Biopolttoaineiden lisäämismahdollisuudet kaukolämmön tuotannossa pienen kokoluokan tuotantolaitoksissa Lahden seudulla

Tämä diplomityö on tehty IMMU-hankkeeseen, jossa selvitetään konkreettisia keinoja ilmastonmuutoksen hillintään Lahden seudulla. Diplomityössä tarkastellaan mahdollisuuksia lisätä biopolttoaineita pienen kokoluokan kaukolämmön tuotantolaitoksissa. Teoria osuuden pohjalta luodaan skenaariot Nastolaan ja Vääksyyn (Asikkala). Skenaarioissa tarkastellaan biopolttoaineiden lisäämisen vaikutuksia kasvihuonekaasu- ja hiukkaspäästöihin käyttämällä elinkaariarviointimenetelmää. Taloudellisia seikkoja tarkastellaan laskemalla takaisinmaksuaikoja eri biolaitosratkaisuille nettonykyarvomenetelmällä. Tutkimuksen tuloksena saatiin, että kasvihuonekaasupäästöt tuotannon elinkaaren ajalta vähenevät eniten tuottamalla kaukolämmön perustuotanto Nastolassa ja Vääksyssä bio-CHP-laitoksella haketta polttamalla. Kiinteitä biopolttoaineita poltettaessa tulevat kuitenkin suurimmat hiukkaspäästöt, mikä vaikuttaa asuinympäristön viihtyvyyteen tuotantolaitoksen läheisyydessä. Bio-CHP-laitoksen investointikustannukset ovat suurimmat ja takaisinmaksuaika pisin. Nastolan kulutusperusteisiä päästöjä pystytään vähentämään eniten investoimalla biolämpölaitokseen tai bio-CHP-laitokseen. Päästöjä Nastolassa pystyttäisiin kyseisillä investoinneilla vähentämään enimmillään 6,4 %. Lahti energian kokonaispäästöjä pystyttäisiin enimmillään vähentämään noin 1,6 %. Johtopäätöksenä tutkimuksesta voidaan sanoa, että kasvihuonekaasupäästöjä pystytään vähentämään investointien avulla. Toiset ratkaisut ovat vain kalliimpia kuin toiset. Lisäksi kiinteitä biopolttoaineita käytettäessä jotkut poltto-ominaisuudet voivat heiketä esim. verrattuna maakaasun polttoon. Biopolttoaineiden lisäämisellä kuitenkin päästään irti riippuvuudesta fossiilisiin polttoaineisiin kuten öljyyn ja maakaasuun. Investointeja tehdessä on vaikea sanoa suoraan, mikä vaihtoehto on paras tapa tuottaa kaukolämpöä. Investointipäätöksiä tehdessä päätökseen vaikuttaa se, mitä tuotannon ominaispiirteitä painotetaan eniten.

Biokaasun tuottaminen ja hyödyntäminen Lappeenrannassa

Lappeenrannassa kerätään ja hyödynnetään tällä hetkellä kaatopaikkakaasua 0,3 milj.m3 vuodessa. Biokaasua voitaisiin tuottaa Lappeenrannassa mädättämällä bioperäisiä jätteitä ja biokaasuntuotantoa varten kasvatettuja energiakasveja. Biokaasuntuotantoon soveltuvia jätteitä ovat erilliskerätty biojäte, jätevedenpuhdistamon jätevesiliete, puutarhajäte, lietelannat ja oljet. Kesannolla olevilla peltoaloilla voitaisiin kasvattaa ruokohelpeä. Biokaasun tuotantoon soveltuvia materiaaleja voitaisiin kerätä 143 000 t/a ja kasvattaa 68 000 t/a. Työssä tarkastellaan vaihtoehtoa, jossa mädätetään vain puhdistamoliete, sekä useita materiaaleja mädättävää yhteismädättämöä, johon liittyen tutkitaan kolmea eri vaihtoehtoa: kunnallisen jätteen mädätystä, kaiken jätteen mädätystä ja jätteen sekä energiakasvien mädätystä. Paras sijoituspaikka mädättämölle olisi jätevedenpuhdistamon läheisyydessä. Jätemateriaalista saataisiin kaasua enintään 12 milj. m3 ja energiakasveista enintään 16 milj. m3. Kaasusta voitaisiin tuottaa energiaa CHP-laitoksessa enintään 184 GWh. Mikäli biokaasun tuotannolla halutaan ensisijaisesti vähentää kasvi-huonekaasupäästöjä, kannattaa kaasu jalostaa ajoneuvopolttoaineeksi. Jalostettu kaasu on mahdollista myös syöttää maakaasuverkostoon. Suurimmat tulot on mahdollista saavuttaa yhdistetyssä sähkön- ja lämmöntuotannossa, mikäli biokaasulle suunniteltu syöttötariffi toteutuu. Muussa tapauksessa suurimmat tulot saadaan jalostamalla biokaasua ajoneuvojen polttoaineeksi.

Luonnon kasvihuonekaasulähteiden ja -nielujen laskenta maakunnallisella tasolla

Kiihtyvän kasvihuoneilmiön aiheuttama maailmanlaajuinen ilmastonmuutos on yksi aikamme suurimmista haasteista. Kasvihuoneilmiön voimistuminen on ihmistoiminnan seurausta, mutta myös luonnon omat prosessit toimivat kasvihuonekaasujen lähteinä ja nieluina. Tässä työssä on selvitetty luonnon kasvihuonekaasulähteiden ja –nielujen määrää ja merkitystä maakunnallisella tasolla. Lisäksi työssä on esitetty maakunnallisia toimenpide-ehdotuksia kasvihuonekaasunielujen ylläpitämiseksi ja lisäämiseksi. Esimerkkinä työssä on käytetty Keski-Suomen maakuntaa ja laskenta on kohdistettu vuoteen 2008. Keski-Suomessa luonnon prosessit toimivat vuonna 2008 nettonieluna, jonka suuruus oli 1 813 701 tonnia hiilidioksidiekvivalenttia. Eniten kasvihuonekaasuja sitoi puusto 3 019 360 hiilidioksidiekvivalenttitonnin nielulla. Laskennassa huomioitiin hiilidioksidi, metaani ja dityppioksidi. Laskenta suoritettiin soveltuvilta osin kansallisen kasvihuonekaasuraportoinnin periaatteiden mukaisesti sekä tutkimuskirjallisuuteen perustuvien päästö- ja nielukertoimien avulla. Tämä työ osoittaa luonnon nielujen olevan tärkeässä roolissa ilmastonmuutoksen hillitsemisessä. Nielujen säilyttämiseen ja lisäämiseen tähtäävillä toimenpiteillä ilmakehän kasvihuonekaasupitoisuuksiin voidaan vaikuttaa kustannustehokkaasti sekä maailmanlaajuisella että alueellisella tasolla.

Computer tools applied to analysis of solar water heaters

The simulation programs are important tools to analyze the different energetic alternatives, including the use of renewable energy. The objective of this study was to analyze comparatively the different computer tools available for modeling of solar water heaters. Among the main simulation software of solar thermal systems, there are: RETScreen International, EnergyPlus, TRNSYS, SolDesigner, SolarPro, e T*SOL. Among the tools mentioned, only EnergyPlus and RETScreen International are free, but they allow obtaining interesting results when applied together. The first one has a detailed module of energy analysis of solar water heaters, while the second one provides an detailed economic feasibility study and an assessment of emissions of greenhouse gases. RETScreen International and EnergyPlus programs are aimed at a diverse audience, including designers, researchers and energy planners.

Solar energy use for water pre-heating in boilers of agro-industries

Energy consumption in the world has been growing every year. The industrial sector represents 27.32% of the world energy demand. Heating systems that use solar energy may contribute with a percentage of the total energy required by industries. This work aimed to study the use of vacuum solar collectors for water pre-heating in boilers. We used four collectors installed according to NBR 15,569; water flow through the tubes was 0.058 L/s, and temperature in the inlet and outlet pipes was measured. Results showed that instantaneous radiation, and inlet fluid and room temperatures are variables that influence the process, reaching water maximum temperature in the solar collector outlet of 97.9 °C, and efficiency of approximately 65% for most experiments. For the financial viability evaluation, the payback study was applied, which resulted in 4; 7 and 5 years, for the respective sources: firewood, LPG (liquefied petroleum gas), and electricity. Regarding the calculation of the annual contribution to the reduction of greenhouse gases, it was, respectively, 2.162 and 356 kg of CO2 per m² of collector tubes, in comparison with firewood and LPG.

Climate driven changes in temperature, pH and food quality : effects on copepod reproduction

Increased emissions of greenhouse gases into the atmosphere are causing an anthropogenic climate change. The resulting global warming challenges the ability of organisms to adapt to the new temperature conditions. However, warming is not the only major threat. In marine environments, dissolution of carbon dioxide from the atmosphere causes a decrease in surface water pH, the so called ocean acidification. The temperature and acidification effects can interact, and create even larger problems for the marine flora and fauna than either of the effects would cause alone. I have used Baltic calanoid copepods (crustacean zooplankton) as my research object and studied their growth and stress responses using climate predictions projected for the next century. I have studied both direct temperature and pH effects on copepods, and indirect effects via their food: the changing phytoplankton spring bloom composition and toxic cyanobacterium. The main aims of my thesis were: 1) to find out how warming and acidification combined with a toxic cyanobacterium affect copepod reproductive success (egg production, egg viability, egg hatching success, offspring development) and oxidative balance (antioxidant capacity, oxidative damage), and 2) to reveal the possible food quality effects of spring phytoplankton bloom composition dominated by diatoms or dinoflagellates on reproducing copepods (egg production, egg hatching, RNA:DNA ratio). The two copepod genera used, Acartia sp. and Eurytemora affinis are the dominating mesozooplankton taxa (0.2 – 2 mm) in my study area the Gulf of Finland. The 20°C temperature seems to be within the tolerance limits of Acartia spp., because copepods can adapt to the temperature phenotypically by adjusting their body size. Copepods are also able to tolerate a pH decrease of 0.4 from present values, but the combination of warm water and decreased pH causes problems for them. In my studies, the copepod oxidative balance was negatively influenced by the interaction of these two environmental factors, and egg and nauplii production were lower at 20°C and lower pH, than at 20°C and ambient pH. However, presence of toxic cyanobacterium Nodularia spumigena improved the copepod oxidative balance and helped to resist the environmental stress, in question. In addition, adaptive maternal effects seem to be an important adaptation mechanism in a changing environment, but it depends on the condition of the female copepod and her diet how much she can invest in her offspring. I did not find systematic food quality difference between diatoms and dinoflagellates. There are both good and bad diatom and dinoflagellate species. Instead, the dominating species in the phytoplankton bloom composition has a central role in determining the food quality, although copepods aim at obtaining as a balanced diet as possible by foraging on several species. If the dominating species is of poor quality it can cause stress when ingested, or lead to non-optimal foraging if rejected. My thesis demonstrates that climate change induced water temperature and pH changes can cause problems to Baltic Sea copepod communities. However, their resilience depends substantially on their diet, and therefore the response of phytoplankton to the environmental changes. As copepods are an important link in pelagic food webs, their future success can have far reaching consequences, for example on fish stocks.

Tuulivoima; kehitys, investoinnit ja työllisyys Suomessa

Tuulivoimalla on pitkä historia. Tuulivoima soveltuu nykyajan energiantuotantoon. Suunniteltaessa ja rakennettaessa uusia tuulivoimaloita on tunnettava tuulisuuteen vaikuttavat tekijät samoin kuin tuulivoimalan sijoituspaikalla on tehtävä perusteelliset tuu-liolosuhdemittaukset. Nykyisellä sähkön hinnalla tuulivoimalat eivät ole täysin kilpailukykyisiä, joten niitä on tuettava. Tukimuotoja on monia. Suomessa pääasiallinen tukimuoto on syöttötariffi. Vallitseva politiikka on ratkaisevassa asemassa luotaessa tukijärjestelmiä tuulivoimalle. Suomessa tehtävät tuulivoimainvestoinnit ovat kasvussa. Tuulivoimaan liittyy niin hyviä kuin huonoja puolia. Huonot puolet ovat ratkaistavissa. Päästökaupan kannalta on tuulivoima yksi keino alentaa kasvihuonekaasuja ilmakehässä. Tuulivoiman osuuden kasvattaminen sähköntuotannossa luo työpaikkoja Suomeen ja luo vientimahdollisuuksia ulkomaille. Tuulivoimalla on valoisa tulevaisuus.

Pressure filtration characteristics of enzymatically hydrolyzed biomass suspensions

Enzymatic hydrolysis of lignocellulosic polymers is likely to become one of the key technologies enabling industrial production of liquid biofuels and chemicals from lignocellulosic biomass. Certain types of enzymes are able to hydrolyze cellulose and hemicellulose polymers to shorter units and finally to sugar monomers. These monomeric sugars are environmentally acceptable carbon sources for the production of liquid biofuels, such as bioethanol, and other chemicals, such as organic acids. Liquid biofuels in particular have been shown to contribute to the reduction of net emissions of greenhouse gases. The solid residue of enzymatic hydrolysis is composed mainly of lignin and partially degraded fibers, while the liquid phase contains the produced sugars. It is usually necessary to separate these two phases at some point after the hydrolysis stage. Pressure filtration is an efficient technique for this separation. Solid-liquid separation of biomass suspensions is difficult, because biomass solids are able to retain high amounts of water, which cannot be readily liberated by mechanical separation techniques. Most importantly, the filter cakes formed from biomaterials are compressible, which ultimately means that the separation may not be much improved by increasing the filtration pressure. The use of filter aids can therefore facilitate the filtration significantly. On the other hand, the upstream process conditions have a major influence on the filtration process. This thesis investigates how enzymatic hydrolysis and related process conditions affect the filtration properties of a cardboard suspension. The experimental work consists of pressure filtration and characterization of hydrolysates. The study provides novel information about both issues, as the relationship between enzymatic hydrolysis conditions and subsequent filtration properties has so far not been considered in academic studies. The results of the work reveal that the final degree of hydrolysis is an important factor in the filtration stage. High hydrolysis yield generally increases the average specific cake resistance. Mixing during the hydrolysis stage resulted in undefined changes in the physical properties of the solid residue, causing a high filtration resistance when the mixing intensity was high. Theoretical processing of the mixing data led to an interesting observation: the average specific cake resistance was observed to be linearly proportional to the mixer shear stress. Another finding worth attention is that the size distributions of the solids did not change very dramatically during enzymatic hydrolysis. There was an observable size reduction during the first couple of hours, but after that the size reduction was minimal. Similarly, the size distribution of the suspended solids remained almost constant when the hydrolyzed suspension was subjected to intensive mixing. It was also found that the average specific cake resistance was successfully reduced by the use of filter aids. This reduction depended on the method of how the filter aids were applied. In order to obtain high filtration capacity, it is recommended to use the body feed mode, i.e. to mix the filter aid with the slurry prior to filtration. Regarding the quality of the filtrate, precoat filtration was observed to produce a clear filtrate with negligible suspended solids content, while the body feed filtrates were turbid, irrespective of which type of filter aid was used.

The European Union and Assembling Biofuel Development – topological investigations concerning the associations between law, policy and space

Biofuels for transport are a renewable source of energy that were once heralded as a solution to multiple problems associated with poor urban air quality, the overproduction of agricultural commodities, the energy security of the European Union (EU) and climate change. It was only after the Union had implemented an incentivizing framework of legal and political instruments for the production, trade and consumption of biofuels that the problems of weakening food security, environmental degradation and increasing greenhouse gases through land-use changes began to unfold. In other words, the difference between political aims for why biofuels are promoted and their consequences has grown – which is also recognized by the EU policy-makers. Therefore, the global networks of producing, trading and consuming biofuels may face a complete restructure if the European Commission accomplishes its pursuit to sideline crop-based biofuels after 2020. My aim with this dissertation is not only to trace the manifold evolutions of the instruments used by the Union to govern biofuels but also to reveal how this evolution has influenced the dynamics of biofuel development. Therefore, I study the ways the EU’s legal and political instruments of steering biofuels are coconstitutive with the globalized spaces of biofuel development. My analytical strategy can be outlined through three concepts. I use the term ‘assemblage’ to approach the operations of the loose entity of actors and non-human elements that are the constituents of multi-scalar and -sectorial biofuel development. ‘Topology’ refers to the spatiality of this European biofuel assemblage and its parts whose evolving relations are treated as the active constituents of space, instead of simply being located in space. I apply the concept of ‘nomosphere’ to characterize the framework of policies, laws and other instruments that the EU applies and construes while attempting to govern biofuels. Even though both the materials and methods vary in the independent articles, these three concepts characterize my analytical strategy that allows me to study law, policy and space associated with each other. The results of my examinations underscore the importance of the instruments of governance of the EU constituting and stabilizing the spaces of producing and, on the other hand, how topological ruptures in biofuel development have enforced the need to reform policies. This analysis maps the vast scope of actors that are influenced by the mechanism of EU biofuel governance and, what is more, shows how they are actively engaging in the Union’s institutional policy formulation. By examining the consequences of fast biofuel development that are spatially dislocated from the established spaces of producing, trading and consuming biofuels such as indirect land use changes, I unfold the processes not tackled by the instruments of the EU. Indeed, it is these spatially dislocated processes that have pushed the Commission construing a new type of governing biofuels: transferring the instruments of climate change mitigation to land-use policies. Although efficient in mitigating these dislocated consequences, these instruments have also created peculiar ontological scaffolding for governing biofuels. According to this mode of governance, the spatiality of biofuel development appears to be already determined and the agency that could dampen the negative consequences originating from land-use practices is treated as irrelevant.

Testing FCM technique for the wind energy scenarios in Finland

In the latter days, human activities constantly increase greenhouse gases emissions in the atmosphere, which has a direct impact on a global climate warming. Finland as European Union member, developed national structural plan to promote renewable energy generation, pursuing the aspects of Directive 2009/28/EC and put it on the sharepoint. Finland is on a way of enhancing national security of energy supply, increasing diversity of the energy mix. There are plenty significant objectives to develop onshore and offshore wind energy generation in country for a next few decades, as well as another renewable energy sources. To predict the future changes, there are a lot of scenario methods developed and adapted to energy industry. The Master’s thesis explored “Fuzzy cognitive maps” approach in scenarios developing, which captures expert’s knowledge in a graphical manner and using these captures for a raw scenarios testing and refinement. There were prospects of Finnish wind energy development for the year of 2030 considered, with aid of FCM technique. Five positive raw scenarios were developed and three of them tested against integrated expert’s map of knowledge, using graphical simulation. The study provides robust scenarios out of the preliminary defined, as outcome, assuming the impact of results, taken after simulation. The thesis was conducted in such way, that there will be possibilities to use existing knowledge captures from expert panel, to test and deploy different sets of scenarios regarding to Finnish wind energy development.

Suomen kasvihuonekaasupäästöt Kioton pöytäkirjan ensimmäisen sopimuskauden lopussa – kokonaistilanne ja vähentämistoimenpiteet

Tämä diplomityö on läpileikkaus kasvihuonekaasupäästöistä sekä niitä koskevista vähennystoimenpiteistä Suomessa Kioton pöytäkirjan ensimmäisen sopimuskauden lopussa. Työ on toteutettu kirjallisuustutkimuksena ja siihen on käytetty painettuja sekä sähköisiä lähteitä. Huoli ilmastonmuutoksesta on saanut aikaan sen, että kasvihuonekaasupäästöjä rajoitetaan tänä päivänä kansainvälisillä sopimuksilla. Vaikka kaikki suuretkaan päästäjämaat eivät ole sopimuksia ratifioineet, ovat EU-maat Suomi mukaan lukien sitoutuneet YK:n ilmastonmuutosta koskevaan puitesopimukseen ja sen noudattamiseen. Puitesopimusta tarkentavassa Kioton pöytäkirjassa EU sitoutui vähentämään kuuden eri kasvihuonekaasun kokonaispäästöjä yhteensä 8 prosenttia ajanjaksolla 2008–2012 vuoteen 1990 verrattuna. Kasvihuonekaasut, joita rajoitukset koskivat, olivat hiilidioksidi, metaani, dityppioksidi, fluorihiilivedyt, perfluorihiilivedyt ja rikkiheksafluoridi. EU:n sisäisessä taakanjaossa Suomen tavoite oli pitää päästöt vertailuvuoden 1990 tasossa ja Suomi alitti tämän noin viidellä prosentilla. Vuoden 2012 jälkeen Suomen kasvihuonekaasupäästöjen vähennystavoite on kiristynyt. Vuosille 2013–2020 Suomen tavoite on vähentää kasvihuonekaasupäästöjä 20 prosenttia alle perusvuoden 1990 tason. Työssä tutustutaan myös keinoihin, joilla aiempien ja tulevien päästöjenvähennystavoitteiden saavuttaminen on mahdollista. Näitä keinoja on mm. erilaisten biopolttoaineiden sekoittaminen fossiilisten polttoaineiden sekaan, energiatehokkuuden parantaminen ja biokaasun käytön lisääminen. Lisäksi työssä käsitellään eräitä merkityksellisiä käsitteitä, kuten EU:n päästökauppajärjestelmä ja hiilidioksidin talteenotto ja varastointi.

Advanced biofuel production: Engineering metabolic pathways for butanol and propane biosynthesis.

Greenhouse gases emitted from energy production and transportation are dramatically changing the climate of Planet Earth. As a consequence, global warming is affecting the living conditions of numerous plant and animal species, including ours. Thus the development of sustainable and renewable liquid fuels is an essential global challenge in order to combat the climate change. In the past decades many technologies have been developed as alternatives to currently used petroleum fuels, such as bioethanol and biodiesel. However, even with gradually increasing production, the market penetration of these first generation biofuels is still relatively small compared to fossil fuels. Researchers have long ago realized that there is a need for advanced biofuels with improved physical and chemical properties compared to bioethanol and with biomass raw materials not competing with food production. Several target molecules have been identified as potential fuel candidates, such as alkanes, fatty acids, long carbon‐chain alcohols and isoprenoids. The current study focuses on the biosynthesis of butanol and propane as possible biofuels. The scope of this research was to investigate novel heterologous metabolic pathways and to identify bottlenecks for alcohol and alkane generation using Escherichia coli as a model host microorganism. The first theme of the work studied the pathways generating butyraldehyde, the common denominator for butanol and propane biosynthesis. Two ways of generating butyraldehyde were described, one via the bacterial fatty acid elongation machinery and the other via partial overexpression of the acetone‐butanol‐ethanol fermentation pathway found in Clostridium acetobutylicum. The second theme of the experimental work studied the reduction of butyraldehyde to butanol catalysed by various bacterial aldehyde‐reductase enzymes, whereas the final part of the work investigated the in vivo kinetics of the cyanobacterial aldehyde deformylating oxygenase (ADO) for the generation of hydrocarbons. The results showed that the novel butanol pathway, based on fatty acid biosynthesis consisting of an acyl‐ACP thioesterase and a carboxylic acid reductase, is tolerant to oxygen, thus being an efficient alternative to the previous Clostridial pathways. It was also shown that butanol can be produced from acetyl‐CoA using acetoacetyl CoA synthase (NphT7) or acetyl‐CoA acetyltransferase (AtoB) enzymes. The study also demonstrated, for the first time, that bacterial biosynthesis of propane is possible. The efficiency of the system is clearly limited by the poor kinetic properties of the ADO enzyme, and for proper function in vivo, the catalytic machinery requires a coupled electron relay system.

Global coordination: weighted voting

In order to halt the depletion of global ecological capital, a number of different kinds of meetings between Governments of countries in the world has been scheduled. The need for global coordination of environmental policies has become ever more obvious, supported by more and more evidence of the running down of ecological capital. But there are no formal or binding arrangements in sight, as global environmental coordination suffers from high transaction costs (qualitative voting). The CO2 equivalent emissions, resulting in global warming, are driven by the unstoppable economic expansion in the global market economy, employing mainly fossil fuel generated energy, although at the same time lifting sharply the GDP per capita of several emerging countries. Only global environmental coordination on the successful model of the World Band and the IMF (quantitative voting) can stem the rising emissions numbers and stop further environmental degradation. However, the system of weighted voting in the WB and the IMF must be reformed by reducing the excessive voting power disparities, for instance by reducing all member country votes by the cube root expression.

The carbon disclosure project, an evolution in international environmental corporate governance : motivations and determinants of market response to voluntary disclosures

This paper examines the factors associated with Canadian firms voluntarily disclosing climate change information through the Carbon Disclosure Project. Five hypotheses are presented to explain the factors influencing management's decision to disclose this information. These hypotheses include a response to shareholder activism, domestic institutional investor shareholder activism, signalling, litigation risk, and low cost publicity. Both binary logistic regressions as well as a cross-sectional analysis of the equity market's response to the environmental disclosures being made were used to test these hypotheses. Support was found for shareholder activism, low cost publicity, and litigation risk. However, the equity market's response was not found to be statistically significant.

Les produits dérivés des marchés européens du carbone

L'analyse statistique des données a été effectuée avec le logiciel R.