## 4 Techno-Economic Assessment
* In addition to the renewable power generation for self-consumption by the olive oil mill, the gasification CHP plant produces two waste heat streams from the gas engine: jacket cooling water and exhaust gases. Since the return temperature of the cooling water from the combustion engine is close to 90 \({}^{\circ}\)C [45], it can be used to supply the hot water demanded by the virgin olive oil extraction process. The use of this residual hot water makes it possible to abandon the current practice of burning olive cake, which can later be sold at about EUR 60/t. * Biomass gasification produces biochar, a carbonaceous solid by-product that can be used as soil amendment in olive groves [20]. Biochar provides several benefits to the soil, including improving water holding capacity, preventing erosion and leaching, supporting plant growth and increasing crop yield, and constituting a long-term carbon sequestration in the soil, thereby reducing greenhouse gas emissions [20]. Biochar production affects the profitability potential of the gasification technology in the olive oil sector. The average sale price of this by-product from gasification in international markets ranges between EUR 150 and EUR 500/t [46; 47; 48]. However, as the potential use of this by-product is yet unknown to most farmers and there is still no consolidated market in Morocco, its future price was estimated at EUR 80/t. * The discount rate (interest rate) was set at 10% [22; 25]. The economic feasibility assessment of the gasification plant was performed in accordance with the standard methods for the financial appraisal of investments. These methods include the net present value (NPV), internal rate of return (IRR), simple and discounted payback period (SPB and DPB, respectively) and levelized cost of electricity (LCOE) [22; 23; 25; 45; 49; 50]. The economic feasibility assessment of the gasification plant within 20 years of the operation period is shown in Figure 12. The economic feasibility assessment considers a 30% subsidy on the initial investment from the Moroccan government. The return on investment is less than 8 years, which lies within the typical range of payback periods (5-10 years) of bioenergy projects [25; 49]. The NPV of the biomass gasification CHP plant is EUR 145,085. In other words, after the break-even period, the project can make a profit of EUR 145,085; this is equivalent to 68.5% accumulated profit based on the initial capital investment. Figure 13 examines the impact of variations in the percentage of subsidy from the Moroccan government on the initial investment, as well as the electricity price and biochar price. The LCOE was not considered in the sensitivity analyses for the prices of biochar and electricity, because it is not affected by these parameters. The electricity price is a variable of extreme importance significantly affecting the viability of the projects as it is a rather uncertain parameter due to the energy market price fluctuations and subsidies, both highly dependent upon political decisions [50]. The NPV considers all costs necessary to maintain the system fully operational. Among the parameters with the highest impact on the NPV are the discount rate and the percentage of subsidy on the initial investment. Figure 12: Results of the techno-economic assessment for the baseline scenario. Figure 13: _Cont._  
The percentage of subsidy on the initial investment is the most influential variable, since the DPB is reduced from 13.5 years with no subsidy to only 4.6 years with a 50% subsidy. The IRR is found within a range of values between 12-28%. The project can withstand an interest rate as high as 20.8% for a 30% subsidy on the initial investment. The LCOE ranges from EUR 0.32/kWh to EUR 0.17/kWh for subsidy percentages of 0% and 50%, respectively. The biochar price does not have as much impact as the percentage of subsidy on the return of investment. There are also no significant variations in the IRR. The NPV ranges from EUR 129,000 to EUR 178,000 for EUR 0/t and EUR 250/t sale prices of biochar, respectively.