Power Generation from Rice Husk

Abstract

The alarming rate at which the deposit of non-renewable or fossil energy resources are depleting around the whole world has been nudging us in the direction of green energy for quite a long time. Considering the upcoming energy crisis in the near future, we have no choice but to divert our focus on renewable energy resources to meet the power demand of an ever-growing global population and industry. Rice husk is a by-product of producing rice from paddy which is consisted of about 20% mass percentage of rice. It is a biomass with low energy density and low bulk density. Due to these properties, it is not efficient or viable to directly combust rice husk as a fuel. In order to improve the fuel characteristics of rice husk and convert it into a coal-like fuel, different thermochemical pretreatment technologies can be implemented. Previously, there have been many studies and researches on pretreatments of rice husk. Most of these studies were experimental. This paper reviews four of the most common of such technologies namely, gasification, torrefaction, pyrolysis and hydrothermal carbonization including multiple sub-categories of each technology. All of these processes are successful in improving the fuel characteristics of rice husk such as higher heating value or calorific value, moisture content, fixed carbon, etc. The second section of the thesis covers the field of power generation using the pretreated rice husk samples as fuels. For the simulation, Recompressed Supercritical CO2 Brayton Cycle with Reheating was chosen. A basic comparison among different pretreatments was shown in terms of power output from the cycle when rice husk undergone corresponding pretreatments was used as fuel for the heat input. The economic and exergy analysis of the thermochemical processes were out of the scope of this thesis thus, this study only focuses on the energy analysis of producing power from rice husk. The results found out of the study shows that each of the thermochemical processes has its own advantages and serves the goal, which is to improve the fuel properties of rice husk. Further investigation on other aspects can help the community understand which process will be better suited for a particular purpose.