A new metro line of eight kilometers will be built in Stockholm between Älvsjö and Fridhemsplan, where WSP has been commissioned to carry out a location work that is an initial stage in the project. As part of the location investigation, it is included to choose which tunnel driving method is to be used for the tunnel operation, where conventional tunneling with drilling and blasting is compared with full- face-boring with a tunnel boring machine. This thesis is a comparison between the two tunneling methods where the investigated parameters are climate impact in the form of greenhouse gas emissions and energy use in the form of primary energy and energy for processes. The methods were investigated through a limited life cycle analysis that included the construction of the metro and a limited part of the use phase. The results showed that for tunneling in hard rock without weakness zones, which is the most advantageous, conventional tunneling performs better from a climate perspective, while the methods have almost the same energy use. The resources with the largest contribution were concrete, shotcrete, rock shafts and rock mass transport. 

A sensitivity analysis was performed to test the methods' sensitivity to changes in input data and conditions. For geological changes where the section was assumed to consist of a water passage with weakness zones, the tunnel boring machine performed best for both parameters. With changes in the form of increased grouting of cement, conventional tunneling showed the greatest sensitivity, but the order of magnitude did not change compared with the standard scenario. Furthermore, it was tested how the methods reacted to the inclusion of reinvestment, in the form of repairs of drainage mat and shotcrete, where the results showed that conventional tunneling had the greatest sensitivity, but even here the magnitude remained the same. In addition, measures were identified whose emission factors could be used to calculate potential climate impact reduction for the two tunneling methods. The measures with the greatest reduction potential included, among other things, electrification, hybridization, carbon dioxide storage and the use of biofuel and biochar. This scenario showed that by 2045 it is possible to reduce the climate impact by 97.6 percent for-face-boring and 87 percent for conventional tunneling. The implementation of the measures resulted in the full-face-boring having the lowest climate impact from 2035 onwards. 

Recommendations for further studies are to include more sustainability parameters but also to design goals that limit energy use to a sustainable level, in the same way that there are climate neutrality goals. It is also recommended to focus on the resources that did not show as high a reduction potential, more specifically drainage mats and explosives. There is great potential for reducing their climate impact, but it is probably a matter of time, costs and risks within it is implemented. It may also be interesting to examine the processes that were excluded from the life cycle, especially regarding the work machines such as the tunnel boring machine. 

Current research shows that large amounts of carbon dioxide will need to be removed from the atmosphere within this century in order to reach the climate goals stated in the Paris Agreement. Two carbon dioxide removal technologies, biochar and bioenergy with carbon capture and storage (BECCS), can be implemented within bioenergy systems. However, there is a need to ensure that the benefits for climate change mitigation accomplished by carbon dioxide removal are not outweighed by additional greenhouse gas emissions in its supply-chain or elsewhere in the system. The results from a comparative life cycle assessment (LCA) can be used to counter these concerns. However, different conclusions may result from differences in methodological choices, such as choice of functional unit and reference activities and differences in data. Therefore, further investigation to determine how these choices affect the results is needed. This study aimed to develop a framework for performing comparative LCAs and to use this framework for comparing the climate change impact of bioenergy systems with and without carbon dioxide removal. The conducted comparative LCA calculated and analysed the impacts of three systems: biochar, BECCS and, as a reference, combined heat and power (CHP). The climate impacts and the ranking of the systems were analysed with regard to choice of functional units and reference activities as well as parametric uncertainty. The results suggest that in most cases, the carbon dioxide removal systems are preferable over the conventional CHP system, especially when the reference activities have low climate change impacts. With heat as functional unit, the Biochar system had the lowest climate impact, while for electricity or biomass use as functional unit, the BECCS system had the lowest impact. The contribution analysis and the parametric analysis revealed that assumptions regarding background energy systems affected the results more than the defined foreground parameters. Therefore, this study suggests that methodological choices for an LCA must be made explicit and, if possible, several options should be considered and compared. In this study, however, parts of the life cycle inventory process were omitted due to lack of information on the new technologies studied, which may affect the precision of the results. In order to further assess the environmental impact of the studied systems, several impact categories should also be included. The framework and code developed in this study can be reused for other comparative assessments. 

The climate on earth keeps getting warmer where heat waves, eutrophication, rising sea levels, extreme weather like flooding, droughts and wildfires are an expanding problem. The focus of this bachelor thesis is to determine the potential of mitigating eutrophication and while contributing to blue growth by harvesting and make use of reeds like Phragmites australis and Arundo donax. Reeds have the ability to quickly absorb nutrients from aquatic environments and there are opportunities to use them as a feedstock for producing biochar to be potentially used in areas such as soil improvement, fodder additive and carbon sequestration. Additionally, optimal biochar properties for the observed applications gets analysed. The thesis is based on a systematic literature review and an interview with Niclas Anvret at the non-profit organisation “Race for the Baltic”. 

Results show that biochar produced according to parameters such as heating rate, biomass species and especially, different temperatures, results in varied characteristics that change the biochar's adsorption abilities, nutrient retention, alkalinity, stability, surface area and porosity volume. The different applications of biochar are, however, not easily determined. This is because of the fact that certain biochar properties, that are prominent in entirely different pyrolysis conditions, could both be beneficial for the same application. Additionally, the different attributes sometimes influence each other which gives rise to unclear patterns affecting use potential. To overcome these issues, more research is needed to clarify the correlations between attributes of the biochar and to determine which characteristics of biochar are best suited for each application. 

In terms of how large-scale harvesting of reed could affect the ecosystem is also unclear, there is not enough research regarding the question to be able to draw clear conclusions. The reasoning behind this is that there are knowledge gaps, geographical differences, different unit measuring and methodology. The potential for biochar in the coal market is high and the demand in Sweden has risen over the past couple of years. There is also interest in using biochar as a soil amendment, to make use of nutrient content as well as applying organic matter to soils to potentially achieve long-term carbon sequestration. However, the production cost of biochar out of reed is relatively expensive, and it cannot compete with coal or other fertilisers/soil amendments on the market, with feedstock management usually being the most expensive part of production. Lastly, there is currently no harvesting method that can measure the amount of reed that needs to be harvested to be able to produce biochar on a large scale. 

Countries that have signed the Paris agreement aims to decrease their greenhouse gas emissions, and with the help of human activity absorb greenhouse gases to prevent a global temperature increase of 1,5°C before the turn of the century. Investments that involve human activity include Bioenergy with carbon capture storage (BECCS) and usage of biochar. Among the sectors that need to make a change regarding their behavior towards greenhouse gas emission are transportation, energy production, real estate, and agriculture.

The purpose of this study is to describe BECCS and biochar as a method for decrease greenhouse gas emissions. Calculate the greenhouse gas emissions for a premise regarding its operational activities and determine how much carbon dioxide the premise need to store in order to obtain climate positive status. Determine students interests regarding climate positive products and services.

The study used the life-cycle analysis method to determine how much greenhouse gas emissions the premise emitted. The information was obtained by the company that is responsible for the operational activities and emission factors for the district heating and electricity was obtained from secondary sources connected to the premise. A survey aimed at students was conducted to determine the interest of the students regarding climate positive products and services. The premise emitted approximately 15,4Kg CO2e/m2 Atemp per year for its’ operational activities. Approximately 70 percent of the students that answered the survey are interested in climate positive products and services. Conclusion from the study involves installing a renewable energy source on the premise and signing an electricity agreement regarding green electricity in order to decrease carbon dioxide emissions.

Environmental pollution of heavy metals has become an increasing problem. Environmental risk assessments can be conducted to investigate and determine the potential risk of polluted terrestrial environments. Traditionally, risk assessments are based on total soil metal concentrations on a dry weight basis. Assessments based on total concentrations do not account for metal bioavailability. The bioavailable fraction of the metal is that available for metabolic uptake over a biological membrane, and it is largely controlled by the physiochemical characteristics of the soil solution. For soil-dwelling organisms the most important physiochemical parameters governing copper toxicity are pH and dissolved organic carbon. To incorporate these parameters into risk assessments mechanistic chemical equilibrium models can be used, such as biotic ligand models. These have previously been applied to mainly aquatic environments and only in recent years they have been expanded to the terrestrial realm. The overall aim of this thesis was to test the applicability of a leachate-based biotic ligand model, which takes pH dependency into account, for ecotoxicological risk assessment of soil-dwelling organisms. Toxicity data with associated soil solution pH for seven soil-dwelling organisms and microbially mediated soil processes were obtained from the Swedish Geotechnical Institute. Physiochemical soil characteristics of three Swedish field sampled soils amended with biochar were also obtained from the Swedish Geotechnical Institute. The toxicity data were used to derive two key parameters for calibration of the soil biotic ligand model through linear regression analysis i.e., the pH dependency and the species-specific intrinsic sensitivity. The calibrated biotic ligand models were applied to the field soils and species sensitivity distributions were derived for each soil to calculate hazardous metal concentrations. A simplified risk assessment of the soils was performed based on the results of the leachate-based biotic ligand models and on measured total concentrations on a dry weight basis. 

As expected, the results of the regression analysis showed a strong pH dependency between toxicity effect concentrations and pH. For all included test organisms, the copper toxicity effect concentration decreased as the pH of the soil solution increased. Although Cu²⁺ toxicity increased with increasing pH, the considered organisms showed individual and varying pH-dependencies especially at pH 3-4 and pH 7-8. Further, the results showed that the risk assessment based on the Swedish EPA method, which use total metal concentrations on a dry weight basis, yielded different results than risk assessment based on the leachate-based biotic ligand models. The soils that had been amended with biochar contained lower total Cu concentrations on a dry weight basis compared to those which had not been amended. Consequently, total Cu concentrations exceeded the guideline value for sensitive land-use only in the non-amended soils. Total Cu concentrations exceeded the guideline value for less sensitive land-use in all field soils. Similar to total Cu concentrations on a dry weight basis, the total dissolved Cu concentrations also decreased with added biochar. The same trend could not be seen for Cu²⁺ in CaCl₂ leachates. DOC in the leachates decreased with added biochar, suggesting that biochar sorbs DOC. A majority of the total dissolved Cu was bound to DOC and only a small fraction left as free ions. 

The lower DOC concentrations led to higher Cu²⁺ concentrations in the leachate. Consequently, two of the biochar amended soils had Cu²⁺ concentrations exceeding the calculated HC50 (protection level for LSL). The predicted toxic effect concentrations ranged from 0.001 μg/L for the most sensitive organism Tomato shoot (L. esculentum) to 3.53 μg/L for the least sensitive organism Soil induced respiration (SIR). The most sensitive field soil had the highest measured pH and had been amended with 6% biochar, the two least sensitive field soils had the lowest measured pH and had been amended with 3 and 6% biochar respectively. The risk assessment based on the soil-BLM approach yielded different, but not less conservative, results compared to the traditional risk assessment based on total concentrations on a dry weight basis. The expected result was for the BLM-based risk assessment to be less conservative as it takes the site-specific bioavailability into account. The leachate-based soil-BLM seems to be sensitive to changes and variations of the input parameters in the speciation. To improve the robustness of the model, and accuracy of risk assessments, additional organisms should be included in the SSDs and speciation should be performed on soils with a wider range of pH. The potential of leachate-based BLMs for risk assessment has been demonstrated. The results invite to further v development of leachate-based soil-BLMs and has the potential to increase the knowledge of the chemistry and toxicology of copper in soils as well as the effects and behaviour of biochar as a metal sorbent.