An energy transition (or energy system transformation) is a major structural change to energy supply and consumption in an energy system. Currently, a transition to sustainable energy is underway to limit climate change. Most of the sustain-able energy is renewable energy. Therefore, another term for energy transition is renewable energy transition. The current transition aims to reduce green-house gas emissions from energy quickly and sustainably, mostly by phasing-down fossil fuels and changing as many processes as possible to operate on low carbon electricity. A previous energy transition perhaps took place during the Industrial Revolution from 1760 onwards, from wood and other biomass to coal, followed by oil and later natural gas. After the 1973 oil crisis, the term energy transition was coined by politicians and media. It was popularized by US President Jimmy Carter in his 1977 Address on the Nation on Energy, calling to "look back into history to understand our energy problem".