Gunboat: sleze: So they tried this with coal and were sued and the Supreme Court ruled against Minnesota.  This sounds like basically the same thing and with Dude Brow and the Handmaid on the Supreme Court, I would expect a similar outcome.

That being said, I don't really understand the rationale that prevents states from passing laws concerning their own powergrid.  Can some smarter Farker explain?

I don't know if I'm smart, but IAAL.

The U.S. Constitution gives Congress the right to regulate interstate commerce. This is known as the commerce clause.
Over the years, courts created a doctrine called the "dormant commerce clause," reasoning that if Congress can regulate commerce between the states, then the states cannot do so.

Sometimes the dormant commerce clause leads to good results. For example, a state passes a law that says only X made here in this state can be sold by grocery stores in this state. Or, only wines made here in Tennessee can be sold in Tennessee.  You get the idea. Courts strike those laws down as violating the dormant commerce clause.

There are some exceptions: bona fide health and safety. Or residency breaks on state government funded things like public university.

Here, ND will argue that by singling out coal, MN it is effectively regulating commerce by targeting ND's primary export and, in essence, saying what other states can make.  It's not a frivolous legal argument.  ND is guilty of bad policy, but its legal argument is sound. Sadly.