A steadily growing human population and the growing global economy have led to a need to reduce CO₂ emissions by using renewable energy sources such as solar, wind, biomass, geothermal, and water power with evergrowing interest in the fields of energy harvesting and storage seen during the past two decades. The harvesting of light is still a challenge, and solutions are needed to achieve both high efficiency and low cost electricity generation. While wind and sun are among the most powerful options for electricity generation in general, their intermittent nature makes large storage capacity necessary. Here, solutions are needed that are based either on chemical compounds, such as hydrogen or hydrocarbons, or on safe, low cost and powerful batteries, which have a long cycle and calendar life and a high energy density. For the reconversion of hydrogen or organic liquids efficient fuel cells are needed as converters. In addition to the harvesting and storage of electrical energy, the storage of heat is another essential element in the future energy landscape.