How to rebuild the grid in Puerto Rico

Hurricane Maria has caused huge damage in Puerto Rico, particularly to infrastructure such as the electricity system. My sincerest sympathies go to everyone there, both in PR and in other regions. As my previous work on electricity network interdiction suggests, repair of electricity networks can depend significantly on the long lead-times to order and build extra-high voltage and high voltage transformers. As Puerto Ricans begin to restore services such as electricity, an issue that should be considered carefully is the desired end-point for their replacement electricity infrastructure and whether they should effectively rebuild their previous network or build according to a new design.

Most expansion of transmission networks, and most repair situations, involves adding or replacing equipment in an existing network. This significantly constrains the sort of solutions that can be accomplished.

However, PR is faced with a rather different problem. Although I am not personally familiar with the full extent of damage, the reports in the press suggest significant destruction of most of the network. Repair back to the state prior to the hurricane may involve rebuilding essentially everything. Under such circumstances, and given that future hurricanes may be at least as destructive to a conventional electricity system, it is prudent to step back and consider alternatives.

As an example of an alternative, perhaps a more distributed structure that plans for distributed renewables would be a better approach. Existing electric distribution networks are typically limited in the amount of distributed generation they can integrate. In the mainland US at least, the limits are typically not due to the distribution line capacity itself, but to things like “protection schemes,” typically using fuses, that were designed with the assumption of one-way flow toward consumers. In an existing system, upgrading to allow for net flow from the distribution system into the transmission system can require significant incremental investment to replace protection systems. For a system being fully built from scratch, however, it may be possible to incorporate more flexible protection systems from the start.

This and other issues should be considered carefully before large amounts of money are spent in PR on rebuilding a system according to a design that has already been shown to be vulnerable to the next hurricane.