30 resultados para Environmental assessment methods
em Doria (National Library of Finland DSpace Services) - National Library of Finland, Finland
Resumo:
Credit risk assessment is an integral part of banking. Credit risk means that the return will not materialise in case the customer fails to fulfil its obligations. Thus a key component of banking is setting acceptance criteria for granting loans. Theoretical part of the study focuses on key components of credit assessment methods of Banks in the literature when extending credits to large corporations. Main component is Basel II Accord, which sets regulatory requirement for credit risk assessment methods of banks. Empirical part comprises, as primary source, analysis of major Nordic banks’ annual reports and risk management reports. As secondary source complimentary interviews were carried out with senior credit risk assessment personnel. The findings indicate that all major Nordic banks are using combination of quantitative and qualitative information in credit risk assessment model when extending credits to large corporations. The relative input of qualitative information depends on the selected approach to the credit rating, i.e. point-in-time or through-the-cycle.
Resumo:
Intelligence from a human source, that is falsely thought to be true, is potentially more harmful than a total lack of it. The veracity assessment of the gathered intelligence is one of the most important phases of the intelligence process. Lie detection and veracity assessment methods have been studied widely but a comprehensive analysis of these methods’ applicability is lacking. There are some problems related to the efficacy of lie detection and veracity assessment. According to a conventional belief an almighty lie detection method, that is almost 100% accurate and suitable for any social encounter, exists. However, scientific studies have shown that this is not the case, and popular approaches are often over simplified. The main research question of this study was: What is the applicability of veracity assessment methods, which are reliable and are based on scientific proof, in terms of the following criteria? o Accuracy, i.e. probability of detecting deception successfully o Ease of Use, i.e. easiness to apply the method correctly o Time Required to apply the method reliably o No Need for Special Equipment o Unobtrusiveness of the method In order to get an answer to the main research question, the following supporting research questions were answered first: What kinds of interviewing and interrogation techniques exist and how could they be used in the intelligence interview context, what kinds of lie detection and veracity assessment methods exist that are reliable and are based on scientific proof and what kind of uncertainty and other limitations are included in these methods? Two major databases, Google Scholar and Science Direct, were used to search and collect existing topic related studies and other papers. After the search phase, the understanding of the existing lie detection and veracity assessment methods was established through a meta-analysis. Multi Criteria Analysis utilizing Analytic Hierarchy Process was conducted to compare scientifically valid lie detection and veracity assessment methods in terms of the assessment criteria. In addition, a field study was arranged to get a firsthand experience of the applicability of different lie detection and veracity assessment methods. The Studied Features of Discourse and the Studied Features of Nonverbal Communication gained the highest ranking in overall applicability. They were assessed to be the easiest and fastest to apply, and to have required temporal and contextual sensitivity. The Plausibility and Inner Logic of the Statement, the Method for Assessing the Credibility of Evidence and the Criteria Based Content Analysis were also found to be useful, but with some limitations. The Discourse Analysis and the Polygraph were assessed to be the least applicable. Results from the field study support these findings. However, it was also discovered that the most applicable methods are not entirely troublefree either. In addition, this study highlighted that three channels of information, Content, Discourse and Nonverbal Communication, can be subjected to veracity assessment methods that are scientifically defensible. There is at least one reliable and applicable veracity assessment method for each of the three channels. All of the methods require disciplined application and a scientific working approach. There are no quick gains if high accuracy and reliability is desired. Since most of the current lie detection studies are concentrated around a scenario, where roughly half of the assessed people are totally truthful and the other half are liars who present a well prepared cover story, it is proposed that in future studies lie detection and veracity assessment methods are tested against partially truthful human sources. This kind of test setup would highlight new challenges and opportunities for the use of existing and widely studied lie detection methods, as well as for the modern ones that are still under development.
Resumo:
Tämän diplomityön tavoitteena on selvittää miksi uudisrakennushankkeeseen ryhtyvän kannattaa huomioida kestävän rakentamisen vaatimukset ja miten asetettuja kestävän ra-kentamisen tavoitteita voidaan hallita rakennusprojektin aikana. Perinteisesti rakennussektorilla on keskitytty tilaajan tavoitteiden saavuttamiseen kustan-nustehokkaasti ja aikataulussa. Kestävän kehityksen ja vastuullisuuden näkökulmat ovat kuitenkin vahvistuneet viime aikoina. Kestävän rakentamisen hallinta vaatii vielä uusia toimintatapoja ja -malleja, jotta voidaan varmistaa kestävän kehityksen kriteerien mukai-suus läpi hankkeen ja valmiissa rakennuksessa. Ympäristöluokitusjärjestelmien avulla voidaan asettaa kestävän rakentamisen tavoitteita, joita seurataan läpi hankkeen. Diplomityössä selvitetään yksityiskohtaisemmin BREEAM (BRE Environmental Assessment Method)-ympäristöluokitusjärjestelmän käyttämistä kestävän rakentamisen ohjaamisessa. Työssä selvitetään myös miten rakennusten tietomallinnusta voidaan käyttää tukemaan kestävän rakentamisen uudisrakennushanketta. Työ toteutetaan kirjalli-suustutkimuksen, asiantuntijahaastatteluiden ja ympäristöluokitusta hakeneesta esimerkki-kohteesta saatujen tietojen avulla. Diplomityön tuloksena muodostettiin toimintamalli varmistamaan halutun kestävän kehi-tyksen tason saavuttaminen uudisrakennusprojektissa. Toimintamallissa on jaettu vastuut ja tehtävät eri osapuolille koko projektin ajalle tarveselvityksestä käytönaikaan.
Resumo:
Life cycle assessment (LCA) is one of the most established quantitative tools for environmental impact assessment of products. To be able to provide support to environmentally-aware decision makers on environmental impacts of biomass value-chains, the scope of LCA methodology needs to be augmented to cover landuse related environmental impacts. This dissertation focuses on analysing and discussing potential impact assessment methods, conceptual models and environmental indicators that have been proposed to be implemented into the LCA framework for impacts of land use. The applicability of proposed indicators and impact assessment frameworks is tested from practitioners' perspective, especially focusing on forest biomass value chains. The impacts of land use on biodiversity, resource depletion, climate change and other ecosystem services is analysed and discussed and the interplay in between value choices in LCA modelling and the decision-making situations to be supported is critically discussed. It was found out that land use impact indicators are necessary in LCA in highlighting differences in impacts from distinct land use classes. However, many open questions remain on certainty of highlighting actual impacts of land use, especially regarding impacts of managed forest land use on biodiversity and ecosystem services such as water regulation and purification. The climate impact of energy use of boreal stemwood was found to be higher in the short term and lower in the long-term in comparison with fossil fuels that emit identical amount of CO2 in combustion, due to changes implied to forest C stocks. The climate impacts of energy use of boreal stemwood were found to be higher than the previous estimates suggest on forest residues and stumps. The product lifetime was found to have much higher influence on the climate impacts of woodbased value chains than the origin of stemwood either from thinnings or final fellings. Climate neutrality seems to be likely only in the case when almost all the carbon of harvested wood is stored in long-lived wooden products. In the current form, the land use impacts cannot be modelled with a high degree of certainty nor communicated with adequate level of clarity to decision makers. The academia needs to keep on improving the modelling framework, and more importantly, clearly communicate to decision-makers the limited certainty on whether land-use intensive activities can help in meeting the strict mitigation targets we are globally facing.
Resumo:
Environmental accountability has become a major source of competitive advantage for industrial companies, because customers consider it as relevant buying criterion. However, in order to leverage their environmental responsibility, industrial suppliers have to be able to demonstrate the environmental value of their products and services, which is also the aim of Kemira, a global water chemistry company considered in this study. The aim of this thesis is to develop a tool which Kemira can use to assess the environmental value of their solutions for the customer companies in mining industry. This study answers to questions on what kinds of methods to assess environmental impacts exist, and what kind of tool could be used to assess the environmental value of Kemira’s water treatment solutions. The environmental impacts of mining activities vary greatly between different mines. Generally the major impacts include the water related issues and wastes. Energy consumption is also a significant environmental aspect. Water related issues include water consumption and impacts in water quality. There are several methods to assess environmental impacts, for example life cycle assessment, eco-efficiency tools, footprint calculations and process simulation. In addition the corresponding financial value may be estimated utilizing monetary assessment methods. Some of the industrial companies considered in the analysis of industry best practices use environmental and sustainability assessments. Based on the theoretical research and conducted interviews, an Excel based tool utilizing reference data on previous customer cases and customer specific test results was considered to be most suitable to assess the environmental value of Kemira’s solutions. The tool can be used to demonstrate the functionality of Kemira’s solutions in customers’ processes, their impacts in other process parameters and their environmental and financial aspects. In the future, the tool may be applied to fit also Kemira’s other segments, not only mining industry.
Resumo:
This report introduces the ENPI project called “EMIR - Exploitation of Municipal and Industrial Residues” which was executed in a co-operation between Lappeenranta University of Technology (LUT), Saint Petersburg State University of Economics (SPbSUE), Saint Petersburg State Technical University of Plant Polymers (SPbSTUPP) and industrial partners from both Leningrad Region (LR), Russia and Finland. The main targets of the research were to identify the possibilities for deinking sludge management scenarios in co-operation with partner companies, to compare the sustainability of the alternatives, and to provide recommendations for the companies in the Leningrad Region on how to best manage deinking sludge. During the literature review, 24 deinking sludge utilization possibilities were identified, the majority falling under material recovery. Furthermore, 11 potential utilizers of deinking sludge were found within the search area determined by the transportation cost. Each potential utilizer was directly contacted in order to establish cooperation for deinking sludge utilization. Finally, four companies, namely, “Finnsementti” – a cement plant in Finland (S1), “St.Gobian Weber” – a light-weight aggregate plant in Finland (S2), “LSR-Cement” – a cement plant in LR (S3), and “Rockwool” – a stone wool plant in LR (S4) were seen as the most promising partners and were included in the economic and environmental assessments. Economic assessment using cost-benefit analysis (CBA) indicated that substitution of heavy fuel oil with dry deinking sludge in S2 was the most feasible option with a benefit/cost ratio (BCR) of 3.6 when all the sludge was utilized. At the same time, the use of 15% of the total sludge amount (the amount that could potentially be treated in the scenario) resulted in a BCR of only 0.16. The use of dry deinking sludge in the production of cement (S3) is a slightly more feasible option with a BCR of 1.1. The use of sludge in stone wool production is feasible only when all the deinking sludge is used and burned in an existing incineration plant. The least economically feasible utilization possibility is the use of sludge in cement production in Finland (S1) due to the high gate fee charged. Environmental assessment was performed applying internationally recognized life cycle assessment (LCA) methodologies: ISO 14040 and ISO 14044. The results of a consequential LCA stated that only S1 and S2 lead to a reduction of all environmental impacts within the impact categories chosen compared to the baseline scenario where deinking sludge is landfilled. Considering S1, the largest reduction of 13% was achieved for the global warming potential (GWP), whereas for S2, the largest decrease of abiotic depletion potential (ADP) was by 1.7%, the eutrophication potential (EP) by 1.8%, and a GWP of 2.1% was documented. In S3, the most notable increase of ADP and acidification potential (AP) by 2.6 and 1.5% was indicated, while the GWP was reduced by 12%, the largest out of all the impact categories. In S4, ADP and AP increased by 2.3 and 2.1% respectively, whereas ODP was reduced by 25%. During LCA, it was noticed that substitution of fuels causes a greater reduction of environmental impact (S1 and S2) than substitution of raw materials (S3 and S4). Despite a number of economically and environmentally acceptable deinking sludge utilization methods being assessed in the research, evaluation of bottlenecks and communications with companies’ representatives uncovered the fact that the availability of the raw materials consumed, and the risks associated with technological problems resulting from the sludge utilization, limited the willingness of industrial partners to start deinking sludge utilization. The research results are of high value for decision-makers at already existing paper mills since the result provide insights regarding alternatives to the deinking sludge utilization possibilities already applied. Thus, the research results support the maximum economic and environmental value recovery from waste paper utilization.
Resumo:
Fatigue life assessment of weldedstructures is commonly based on the nominal stress method, but more flexible and accurate methods have been introduced. In general, the assessment accuracy is improved as more localized information about the weld is incorporated. The structural hot spot stress method includes the influence of macro geometric effects and structural discontinuities on the design stress but excludes the local features of the weld. In this thesis, the limitations of the structural hot spot stress method are discussed and a modified structural stress method with improved accuracy is developed and verified for selected welded details. The fatigue life of structures in the as-welded state consists mainly of crack growth from pre-existing cracks or defects. Crack growth rate depends on crack geometry and the stress state on the crack face plane. This means that the stress level and shape of the stress distribution in the assumed crack path governs thetotal fatigue life. In many structural details the stress distribution is similar and adequate fatigue life estimates can be obtained just by adjusting the stress level based on a single stress value, i.e., the structural hot spot stress. There are, however, cases for which the structural stress approach is less appropriate because the stress distribution differs significantly from the more common cases. Plate edge attachments and plates on elastic foundations are some examples of structures with this type of stress distribution. The importance of fillet weld size and weld load variation on the stress distribution is another central topic in this thesis. Structural hot spot stress determination is generally based on a procedure that involves extrapolation of plate surface stresses. Other possibilities for determining the structural hot spot stress is to extrapolate stresses through the thickness at the weld toe or to use Dong's method which includes through-thickness extrapolation at some distance from the weld toe. Both of these latter methods are less sensitive to the FE mesh used. Structural stress based on surface extrapolation is sensitive to the extrapolation points selected and to the FE mesh used near these points. Rules for proper meshing, however, are well defined and not difficult to apply. To improve the accuracy of the traditional structural hot spot stress, a multi-linear stress distribution is introduced. The magnitude of the weld toe stress after linearization is dependent on the weld size, weld load and plate thickness. Simple equations have been derived by comparing assessment results based on the local linear stress distribution and LEFM based calculations. The proposed method is called the modified structural stress method (MSHS) since the structural hot spot stress (SHS) value is corrected using information on weld size andweld load. The correction procedure is verified using fatigue test results found in the literature. Also, a test case was conducted comparing the proposed method with other local fatigue assessment methods.
Resumo:
The purpose of the thesis is to give an overview of the cleantech sector and to give an answer how cleantech companies can evaluate the environmental sustainability of their business by utilizing various indicators and measures. The thesis is a literature study and it is based on a secondary data. Thesis presents the definitions to cleantech as well as its history and the main industries. Cleantech market overview in Finland and worldwide is also introduced. Furthermore, various indicators are presented in order to evaluate the environmental sustainability of companies' business. In the end, indicators used in cleantech sector are evaluated. As a result, the thesis presents the following methodologies that can be used in evaluating the environmental sustainability in the cleantech sector: Sustainability assessment framework, Environmental value analysis, COMPLIMENT - Environmental performance index for industries and Environmental assessment for cleaner production. More tools are still needed to evaluate environmental sustainability in the cleantech sector.
Resumo:
This applied linguistic study in the field of second language acquisition investigated the assessment practices of class teachers as well as the challenges and visions of language assessment in bilingual content instruction (CLIL) at primary level in Finnish basic education. Furthermore, pupils’ and their parents’ perceptions of language assessment and LangPerform computer simulations as an alternative, modern assessment method in CLIL contexts were examined. The study was conducted for descriptive and developmental purposes in three phases: 1) a CLIL assessment survey; 2) simulation 1; and 3) simulation 2. All phases had a varying number of participants. The population of this mixed methods study were CLIL class teachers, their pupils and the pupils’ parents. The sampling was multi-staged and based on probability and random sampling. The data were triangulated. Altogether 42 CLIL class teachers nationwide, 109 pupils from the 3rd, 4th and 5th grade as well as 99 parents from two research schools in South-Western Finland participated in the CLIL assessment survey followed by an audio-recorded theme interview of volunteers (10 teachers, 20 pupils and 7 parents). The simulation experimentations 1 and 2 produced 146 pupil and 39 parental questionnaires as well as video interviews of volunteered pupils. The data were analysed both quantitatively using percentages and numerical frequencies and qualitatively employing thematic content analysis. Based on the data, language assessment in primary CLIL is not an established practice. It largely appears to be infrequent, incidental, implicit and based on impressions rather than evidence or the curriculum. The most used assessment methods were teacher observation, bilingual tests and dialogic interaction, and the least used were portfolios, simulations and peer assessment. Although language assessment was generally perceived as important by teachers, a fifth of them did not gather assessment information systematically, and 38% scarcely gave linguistic feedback to pupils. Both pupils and parents wished to receive more information on CLIL language issues; 91% of pupils claimed to receive feedback rarely or occasionally, and 63% of them wished to get more information on their linguistic coping in CLIL subjects. Of the parents, 76% wished to receive more information on the English proficiency of their children and their linguistic development. This may be a response to indirect feedback practices identified in this study. There are several challenges related to assessment; the most notable is the lack of a CLIL curriculum, language objectives and common ground principles of assessment. Three diverse approaches to language in CLIL that appear to affect teachers’ views on language assessment were identified: instrumental (language as a tool), dual (language as a tool and object of learning) and eclectic (miscellaneous views, e.g. affective factors prioritised). LangPerform computer simulations seem to be perceived as an appropriate alternative assessment method in CLIL. It is strongly recommended that the fundamentals for assessment (curricula and language objectives) and a mutual assessment scheme should be determined and stakeholders’ knowledge base of CLIL strengthened. The principles of adequate assessment in primary CLIL are identified as well as several appropriate assessment methods suggested.
Resumo:
Tässä diplomityössä tarkastellaan teollisuuden avainasiakkaan tarpeiden kartoitusta yhden case-yrityksen näkökulmasta. Diplomityön tavoitteena on systemaattisesti kartoittaa avainasiakkaan palvelutarpeet ja luoda menetelmät niiden tyydyttämiseksi. Kirjallisuustutkimuksessa tarkastellaan tiedon synnyn, jalostamisen ja välittämisen merkitystä asiakaspalvelun ja asiakastarvekartoituksen näkökannalta. Tutkimuksen perusteella tunnistetaan modernin asiakaspalvelun ja avainasiakkaan tarvekartoituksen vaatimukset, merkitys sekä olennaiset menetelmät. Diplomityön empiirisessä osassa toteutetaan avainasiakkaan ja niihin vaikuttavien sidosryhmien kartoitus, haastattelut tarvetiedon löytämiseksi sekä luodaan menetelmät ja rakennetaan dynaaminen palvelumalli tarpeiden tyydyttämiseksi. Empiiriset tulokset osoittavat, että avainasiakkaan tarpeita ei tunneta riittävän laajasti ja että systemaattisilla tarvekartoitusmenetelmillä voidaan identifioida ne, sekä ohjata palvelutyön menetelmien suunnittelua ja vyöryttää tarpeita edelleen arvoketjussa ratkaistavaksi. Tulosten perusteella suositellaan liiketoimintaprosessien uudistamista ja dynaamisen palvelumallin käyttöönottoa konsernissa.
Resumo:
Diplomityön tarkoituksena on selvittää tämänhetkiset Fortum Oil and Gas Oy:n Porvoon öljynjalostamolla suoritettavat ympäristömittaukset ja –määritykset. Samalla arvioidaan täyttävätkö ympäristömittaukset ja –määritykset niille ympäristölainsäädännössä jo asetetut ja lähiaikoina voimaan tulevat vaatimukset. Työssä esitetyissä jalostamoa koskevissa uusissa lainsäädännön velvoitteisssa päästötiedontuotannon laadun varmennuksella on suuri rooli. Työn ensimmäisessä osassa selvitetään ympäristömittausten nykykäytäntö Porvoon jalostamolla. Nykykäytännön selvitys perustuu jalostamon olemassa oleviin toimintajärjestelmän ohjeisiin ja henkilöhaastatteluihin. Samalla tarkastellaan jalostamon toimintaa koskevia uusia lainsäädännön tuomia velvoitteita päästöjen tarkkailulle ja raportoinnille. Työn toisessa osiossa esitetään käytetyt laadunvarmennusmenetelmät mittausten ja määritysten eri tiedontuotantoketjujen vaiheissa. Samalla verrataan toteutettuja päästö- ja ympäristömittauksia uusiin lainsäädännön tuomiin vaatimuksiin, toimintajärjestelmän ohjeistukseen, standardeihin ja tarkkailun parhaan käyttökelpoisen tekniikan vertailuasiakirjaan (Monitoring-BREF). Selvityksen tuloksia voidaan käyttää jalostamon päästötietojen keräysmenetelmien ja tiedontuotantoketjujen laadun varmentamisen saattamiseksi vastaamaan niille asetettuja vaatimuksia. Selvityksen perusteella lupaehdoissa Porvoon jalostamolle asetetut nykyiset vaatimukset päästöjen ja ympäristövaikutusten seurannalle täyttyvät. Jalostamolla on tehtävä parannuksia päästöjentarkkailu ja –raportointimenetelmiin, jotta tulevat lainsäädännön vaatimukset tulevat täytetyksi. Jalostamon päästömittausten tiedontuotantoketjut eivät kaikissa määrityksissä täytä tarkkailun BREF-asiakirjassa esitettyjä vaatimuksia määritysten laadunvarmennukselle ja läpinäkyvyydelle. Työssä on esitetty korjaavat toimenpiteet.
Resumo:
Yrityksen ulkoisen toimintaympäristön arviointia pidetään yleisesti yhä tärkeämpänä yrityksen menestymisen kannalta. Kuitenkaan ympäristöanalyysiä ei juurikaan systemaattisesti hyödynnetä varsinkaan pk-yrityksissä. Tämän työn tavoitteena on saada pk-yrittäjät ymmärtämään paremmin ympäristön arviointia, sen tärkeyttä ja sen soveltamista käytännössä. Työssä keskitytään makrotason ympäristöanalyysiin, sillä se toimii lähtökohtana kokonaisvaltaiselle ympäristön arvioinnille. Ympäristön arvioinnista esitetään useita eri näkökulmia, jonka jälkeen makrotason analyysiä lähestytään PESTEL-viitekehyksen kautta. Työn liitteenä on PESTEL-viitekehyksen pohjalta rakennettu työkalu, jonka avulla pk-yrityksille on helpompaa lähteä toteuttamaan ympäristön arviointia. Työssä käsitellään myös vuonna 2009 käsillä olevaa talouskriisiä PESTEL-mallin kautta. Talouskriisi luo yrityksille poikkeukselliset olosuhteet, jotka osaltaan vaikeuttavat ympäristön arviointia. Työn perusteella toimintaympäristön arviointi on yrityksille tärkeää elossa säilymisen kannalta. Ympäristön muutoksiin voidaan varautua ennakkoon esimerkiksi skenaarioin tai heikoin signaalein. PESTEL-tekijät riippuvat yrityksen koosta ja kansallisuudesta, tässä työssä on keskitytty käsittelemään asiaa suomalaisten pk-yritysten kannalta. Asian käsittely kirjallisuudessa on pintapuolista ja hajanaista, vaikka keskeinen sisältö olisi hyvä saada kattavasti yhdeksi kokonaisuudeksi.
Resumo:
Diplomityön aiheena ovat hankintatoimen strateginen johtaminen ja toimittajasuhteiden hallinta pk-yrityksen näkökulmasta. Tutkimuksessa selvitettiin hankintatoimen merkitystä yrityksen strategisena kilpailutekijänä. Tutkimus määrittelee toimittajien yhteistyön periaatteet ja strategisen kumppanuuden lähtökohdat. Työn teoriaosuudessa selvitetään perusteet hankintastrategian määrittämiseksi. Hankintojen luokittelun perusteella tehtävät toimittajastrategiat ovat lähtökohtina toimittajasuhteiden kehittämiselle ja kumppanuudelle. Arviointimenetelmistä työssä esitellään EFQM-malli, erityisesti hankintatoimen näkökulmasta katsottuna. Tutkimuksen empiirisessä osuudessa kehitetään uusi arviointimenetelmä hankintatoimen johtamisen kartoittamiseen. Itsearvioinnin perusteella yritys saa kokonaiskuvan strategisen hankintatoimensa nykytilasta ja tärkeimmistä kehityskohteista.
Resumo:
Tämän kandidaatin työn tavoitteena on selvittää, miten olemassa olevat kansainväliset ympäristöluokitusjärjestelmät soveltuvat suomalaisen koulurakennuksen ympäristönsuojeluntason arviointiin. Kysymystä lähestytään tutustumalla kolmeen kansainväliseen ja yhteen suomalaiseen rakennusten ympäristöluokitusjärjestelmään. Tarkasteltavat järjestelmät ovat Building Research Establishment’s Environmental Assessment Method (BREEAM), Leadership in Energy and Environmental Design (LEED) ja Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB) ja Promise. Tämän jälkeen tunnistetaan suomalaisen rakentamisen ja koulurakentamisen erityispiirteitä. Lopuksi arvioidaan BREEAM:n ja LEED:n koulurakennuksille tarkoitettujen ohjelmien soveltuvuutta suomalaisen koulurakennuksen ympäristönsuojelutason arviointiin.
Resumo:
Sequestration of carbon dioxide in mineral rocks, also known as CO2 Capture and Mineralization (CCM), is considered to have a huge potential in stabilizing anthropogenic CO2 emissions. One of the CCM routes is the ex situ indirect gas/sold carbonation of reactive materials, such as Mg(OH)2, produced from abundantly available Mg-silicate rocks. The gas/solid carbonation method is intensively researched at Åbo Akademi University (ÅAU ), Finland because it is energetically attractive and utilizes the exothermic chemistry of Mg(OH)2 carbonation. In this thesis, a method for producing Mg(OH)2 from Mg-silicate rocks for CCM was investigated, and the process efficiency, energy and environmental impact assessed. The Mg(OH)2 process studied here was first proposed in 2008 in a Master’s Thesis by the author. At that time the process was applied to only one Mg-silicate rock (Finnish serpentinite from the Hitura nickel mine site of Finn Nickel) and the optimum process conversions, energy and environmental performance were not known. Producing Mg(OH)2 from Mg-silicate rocks involves a two-staged process of Mg extraction and Mg(OH)2 precipitation. The first stage extracts Mg and other cations by reacting pulverized serpentinite or olivine rocks with ammonium sulfate (AS) salt at 400 - 550 oC (preferably < 450 oC). In the second stage, ammonia solution reacts with the cations (extracted from the first stage after they are leached in water) to form mainly FeOOH, high purity Mg(OH)2 and aqueous (dissolved) AS. The Mg(OH)2 process described here is closed loop in nature; gaseous ammonia and water vapour are produced from the extraction stage, recovered and used as reagent for the precipitation stage. The AS reagent is thereafter recovered after the precipitation stage. The Mg extraction stage, being the conversion-determining and the most energy-intensive step of the entire CCM process chain, received a prominent attention in this study. The extraction behavior and reactivity of different rocks types (serpentinite and olivine rocks) from different locations worldwide (Australia, Finland, Lithuania, Norway and Portugal) was tested. Also, parametric evaluation was carried out to determine the optimal reaction temperature, time and chemical reagent (AS). Effects of reactor types and configuration, mixing and scale-up possibilities were also studied. The Mg(OH)2 produced can be used to convert CO2 to thermodynamically stable and environmentally benign magnesium carbonate. Therefore, the process energy and life cycle environmental performance of the ÅAU CCM technique that first produces Mg(OH)2 and the carbonates in a pressurized fluidized bed (FB) were assessed. The life cycle energy and environmental assessment approach applied in this thesis is motivated by the fact that the CCM technology should in itself offer a solution to what is both an energy and environmental problem. Results obtained in this study show that different Mg-silicate rocks react differently; olivine rocks being far less reactive than serpentinite rocks. In summary, the reactivity of Mg-silicate rocks is a function of both the chemical and physical properties of rocks. Reaction temperature and time remain important parameters to consider in process design and operation. Heat transfer properties of the reactor determine the temperature at which maximum Mg extraction is obtained. Also, an increase in reaction temperature leads to an increase in the extent of extraction, reaching a maximum yield at different temperatures depending on the reaction time. Process energy requirement for producing Mg(OH)2 from a hypothetical case of an iron-free serpentine rock is 3.62 GJ/t-CO2. This value can increase by 16 - 68% depending on the type of iron compound (FeO, Fe2O3 or Fe3O4) in the mineral. This suggests that the benefit from the potential use of FeOOH as an iron ore feedstock in iron and steelmaking should be determined by considering the energy, cost and emissions associated with the FeOOH by-product. AS recovery through crystallization is the second most energy intensive unit operation after the extraction reaction. However, the choice of mechanical vapor recompression (MVR) over the “simple evaporation” crystallization method has a potential energy savings of 15.2 GJ/t-CO2 (84 % savings). Integrating the Mg(OH)2 production method and the gas/solid carbonation process could provide up to an 25% energy offset to the CCM process energy requirements. Life cycle inventory assessment (LCIA) results show that for every ton of CO2 mineralized, the ÅAU CCM process avoids 430 - 480 kg CO2. The Mg(OH)2 process studied in this thesis has many promising features. Even at the current high energy and environmental burden, producing Mg(OH)2 from Mg-silicates can play a significant role in advancing CCM processes. However, dedicated future research and development (R&D) have potential to significantly improve the Mg(OH)2 process performance.