ing countries grow and process sugarcane, generating substantial
quantities of by-product biomass fiber (bagasse) that is used today
at most mills as a fuel for combined heat and power (CHP) generation.
CHP systems typically generate just enough electricity (a
few megawatts at an average-sized facility) and process steam
to run the mill. Because such an abundance of bagasse is generated,
however, the CHP systems are designed to be inefficient in
order to consume all of the bagasse and thereby avoid disposal
problems. With more efficient CHP systems, sugar factories can
generate substantial amounts of electricity in excess of their own
needs. Fig. 1 shows the excess electricity generation possible per
ton of cane processed with condensing-extraction steam turbines
(CEST), a commercially established technology increasingly being
considered for sugar mill application and with biomass-gasifier/gas
turbine combined cycles demonstration today offers some perspective
on the potential contribution of “cane power” to overall
electricity supply in the future. For developing countries as whole,
“excess” electricity (i.e., above and beyond that needed to run
the sugar or ethanol factory) from cane residues could amount to
15–20% of the projected electricity generation from all sources in
these countries in 2025 [13,53]. Fig. 1 shows electricity generated
in excess of on-site needs per ton of sugarcane crushed at a sugar
or ethanol factory using different cogeneration technologies. CEST
is a condensing extraction steam turbine (steam pressure of about
60 bar). BIG/GTCC is a biomass-gasifier/gas turbine combined cycle.
A typical milling season lasts about 6 months, during which time
bagasse is available as a fuel. Sugarcane trash (tops and leaves),
if collected, would enable electricity to be generated year-round,
thereby enabling much greater quantities of electricity to be generated.