Sverige har som mål att bli helt fossilfri till år 2045. Energymyndigheten har därför tagit fram ett förslag till Vätgasstrategi för att ställa om vätgasproduktionen till att vara helt fossilfri till 2045. Idag används ca 180 000 ton vätgas, vilket motsvarar ett energiinnehåll på ca 6 TWh. Termo-kemisk omvandling av fossila bränslen står för 67% av Sveriges vätgasproduktion, medan 30% är biprodukter från industriella processer och 3% produceras med elektrolysörer. Att ersätta all fossil vätgas med elektrolysör-baserad vätgas innebär en elförbrukning motsvarande 60-126 TWh/år, vilket är en ökning på 40-80% jämfört med de 159 TWh el producerade i Sverige 2020. Energimyndigheten bedömer att vätgas har en viktig roll i att lyckas göra Sverige fossilfritt, delvis genom att den ska kunna fungera som energibärare eller energilagring för att jämna ut variationer i produktion hos förnybara energikällor. Av den anledningen kommer antagligen behovet av vätgas öka, och därmed även energibehovet för att producera vätgas öka ännu mer än 60-126 TWh/år om den fossila vätgasen ska bli ersatt med endast elektrolysör-baserad vätgas. Med tanke på begränsningar i expansion av förnybar elproduktion, kommer behovet av vätgas antagligen inte kunna täckas av endast elektrolysör-baserad vätgas. Därför bör möjligheterna för att även satsa på bio-vätgas, där vätgas produceras av antingen bakterier eller genom refinery av biobaserade råvaror, undersökas. Detta examensarbete ska undersöka möjligheter för vätgasproduktion i Sverige och jämföra olika produktionteknikers förutsättningar. En hypotes är att en hållbar strategi är att kombinera elektrolysör-baserad vätgas med bio-vätgas för att få en diversifierad produktion. Att ha olika produktionsmetoder som komplementerar varandra ger en mer stabil och säker produktion, eftersom de kommer påverkas olika av förändringar i produktionsförutsättningar i samhället. Detta arbete söker svara på följande frågor: Vilka tekniker finns tillgängliga för industriell/kommersiell produktion, var borde R&D riktas för de tekniker som inte är redo för kommersiell produktion, vilket Carbon Footprint (CF) har de olika teknikerna, en uppskattad produktionskostnad för de olika teknikerna, och vilken tillgänglighet för de olika råvarorna finns i Sverige? / Sweden has a goal to be completely fossil-free by 2045. Accordingly, the government has published a suggested Hydrogen Strategy to have made all hydrogen production in Sweden fossil-free by 2045. The Swedish hydrogen use is 180,000 ton, equaling an energy content of 6 TWh/year. Thermo-chemical conversion of fossil fuels accounts for 67% of Swedens hydrogen production, while 30% is byproducts from industry and 3% is electrolysis production. To replace all fossil hydrogen with electrolysis production, would give an increase of electrical demand with 60-126 TWh/year, or 40-80% increase compared to the 159 TWh electricity produced during 2020 in Sweden. Furtherly, the Ministry of Energy deem hydrogen to be key in the general transformation of Sweden to become fossil-free, with one reason being that hydrogen can be used as energy carrier to even out the variations in electricity production that renewable energy has. The need of hydrogen will therefore most likely increase until 2045, thus the electric energy demand for hydrogen production will increase as well, if it would be replaced solely with production using electrolysis. Given the constraints to the capacity of electricity production from renewable sources alone in Sweden, the electricity demand for hydrogen cannot be met by the electricity production. Thus, the possible role of biohydrogen, where hydrogen is produced using biorefinery or microbial production, should be investigated. This master thesis project will investigate the feasibility of hydrogen production in Sweden and compare different options for hydrogen production. A hypothesis of the project is that the most sustainable strategy for hydrogen production in Sweden will be with a diversified portfolio of production designs. Both biohydrogen and electrolysis hydrogen from renewable energy will complement each other in the future. By doing so, the energy sector will be more sustainable and stable since the techniques do not react alike to change in production conditions. The report aims to answer: What techniques are available for industrial production, where should R&D be directed for techniques not ready for industry, what is the estimated carbon footprint (CF) of the industrially available techniques, what is the estimated production cost for each technique, what availability is there in Sweden for the feedstock needed for each technique?

In the last half a century, Computational Fluid Dynamics (CFD) has been established as an important complementary part and some times a significant alternative to Experimental and Theoretical Fluid Dynamics. Development of efficient computational algorithms for digital simulation of fluid flows has been an ongoing research effort in CFD. An accurate numerical simulation of compressible Euler equations, which are the gov-erning equations of high speed flows, is important in many engineering applications like designing of aerospace vehicles and their components. Due to nonlinear nature of governing equations, such flows admit solutions involving discontinuities like shock waves and contact discontinuities. Hence, it is nontrivial to capture all these essential features of the flows numerically. There are various numerical methods available in the literature, the popular ones among them being the Finite Volume Method (FVM), Finite Difference Method (FDM), Finite Element Method (FEM) and Spectral method. Kinetic theory based algorithms for solving Euler equations are quite popular in finite volume framework due to their ability to connect Boltzmann equation with Euler equations. In kinetic framework, instead of dealing directly with nonlinear partial differential equations one needs to deal with a simple linear partial differential equation. Recently, FEM has emerged as a significant alternative to FVM because it can handle complex geometries with ease and unlike in FVM, achieving higher order accuracy is easier. High speed flows governed by compressible Euler equations are hyperbolic partial differential equations which are characterized by preferred directions for information propagation. Such flows can not be solved using traditional FEM methods and hence, stabilized methods are typically introduced. Various stabilized finite element methods are available in the literature like Streamlined-Upwind Petrov Galerkin (SUPG) method, Galerkin-Least Squares (GLS) method, Taylor-Galerkin method, Characteristic Galerkin method and Discontinuous Galerkin Method. In this thesis a novel stabilized finite element method called as Kinetic Streamlined-Upwind Petrov Galerkin (KSUPG) method is formulated. Both explicit and implicit versions of KSUPG scheme are presented. Spectral stability analysis is done for explicit KSUPG scheme to obtain the stable time step. The advantage of proposed scheme is, unlike in SUPG scheme, diffusion vectors are obtained directly from weak KSUPG formulation. The expression for intrinsic time scale is directly obtained in KSUPG framework. The accuracy and robustness of the proposed scheme is demonstrated by solving various test cases for hyperbolic partial differential equations like Euler equations and inviscid Burgers equation. In the KSUPG scheme, diffusion terms involve computationally expensive error and exponential functions. To decrease the computational cost, two variants of KSUPG scheme, namely, Peculiar Velocity based KSUPG (PV-KSUPG) scheme and Circular distribution based KSUPG (C-KSUPG) scheme are formulated. The PV-KSUPG scheme is based on peculiar velocity based splitting which, upon taking moments, recovers a convection-pressure splitting type algorithm at the macroscopic level. Both explicit and implicit versions of PV-KSUPG scheme are presented. Unlike KSUPG and PV-KUPG schemes where Maxwellian distribution function is used, the C-KUSPG scheme uses a simpler circular distribution function instead of a Maxwellian distribution function. Apart from being computationally less expensive it is less diffusive than KSUPG scheme.

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