Except it won't work. The intermittency problem of renewables doesn't make them cheaper - there is no low-cost solution to that. The intermittency makes energy more expensive. Further, their population is already shrinking. Labor costs will start to rise quite rapidly in Chain, making things more expensive.
Renewable penetration hasn't made energy cheaper anywhere where it is a significant portion of the supply grid.
Wrong. Storage has opex, because it has energy losses. Not all the energy that goes in can come out. 2nd Law and all that. On top of that, there will be maintenance and operating staff costs.
This is true of all knowledge-work. Traditional engineering is fraught with the same problem - you don't know EXACTLY how you will solve the challenges, so how can one accurately estimate them? Even worse - if you don't have a clear set of requirements, or they are expected to change as you progress (a critical feature of AGILE), then estimating with any likelihood of achieving same becomes all but impossible.
The more uncertainty in the path, the less accuracy in the estimate. Kahnemann's latest book "Noise" provides some good background on why this happens.
Having multiple people do independent estimates and averaging them probably gives better results, and having a clear process to document assumptions and test sensitivity to those estimates can also help.
But you can't get one. You can't get ANY truck from Ford right now. They have blanket changed the delivery of ALL truck orders to 31 October this year due to parts shortages.