Most renewable energy plants are considered to be infrastructure assets, mainly for their size and their capital-intensive nature but also because of their long-term lifespan. Wind power and solar power are the most mature technologies, they are now cheap and quickly deployable, however, they produce variable energy (VRE). This is a growing concern, as it matters a lot, especially in energy systems that intend to become almost fully electrified and primarily powered with renewables. There is practically no discussion on whether renewables are necessary: most jurisdictions have already started policies to encourage the implementation of renewable energy. What is still being discussed is the pace at which the energy transition should be implemented. This chapter discusses the renewable energy infrastructure from a broader perspective. It even goes beyond the system perspective, as it includes all the ingredients needed to build an efficient low-carbon, resilient economy, with today’s available technology and the technologies being developed. To ensure a good comprehension of the book, key concepts will be introduced and sometimes illustrated with concrete examples, including the climate-critical sectors, the place of electricity in the energy system, current investments in the energy transition, the costs of the available technology, the different scenarios and what they imply and finally the latent challenges related to the cost of capital for emerging countries and the support for nascent technology.