3 Sources of energy from the natural environment
The natural environment itself is bathed in energy from other sources. Standing on a cliff top on a bright spring day you can feel the warmth of the Sun and the freshness of the breeze and hear the crashing of breaking waves below. All these energetic processes can be compared in terms of energy and power.
In order to put the total global energy supply and demand into proper perspective we need to know the contribution made by different natural energy sources to the Earth's energy supply. By far the most important source on Earth is the Sun, but some energy comes from the gravitational attraction between Sun, Moon and Earth, and some from the Earth's own internal heat. Figure 1.7 gives all the data on natural energy sources you will need in working through this section.