I dagens samhälle genereras en stor mängd avfall, där stora delar av avfallen förbränns vilket inte är gynnsamt för vare sig miljön eller klimatet. Därför finns det idag ett stort behov av klimatsmarta metoder där avfallen kan användas till att producera produkter som kan motverka klimatförändringar. Största delen av avfallen som genereras kommer från större företag som till exempel IKEA och de är i ständigt behov av nya metoder för att kunna använda sina avfall till klimatsmarta resurser. Att producera biokol av avfallen är en sådan klimatsmart metod, där biokolet är en hållbar produkt som både motverkar klimatförändringar och andra miljöproblem såsom övergödning. I denna rapport undersöktes två avfallsfraktioner från IKEA, vilka var Dust2k och Hogger. Det som undersöktes var hur lämpliga avfallsfraktionerna från IKEA är för produktion av biokol som skulle kunna appliceras i jordbruket samt hur denna lämplighet påverkas av avfallsfraktion och processförhållanden som används under pyrolysen.

För att besvara frågeställningarna utfördes pyrolys på avfallsfraktionerna vid pyrolystemperaturerna 550℃ och 750℃, vilket gav fyra olika prover av biokol. Dessa prov analyserades med ett antal analysmetoder för att avgöra biokolets lämplighet som jordförbättrare och för att motverka klimatförändringar. De analyser som utfördes var elementaranalys, pH-mätning, termogravimetrisk analys (TGA), Brunauer-Emmet-Teller (BET) och svepelektronmikroskopi (SEM). Från pyrolysen och TGA kunde utbytet bestämmas, vilket uppgick till över 20% för samtliga prov. Elementaranalysen visade att biokol producerat av Hogger vid 900°C uppfyllde de EBC-krav som analyserades. Genom att mäta pH på avfallsfraktionerna samt biokolen gick det att se att pH höjdes under pyrolysen. Från BET och SEM erhölls information om porositet, ledningsförmåga och ytarea. Porositeten ökade med temperaturen och ledningsförmågan var högre för biokolet än biomassan. Ytarean låg mellan 347,2 m²/g och 422,8 m²/g och porvolymen mellan 0,173 cm³/g och 0,205 cm³/g. Det erhölls bäst egenskaper för avfallsfraktionen Hogger samt pyrolystemperaturen 750℃, vilket gjorde att slutsatsen att produktion av biokol från Hogger vid 750℃ lämpar sig bäst för användning som jordförbättrare kunde dras.

Demand for high-quality graphite is expected to experience an extraordinary growth rate, in large part due to its wide range of industrial applications such as adsorbents, lubricants, electrodes, etc. This thesis developed a novel sustainable approach to produce green-graphite materials by applying biochar, acarbon-rich valuable by-product obtained from biomass, as a carbon precursor. Meanwhile, iron-based catalysts are applied to enable the graphitization at a relatively lower temperature. This study focuses on the different parameters which could affect the evolution of carbon structure. The samples were mixed with catalyst in two ways, dry mixing and wet impregnation. Aside from the addition method, several parameters including temperature, heating duration, and iron loading amount were varied from 800 to 1300 ℃, 1 to 6 hours, and 0 to 33.6% respectively, to figure out an optimum graphitization process. The samples were characterized by X-ray diffraction, Raman scattering, SEM and particle size distribution analysis. Based on the characterization results, it was confirmed that with the increase of the graphitization temperature, duration and amount of iron loading, synthetic graphite performs a better graphitization and a higher conversion rate. Meanwhile, a detailed dissolution-precipitation mechanism was introduced and discussed in the context of iron-carbon equilibrium phase diagram to explain this catalytic process.

In recent years the material graphite has been heavily studied since its use in widespread applications have increased, for example batteries, vehicles, and solar cells. When the need for this type of material increases the efficiency and the sustainability of the production methods must be taken into consideration. This thesis presents an alternative method to produce graphite from biochar which is renewable. Biochar in combination with a catalyst was used rather than the more traditional method, which is known for its high temperatures and time-consuming procedures. The weight ratio of pure iron (catalyst) to biochar was approximately 22.4 wt-% in the graphite production process. The result was analyzed using X-Ray Diffraction and showed that the method managed to produce a high crystalline graphite at a temperature of 1300 °C within 3 hours. The result also showed that by using a catalyst a graphite sample with a high “degree of graphitization” with a moderate crystal size was produced.

With global warming, rising environmental issues, and increased beach-cast production, climate change mitigation efforts are important for the future of the planet. Carbon dioxide removal technologies are now deemed essential to reach the Sustainable development goals and keep the temperature rise under 1.5 or 2 degrees °C. Biochar produced from beach-cast seaweed has great potential as a fuel or as a means of carbon sequestration, while also proposing a way of dealing with unwanted beach-cast at public beaches. This study compares the alternative methodologies for performing carbon- and energy balances of the production of biochar from beach-cast seaweed. The methodologies differ in the accounting of emissions and energy consumption, either only accounting for consumed energy, including energy embodied in materials, or including avoided emissions. The viability of producing biochar from beach-cast seaweed is assessed while trying to answer if the biochar is best used as a fuel or as a means of carbon sequestration. Furthermore, the effect of pyrolysis peak temperature on the pyrolysis products is assessed.

The study provides evidence that waste products such as beach-cast seaweed can be a valuable resource both in the field of power production and for climate mitigation. Beach-cast has the potential to mitigate climate change by offsetting 0.5 kg CO₂e per kg of dry beach-cast. Using the full potential of Gotland, this would mean a carbon capture potential of 1 600 tonnes CO₂e per year. Furthermore, the energy balance suggests a best-case scenario of 4.5 proving that biochar production from beach-cast is viable as a fuel. However, the results vary depending on the methodology used for the assessment. If energy bound in materials is included, the carbon balance is not good enough for carbon sequestration while including avoided emissions leads to a more optimistic result. The study shows that a peak temperature of 500°C is optimal for producing biochar with a high energy content and that natural drying should be included in the drying process to reduce CO₂e emissions and energy consumption in the production process.

The expectations on companies to introduce better business models to enhance environmental performance are increasing. Sweden is aiming at becoming climate neutral in 2045 which requires methods to capture and store carbon in addition to decrease emissions. Research has shown that biochar production can be one way to support the target. The process to produce biochar is called pyrolysis and is still only implemented in a smaller scale in Sweden. This study aims to facilitate implementation of pyrolysis in heat-requiring industries. By collecting knowledge from existing literature of the topic, as well as exploring a case at Skanska, the objectives to answer are related to the design of the pyrolysis process, the suitable feedstocks and where in the value chain cooperation is needed. Additional objectives are to develop guidelines and apply them on a case study for evaluation. Pyrolysis is the name of thermal decomposition of biomass, a process that generates biochar, bio-oil and syngas.

Based on a literature review on the pyrolysis process with its products, some criteria for a successful implementation of pyrolysis are created. Those criteria are the foundation to address the first objective with relevance to heat-requiring industries. The answers are used to develop guidelines that are meant to support stakeholders that are interested to invest in a pyrolysis facility. Additionally, the results indicate that more industries could see benefits from biochar production as the design can be customized. Cooperation is considered important to deliver feedstocks and possibly sell the products, where pyrolysis is also a good example of integrating more circularity in business. It is recommended that heat-requiring industries should indeed consider an investment in pyrolysis in order to improve the environmental work. Intermediate pyrolysis with good flexibility of both feedstocks and product distribution is considered most suitable. However, further research and practical cases are needed to optimize the process for the desired objectives as well as explore the products’ markets more.