Assessment of Second Generation Bioethanol Production Technologies with Integration to Combined Heat and Power (CHP) Plant

Abstract

The imamate threat of energy security and concern about greenhouse gas reduction have revived widespread interest in production and use of second generation bioethanol as a transportation fuel from renewable lignocellulosic material. The so called "cellulosic ethanol" can be produced via different routes. One of the most interesting ways to produce ethanol from lignocellulosic material is to integrate the cellulosic ethanol plant with coal-fire CHP plant. This research investigate the global development of commercialization of second generation ethanol technologies and combine the energy efficient combined heat and power production to form a polygeneration model in order to evaluate the most promising ethanol technologies. Six different biochemical ethanol processes mass and energy balance were performed in excel sheet based on publically available experimental data and offline existing steady state stand-alone CHP plant is validated without additional heat load in Solvo^TM to analyse the technical feasibility. The main difference between the Ethanol process lies in between the pre-treatment (dilute acid, acid catalysed steam explosion and LHW) and hydrolysis (acid and enzymatic) step.

The steady state simulation model were then developed to form the integration model by burning the by-product from ethanol process in CHP plant and the live steam required for ethanol process was supplied by CHP plant. Several simulations were performed varying the total heat demand for the ethanol process. The integrated models were analysed in terms of ethanol yield, performance of CHP plant and overall efficiency. Result shows that, even without additional heat load the CHP plant still can run with high efficiency when integrated with reference commercial cellulosic ethanol plant (103.5 t/h biomass flow). The finding shows that compared to different process variations, steam explosion followed by enzymatic hydrolysis shows the most promising result in terms of fossil fuel reduction when integrated to CHP plant. The key finding provides that there is significant impact on ethanol yield in production of heat and power. Furthermore electricity production can be increased when CHP production used the same amount of fossil fuel as in stand-alone case and integrated with cellulosic ethanol plant. The integration also shows that the amount of fossil fuel can be reduced by 60 to 96.6% depending on the applied ethanol process.