# Techno-Economic Analysis of Waste Heat Recovery in Automotive Manufacturing Plants
## 4 Results and Discussion
### Economic Analysis of Different Scenarios  
The economic viability of the proposed system, as illustrated in Figure 1, was carefully assessed. To provide a comprehensive evaluation, this study introduces three additional scenarios, each aimed at further analysing the economic potential of the project. These scenarios examine the economic impact of integrating or excluding a PV system and a recuperation process within the ORC system. The scenarios are described as follows. * Case 1 baseline scenario evaluates the project by considering both the PV system and the recuperation process within the ORC, as illustrated in Figure 1.
* Case 2 analyses the economic performance of the project with the recuperation process in the ORC, but without including the PV system. In this scenario, the ORC-heat pump-TES system, functioning as a Carnot battery, can continue to operate even without the PV system. The electricity needed to power both the heat pump and the ORC pump is obtained from the grid. * Case 3 examines the project setup where only the PV system is included, omitting the recuperation process in the ORC. * Case 4 assesses the project without incorporating either the PV system or the recuperation process in the ORC. Figure 6 shows the breakdown of investment costs for each project scenario, categorised into four main components: the ORC system, heat pump, TES, and PV system. For clarity in this study, the investment costs associated with the ORC, heat pump, and TES are collectively considered as the investment cost of the Carnot battery. This grouping highlights the cost associated with the energy storage and conversion components, distinguishing them from the PV system, which serves as an optional energy source. This cost distribution provides insight into how each component contributes to the overall investment, offering a clear basis for economic comparison across different configurations. The following cases highlight how various configurations impact the total investment costs. The total investment cost of Case 1 is approximately 2.56 million EUR. Here, the PV system accounts for 61.3% of the cost (~1.57 million EUR), while the Carnot battery contributes 38.7%, divided into 33.9% (~0.99 million EUR) for the ORC, 4% for the TES, and 0.8% for the heat pump. Moreover, without the PV system, but including a recuperation process in the ORC system, described as Case 2, the total investment cost is reduced to approximately one million EUR, representing only the Carnot battery costs. This distribution is 87% for the ORC, 10.3% for the TES, and 2.1% for the heat pump. In addition,Case 3, which includes the PV system, but excludes a recuperator in the ORC system, offers about 2.49 million EUR, with the PV system contributing 64.3% (~1.57 million EUR) and the Carnot battery covering 35.7% (30.6% ORC, 4.2% TES, and 0.9% heat pump). Excluding a recuperator necessitates a larger liquid heater area, increasing its investment cost. In this study, Case 4 offers the lowest total investment cost, approximately 0.87 million EUR, achieved in this configuration, which excludes both the PV system and the recuperator. This cost was allocated to the Carnot battery, with a breakdown of 85.9% for the ORC (around 0.75 million EUR), 11.7% for the TES (approximately 0.10 million EUR), and 2.4% for the heat pump (around 21.24 thousand EUR). From the investment mentioned above, the discounted cash flow can be estimated and evaluated using a specific discount of 6%. This discounted rate value presents the case in Indonesia and reflects the value of the money and the associated risks of the investment. By discounting the future cash flow to their present value, the NPV can then be determined. This discounted cash flow can be seen in Figure 7. It is important to note that the cumulative discounted cash flow is presented, so the NPV and PBP can be evaluated. The discounted cash flow for each case varies depending on electricity production and investment.