Techno-economic evaluation of two alternative processes for production of green diesel from karanja oil: A pinch analysis approach

Abstract

Hydrodeoxygenation (HDO) of vegetable oil is a potential technology for the production of green diesel for direct application in unmodified combustion engines. This study provides the conceptual process design for HDO of karanja oils by two different routes: (i) direct HDO of vegetable oils (direct HDO) and (ii) HDO of fatty acids derived from hydrolysis of vegetable oils (two-step HDO). Pinch analysis was carried out to obtain energy targets and the maximum level of heat recovery and to design the heat exchange network. An economic analysis was then performed using USD 0.5 per kg as the retail price of karanja oil. The production costs of green diesel were estimated as USD 0.84 per kg and USD 0.798 per kg for direct and two-step HDO, respectively, for an optimum plant capacity of 0.12 × 106 metric ton per annum of karanja oil. The analysis was further extended to understand various cost-contributing factors and the effect of feedstock and the price of co-products on the manufacturing costs of green diesel. A discounted cash flow analysis was carried out to determine the minimum selling price of green diesel.