Meeting global climate targets means replacing almost all fossil fuel energy with renewables by 2050, leaving roughly one generation to pull off the largest infrastructure change in industrial history. This first part of a two-part DW documentary asks whether enough green energy can actually be produced to cover world demand. Cameras visit the North Sea's offshore wind farms and Spain's newest solar fields, sites the film frames as future energy exporters comparable to today's oil states. At the Technical University of Ilmenau in Thuringia, researchers working with a team from Caltech demonstrate high-tech materials designed to make solar and wind power cheaper and more efficient than the fossil fuels they would replace. Engineers, scientists, and energy planners lay out the scale of the transition required, from grid capacity to material costs, without pretending the answer is simple. The film treats the shift to renewables as an engineering and economic problem first, leaving the political fight for the second installment.