https://spectrum.ieee.org/podcast/energy/renewables/why-does-the-us-have-three-electrical-grids
What about the financial benefits of tying together these three interconnects? Are they substantial? And are they enough to pay for the work that would be needed to unify them into a supergrid?
Peter Fairley The financial benefits are substantial and they would pay for themselves. And there’s really two reasons for that. One is as old as our systems, and that is, if you interconnect your power grids, then all of the generators in the amalgamated system can, in theory, they can all serve that total load. And what that means is they’re all competing against each other. And power plants that are inefficient are more likely to be driven out of the market or to operate less frequently. And so that the whole system becomes more efficient, more cost-effective, and prices tend to go down. You see that kind of savings when you look at interconnecting the big grids in North America. Consumers benefit—not necessarily all the power generators, right? There you get more winners and losers. And so that’s the old part of transmission economics.
What’s new is the increasing reliance on renewable energy and particularly variable renewable energy supplies like wind and solar. Their production tends to be more kind of bunchy, where you have days when there’s no wind and you have days when you’ve got so much wind that the local system can barely handle it. So there are a number of reasons why renewable energy really benefits economically when it’s in a larger system. You just get better utilization of the same installations.