The ongoing change towards completely renewable power production in Sweden entails new challenges in maintaining a stable power system and puts greater demands on the frequency control. Hydropower caters for all frequency control in the Swedish grid today. However, the new challenges make it necessary to explore other technologies that potentially could provide frequency control. The aim of this master thesis is thus to map different technologies that potentially could deliver the reserves FCR and aFRR, with the main focus of investigating the economic potential of these technologies and their competitiveness during different seasons.

The technologies investigated were lithium-ion batteries, flywheels, demand response and wind power plants. Different applications for these technologies were also investigated. The different investment alternatives were evaluated by calculating the net present value and the net present value ratio.

The results show that the economic potential is greatest in cases where existing infrastructure could be used. Investments in stand-alone energy storage systems are not profitable today but might be so in the future as the prices continue to decrease. The results also show that many of the technologies and applications are competitive alternatives to hydropower during different seasons, which shows that there is potential in participating in the balancing markets with these technologies. However, it seems relevant to investigate further if, and if so how, the regulations on endurance can be adapted to actual conditions to further opening up the markets to more actors while maintaining a stable power system.