Zero Emission Fuel (ZEF) has the goal to create affordable high-grade methanol, produced from absorbed carbon dioxide and water from the air. The methanol is produced in a solar methanol (MeOH) farm, consisting of 13225 micro-plants which are powered by PhotoVoltaicsolar panels (PV panels). The solar capacity of the solar MeOH farm is 12 MW and produces 7.8 tons of grade AA methanol per day (grade AA methanol has a purity of 99.8%). One of the main goals of ZEF is to produce methanol with a smaller environmental impact compared to the currently commonly used production methods. A part of the research focuses on an advice for the type of PV panels to use. The main goal of the research is to determine the environmental impact of methanol produced by the solar MeOH farm. The results lead to an advice for ZEF concerning reducing their environmental impact, also the research advises on further research.
To determine the environmental impact a life cycle assessment (LCA) is performed according to ISO 14040 and ISO 14044 standards, using the ReCiPe 2016 method. The midpoint impact categories researched are the global warming potential (GWP), the mineral resource scarcity, and the fossil resource scarcity. The functional unit of the LCA is one ton methanol. A set of assumptions is made concerning the solar MeOH farm, which are tested in the sensitivity analyses. A second LCA is performed, which compares different PV technologies. This LCA focuses on the endpoint impact categories, and the goal of this LCA is to show which PV technologies have the least environmental impact. The PV technology with the smallest environmental impact, polycrystalline silicon PV panels, is used in the LCA concerning the solar MeOH farm. One ton of methanol produced by the solar MeOH farm has a GWP of -835 ± 50 (6.5%) kg CO₂ equivalent, proving that the methanol produced by ZEF absorbs CO2. When the end-use of methanol is included, approximately 40% of the methanol produced by ZEF should be used for the production of plastic and chemicals to produce zero-emission methanol. After 7.9 ± 0.8 years of production, the solar MeOH farm has reached the CO₂ break-even point. The mineral resource scarcity of one ton methanol produced by the solar MeOH farm is 10.7 ± 0.7 (6.3%) kg Cu equivalent, the fossil resource scarcity is 127 ± 13 (10%) kg oil equivalent, and the energy payback time (EPT) is 6.9 ± 0.7 years of methanol production. The most crucial factor that influences the environmental impact is the amount of equivalent sun hour (ESH), therefore, the solar MeOH farm should operate on a location with a high amount of ESH to decrease the environmental impact. A 1% decrease of micro-plant efficiency increases the environmental impact with more than 1%. The recommendation is to focus on lifetime and efficiency when designing new subsystems, since lifetime is a more important factor than the materials used.

In 2015, 30% of the world's energy demand was met through petroleum based sources, whose burning has affected the world's climate. The Paris Climate Agreement, among other policies, has shifted the focus towards usage of renewable energy sources. Currently, the renewable market caters predominantly to meeting the electric demand, which only represents 19% of the world's energy consumption. Zero Emission Fuels (ZEF) aims to create a small-scale chemical plant that uses renewable energy sources to create synthetic methanol. This follows the vision of adapting renewable energy sources for non-electric usage. Methanol is the simplest liquid hydrocarbon at atmospheric condition; it can be used as a fuel or as a base chemical for other products. Presently, the industry reforms syngas obtained from fossil fuels to create methanol, predominantly using large-scale catalytic reactors. For production of methanol from renewable sources, Bos and Brilman developed a small-scale catalytic reactor driven by natural circulation. ZEF adapted the Brilman reactor for their chemical plant, creating a prototype of the modified Brilman reactor (MBR). The present work aims to create a model that describes the steady-state methanol production of the prototype using computational fluid dynamics (CFD) and chemical process models.

The MBR is an innovative design based on a closed loop geometry. The gases are driven by buoyant forces from a temperature difference between the high-temperature catalytic reaction zone and the low-temperature condensation zone. Heat recovery elements are used to exchange heat between the hot and cold streams as they travel in the loop. The CFD model developed on Fluent 18.2, uses a RNG k-e turbulent model, with multicomponent species transport, convective heat transfer and momentum loss effects from the catalytic zone. The boundary conditions are based on the operating conditions of the prototype. The model calculates flow-rate, and the effect of heat recovery elements inside the natural circulation loop. A chemical process model developed in COCO 3.2 is used to calculate a mass and energy balance for the two-phase behavior of the gas mixture inside the MBR.

A study of the effects of a natural circulation loop with a configuration similar to the reactor is performed, observing potential benefits by tilting the system. The combination of effects due to heat recovery and flow blockage in the reactor is studied, and the results are evaluated with experimental measurements. The chemical process model developed closely resembles the experimental characterization of the reactor. The parameters of flow-rate and internal temperatures can not be validated due to limited data available from experimental procedures.

The Need for Renewable Fuels
Global warming demands an urgent and thus dramatic change in the current focus and approach of producing energy. Current renewable energy production is mainly focused on solar and wind. However, for many industries their infrastructure is not adapted to electricity as an energy source. Therefore, a full transition to wind and solar is not viable on the short term. More than 50% of the current industry still relies on fossil fuels. This means there is a strong need for renewable fuels, like liquid hydrocarbons, which can directly be applied in the existing infrastructure.

ZEF: Reinventing the Chemical Industry
Zero Emission Fuels (ZEF), a startup focusing on the production of renewable methanol (also a liquid hydrocarbon), aims for a different approach in chemical industry. Current commercial routes to renewable hydrocarbons have not been succesful so far in the global market. By using a scalable number of microplants, opposed to upscaling an industrial size plant, the advantage in terms of cost per kilogram, saving money and time could be significant, because no intensive research and testing regarding upscaling is required. Instead of upscaling the entire plant, simply the number of microplant could be increased to satisfy the renewable MeOH demand. Hence, a small player as ZEF, with fast and cheap growing potential, is able to enter the methanol market by offering renewable methanol at competitive prices of $350/ton in a mainly fossil fuel driven methanol market. ZEF’s product is a fully automated solar panel add-on which converts air to liquid methanol. The microplant extracts H2O and CO2 from the air and uses it to synthesize methanol. This means that CO2 emitted in the atmosphere can be recycled into a renewable fuel. Hence, ZEF poses a solution to close the CO2-cycle. An advantage of the microplant is that it is location independent because water and carbon dioxide are available everywhere. The system is a series of nine subsystems, all of which are based on existing technologies and powered by solar energy. The aim of ZEF is to reach an overall system efficiency of 55%. The numbering-up approach requires the microplant to be suitable for mass-production.

The challenge
The backbone of the microplant is the subsystem which integrates the eight other subsystems. By integrating the different subsystems, the number of parts and thus cost can be reduced significantly. This is a requirement indispensable to the feasibility of the business idea. Thus, the central question in the perspective of the business case and this thesis is to verify whether a reserved budget of EUR 3,5 per backbone is realistic. Is there a backbone which can be designed to correspond to the technical and financial requirements?

Objective
The combination of technical requirements and a tight cost target demands a smart design of the backbone. Therefore, the focus is on product architecture, material choice and mass-manufacturing at a minimal cost. The result is a feasibility study towards the mass-manufacturing aspect applied on the backbone of an energy system. This should all be carried out within the boundaries of the business plan.
 
Approach
In essence, the feasibility study in terms of a cost analysis is straight forward. A material, volume and production method need to be determined in order to validate the business plan. First, a material needs to be found which is as cheap as possible and complies with the technical requirements. The technical requirements involve coping with aggressive chemicals, elevated temperatures and high pressures. Once a suitable material is found, the volumes are to be looked into. The size of the several subsystems needs to be estimated. Subsequently, a compact layout positioning is needed to minimize the total backbone surface area. Ultimately, the volume is determined by applying a Finite Element Method (FEM) and topological optimization through simulations using Computer Aided Design (CAD) software on the chosen backbone concept. This concept is an approach to integrate all essential functionalities related to the aforementioned other eight subsystems. A prototype of the concept, called the backbone “sample”, has been manufactured by computer numerical controlled (CNC) milling. Finally, a feasibility study was carried out to investigate the possibility for mass manufacturing of the backbone. This feasibility study was based on a cost analysis and on the results of the backbone testing.

Results
The result of this thesis is a product architectural layout applied on a three-plated backbone concept. The CNC-milled prototype (figure c) contains real size partial solutions for all main functionalities of the targeted backbone. These functionalities range from crossing canals subjected to different pressures towards the integration of valves, a buffer and actuators. Hence, the merit of the design is the possibility to copy-paste sub-solutions wherever needed in a future backbone design, even an injection moldable variant. Regarding the cost model, an approach is presented to quickly estimate the material price for a new backbone design. This approach is driven by a fixed amount of material required per functionality. This amount is based upon the material choice and the topology optimization. Regarding testing the CNC-milled backbone sample, the integration of functionalities has proven to be successful. However the custom made seals failed to be leak tight.

Conclusion
The feasibility study of the mass-manufacturing aspect of the backbone based on a cost analysis and results gathered from testing the backbone sample. A cost analysis has been carried out, based on a material suited for mass-manufacturing, design for mass-manufacturing itself and an amount of material necessary. This cost analysis was compared to the target backbone cost defined by ZEF. Based on the developments regarding the entire microplant design of May 2018, the backbone weight is estimated at 7kg and it is made out of the material PET 45% glass fiber (GF). This material is found to be in line with the numerous technical and financial challenges. The weight of 7kg assumes the integration of a 1.3l hydrogen buffer for 1 hour, a 0.7l carbon dioxide-water buffer for two hours, 1.5m piping, 14 one-way partially servomotor controlled valves and three solenoid operated valves. A safety factor of two was applied to guarantee the backbone to be self-bearing and provide support to the subsystems. The final design is a three-plated backbone measuring 200x400mm. Considering a production volume of 500 000 injection mold backbones, one backbone is expected to cost EUR 9,22. Thus, the cost estimation is not in line with the targeted cost of EUR 3,5. Also, regarding testing the backbone sample, the custom made seals have proven not to work. Therefore, the design should be reviewed in terms of weight optimization and detail design. Despite the results, the costs are not far off. Possible opportunities to cut costs are mentioned in the recommendations.

Recommendations
Based on new input of the overall microplant design, the parametric models of the material search and the volume estimation of subsystems, the cost analysis can be adjusted. Hence, these models are a valuable benchmark for further research. Regarding the detail design, it is recommended to work around seals in the next backbone design. These seals are a weak point in the current backbone design and are susceptible to failure. By avoiding seals, the risks with regard to performance and assembly are seriously reduced. Therefore, in a next design step injection molding experts could be approached to help think about a backbone design which is suitable for injection molding without seals.
With respect to the design of the backbone, it is advised to keep cavities as small as possible. For every aspect, which is subjected to higher pressures, ranging from canals to buffers, it must be checked whether it can be reduced in volume. The smaller the pressurized surface area, the lower the stresses on the material, the less material is needed, the lower the backbone cost. Thus, it is recommended to prioritize design for weight optimization in the next backbone design. In relation to weight optimization, design for hybrid materials needs more attention. Other important considerations are mounting the backbone to the solar racking system, cavity creep as a result of a long term load case exposure, permeability of the material with respect to H2 and CO2 and the effect of mutual influences of temperature, chemicals and pressure on the material choice.

At the United Nations Climate Change Conference held in Paris in 2015, ambitious goals for the worldwide CO2 emissions were set. To achieve these goals, a huge reduction in CO2 emissions must be realized. For the energy market, the current aim is to use renewable electricity instead of fossil fuels. However, there are multiple sectors where electricity is not a suitable form of energy, due to storage issues. For example, the chemical industry is heavily based on fossil fuels as a resource to synthesize chemicals. It is therefore useful to investigate the feasibility of renewable synthetic fuels.

The goal of this thesis is to design a process that converts the hydrocarbon fuel combustion products CO2 and H2O into a fuel that is a liquid at atmospheric conditions. Methanol is selected as the liquid fuel because of its basic molecule structure. It requires much more energy to obtain methanol from CO2 and H2O than it does from natural gas. The process is determined to be container-sized to become cost competitive through mass production. The technical feasibility of a mass produced, autonomous, renewable and container-sized methanol production plant is studied in this thesis. The whole process is divided into sub processes. H2O is obtained from desalination of seawater. The H2O is split into H2 and O2 using alkaline electrolysis. The CO2 is adsorbed from the air and recovered using pressure and temperature swing. The required energy is obtained using solar PV and solar thermal. The H2 and CO2 are finally converted to methanol in the methanol synthesis sub process. The intermittent character of solar energy yields a dynamically operated process. The methanol synthesis sub process is studied further because of the small scale and dynamic operation that are new concepts for this technology. The other sub processes are considered as black boxes with fixed in- and outputs. The steady state operation of the whole process is modeled using Aspen Plus™ and the distillation process is modelled in MATLAB®. Using the results from Aspen, pinch analysis is performed for optimal use of the available heat.

From the results of the model, it is found that an autonomous container-sized methanol production plant is technically feasible. 140 kg of methanol can be produced daily with a purity of at least 96.6 %, using a set-up of three 40 feet sea containers, two of which are dedicated to the capture of CO2. 288 kW of electrical power and 24 kW of heat is required for the operation. This is equal to a solar park with an area of 1663 m2 assuming an average 6 hours of solar irradiance. Using the LHV of methanol in the calculation, the total efficiency of the process is estimated at 45 %. The results from the MATLAB® model of the distillation cannot be validated because the used equation of state of REFPROP underestimates the concentration of methanol in each iteration, yielding an invalid mass balance. Fixing this issue results in an invalid energy balance. It is therefore concluded that REFPROP is not suitable for iterative calculations of distillation columns.