This paper discusses the development of an energy systems model for Swedenconsidering electricity, heat and direct fossil fuel consumption in the residential,industrial and transport sectors as well as the energy interaction with the other Nordiccountries and its impact on the Swedish energy system. The model is developed in theOpen source energy modelling system (OSeMOSYS) (Mark Howells 2011) andshowcases potential energy investment options for Sweden in the next four decades(2010-2050). It considers different scenarios and provides a technology neutralassessment of how Sweden can invest in energy infrastructure in the most judiciousway. The paper also describes the new user interface developed called ANSWEROSeMOSYS.The paper further discusses the results of the different scenarios. Thebusiness as usual scenario shows an inclination towards investments in nuclear power.Further scenarios consider the gradual phasing out of the use of oil in CHP plants andnuclear power as well as new energy policies and tax reforms. The paper discusses theseresults in detail and demonstrates how Sweden could improve its energy infrastructureconsidering different policy implications and constraints put up by the availability andfeasibility of different resources. Finally, the prospect of wider stakeholder engagementbased on this model is discussed. Building on the open-source nature of the model,inputs and modifications from research institutes, energy modelling experts,government bodies, as well as the wider public will be incorporated into the model. Thesource code and modelling data will be made publicly available.