Abstract
The atmospheric carbon
dioxide concentration increased with industrial development. After 1970 it increased with incrasing rate
and now exceeded 400 ppm corresponding to the level in 3.5 million years ago,
in spite of the fact that our Homo Sapiens appeared only 200,000 years
ago. The world average temperature
increased 0.26°C for 10 years since 2007.
There is no solution to avoid global warming as far as we burn fossil
fuel. Extrapolation of recent increase
in the world primary energy consumption indicates that all reserves of fossil
fuels and uranium will be completely exhausted until the middle of this
century. In order to avoid the crisis of
intolerable global warming and no fuels for combustion we have to establish and
spread the technologies by which the whole world can keep sustainable
development only using renewable energy.
We are studying for about
30 years to supply renewable energy to the world in the form of synthesized
natural gas methane by
electrolytic hydrogen generation and subsequent methane formation from hydrogen
and captured carbon dioxide. We created
necessary key materials. Those are
anodes and cathodes for water electrolysis and catalysts for carbon dioxide
methanation. We constructed a prototype
plant consisting of solar cell, water electrolyzer, carbon dioxide methanation
unit, methane combustor with oxygen and piping connecting
methane production and combustion units in 1995. Industrial plants are available.
There are superabundant renewable energy sources on our
planet, and we have a variety of power generation systems. The major sources are solar and wind powers
characterized by intermittent and fluctuating nature. For the use of only renewable energy we need
to store the surplus electricity by which we make up for a deficiency of
intermittent power. The
most convenient and easily applicable technology to store the surplus
electricity is the formation of methane.
If we regenerate steady electricity from methane the whole world can
keep the sustainable development only by renewable energy.