Ministry of Agriculture, Livestock and Food Supply - Embrapa

production is concentrated in the State of Rio Grande do Sul. Santa Catarina, the
second largest rice producer in the country, is the largest parboiled rice producer.
According to the IBGE (2003), Rio Grande do Sul and Santa Catarina produce
700,000 tons/year of unhulled rice.
The moisture content of the paddy leaving the field varies from 25% to 30%
depending on the farming conditions and time of year. The moisture content must
be reduced to 12-15% before milling and to no more than 13% for storage. The
combustion gases from burning the hulls are used as heat source for drying the
grains. Mills that produce only white rice do not require steam. The higher caloric
power of dry-base rice hulls is 15.84 GJ/t. The lower caloric power of rice with
11% moisture is 12.96 GJ/t, much higher than sugarcane bagasse.
The following parboiled rice milling operations require steam: (i) soaking;
(ii) autoclaving; (iii) parboiling, and (iv) drying, in some industries.
Rice mills receive the harvested rice, which is taken to the mill as paddy.
Approximately 15% of the hulls produced per year are burned to dry the rice;
this operation usually takes place as the harvest proceeds (January through
April) and consumes 60% of the hulls collected. It is estimated that only 50%
of the total hull volume is used to produce electric power, since in addition to
the 15% used in the drying operation, approximately 35% are produced in
small, dispersed mills. The energy density of hulls is very low, so that
transportation is only economically feasible with return freight.
Carbon credit market and agroenergy
Background
Atmospheric CO 2 concentrations have increased by 31% in the last
250 years (Figure 14), and have probably reached an all-time high. CO 2
concentrations tend to increase significantly if greenhouse gas (GG) emissions
are not kept under control. Fossil fuel burning and cement production account
for almost 75% of GG emissions. Changes in land use that demand
deforestation have also contributed significantly: 25%.
Global warming from anthropic sources – resulting from greenhouse
gas emissions (GGE) – has been a source of concern to modern societies.
These emissions occur associated with the growing demands for energy
(from non-renewable sources mostly) resulting from population growth.
Climate changes can have negative consequences for future generations.
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