## 6 Economic Evaluation  
Economic evaluation of the novel WTE design is required to examine the financial feasibility of integrated design. In separate and integrated designs, the costs and benefits of CFPU are considered unchanged, and the economic benefit of WTE system is investigated independently. When the WTEU employs domestic equipment, its investment cost is 52,975 $/t [40]. The proposed WTE project is considered a 25-year build-operate-transfer project, including two years for building and twenty-three years for capital recovery. The incomes of WTE plants rely on electricity sales and waste disposal. The Chinese government usually determines the on-grid tariff and waste disposal subsidy [41]. The essential data of economic analysis is provided in Table 16.  
In the proposed WTE design, several components are changed in comparison with the initial WTEU. The cost of altered equipment is assessed by the scale-up method and estimation function. The expenses of equipment (such as turbine, pump and EG) are determined by estimation functions. The charges of devices (including PAH, SAH and SH) are calculated by the scale-up method, as depicted in Equation (11) [31]. The primary data of estimation function and scale-up method are described in Tables 17 and 18.  
\[C_{\text{ch}}=C_{\text{ref}}\times\big{(}\frac{S_{\text{ch}}}{S_{\text{ref}}} \big{)}^{f} \tag{11}\]  
where \(C_{\text{ch}}\) and \(S_{\text{ch}}\) denote the capital costs ($) and scale parameters of changed equipment in the present scale; \(C_{\text{ref}}\) and \(S_{\text{ref}}\) are the reference capital cost ($) and reference scale parameters of transformed equipment in the basic scale; \(f\) is the scale factor.  
Figure 6: Exergy loss variation of several main components after system integration.  
The total cost of new WTE system is affected by the changed equipment. The expenses of changed components are displayed in Table 19. Some equipment (ST, EG, CON, etc.) of the hybrid WTE system are removed, saving about $6.07 million. Several devices (ECO, SAH, PAH and SH) are transformed in the integrated design, resulting in an increased cost of $0.72 million. Furthermore, an extra cost of $0.07 million is produced because of the employment of several components such as EP and AE. Consequently, the total cost of proposed WTE system is decreased by around $5.15 million after the system combination. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Unit** & **Value** & **Source** \\ \hline Total investment of proposed WTEU & M\$ & 26.49 & [40] \\ \hline Yearly operation and maintenance cost of WTEU & M\$ & 10\% of total investment cost & [31] \\ \hline Yearly operating time of WTEU & h & 7000 \\ \hline Project period & Building period & year & 2 \\ \hline Payback period & year & 23 \\ \hline Discount rate & - & 8\% & [42] \\ \hline Waste disposal subsidy & \$/t & 13.04 & [40] \\ \hline On-grid power tariff & \$/MWh & 99.97 & [43] \\ \hline \multirow{3}{*}{Income tax rate} & 1 st to 3 rd year & 0 \\ \cline{2-2}  & 4 th to 6 th year & \% & 12.5 \\ \cline{1-1} \cline{2-2}  & 7 th to 25 th year & \% & 25.0 \\ \hline \end{tabular}
\end{table} 
Table 16: Essential parameters of the economic analysis. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Component** & **Function** & **Source** \\ \hline Turbine & \(IC_{\text{T}}=6000\times(W_{T})^{0.71}\) & [44] \\ EG & \(IC_{\text{EG}}=60\times(P_{EG})^{0.95}\) & [45] \\ CP, EP, FWP and CWP & \(IC_{\text{P}}=3540\times(W_{\text{P}})^{0.71}\) & [44] \\ RH2 & \(\log_{10}(IC_{\text{HX}})=4.8306-0.8509\times\log_{10}(A)+0.3187\times\left[ \log_{10}(A)\right]^{2}\) & [46] \\ DEA & \(IC_{\text{DEA}}=6014\times(m_{\text{fw}})^{0.7}\) & [45] \\ AE & \(IC_{AE}=130\times(\frac{A_{AE}}{0.993})^{0.78}\) & [44] \\ \hline \hline \end{tabular}
\end{table} 
Table 17: Estimation function for the cost of partial components.