ABSTRACT
This chapter will provide an overview of the supply side of the energy system. The historic development of primary energy supply by source is given in Figure 5.1. Before the Industrial Revolution, bio-energy was the main energy source. In the course of the twentieth century, fossil fuels became dominant, first coal, then oil and natural gas. There are small roles for nuclear energy and hydropower. Bio-energy supply remained quite stable, but displayed growth in recent years. New renewable energy sources, like solar energy and wind energy still have a very small share, but are growing rapidly.
