1.3.1
In nuclear power plants, energy is released as heat during nuclear fission reactions.
The heat generates steam which drives a steam turbine and subsequently an electric
generator just as in most fossil fuel power plants.
Renewable energy carriers
All the energy carriers discussed above are either fossil or nuclear fuels. They are not
renewable because they are not “refilled” by nature, at least not in a useful amount of
time. In contrast, renewable energy carriers are energy carriers that are replenished by
natural processes at a rate comparable or faster than their rate of consumption by humans.
Consequently, hydro, wind and solar energy are renewable energy sources.
Hydroelectricity is an example of an energy conversion technology that is not based
on heat generated by fossil or nuclear fuels. The potential energy of rain falling in
mountainous areas or elevated plateaus is converted into electrical energy via a water
turbine. With tidal pools the potential energy stored in the tides can also be converted to
mechanical energy and subsequently electricity. The kinetic energy of wind can be
converted into mechanical energy using windmills.
Finally, the energy contained in sunlight, called solar energy, can be converted into
electricity as well. If this energy is converted into electricity directly using devices based
on semiconductor materials, we call it photovoltaics (PV). The term photovoltaic is
derived from the greek word φως (phos), which means light, and volt, which refers to
electricity and is a reverence to the Italian physicist Alessandro Volta (1745–1827) who
invented the battery. As we will see in this book, typical efficiencies of the most
commercial solar modules are in the range of 15-20%.
The energy carried with sunlight can also be converted into heat. This application is
called solar thermal energy and is discussed in detail in Chapter 22. Examples are the
heating of water flowing through a black absorber material that is heated in the sunlight.
This heat can be used for water heating, heating of buildings or even cooling. If
concentrated solar power systems are used, temperatures of several hundreds of degrees
are achieved; this is sufficient to generate steam and hence drive a steam turbine and a
generator to produce electricity.
Next to generating heat and electricity, solar energy can be converted into chemical
energy as well. This is what we refer to as solar fuels. For producing solar fuels,
photovoltaics and regenerative fuel cells can be combined. In addition, sunlight can also
be directly converted into fuels using photoelectrochemical devices. We will discuss solar
fuels in Chapter 23.
In nuclear power plants, energy is released as heat during nuclear fission reactions.
The heat generates steam which drives a steam turbine and subsequently an electric
generator just as in most fossil fuel power plants.
Renewable energy carriers
All the energy carriers discussed above are either fossil or nuclear fuels. They are not
renewable because they are not “refilled” by nature, at least not in a useful amount of
time. In contrast, renewable energy carriers are energy carriers that are replenished by
natural processes at a rate comparable or faster than their rate of consumption by humans.
Consequently, hydro, wind and solar energy are renewable energy sources.
Hydroelectricity is an example of an energy conversion technology that is not based
on heat generated by fossil or nuclear fuels. The potential energy of rain falling in
mountainous areas or elevated plateaus is converted into electrical energy via a water
turbine. With tidal pools the potential energy stored in the tides can also be converted to
mechanical energy and subsequently electricity. The kinetic energy of wind can be
converted into mechanical energy using windmills.
Finally, the energy contained in sunlight, called solar energy, can be converted into
electricity as well. If this energy is converted into electricity directly using devices based
on semiconductor materials, we call it photovoltaics (PV). The term photovoltaic is
derived from the greek word φως (phos), which means light, and volt, which refers to
electricity and is a reverence to the Italian physicist Alessandro Volta (1745–1827) who
invented the battery. As we will see in this book, typical efficiencies of the most
commercial solar modules are in the range of 15-20%.
The energy carried with sunlight can also be converted into heat. This application is
called solar thermal energy and is discussed in detail in Chapter 22. Examples are the
heating of water flowing through a black absorber material that is heated in the sunlight.
This heat can be used for water heating, heating of buildings or even cooling. If
concentrated solar power systems are used, temperatures of several hundreds of degrees
are achieved; this is sufficient to generate steam and hence drive a steam turbine and a
generator to produce electricity.
Next to generating heat and electricity, solar energy can be converted into chemical
energy as well. This is what we refer to as solar fuels. For producing solar fuels,
photovoltaics and regenerative fuel cells can be combined. In addition, sunlight can also
be directly converted into fuels using photoelectrochemical devices. We will discuss solar
fuels in Chapter 23.