4. Economical analysis

bio-methanol. The CO2 obtained comes from the CO2 removal system and the flue gases of a boiler used to supply steam for the hydrolysis reactor, the HTS reactor, the CO2 reboiler and the distillation reboilers. The cooling water (CW) reported in Figure 13 is low because it just

A comparison between a WtE and a WtC process with a typical incinerator, in terms of CO2 emission and methane consumption, is necessary to understand the relevance of a waste to chemical conversion. To evaluate those parameters, the same gasified quantity has been assumed. In Table 3, CO2 emissions of each process are reported in terms of CO2 kg per kg of

A WtE process could be seen as a waste disposal method and as an energy production system; likewise, a WtC process could be seen as a waste disposal method and as a methanol production process. Therefore, in order to correctly compare them, CO2 emission of WtE has to be added with the emission of a conventional methanol process, per unit of methanol produced. For that, waste combustion emission is equal to 2.96 kg CO2/kg MeOH, considering that 2.4 kg RDF, which would be converted for 1 kg of methanol produced and that the direct emission of process is 1.23 kg CO2/kg RDF. According to the same rules, WtC emissions are equal to the sum of the direct process emission (1.7 kgCO2/kg MeOH) and the emission connected to the conventional energy production related to the same MW amount which would be produced by converting, through WtE, the RDF quantity, used for 1 kg of methanol synthesis (0.96 kg CO2/

WtE Conventional methanol production process 0.76 0.69

WtC Conventional energy production 0.96 0

Waste combustion 2.96 0.07

Waste-to-methanol process 1.7 0.17

Table 3. Value considered to compare waste to energy and waste to chemical in terms of CO2 emission [8] and CH4

kgCO<sup>2</sup> kgCH3OH

kgCH4 kgCH3OH

represents the reintroduction of water in the cooling tower system.

methanol.

158 Gasification for Low-grade Feedstock

Figure 13. Overall process analysis consumption.

consumption.

The process scheme reported in Figures 1–6 provides an idea of the units required in a wasteto-methanol process. To evaluate the techno-economical feasibility of this process and decide whether or not this technology has a chance to be applied, a deep economical evaluation is required. Economic parameters used to estimate the cost of production (COP) are summarized in Table 4.

First of all, an analysis of the equipment employed is necessary to evaluate the CAPEX of the process.

As depicted from Table 4, the most relevant cost is related to the gasification lines, including the first purification treatment unit. Moreover, an Air Separation Unit is required when a gasification with pure oxygen is used. The additional costs for oxygen production appear justified on the basis that a higher syngas heating value is obtained [5] and less inert compounds circulate on the overall conditioning and synthesis unit. Once the total equipment cost is defined, an estimate of the total investment cost is predictable, as shown in Table 5. To define the CAPEX, an analysis of the total direct and indirect costs is necessary, including also the contract profit and the contingency.


Table 4. Total equipment cost.


Table 5. Estimated investment cost.

The key assumption parameters used to make this evaluation are presented in Table 6.

The main advantage of producing bio-methanol by gasifying RDF is that according to UNI EN 15359, when an RDF with an LHV value less than a classified 'Type 3' is used, the process is considered as a disposal method and the usage of RDF becomes an income and not a cost. Moreover, nowadays, CO2 with a high purity level is employed in many agro-industrial processes, so the CO2 obtained from the CO2REMOV UNIT could also be considered as an income, since it has a secondary usage. Therefore, the inert and sulfur compounds coming, respectively, from the gasification and the conditioning unit could also be used as an additional income, but they are less effective than RDF and CO2, so they were not taken into account for the scope of this economical analysis.

On this assumption, the total cost of production is equal to 186 €/t (Table 7). The selling methanol price (methanol produced in a conventional way) is 300–320 €/t, whereas the biomethanol price is estimated as 464 €/t; in this way, a margin of 278 €/t of methanol is obtained. The estimated Internal Rate of Return (IRR) is in the range of 22–23%, as shown in Table 8, which indicates a good profitability in the waste-to-methanol process. Moreover, the IRR value is strictly dependent on the price of RDF, here estimated as 85 €/t by increasing this, the IRR

Profit from methanol 35.5 Other revenues (including ones from RDF and CO2 certificate) 18.6 Total variable cost (15.14) Bank loan (considering 2/3 of the Capex as loaned) (9.11) Profit before taxes 29.84 Taxes (50%) 14.92 Net Profit 14.92 IRR% 22.4

M€

Costs M€/y Power consumption 6.0 Natural gas 1.74 Slag disposal 0.34 Maintenance 4.1 Other (including labor and chemicals) 2.96 Total costs 15.14 Depreciation rate 17.7 Total costs + Depreciation 32.84 Incomes M€/y RDF 15.5 CO2 recovered 3.1 Total Incomes 18.6 COP €/t (Total Costs � Total Incomes)/Methanol capacity 186

Analysis on High Temperature Gasification for Conversion of RDF into Bio-Methanol

http://dx.doi.org/10.5772/intechopen.74218

161

could become higher.

Table 8. Calculation of return on investment.

Table 7. Cost of production per ton of methanol produced.


Table 6. Key economic assumption and parameters.


Table 7. Cost of production per ton of methanol produced.

The key assumption parameters used to make this evaluation are presented in Table 6.

RDF price (flock type), €/t (Italian basis) 85 Electricity price, €/MWh 50 Natural gas, €/kg (considering 115,000 kcal/kg) 0.30 Slag disposal costs, €/t 10 CAPEX, M€ 202 RDF capacity, t/y 182,115 Methanol capacity, t/y 76,518 Slag capacity, t/y 33,691 Plant factor, h 7650 Depreciation factor (based on a 20-year life and 6% interest rate) 0.0875 Calculated cost of excess CO2 capture, €/t 30

Equipment costs 54 100 Bulk materials (piping, instrumentation, electrical) 38 70 Building and civil works 16 30 Total Direct Costs 108 200 Engineering and site supervision 13 25 Construction 51 90 Total Direct Costs + Indirect Costs (TOT) 172 315 Contractors profit 7% 13 25 Contingency 10% 17 32 Fixed capital investment (CAPEX) 202 372

account for the scope of this economical analysis.

Table 6. Key economic assumption and parameters.

Table 5. Estimated investment cost.

160 Gasification for Low-grade Feedstock

The main advantage of producing bio-methanol by gasifying RDF is that according to UNI EN 15359, when an RDF with an LHV value less than a classified 'Type 3' is used, the process is considered as a disposal method and the usage of RDF becomes an income and not a cost. Moreover, nowadays, CO2 with a high purity level is employed in many agro-industrial processes, so the CO2 obtained from the CO2REMOV UNIT could also be considered as an income, since it has a secondary usage. Therefore, the inert and sulfur compounds coming, respectively, from the gasification and the conditioning unit could also be used as an additional income, but they are less effective than RDF and CO2, so they were not taken into

M € % of delivered equipment cost

On this assumption, the total cost of production is equal to 186 €/t (Table 7). The selling methanol price (methanol produced in a conventional way) is 300–320 €/t, whereas the biomethanol price is estimated as 464 €/t; in this way, a margin of 278 €/t of methanol is obtained.

The estimated Internal Rate of Return (IRR) is in the range of 22–23%, as shown in Table 8, which indicates a good profitability in the waste-to-methanol process. Moreover, the IRR value is strictly dependent on the price of RDF, here estimated as 85 €/t by increasing this, the IRR could become higher.


Table 8. Calculation of return on investment.
