With population increases, the traditional linear economy has become increasingly unsustainable creating environmental pressures such as climate change and resource scarcity. The Dutch government has set lofty goals to create a circular economy by 2050. The agricultural sector in the Netherlands is vulnerable to climate pressures but is also highly profitable at the cost of sustainability making circular models difficult to implement. The world's first Floating Farm in Rotterdam, NL was created to bring food production into urban areas to increase the resilience of food supply chains. The Floating Farm has worked to implement a more circular dairy farming model by reducing land use and using recycled feed.

In this study, the circularity performance of the Floating Farm (FF) dairy production process was quantified using an indicator-based circularity assessment method. Indicators were derived from the FF's self-proclaimed circular actions and calculated using derived water, nutrient, and energy balances. A typical baseline farm was identified and used to compare indicator performance for which data was available and a comparison was relevant. From the mass and energy balances and indicator calculations, gaps in circularity were identified. To help close the gaps, scenarios to improve the farm's circularity were identified and assessed for feasibility. Each scenario was added to the indicator calculations to quantify the impact on indicator performance.

The results revealed several gaps in circularity, particularly concerning water and waste management. Once through cooling is currently used in the milk processing step leading to a very high water usage and wastewater production. In waste management, the entire liquid fraction of manure ends up in the sewer leading to significant nutrient and water losses. Generally, the farming model involves a trade-off that results in a loss of self-sufficiency, particularly regarding feed, water use, and electricity consumption. This is because no feed crops are grown, and there is no space for large-scale rainwater collection or solar energy production.

The scenario investigation revealed that switching the water source of once-through cooling water from the tap to river water is feasible, greatly impacts indicator calculations, and should be the priority for the farm to improve. The other three scenarios had several pros and cons but may be better suited for future versions of the farm due to the farm's current scale and lack of operational expertise in water treatment.

Despite the farm's efforts and enthusiasm, the indicator performance for most of the farm's circular actions have room for improvement. The farm has put effort into creating a circular economy but still must make significant strides to meet its goals. On top of the scenario recommendations, it was recommended that the farm install more measurement devices to increase the accuracy of future analyses and have a clearer view of process flows to more accurately identify losses.

Coffee is a beverage that millions of people around the globe enjoy on a daily basis. Although coffee consumption is becoming increasingly popular, the cultivation of coffee is under threat of: climate change, economic inequality in the coffee value chain, and unsustainable coffee cultivation and processing. Studies predict that all land currently used for the cultivation of Arabica coffee might become unusable by 2080 because of the sensitivity of the crop to changes in temperature, humidity, and the amount of UV irradiation. A shift is needed in the coffee value chain to ensure the livelihood of the current 25 million smallholder coffee farmers responsible for 70 to 80\% of coffee production worldwide. The Climate Smart Coffee Program in the state of Kerala in India focuses on making coffee cultivation and processing more resilient, sustainable, and economical in the future. This is accomplished by conducting research on more sustainable agriculture (such as agroforestry to preserve and nurture valuable land) and reduce carbon emissions and waste generation during the processing of coffee.

The focus of this study is on the use of biomass residues produced during the processing of coffee to meet the energy needs of coffee processing units in the Wayanad district in Kerala. The goal is to make the processing of coffee less carbon-intensive, produce less waste, improve the quality of the coffee, and make coffee processing less energy dependent. This study presents a technoeconomic analysis for a novel approach to the use of these coffee processing mill residues (CPMRs) by using a combination of gasification to produce syngas, a solid-oxide fuel cell (SOFC) to transform the syngas into electricity and heat, and the use of an afterburner to further optimize the energy efficiency of the biomass plant. The biomass plant's goal is to replace the current energy need of the processing units: electricity from the grid and liquefied petroleum gas (LPG).

The results of the technoeconomic model show that the biomass plant produces enough electricity and heat to cover the energy needs of the coffee processing unit that supplies the biomass material. With an hourly feed rate of 1295 kilograms of biomass material the plant produced 2,681 kW of electricity with an electrical efficiency of 41\% and an overall system efficiency of 62\%. The financial analysis of the biomass plant yielded a capital expenditure of \$ 24.1 million, or 8,984 \$ per kWh of electricity generated. The levelized cost of electricity (LCOE) of the plant was 0.45 \$/kWh. A sensitivity analysis revealed that by optimizing the operating conditions of the biomass conversion plant, the LCOE could be decreased to 0.35 \$/kWh. Improving the capacity factor would have the most substantial effect on the costs of the system, increasing the days of operation from 90 in the base model to 300 could result in an LCOE as low as 0.12 \$/kWh.

Energy storage systems are an emerging field of interest for the future of electrical grids. With the rapid growth of renewable but intermittent sources of electricity, energy storage systems can help smooth the variations, making the grid more stable and reducing the need for maintaining an overcapacity of power production infrastructure. Among energy storage solutions, power-to-chemical storage is of particular interest due to the high energy density of chemicals and seasonal storage capabilities. Developments made in power-to-chemical technologies can also go a long way towards making the transportation and chemical industries sustainable. The chemical considered in this work is ammonia (NH3), which has advantages of being an easily liquefiable fuel, and has also been in industrial use for over a century. This thesis project aims towards the development of an efficient power-to-ammonia energy storage system using reversible solid oxide cells. The system designed in this thesis is based on direct ammonia utilisation in fuel cell mode, and steam electrolysis coupled with Haber-Bosch ammonia synthesis in the electrolysis mode. A steady state process model is designed in Aspen Plus. This is followed by extensive thermodynamic exergy analysis, used as the basis for the further design and optimisation of the system, with a goal to maximise the round trip efficiency. Exergy analysis is used to identify the sources with most scope for improvement.
The final system can attain a maximum round trip efficiency of 61.20 %, improved from a basic system efficiency of 19.79 %. The maximum round trip efficiency is comparable to values reported in recent times for thermodynamically studied models from literature using other fuels, such as 56.72 % for methanol. The optimised system attains high efficiencies without the need for thermal energy storage or an afterburner. Further, it is demonstrated that the designed system is efficient enough that heat integration across modes with high temperature energy storage does not provide any significant benefit.

This thesis researches the interaction between the revitalisation of an industry through industrial symbiosis and its local workforce, via a case study on the sugar industry in Norte Fluminense, Brazil. Agent-based modelling is used to gain insights in the case study with regards to the workers’ perception of their own status, power, their skills, (un)employment and the company’s ability to hire those workers. The case is contextualised by the proposal of Santos and Magrini (2018) to sustainably develop the Norte Fluminense region through the implementation of an agro-industrial symbiosis network. It is analysed that an industry revitalised through industrial symbiosis could positively influence its local workforce in terms of job quality and occupational skills. However, this depends on the kind of industry involved, the incentives for the industrial symbiosis network for including the local workforce, and the context and history of that industry. The prerequisite for these positive effects is the provision of additional education needed for the workforce to be included in the revitalisation of the industry. When the appropriate education is organised, the workforce could positively influence the revitalisation of an industry by providing the local support that is needed for industrial symbiosis exchanges to take place. These exchanges are build on the mutual trust of the key personnel of the industrial symbiosis network. The emergence of an industrial symbiosis network from an existing industry should happen gradually; the education for the potential workforce and the creation of jobs should be aligned to avoid unnecessary mismatching between skills required and skills available.