Dear Charlie and Jason,

Another issue that arises when modeling net zero scenarios for the power sector in various ASEAN countries up to 2070 is that the built capacity exceeds the specified maximum capacity at some point in time. However, the boundary conditions aren't completely ignored. Rather, the optimizer runs up to the maximum capacity, stays there for some time, and then suddenly builds capacity on top of it. We model different potential steps for solar PV and wind with different availability curves and maximum capacity values for each step. In the following example, the capacity for Solar PV #1 (best locations with highest availability) reaches the specified maximum in 2054, but continues to build capacity until 2070. The same is true for Solar PV #2. For solar PV #3 and #4 and onshore wind #2, the maximum capacity is exactly reached without exceeding it. On top of this, "expensive technologies" such as various storage technologies and simple cycle H2 turbines (fueled by imported H2) are built in order to meet both the electricity demand and the overall emission limit specified in the model's "Effects" folder.

For other countries, it is even the case that certain technologies exceed the maximum capacity, although other (more expensive) would still be available. Do you have an explanation for this behavior? Have you ever seen it in other NEMO models?

Thanks in advance! Best,

Viktor

P.S. I used NEMO v1.90 with the HIGHS solver. The issue appeared for multiple different country models and scenarios both with LEAP 2020.1.081 and LEAP 2020.1.091