Environmental Engineering Reference
In-Depth Information
Figure 1.9
Energy Cubes: the Annual Solar Irradiation Exceeds Several Times
the Total Global Energy Demand and All Fossil Energy Reserves
The largest tidal power plant, with a capacity of 240 MW, is situated at the
Rance estuary in France. However, tidal power plants always have large
impacts on nature. The amount of power that can be theoretically produced
by tidal power plants globally is relatively low.
Solar energy
By far the largest energy resource is the sun. Annually, 3.9
•
10
24
J = 1.08
•
10
18
kWh of solar energy reaches the surface of the Earth. This is about ten
thousand times more than the annual global primary energy demand and much
more than all available energy reserves on earth. In other words, using one-
ten-thousandth part of the incoming sunlight would cover the whole energy
demand of mankind. Figure 1.9 illustrates these values with energy cubes.
There is a distinction between direct and indirect solar energy. Technical
systems using direct solar energy convert incoming solar radiation directly into
useful energy, for instance electricity or heat. Wind, river water and plant
growth are indirect forms of solar energy. Here, natural processes convert solar
energy into other types of energy. Technical systems can use these indirect types
of solar energy as well.
The theoretical foundations of solar radiation needed for all technical solar
systems are reviewed in Chapter 2. The following sections briefly describe the
different technologies using direct and indirect solar energy. Some of them are
described in more detail in the following chapters.
Use of direct solar energy
The following technologies can utilize direct solar energy:
