* Last I heard Caltrain wants to use EMUs if/when they electrify. 
  That makes for much better and more consistent hp/ton than with 
  locomotives, and better accel/decel which helps with schedule-keeping 
  and shorter run times.
* Recent tech- and economics-news stories suggest that California 
  actually has too much base-load generating capacity right now. 
  Several new gas-fired power plants are sitting idle or nearly so 
  (only partial output and only at peak times) because the demand 
  doesn't exist, especially with the growing amount of solar and wind 
  capacity in the system. And the PUC continues to approve construction 
  of more of them. Duke and others are also looking at shutting down 
  their older base-load plants for similar reasons - they aren't used 
  enough to make them cost-effective in their present form.
* As for demand, the state's energy standards for appliances, equipment, 
  and buildings have been very effective at reducing it. Which is possibly 
  one reason for the softness in base-load demand.
* Batteries and other power storage systems are mandated by the state 
  PUC for private utilities, and most public ones are also installing them. 
  They are very useful at soaking up excess solar and wind generation then 
  spitting it back out at peak times, even if their total capacity is still 
  relatively small as a percentage of total system capacity so far. 
  Note: California has almost 5GW of pumped-hydro storage already, and has 
  been using it for years - nothing new in principle, except that the battery 
  systems being smaller and more portable can be installed closer to the 
  load and react more quickly.
* Regenerative braking for electric trains is nothing really new. And it 
  has the disadvantage that there has to be a load to soak up the 
  generation or it doesn't work. In simple setups, that means there has 
  to be a train using power in the same electrical block as one generating 
  it. There are ways to get around that, but they're expensive. So 
  electrics usually have to carry traditional dynamic braking grids as 
  well for times when the regeneration has no target. Some transit lines 
  have tried installing battery, flywheel, and/or ultracap units at 
  substations where large amounts of regen and power demand exist, but 
  aren't balanced - those store regenerated power short-term, supplying 
  it later to trains going up the hill and reducing peak demand on the 
  power system. It works, but so far it isn't cheap enough to use 
  everywhere.
* HSR is just a big, fast, high-peak-power-demand electric railroad. 
  Everything that is done for a standard electric line is also done 
  there, just on steroids.
* Do you care where the power comes from when you turn on your lights 
  or charge your Tesla? No. You just demand that it works. The power 
  companies/agencies figure out how to meet that demand; that's their 
  job. You might have to pay more for usage at peak demand times - 
  there's nothing new about that, either, for industrial and 
  commercial accounts. Trains add more load, but as noted in the 
  first point California currently has (and likely can continue to 
  have) a surplus of power overall. Yes, there are places that might 
  have local issues, like parts of SoCal due to lack of gas storage 
  (with Aliso Cyn empty) for peak-load generators. That's a short-term 
  issue, not a long-term problem, and will be fixed long before the 
  first HSR train even starts test runs in the Valley.