Environmentally-Benign Conversion of Biomass Residues to Electricity

As petroleum resources are finite, it is imperative to use them wisely in energy conversion applications and look for alternative options as an energy source. Biomass is one of the renewable energy sources that can be used to partially replace fossil fuels. Biomass-based fuels can be produced domestically and may thus reduce dependency on fuel imports. Due to their abundant supply, and given that to an appreciable extent they are considered to be carbon-neutral, their use for power generation is of technological interest. However, whereas biomasses can be directly burned in furnaces, such a conventional direct combustion technique is ill-controlled and typically produces considerable amounts of health-hazardous airborne compounds [1,2]. Thus, an alternative technology is described herein to further address our increasing energy needs and, at the same time, utilize our biomass streams in an environmentally-benign manner. More specifically, a multi-step process/device is outlined to accept biomass, of various types and shapes, and generate an easily-identifiable form of energy as a final product. To achieve low emissions of products of incomplete combustion, the biomass is gasified pyrolyticaly, mixed with air, ignited and, finally, burned in nominally premixed low-emission flames. Combustion is thus indirect, since the biomass is not directly burned, instead its gaseous pyrolyzates are burned upon mixing with air. Thereby, combustion is well-controlled and can be complete. A demonstration device has been constructed to convert the internal energy of plastics into clean thermal energy and, eventually to electricity.