The principal forms of modern renewable energy: solar photovoltaic energy, wind power, and hydropower, are increasing in capacity and power output much faster than fossil fuels such as coal, oil, and natural gas. One reason for this is that their costs are falling rapidly. Megawatt-scale batteries are now cost-effective and when coupled up to utility-scale solar and wind power, these renewable energy generation systems provide instant dispatchable power to the grid. This chapter examines the European Union’s plan to reduce emissions of greenhouse gases by 80% by 2050. Emissions from the power sector essentially fall to zero. In other sectors there are deep cuts in emissions as a range of cost-effective renewable energy technologies are rolled out. In the transport sector, the number of electric vehicles is ramping up exponentially. Significantly raising the efficiency with which energy is used is another key element in the transition to a low carbon energy future. This is particularly important in the built environment where net zero energy buildings are technically feasible.