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The transition from fossil fuels to renewable energy sources has accelerated over the past fifteen years, driven by steep declines in the cost of solar photovoltaic panels and wind turbines, which have fallen by more than eighty percent and fifty percent respectively since the early 2010s according to industry cost surveys. This price collapse has made renewables the cheapest source of new electricity generation in many regions, even without accounting for government subsidies or carbon pricing. Despite this progress, the intermittency of solar and wind power, which generate electricity only when weather conditions permit, remains a fundamental engineering constraint on how quickly fossil fuel plants can be retired. Grid operators must maintain backup capacity, historically supplied by natural gas plants that can ramp production up or down quickly, to cover periods of low renewable output. Battery storage technology has advanced considerably and costs have fallen, yet current battery capacity remains sufficient to cover only hours, rather than the days or weeks, of low wind and solar output that can occur during extended unfavourable weather patterns. Some countries have pursued alternative solutions, including pumped-hydro storage, which uses surplus electricity to pump water uphill for later release through turbines, and expanded transmission networks that allow regions with surplus renewable generation to export power to areas experiencing shortfalls. Nuclear power, which produces minimal carbon emissions and can supply consistent baseload electricity regardless of weather, has re-entered policy discussions in several countries as a complement to intermittent renewables, though high construction costs and lengthy regulatory approval processes have limited new plant construction. Energy analysts broadly agree that a fully decarbonised electricity grid will require not a single technology but a diversified combination of generation, storage, and transmission solutions, since renewable energy's falling costs alone do not resolve the underlying challenge of matching electricity supply to demand at every hour of the year.