7.2 Superconductor Technology in the Future
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The principle is the same as that for the ship propulsion, and the superconducting
generator and motor will contribute to the reduction of CO 2 emissions. In this case an
effective and environmentally friendly system, in which the liquid hydrogen used for
cooling superconducting devices is used as fuel for superconducting generators, will
be examined. Various types of aircraft are now being designed, and it is imagined
that aircraft with much different shapes will fly in the sky around the world in the
future.
(4) Applications for energy problems
Recently, the global warming of the earth by CO 2 has been recognized as a serious
problem. On the other hand, although nuclear electricity generation does not emit
CO 2 , people are quite sensitive to radioactive contamination caused by an accident
at a nuclear electric power plant after the Great East Japan Earthquake. In addition,
uncertainty about the safety of radioactive waste that has to be managed for over a
long period of time that human beings have never experienced makes people anxious.
Hence, nuclear electricity generation will diminish without public support. Thus, the
use of renewable energy that does not emit CO 2 will advance. Solar power generation,
the cost of which is expected to be dramatically reduced, is particularly promising.
The problems in progressing the use of renewable energy are the installation of
power transmission cables to the regions in which the electric power is used and
devices to store the excess electrical energy. In particular, the energy storage devices
that can store energy instantaneously are quite expensive now. This prevents local
governments that intend to consume generated energy from ever starting solar power
generation. If we look at Europe, they solve this problem by delivering excess energy
to regions of power shortage instead of storing energy. Electric power may not be
generated because there is no wind in some regions, while excess electric power is
generated by strong wind in other regions. It is important to send excess electrical
energy to regions of shortage over a wide area, which averages the demand for
electrical energy. A similar situation occurs for solar power generation when it is
diminished by cloud. This is the same principle as the improvement of signal to
noise ratio by overlapping small signals buried in noise many times. If the area
connected with the power line becomes wider, averaging becomes more effective.
This reduces the necessity for installing expensive energy storage systems. In this
case, the cost of the power line is an important factor.
When the power line becomes long, superconducting power transmission with
small energy dissipation is advantageous. Direct current (DC) is advisable instead
of alternating current (AC) for the power transmission. This is because the solar
power generation is DC. DC electric power transmission is also better for wind
power generation. Although the power generation takes place under AC conditions,
the frequency and phase of the induced voltage are random among many generators. DC power transmission is also beneficial from the viewpoint of superconductor
technology; there is no AC loss in the superconductor, and the structure of the superconducting cable becomes simple. In addition, the demand for DC electricity in
society is larger than that for AC electricity. In modern homes, most of the electrical
163
The principle is the same as that for the ship propulsion, and the superconducting
generator and motor will contribute to the reduction of CO 2 emissions. In this case an
effective and environmentally friendly system, in which the liquid hydrogen used for
cooling superconducting devices is used as fuel for superconducting generators, will
be examined. Various types of aircraft are now being designed, and it is imagined
that aircraft with much different shapes will fly in the sky around the world in the
future.
(4) Applications for energy problems
Recently, the global warming of the earth by CO 2 has been recognized as a serious
problem. On the other hand, although nuclear electricity generation does not emit
CO 2 , people are quite sensitive to radioactive contamination caused by an accident
at a nuclear electric power plant after the Great East Japan Earthquake. In addition,
uncertainty about the safety of radioactive waste that has to be managed for over a
long period of time that human beings have never experienced makes people anxious.
Hence, nuclear electricity generation will diminish without public support. Thus, the
use of renewable energy that does not emit CO 2 will advance. Solar power generation,
the cost of which is expected to be dramatically reduced, is particularly promising.
The problems in progressing the use of renewable energy are the installation of
power transmission cables to the regions in which the electric power is used and
devices to store the excess electrical energy. In particular, the energy storage devices
that can store energy instantaneously are quite expensive now. This prevents local
governments that intend to consume generated energy from ever starting solar power
generation. If we look at Europe, they solve this problem by delivering excess energy
to regions of power shortage instead of storing energy. Electric power may not be
generated because there is no wind in some regions, while excess electric power is
generated by strong wind in other regions. It is important to send excess electrical
energy to regions of shortage over a wide area, which averages the demand for
electrical energy. A similar situation occurs for solar power generation when it is
diminished by cloud. This is the same principle as the improvement of signal to
noise ratio by overlapping small signals buried in noise many times. If the area
connected with the power line becomes wider, averaging becomes more effective.
This reduces the necessity for installing expensive energy storage systems. In this
case, the cost of the power line is an important factor.
When the power line becomes long, superconducting power transmission with
small energy dissipation is advantageous. Direct current (DC) is advisable instead
of alternating current (AC) for the power transmission. This is because the solar
power generation is DC. DC electric power transmission is also better for wind
power generation. Although the power generation takes place under AC conditions,
the frequency and phase of the induced voltage are random among many generators. DC power transmission is also beneficial from the viewpoint of superconductor
technology; there is no AC loss in the superconductor, and the structure of the superconducting cable becomes simple. In addition, the demand for DC electricity in
society is larger than that for AC electricity. In modern homes, most of the electrical