The 70% Report does not provide the base assumptions for CO₂ allowances and future fuel prices. In addition, while the focus of proposed legislation has been on a cap-and-trade system, there has been discussion of a different structure such as a carbon tax. A carbon tax could have significantly different implications for power plants using conventional fossil-fuel-fired equipment and power plants designed around renewable fuels (e.g., biomass or solar) than would a cap-and-trade system for greenhouse gas credits. Given the uncertainty in future greenhouse gas regulations and the potential variability in future fuel prices (either as a result of the inherent variability in fuel prices or as the result of a carbon tax), the committee suggests that the life-cycle costs include an analysis of sensitivity to variations in CO₂ allowances and fuel prices. Because implementation of certain options will be phased in over time, the impacts of variations in CO₂ allowances and fuel prices may differ over the life of each option.

The 70% Report discusses only one deep tunnel option for the utility distribution system. In order to provide an adequate basis for comparing options, it is suggested that a study be made of potential distribution tunnel layouts and available construction methods (e.g., microtunneling, horizontal directional drilling) to assess the best approaches for minimizing disruptions to the surface, traffic, and the community while optimizing the efficiency, phasing, and redundancy of the system, and improving the safety of the tunnel environment for workers conducting maintenance and repair activities. As noted above, such options may require renegotiating current agreements with the Office of Compliance regarding maximum distances between egress points.

The final report should provide a concise summary of the results and rationale for the selected option(s). The methodology and indices (including the acceptable level(s) for these indices) used for evaluating and selecting the appropriate option(s) should be included.