Biomass
Biomass
is biological matter (anything that 'recently' lived - by 'recently' I
mean within the last few thousand years!).
Biomass
makes excellent fuel as it is made up of carbon based complex molecules
that generally react exothermically with oxygen (burn!!!). This process
is easier if the biological material has completely dried out and lost
all of its water content.
Before
the Industrial Revolution biomass was the primary source of fuel - since
then it has been overtaken by the use of fossil fuels. Recently, due to
concerns over Global Warming biomass
has regained ground.
Although
CO2 goes into the atmosphere when biomass is burned it does
not contribute to a worrying shift in equilibrium of the carbon cycle
because as the carbon products are 'new' they got their carbon from the
atmosphere anyway - so it just goes back! Also, when the new biomass is
formed it takes carbon in from the atmosphere - either directly, if it
is a plant, or indirectly, if an animal.
Examples
of biomass
- Wood, sawdust,
straw, plant 'stubble' from crops, wood products such as cardboard and
paper
- Plant oils, rape
seed oil
- Animal waste products,
dung
- camel dung
makes excellent fuel for nomads - no need to pack it!
Fossil
fuels are NOT biomass - biomass is made up of biological material that
is in the rapid part of the carbon cycle.
Plants take carbon
dioxide out of the atmosphere for photosynthesis and 'trap' it as organic
matter, but respiration, decomposition of dead organic materials and burning
put carbon dioxide back into the atmosphere.
During the carboniferous
period (over 300 million years ago) large amounts of carbon accumulated
as fossil fuels (coal, peat, oils and natural gas- methane).The "fossil
fuels" box was getting bigger and bigger. The other boxes were getting
smaller. It took millions of years to make these fuels, but we are burning
them all up in a few hundred years. This is upsetting the balance of carbon
in the cycle. At present the "fossil fuels" box is getting smaller;
we are burning it all. At the same time the "atmosphere" box
is getting bigger; i.e. carbon dioxide is being added to the atmosphere.
This gas contributes to the "green house effect" and therefore
to the problem of "global warming".
The biomass part of
the cycle is quite rapid - animal and plant life cycles are relatively
short. The 'fossil fuels' box is in a section of the cycle that is slow
running and requires organic matter to be sealed off from the atmosphere.
There is grave concern that simply increasing the plant life on the planet
will not shift the equilibrium far enough to prevent rapid global warming.
Deforestation and burning of vast areas of land are human activities that
are affecting the balance of the carbon cycle but they are not as unsolvable
as the problem of putting vast quantities of fossil fuel carbon back into
the atmosphere, that had until recently been effectively trapped out of
the biomass part of the cycle.
Links:
http://www.bera1.org/about.html
http://www.eere.energy.gov/RE/bio_resources.html
http://www.fao.org/sd/egdirect/egre0028.htm
http://www.eere.energy.gov/biopower/basics/index.htm