The Production of Gaseous Biofuels Using Biomass Waste from Construction Sites in Recife, Brazil

Abstract

Due to climate change problems caused by greenhouse gas emissions generated by fossil fuels and from waste disposition, fuel alternatives for power generation are being extensively researched. Currently, in Brazil and in many countries, wood waste is disposed in landfills. However, due to lignin, one of the major constituents of biomass, which prevents wood waste from suffering microbial degradation, there is no significant mass degradation, even over decades, when landfilled. Hence, landfilling is not a solution to discard wood waste. Hence, one of the solutions to get rid of the great amount of wood waste is to use it as feedstock in waste-to-electricity (WTE) projects. WTE projects are in high demand in the world, as they can replace fossil fuels and they reduce two major environmental problems (greenhouse gas emissions due to the use of fossil fuels and the accumulation of waste in landfills), while generating biofuels and/or electricity. One of the residues that can be used in WTE projects is biomass residue from construction sites (CCbiowaste). CCbiowaste could be converted into gaseous biofuels through pyrolysis or gasification. These gaseous biofuels can be used in Otto engines connected to an electricity generator (gensets) to produce electricity and/or heat (cogeneration applications). Hence, the objective of this research was to characterize (physically, chemically, and energetically) civil construction biomass wastes (CCbiowaste), produced in a residential building construction site in Recife, Brazil, and to use these wastes in a bench-scale gasifier to produce gaseous biofuels at the temperatures of 700 °C, 800 °C, and 900 °C. The gaseous fuels were collected in the gasifier and analyzed in a gas chromatograph equipped with a thermal conductivity detector (TCD) to determine their composition and heating values. The lower heating value (LHV) results varied from 8.07 MJ∙m−3 to 10.74 MJ∙m−3 for 700 °C to 900 °C gasification temperature. These gaseous fuels were tested in an adapted Otto cycle engine connected to an electricity generator to prove the feasibility of this application. The highest total energy per ton of biomass was obtained for mixed wood and Pinus at 900 °C, with approximately 13 GJ∙ton−1. Hence, the use of CCbiowaste can become an option for the reuse of wasted wood instead of simply dumping in a landfill.