wind power plants in the power systems together with oil-shale power plants is quite limited. If the share of wind power should exceed this limit, notable losses in the ability to regulate power balance and power of oil-shale power plants may be caused. [ABSTRACT FROM AUTHOR]

The main task of the energy system is to supply the consumers with high-quality electric and heat energy. As possibilities for accumulation of the energy and especially electrical energy in Estonia are very limited, one of the main energy parameters is its uninterrupted supply. The needs of consumers are characterized by the demand curve - the variation of load for a given time period (day, month, year). It is necessary to stress the difference between load and demand curves for the producer and consumer. Up to the recent time the producer load curve consisted of the individual consumers' demand curves sum plus losses in the distribution elements (in electric networks). Nowadays when by economical and ecological reasons the renewable energy sources are more intensively used, the part of the energy producers using wind and solar energy is constantly rising, and they are increasingly influencing the work of the whole energy system. That complicates significantly the work of the high-powered electric energy generators (with large inertia) at power stations as, in addition to the load variations depending on demand, they have to compensate extremely stochastic production of wind turbines. In this paper the problem is discussed on the basis of load and demand curves of the Energy system of Estonia and Pakri wind farm. It is shown that these curves are not suitable for mutual compensation and that may disturb the stability of the energy system at the wind park maximum power. The result is that the Energy system dispatcher is forced to limit the production of the wind park. [ABSTRACT FROM AUTHOR]

Wind power (WP) is the most developing area in the Estonian renewable energy sector, but there are technical limitations on its integration. At a certain capacity some balancing measures are required to handle large amounts of WP. This could be achieved by introducing combined heat and power plants (CHP) at regional level. The use of gas engine allows quick response to load changes and therefore is suitable for regulating activities. As for principles of distributed power generation, the aim is to locally minimise the shortfall and surplus of electricity. By this additional costs of rebuilding power lines and building new balancing generation units can be avoided. In this paper possibility of balancing WP with CHP is analysed. The investigation is carried out with the help of energyPRO software, which allows simulating the cooperation of WP and CHP. Also the essence of building heat storage is analysed, to add flexibility into the plant operation. [ABSTRACT FROM AUTHOR]

During the negotiations with EU, Estonia was set an indicative target to increase the share of renewable energy sources in the electricity production to 5.1% of inland consumption by the year 2010. Similarly to the rest of Europe, one of the main means to achieve this target is to install wind turbines. The current paper analyses the capability of existing oil-shale power plants to cover differences between forecasted and actual generation of wind energy and shows that participation of fossil fuel-based power plants in the compensation of fluctuating production of wind turbines eliminates part of the expected positive effect of wind energy. [ABSTRACT FROM AUTHOR]

This paper deals with tile risk assessment method of roadheader feasibility in underground conditions of Estonia mine. In modernization of Estonian underground mining, roadheaders that extract oil shale selectively play the most important role. Selective extraction allows reduction of rock mass volumes during the loading, transportation and enrichment processes. Thus, about 23% of limestone extracted together with oil shale will be left in the mine for backfilling the excavated areas. Backfilling increases carring capacity of pillars reducing losses of oil shale and restores, in a certain measure, filtrational, hydrodynamical, and aerodynamic properties of the geological environment. For selective extraction four variants of different excavation thicknesses, depending on geological conditions, have been proposed. Risk analysis allows comparison of the advantages and disadvantages of full and selective extraction. Risks of oil shale losses during selective extraction are estimated using the event tree. Preliminary calculations have shown sustainability of roadheaders for selective extraction under the mining and geological conditions of Estonia mine. [ABSTRACT FROM AUTHOR]

Power generation of Estonia is based on oil shale today. The share of oil shale ill power generation is over 90 per cent. According to prognoses of Estonian economic growth, the need for energy will grow and even if applying alternative power sources, it cannot be realistic that it could be reduced to less than 50 per cent of today's volumes in 2020. Because of the increasing cost of crude oil, oil generation from shale is of growing importance. But oil shale is very rich in ash, which results in huge amounts of solid residues. In addition Estonian oil shale has a great content of carbonate minerals thus combusting and oil processing is accompanied by abnormally high emissions of C02. Though emission of sulphur dioxide is low due to carbonate minerals, limitation of S02 pollution is expected in the near future. In relation to growing environmental requirements, the interest towards utilisation of oil shale of higher calorific value has grown. As it is clear that higher calorific value of product causes higher production expenditures, the question arises where is the optimal point. Consumers are interested in a fuel raw material of higher quality. Upgrading of oil shale results in higher operating expenses and requires also applying of a new price scale. Optimizing the grade of the oil shale as well as the quality of the shale oil to best fit the interests of the mines and consumers is the subject of this paper. [ABSTRACT FROM AUTHOR]

The paper deals with risk management problems in Estonian oil shale mines. Investigations are focused on application of the method to determination of the quality of geological data. Various factors relevant to mining technology in Estonian oil shale deposit have been determined. For risk estimation, the empirical and judgmental approaches and the event tree were used. They allow determining the probability of the occurrence of geological features and its influence on the mining process. Analysis of obtained results showed that it is necessary to elaborate special methods for determination of the geological conditions in the mining area. The obtained information affords specialists to improve the quality of geological information and consequently the mine work efficiency. The analysis shows that the used method is applicable in conditions of Estonian oil shale industry. The results of the investigation are of particular interest for practical purposes. [ABSTRACT FROM AUTHOR]

The Environmental Chemistry and Ecotoxicology Group of Lancaster University, United Kingdom, has completed a large European-scale air sampling campaign within the framework of the project, POPs Fate Modelling. Samplers were deployed at remote, rural and urban locations (71 stations) in 22 countries, two Estonian stations -- Lahemaa-background EMEP station and Kohtla-Järve industrial (oil shale chemistry) region station -- among them. This paper presents data on a range of polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (hexachlorocyclobenzene (HCB), hexachlorocyclohexane (HCH), ppDDE, ppDDT), polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCN) determined in ambient air samples collected at Estonian stations. [ABSTRACT FROM AUTHOR]

Semi-coke is a solid waste material left after oil shale retorting in oil shale chemical industry. During more than 80 years of operation more than 110 million tonnes of semicoke have been deposited at retorting plants in Estonia but so far very little is known about the mineral composition of this waste. This paper presents new data on mineral composition of semi-coke and its spatial variation in waste heaps. The composition of semi-coke reflects the changes of mineral matter during the retorting process. The changes with the terrigenous and carbonate matter is almost negligible during the main phase of retorting, only dehydration and partial transformation of clay minerals and decomposition of sulfur compounds occur. At the final step of retorting (900-1000 °C) a slag-like material forms, which consists of amorphous and Ca-silicate phases. The deposition and subsequent hydration causes the change in the composition of semi-coke. The most notable change is the formation of ettringite. The composition of mineral matter in semi-coke waste heap is relatively uniform. The variations are probably due to both physical and chemical separation during deposition of the sediment and to different diagenetic/hydration processes. [ABSTRACT FROM AUTHOR]

This paper presents the results of elaboration of long-term national energy plans. The most important aim was reduction of CO2 emissions. Long-term national energy plans can be worked out with special computer programs, such as MARKAL, which is one of the well-known programs in this field. MARKAL is a dynamic linear programming "bottom-up" model, which finds the optimal development of the energy system under given technological characteristics and boundary conditions. Estonia differs greatly from other countries in the world. Oil shale is the most important fuel for power stations in Estonia. [ABSTRACT FROM AUTHOR]

The paper deals with risk analysis/assessment problems in Estonian oil shale industry. Investigations are focused on application of these methods for railway transport from mine to consumer. Various factors relevant to oil shale transport have been determined. For risk estimation an empirical approach, the event/fault tree is used. It allows to determine probability of deviations of the process duration from the mean value for different pathways. The obtained information affords specialists to improve the quality of the railway transport. The analysis shows that the used method is applicable in conditions of Estonian railway systems. The results of the investigation are of particular interest for practical purposes. [ABSTRACT FROM AUTHOR]

This paper presents a short overview about the discussion about the hydrogeological problems connected with oil shale exploration in NE Estonia. On the basis of the results of the solution to the hydrogeological model developed at Geological Survey of Estonia it was found that the proportion of unconfined groundwater in different open-cast mine fields accounts for 6-34% and precipitation water makes up 66-84% in the depleted area. Presently a unified groundwater model of Estonian-Russian border region comprising a 200x200-km area north from Lake Peipsi is being compiled under the initiative of French Geological Survey (BRGM). [ABSTRACT FROM AUTHOR]

The Estonia oil shale deposit is not only of national but also of regional importance. The paper shows the urgent need for a long-term general strategy of sparing and sustainable extraction and protection of oil shale reserves which is elaborated by specialists and accepted at governmental level. Regulating the land use within the mineral deposit guarantees the most complete use of oil shale reserves and flexibility to avoid/reduce/mitigate impact of mining. [ABSTRACT FROM AUTHOR]

Oil shale has a major role in Estonia's energy supply. This paper gives a brief analysis of indicators on efficiency and on environmental impact of the energy sector in Estonia. A more detailed overview is given on emission of greenhouse gases and on relevant possibilities of their reduction. Increase in energy efficiency is an important factor for the energy usage but also for the economic development of society. Therefore an overall assessment of trends on the national level is given, and a brief comparison with relevant indicators in other EU member states is presented. [ABSTRACT FROM AUTHOR]

Chlorine in Estonian oil shale is bound with the organic part, and that determines its behavior in boiler. The behavior of chlorine is also affected by sulphur dioxide present in flue gas. The objective of the present paper was to study the influence of sulphur dioxide and hydrogen chloride present in flue gas on hardness and chemical composition of possible deposits on heating surfaces of CFB boilers. A laboratory test facility at the Department of Thermal Engineering of the Tallinn University of Technology was used for the study. Experiments with filter and cyclone ashes of circulating fluidized-bed combustion of oil shale were carried out at 700°C at atmospheric pressure. Gas mixtures studied contained hydrogen chloride, sulphur dioxide, oxygen, and nitrogen as the balance gas. Experiments established that sulphur dioxide present in the surrounding gas fosters hardening of ash (test samples). Experiments with a gas mixture containing sulphur showed that CFBC fly ashes relatively rich in free lime are able to bind sulphur from flue gas. At heating of samples in a chlorine-containing atmosphere sulphur does not volatilize in these conditions. The results of chemical analysis of some deposits collected after approximately 4000 hours of operation of industrial CFBC boilers are presented. These results show high chlorine content of deposits formed on economizer tubes. Chlorine content of these deposits is comparable with chlorine content of a test sample heated for one hour. [ABSTRACT FROM AUTHOR]

Estonian basic power supply is over 90% covered by oil shale-fired thermal power plants. The original units, commissioned between 1959 and 1973, used pulverized firing (PF) technology. Because of their age and problems related to environmental and economical performance, it was decided to replace two old blocks with new ones applying a more advanced circulating fluidized-bed (CFB) technology. In 2001 AS Narva Elektrijaamad contracted Foster Wheeler to repower two blocks, Block No. 8 at the Eesti Power Plant and Block No. 11 at the Balti Power Plant. The first of the renovated blocks started commercial operation at the Eesti Power Plant near the town of Narva at the beginning of 2004. Now, when the repowering project is virtually complete, it is time to review how well the new units have met expectations. Foster Wheeler's concept for oil shale combustion in CFB brings multiple benefits and opens up new opportunities for using oil shale as a clean-burning fuel capable of meeting today's emission standards. This paper will review Foster Wheeler's boiler concept for combustion of Estonian oil shale and the first operational experiences of the new units. The environmental and economical performance of the old PF and the new CFB units is compared. [ABSTRACT FROM AUTHOR]

It is suggested that there are about 86 million t (at Kiviõli 12.5, Kohtla-Järve 70.7 and Narva 3.0 million t) oil-shale semi-coke and coke deposited in the Estonian landfills since 1921. However, there is no explanation how these volumes were calculated and no data about the volumes of semi-coke formed at Vanamõisa, Kohtla-Nõmme and Sillamäe. According to the calculations based on operation of processing units, 74.7% of dry spent oil shale deposited in Estonia is located at Kohtla-Järve. These deposits (83.22 million t) consist of semi-coke and coke, 48.75 and 34.47, respectively. At Kiviõli mostly semi-coke is deposited 19.2 million t (17.2%). Ash-like spent shale is deposited at Narva (4.34 million t, 3.9%), the landfills of other locations at Vanamõisa, Kohtla-Nõmme and Sillamäe hold 2.77, 1.09 and 0.7 million t of SC (2.5, 1.0 and 0.7%), respectively. This paper presents a method for calculation the volume of spent shale. [ABSTRACT FROM AUTHOR]

The most distinguished landforms in East-Viru County, Estonia, apart from the Baltic Klint, are the artificial landforms1 generated by mining and processing of oil shale. The data in scientific literature about the height of artificial mountains is poor and sometimes controversial. Ambiguous estimations exist regarding the highest mountain. In the present paper the height of the artificial landforms in North-East Estonia is investigated. Kohtla-Järve semi-coke mountain is found to be the highest artificial landform in the Baltic States. In addition, typology, history, and future of artificial mountains are studied. [ABSTRACT FROM AUTHOR]

Customers' perceptions of reliability do not always reflect the level of reliability suggested by traditional reliability indices. Thus the electricity supply industry in Estonia intends to relate reliability investments with customers' benefits obtained from such investments. A difficulty encountered by such efforts is the lack of appropriate valuation of these benefits. With a view to correcting this paucity, the authors have conducted a study aimed at assessing the characteristics needed to estimate the expenses of customers due to electric service interruptions. Because the time frame stated for the study was relatively short for a comprehensive large-scale customer survey, the results of the preliminary pilot survey were complemented with indirect analytical methods on basis of GNP and annual household income as well as on basis of analysis of corresponding characteristics of other countries. The final estimates for different customer sectors as well as for the whole country were found as averages of estimates found by different methods. Estimated were the characteristics of cost models most widely used by power system planners and briefly overviewed also in the paper. The used methodology can be applied for evaluation of electricity supply interruption costs under restricted time and information resources. [ABSTRACT FROM AUTHOR]

During the negotiations with EU, Estonia was set an indicative target to increase the share of renewable energy sources in the electricity production to 5.1%; by the year 2010. One of the main means to achieve this target is to install wind generators. This paper analyzes the capability of the existing power system to integrate large amounts of wind power and shows that involvement of large-scale oil shale power plants in the compensation of fluctuating production of wind turbines eliminates a substantial part of the expected positive effect of wind energy. [ABSTRACT FROM AUTHOR]

An overview of the Estonian hydropower resources and their utilization at present as well as prospective for the future are presented in this paper. A short overview of advantages of small hydropower stations and related issues is given. Some technological aspects are treated briefly. [ABSTRACT FROM AUTHOR]

In this paper, the authors analyze the nature and structure of external costs in Estonian oil shale-based power plants. The methods for internalizing these costs are also introduced. The external costs discussed here primarily include the expenses related to exhaustion of natural resources and environmental damage in the context of the formation of the oil shale-based electricity production price. The authors calculate these expenses currently and prognosticate various scenarios of oil shale-based electricity production price and external costs until 2010. The scenarios take into consideration possible developments of the legislation that regulates the energy sector, and other energy related factors in the Baltic Sea region and in the European Union in general. More adequate assessment of the environmental costs is a factor that is increasingly influencing development trends of the energy sector on global scale. This is highly important also in Estonia since planning of further development of oil shale-based energy complex is still very topical. [ABSTRACT FROM AUTHOR]