<![CDATA[Objective: This paper looks at the interrelation between capital allocation and reliability in the context of sustainable energy systems, stressing the importance of renewable resource deployment, obstacles to investments, energy storage, and grid infrastructure development, as well as flexibility. Method: This study employs a narrative literature review approach by examining recent evidence on renewable energy deployment, investment trends, energy storage, electricity transmission, grid flexibility, and infrastructure resilience. The review synthesizes relevant statistics and findings on renewable energy capacity expansion and cost competitiveness to assess how capital allocation strategies can support the reliability and sustainability of future energy systems. Results: Recent facts demonstrate that the competitive position of renewable technologies has been improving quickly. In 2024, global renewable power capacity additions amounted to 582 GW, which is a 19.8% rise from 2023. In addition to this, in 2024, 91% of newly built utility-scale renewable projects produced supply at a cheaper price compared to the cheapest possible fossil fuel alternative. At the same time, the quick implementation of renewable energy is, however, creating new expectations regarding storage, transmission, flexibility, and digital management of grids. Novelty: For this reason, the review states that future capital investments need to undergo a paradigm shift from generation-centered approaches to integrated portfolios that comprise renewable generation technologies, storage, transmission, flexibility, and resilience improvement infrastructure.]]>
