The energy transition confronts us with major challenges. In the electrical grid, mainly volatile renewable energy sources are available, but simultaneously we lack the possibility of saving this energy. This leads to a heavy load on the electrical system. Nowadays, the generation of heat as well as our transport system still rely heavily on fossil fuels. However, energy sources such as heat, gas, or fuel provide storage facilities to complete the missing flexibilities for a volatile power generation. Sector coupling enables the usage of energy from volatile, renewable energy sources by coupling different, currently separately acting energy sectors. It can store this energy in other sectors and thus provides flexibility options in the electricity sector. In addition, the demand of primary or fossil energy can be reduced and at the same time sector coupling can decarbonize other energy sectors. In cooperation with the Energie AG and the Montanuniversität Leoben, the aim of this master thesis is to analyse the effects of sector coupling from a technical perspective with the help of the HyFlow program, developed at the University of Leoben. Additional aspects of thesis are the identification of sector coupling actions that are particularly effective in decarbonising the energy system in Upper Austria, as well as which effects the volatility of renewable energy sources has on the electricity grid and how this can be countracted. The analysis of this master thesis has shown that sector coupling is going to be a significant part of the energy system of the future. It is possible to reduce the demand of primary energy and sector coupling technologies such as heat pumps and electromobility can also decrease the load on the electrical grid. In addition, sector coupling via power-to-gas technology currently provides the only reasonable option for long-term storage of electricity in big amounts. The decisive factor in a centralized PtG system is the control strategy. Decentralized systems should also be investigated, because the current electrical network is not designed for a central PtG system. However, it has also been shown that the expansion of renewable energy sources and sector coupling alone will not be enough to deal with the energy transition. Energy conservation through efficiency and ecological sufficiency measures are going to be essential.