Herein pyrolysis, torrefaction and hydrothermal carbonization of olive tree pruning were compared from an economic perspective. For this economic comparison a hypothetical industrial plant of 1250 kg/h of capacity was selected, and the profitability analysis was performed through the discounted cash flow method. A baseline scenario was defined, which serves for basis of later comparison. Results show that under these circumstances, none of the alternatives are profitable, with net present values between -37 M€ and -45 M€. Therefore, different scenarios were studied regarding either the reduction of the associate costs or the improvement of the revenues to analyze the negative economic outputs obtained in the baseline scenario. From the revenues side, breakeven prices for the different solid products between 1.14 and 1.35 €/kg are needed to reach profitability. To reach such values, either subsidies from governments or greater selling product prices are required. When examining the associated costs share, the energy consumption is the main cost factor (representing between 70 and 90% of the total, depending on the technology). This means that a variation on the rest of the parameters will not significantly affect the overall performance. Covering the total investment needed for the plants would still present negative net present values (around -34 M€ for the three alternatives). Similarly, even if the price of electricity could be reduced to 0.02 €/kWh, none of the alternatives would reach profitability. This study reveals the importance of finding economic solutions to evolve towards circular economy societies.
Keywords: Hydrothermal carbonization; Profitability analysis; Pyrolysis; Techno-economic; Torrefaction.
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