Climate change is increasing the temperature rise, which damages nature and people. Increasing and using carbon dioxide removal (CDR) techniques are crucial to limit global warming to staying under 2 °C and fulfilling the Paris Agreement. There are several different CDR techniques, and biochar is one. Biochar is estimated to be able to contribute significantly as a carbon sink, and using biochar in agriculture can have several additional benefits, such as increasing crop yields. Most farmers in low- and lower-middle-income countries are smallholder farmers who cultivate two hectares of land or less. This can present an opportunity for them to explore the use of biochar. Carbon credits are sold and traded on carbon markets and can broadly be divided between compliance such as EU ETS and voluntary, for example, companies wanting to fulfil climate targets. One credit is equivalent to one tonne of carbon dioxide being sequestered. The aim of the study is to provide knowledge about the enablement of small-scale biochar as a technology in carbon markets, focusing on low- and lower-middle-income countries using a multi-actor governance approach. The study combines a literature review and qualitative interviews. Carbon markets are signified by several attributes of multi-actor governance, including public and private cooperation and cooperation on several scales. The main drivers and barriers for biochar in carbon markets concern sustainability aspects, training and education, expenses and income, small-scale production, and technological maturity. The income from carbon credits can facilitate several barriers to applying and using biochar. Still, it also has challenges such as measuring, verifying, reporting and fulfilling the requirements of high-quality carbon credits, which can be extra demanding for smallholder farmers. Small-scale biochar production potentially has better conditions for voluntary markets due to more variations in the demand for credits. In compliance markets, buying countries often want to buy large amounts of credits, and a majority of countries do not recognise biochar as a carbon sink for countries’ own target fulfilment. Small-scale biochar production has potential for carbon markets. Still, more research is needed on the carbon credit-specific aspects and the threshold for cooperatives of smallholder farmers, and what will happen when the central market mechanism under Article 6 in the Paris Agreement is final. 

Waste management is of growing concern with increasing amount of municipal waste generation and the industry standards are becoming stricter due to climate goals and sustainable development. Waste-to-energy (WTE) systems in the form of waste incineration have been promoted as a low-carbon energy source, but nevertheless have high greenhouse gas (GHG) emissions. Pyrolysis offers an alternative way of utilizing energy which at high temperatures and in the absence of oxygen thermally decomposes material and yields products such as synthetic gas and biochar.

Bodø Storstue, a development project for a new sports arena in Northern Norway, has high ambitions for sustainable development. WTE by pyrolysis has been identified as a potential step toward reducing GHG emissions. Thus, this thesis looked into the technical and economic aspects of integrating pyrolysis as a decentralized WTE system.

A simulation model was built in Aspen Plus, which shows the energy and mass balance through the different modules in the system. An economic analysis was performed using MS Excel which included the levelized cost of electricity and net present value calculation. The results suggest that the electricity demand in Bodø Storstue can be met by using pyrolysis for power generation, and that carbon can be stored in biochar which reduces the emissions compared to traditional waste incineration.

Future studies should include a simulation model based on tested feedstock composition which would make the simulation more representative of true conditions. The price of biochar should also be included in the economic analysis to obtain more precise conclusions about the economic conditions that impact investment decisions.

Circular economy is an economic model that is gaining more and more attention, themodel aims to close production chains by recirculate waste into the system as newraw material. Spent coffee grounds are a waste that has great potential to becomenew products since the spent coffee ground contains many valuable substances suchas polysaccharides, polyphenols, and lipids. Swedes are the sixth largest coffeeconsumers per capita in the world, which means that large quantities of coffeegrounds are produced in the country. Therefore, the purpose of this report is toinvestigate possible ways to valorize spent coffee grounds in the municipality ofStockholm, as an alternative to the treatment processes that exist today. Toinvestigate this, the main methods have been a literature review, a field study andeconomic analyses based on existing data. The results show that from 5 large coffee-shop chains in the municipality of Stockholm, approximately 138,477 kg of coffeegrounds can be collected each year. Furthermore, it shows that five differentmethods for extracting polysaccharides, polyphenols, biochar, oil, and protein fromspent coffee grounds have been effective and that these substances and products canbe used in, for example, the food industry, in cosmetics, as plastics and asadsorbents. The economic assessment shows that biochar, polyphenols, and oil arethe compounds and products that are economically profitable to extract, and theycan give a maximum profit of SEK 482.28/kg of spent coffee grounds. The resultsare consistent with previous research on the subject, but there are someuncertainties in the exact figures as there is a lack of economic analyses for spentcoffee grounds in the previous research. However, the results show great potentialfor spent coffee grounds in a circular economy, but further research is required toensure the economic gain. In addition, analyses need to be done on the ecologicalsustainability and more studies need to be done on coffee grounds in Sweden tovalidate the results.

As the anthropogenic emissions of greenhouse gases (GHGs) have increased and received moreattention, the need for climate mitigation solutions has become more urgent. Today, several methodologies for carbon accounting exists, as well as the possibility to offset emissions by buying carbon offsets. All these methodologies directly or indirectly spring from LCA but have developed to metrics considering only climate and with a dissatisfying sustainability performance in other aspects. Four carbon accounting methodologies (VCS, Gold Standard, GHG Protocol, XPRIZE Carbon Removal) have been examined and compared, showing differences in the approach to quantification and to more holistic sustainability aspects. They have also been analysed in comparison to the QU.A.L.ITY framework proposed by the European Commission, which aims to ensure the quality of carbon removals and prevent greenwashing. The results showed a lack of coherence between the carbon offset standards as well as a low coherence with the criteria in the proposed framework and lack of holistic sustainability perspectives.

Algae are photosynthesizing organisms fixating CO₂ in the same process as terrestrial plants. They are fast growing and does not require land or much maintenance, which is why seaweed aquaculture has been suggested as a method for carbon removals. This have given birth to a plethora of start-ups aiming to sell carbon offsets from systems based on macroalgae, here called “seaweed offsets”. Nine companies/projects were identified and examined. The results showed that most of the companies used systems involving cultivation, while one company use wild seaweed. The two largest techniques for sequestration of the carbon fixated in the biomass were 1) sinking the seaweed into the deep sea and 2) making biochar from the biomass. However, there are not yet any standards covering this type of carbon offset methodologies and these offsets are thus not certified and the results also show that the efficiency of these activities is highly unreliable. Large uncertainties remain regarding the net carbon removal, sequestration, and potential ecological impacts. These uncertainties and knowledge gaps also cause the suggested methods for seaweed offsetting to clash with the QU.A.L.ITY framework.

This study develops a novel pyrolysis process combined with in-line catalytic reforming toproduce high purity hydrogen and carbon products from waste plastics. The input resource is waste plastic material in the form of discarded Covid masks. Results show that for the optimized pyrolysis followed by in-line biochar-based catalytic reforming process, the hydrogen yield is 98.2 mg/g-mask (up to 87% purity), and the carbonyield is 642.4 mg/g-mask, with over 70% of the waste plastic being completely cracked to elemental carbon and hydrogen. The overall process has virtually no CO2 emissions. The use of biomass char catalysts has been studied to contribute to increased hydrogen yield. This is because the unique porous structure of the biochar catalyst increases the residence time of the pyrolysis vapor in the catalytic layer, allowing sufficient cracking of the macromolecular vapor, therefore, increasing the hydrogen yield. The process is also facilitated by the cracking temperature, which increases the cracking of the pyrolysis vapor, resulting in an increase in char yield. However, high temperatures may breakdown the structure of the biomass char catalyst, causing more of the pyrolysis vapor to be converted to CH4, reducing the hydrogen yield. The optimum hydrogen yield was obtained at process parameters of a Biochar catalyst-to-Maskratio (C/M ratio) of 2 and a cracking temperature of 900 oC.