Energy consumption minimization always implies OpEx reduction but may come at an extra CapEx. This is true for any communication system. However perhaps I misunderstood your question so please feel free to contact me directly to discuss the relevant issues.

Agree with Ioannis. In addition to that, in MLR when you use different line rates, if you design a optimization algorithm, which reduces the number of Line Modules in the Line systems, you will have CapEx reduction. This is related with the efficient bandwidth utilization by service grooming to reduce the number of line module cost. This works in all the cases when a cheap deployment requirement comes.

Thanks for the answers. Further, according to my study on till now, the following appears:

The energy-consumption models for different architectures (transparent / translucent) may also work as the models for CapEx-minimized networks. However, the designed optimization costs would have to be changes accordingly from energy consumption to CapEx values for different components. I think intuitively that must be the case as more energy consuming components would also be more expensive. I agree, energy minimized may not always be CapEx minimized, but will be OpEx minimized.