Large-scale penetration of renewables in the Iberian power system: Evolution, challenges and flexibility options

The seriousness of the global climate crisis makes the path towards the decarbonization of societies irreversible. In response to this call for action, the entire power system community has been actively researching, proposing, and implementing measures to minimize the share of emissions. Instigated by ambitious (EU) legislation, increasing public awareness of the problem, and the competitiveness of PV and onshore wind technologies, the past two decades have seen several EU countries paving the way towards large-scale penetration of renewables, such as Portugal and Spain, where the share of renewables has grown by leaps and bounds. As this process has unfolded, the large scope of challenges posed by integrating these two technologies requires further debate. These include technical and conceptual aspects of the infrastructure, such as an increasing number of grid connections, lack of inertia, power balancing issues derived from the stochastic nature of renewables, and issues of market participation and fairness. Notwithstanding, this has also "opened the door"to a broad range of solutions that can effectively tackle the lack of system flexibility. Among them, the Iberian Peninsula is a privileged spot to invest in promising renewable energy sources with attractive energy densities to complement the existing portfolio, namely ocean, offshore wind, and hydrogen technologies. Hence, this study analyzes and discusses this transformative process, promotes a better understanding of its challenges, and provides guided policy suggestions to move forward while preserving the security and resilience of the system.