Technology
The idea to improve
the quality of waste heat for repeated usage as energy is in progress. The part
of energy usable for work is called exergy, and the ratio of exergy is called
exergy ratio. Such fossil energies as oil, coal, and natural gas have a high
exergy ratio, but they will be low quality energy once they are burnt to
generate heat. It is impossible to increase the gross volume of energy because
energy has the conservation law, but it is possible to improve the quality of
energy.
Nippon Steel Engineering is working on the substantiative study of the self-heat generation
that Tokyo University professor Atsushi Tsutsumi proposed about five years ago,
by applying pressure to the steam in the process of decreasing the temperature.
The high-temperature steam with high exergy does not need application of heat
from outside. The self-heat generation method has a wide range of applications.
As compared with the traditional energy-saving technology, it can reduce energy
and fuel by more than 70% in naphtha desulfurization, carbon dioxide
separation, and drying coals with a large amount of moisture.
Kyusyu University professor Tatsumi Ishihara proposed the technology to collect waste energy and
regenerate exergy with the help of the solid oxide fuel cell (SOFC) method. The
SOFC method does not need pure hydrogen as fuel, and it can generate
electricity using methane of city gas as fuel. That is, it can change methane
into such fuel gas with a high exergy ratio as hydrogen and carbon monoxide.
The professor is developing the technology to collect waste heat and generate
hydrogen simultaneously by running the system of a fuel cell in the opposite
direction.
The concept of exergy efficiency
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