5.7 Fourth Industrial Revolution and Global Energy Prospects
189
wavelengths only and the energy from long wavelengths is lost. But there are other
elements such as gallium and indium that can absorb solar energy in the infrared and
ultraviolet spectrum. Improved version of solar cells consists of a stack of four, one
on top of each other where each layer in the stack is made of different materials such
as gallium and indium and stacked in such a manner that each layer absorbs energy
from certain part of the spectrum, converts it efficiently into electrical energy, and
passes the rest onto the next layer. Future solar cells will be made of substances that
will absorb sunlight in invisible spectrum and allow visible light to pass through. This
will bring in revolution in solar energy as we will then have solar energy produced
from wind shields of cars, buses, glass panes of buildings, and so on.
Besides silicon, solar cells are also made of perovskites that are more efficient.
These are compounds that share similar crystal structure and are named after the
mineral that was first found to have this structure. These compounds are cheaper
than silicon and can convert almost 20% of the sunlight falling on it into electricity.
25
One major difference between these two semiconductors is that in a silicon-based
solar cell, a thin wafer of 200 micron is used that is sliced off from the bigger block.
However, a perovskite solar cell can be made by dispensing the chemical solution
on a surface and making a cell of desired thickness. Moreover, perovskites can be
made with different combinations that can absorb maximum photons in different
parts of the visible spectrum. Each type of semiconductor has a property called band
gap that determines the longest wavelength of light a semiconductor can absorb as
well as maximum amount of energy that can be captured from photons of shorter
wavelengths. The photons absorbed are converted into electrons which are gathered
by electrodes to flow into a circuit.
The fourth industrial revolution has the potential to change the energy outlook
of the world. We have already graduated from wood–coal–oil era and entered white
gold stage that is dominated by nanotechnology. With its unique physical, chemical,
mechanical, and optical characteristics, this technology offers solution by squeezing
the size of large heavy-weight batteries (such as lead-acid) using new class of material called nanoparticles. The fundamental premise of nanotechnology is that all
materials are made of atoms and possess distinct chemical properties that depend
on the structure of the clouds of electrons. Sometimes an atom will pair off one of
its electrons with an electron from a neighboring atom to form a chemical bond and
form a molecule or a kind of crystalline structure such as semiconductors. Advocates
of nanotechnology aim at building things atom by atom so that we can have floods
of new materials and new inventions.
One of the significant applications of nanotechnology has been in lithium batteries.
A typical lithium cell consists of two electrodes (a cathode and an anode) where
anode is made of graphite and cathode is of lithium cobalt oxide. The electrolyte
used in the cell is made of a solution of lithium salts and organic solvents. During
the charging of cell, positively charged lithium ions in the electrolyte move toward
negatively charged anode and gets deposited. When the cell is used for operating any
device, the electrons flow from the anode into the device circuit and re-enter the cell
25 Science and Technology, The Economist, May 16, 2015.
189
wavelengths only and the energy from long wavelengths is lost. But there are other
elements such as gallium and indium that can absorb solar energy in the infrared and
ultraviolet spectrum. Improved version of solar cells consists of a stack of four, one
on top of each other where each layer in the stack is made of different materials such
as gallium and indium and stacked in such a manner that each layer absorbs energy
from certain part of the spectrum, converts it efficiently into electrical energy, and
passes the rest onto the next layer. Future solar cells will be made of substances that
will absorb sunlight in invisible spectrum and allow visible light to pass through. This
will bring in revolution in solar energy as we will then have solar energy produced
from wind shields of cars, buses, glass panes of buildings, and so on.
Besides silicon, solar cells are also made of perovskites that are more efficient.
These are compounds that share similar crystal structure and are named after the
mineral that was first found to have this structure. These compounds are cheaper
than silicon and can convert almost 20% of the sunlight falling on it into electricity.
25
One major difference between these two semiconductors is that in a silicon-based
solar cell, a thin wafer of 200 micron is used that is sliced off from the bigger block.
However, a perovskite solar cell can be made by dispensing the chemical solution
on a surface and making a cell of desired thickness. Moreover, perovskites can be
made with different combinations that can absorb maximum photons in different
parts of the visible spectrum. Each type of semiconductor has a property called band
gap that determines the longest wavelength of light a semiconductor can absorb as
well as maximum amount of energy that can be captured from photons of shorter
wavelengths. The photons absorbed are converted into electrons which are gathered
by electrodes to flow into a circuit.
The fourth industrial revolution has the potential to change the energy outlook
of the world. We have already graduated from wood–coal–oil era and entered white
gold stage that is dominated by nanotechnology. With its unique physical, chemical,
mechanical, and optical characteristics, this technology offers solution by squeezing
the size of large heavy-weight batteries (such as lead-acid) using new class of material called nanoparticles. The fundamental premise of nanotechnology is that all
materials are made of atoms and possess distinct chemical properties that depend
on the structure of the clouds of electrons. Sometimes an atom will pair off one of
its electrons with an electron from a neighboring atom to form a chemical bond and
form a molecule or a kind of crystalline structure such as semiconductors. Advocates
of nanotechnology aim at building things atom by atom so that we can have floods
of new materials and new inventions.
One of the significant applications of nanotechnology has been in lithium batteries.
A typical lithium cell consists of two electrodes (a cathode and an anode) where
anode is made of graphite and cathode is of lithium cobalt oxide. The electrolyte
used in the cell is made of a solution of lithium salts and organic solvents. During
the charging of cell, positively charged lithium ions in the electrolyte move toward
negatively charged anode and gets deposited. When the cell is used for operating any
device, the electrons flow from the anode into the device circuit and re-enter the cell
25 Science and Technology, The Economist, May 16, 2015.