Jeff,
This is really a grid reliability program directed by the CA ISO under stage 
3 emengency, it is therefore not dependent on whether the customer is 
receiving "energy" product from PG&E the utility or other ESPs since everyone 
is a user of the grid for transmission services.  My understanding is that 
the only way to avoid curtailments is to get certified by CPUC as "essential" 
end-user.  I think recently the BART train system successfully lobbied the 
CPUC to certify it as essential.  Of course it will be a tough sell to do the 
same for a private enterprise.  Realistically the only way to cover such 
non-econcomic driven interruption is to put in on site back up generation.  

Ress