Towards 100% renewable electricity for Indonesia: the role for solar and pumped hydro storage

60% of global annual net new capacity comprise the addition of solar photovoltaics (PV) and wind. Indonesia has good solar resources by world standards, with low seasonal variation. There is also some wind energy potential. Solar PV is likely to be cheaper than new coal generation and can be rapidly deployed at every scale throughout Indonesia. Balancing an electricity system with large fractions of variable solar PV and wind can be managed with established techniques comprising stronger interconnection over large areas to average out local weather variations; storage; demand management; and occasional spillage of renewable electricity. Pumped hydro is by far the leading method of energy storage. Indonesia has 26,000 good pumped hydro sites with storage capacity of 821,000 Gigawatt-hours (GWh), which is about 1,000 times more than needed to support a 100% renewable Indonesian electricity system.