Aspects for a cleaner production approach for coal and biomass use as a decentralized energy source in southern Brazil

Biomass and coal are two vastly available energy sources that have been under-utilized for thermoelectric generation within the available energy matrix in Brazil, considering that the southern region has an excellent potential for the use of biomass as a decentralized energy source and the Brazilian coal reserves are totally distributed in this region. So, this paper makes an analysis concerning the use of the southern Brazilian coal together with the biomass available in the same region through a cleaner production approach in order to decrease the generation of solid wastes – ashes – and produce atmospheric emissions on a more environmental friendly way through a decentralized energy generation system. A review on the possibility of using the coal ash – from its cofiring with wood wastes and the use of limestone for desulfurization – as a low-cost material for the production of sand lime bricks is evaluated. Then, results obtained from tests that technologically evaluated the use of those fuels on a bubbling fluidized bed are presented. Finally, the economical possibility of developing an integrated system for energy production, carbon crediting and production of building materials using the cofiring of biomass and coal with limestone addition in Small Thermal Power Plants is assessed. The results showed a good possibility for the increment of biomass use in the southern Brazilian region and the data obtained from combustion tests are already sufficient to support the launch of definitive projects to provide steam generation from renewable sources on a decentralized way. The revision reveals that the Brazilian ash composition is prone to react with the high CaO content in wood ashes and the limestone addition can be adjusted for the production of a suitable composition for the direct use on sand lime brick production. This integrated system proposed has the possibility of having annual revenue about US$ 1,105,000.00.

► The potential for the use of biomass and coal in southern Brazil has been studied.
► The possibility of producing a byproduct from the ashes was assessed.
► Fluidized bed tests proved the technical availability of cofiring those fuels.
► The use of biomass as a decentralized energy source showed a high potential.
► The economical evaluation confirmed the possibility of implementing the system.