Establishing a techno-economic base case for a second generation bio-refinery : a South African perspective

Abstract

A baseline techno-economic assessment for converting organic municipal waste via a novel continuous hydrothermal liquefaction (cHTL) pilot plant is presented. Feed streams, product yields, and product quality were based on real-time data. Pilot plant data was used to estimate the capital investment and operating costs, cashflow and economic indicators for a commercialscale cHTL plant. Results showed that a return on investment of 31 %, an internal rate of return of 31 %, and a profitability index of 5.5–6.0 could be realized with a satisfactory nett cashflow over an estimated plant life of 20 years. Sensitivity analyses showed that both plant capacity and capital investment had a significant effect on product unit cost. The potential of using cHTL technology to sterilize and co-treat primary sewage with municipal waste was demonstrated for underpinning a circular economy where waste would be re-directed towards new energy products, while offsetting localized municipal operating costs.