I was surprised to see some resistance to the cost causation. I think it might be helpful for our financial discussions to become more aware of the state of the art in this topic. Here is a section of administrative law drawn from energy utility regulation Section 791.30 Cost Causation Principle http://www.ilga.gov/commission/jcar/admincode/083/083007910000300R.html Here is a more detailed slide presentation about how the cost causation principle is recognized in case law and how the principle is applied to effect cost allocation - again, in an energy regulation context https://pjm.com/-/media/committees-groups/task-forces/emustf/20141113/201411... Here is a complete article from economists on "Cost-Causation and Integration Cost Analysis for Variable Generation" https://www.nrel.gov/docs/fy11osti/51860.pdf Dr. Milton L Mueller Georgia Institute of Technology School of Public Policy [IGP_logo_gold block]