Fossil fuels
such as petroleum oil, coal, and natural
gas have been accumulated in the earth over
a fairy long period of time. To burn these
fossil resources and release carbon dioxides
into the air means that the carbons, which
have been restored deep in the earth, are
exhausted to the atmosphere all of a sudden,
which leads to a big increase of carbon
dioxides content in the atmosphere.
Meanwhile, the resource of biogas plant
is organic matter, the production of plant’s
photosynthesis. Plants produce oxygen and
carbohydrates from carbon dioxides by photosynthesis.
So even if the organic matter produces carbon
dioxides in the course of biogas formation,
there is a good balance between the exhaustion
of carbon dioxides into the atmosphere and
absorption of carbon dioxides from the atmosphere.
And what is important is that this process
of giving out and taking in should occur
in a short span of time.
This idea of carbon circulation is “carbon
neutral”.
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