Thursday, July 5, 2018

The Not-Stressed Grid in Summer

The grid is not stressed

The Northeast is using a lot of power, but the grid is not particularly stressed.  "Using a lot of power" and "stressed grid" are not the same thing.  Many local utilities are urging conservation...but this is not because the grid is stressed.  More about conservation in the next post.

How can I say the grid is not stressed? We're having a major heat wave! For days, Vermont temperatures have been in the high nineties. A number of communities opened "Cooling Stations" in public building such as fire departments. People were encouraged to go to air-conditioned malls, drink water, check in on elderly people who may need assistance, etc.

Okay, it's hot.  But I will start by comparing the grid situation on this heat wave with the grid  situation in the cold snap in December-January.

Hot weather electricity use and prices

Let's look at the ISO-NE electricity usage  chart for July 3.  The peak is near 25,000 MW. The LMP (local marginal price) prices for electricity were between about $25 and $80 per MWh, or about 3 cents to 8 cents per kWh.

Cold weather electricity use and prices

In contrast, during the cold snap at the beginning of this year, electricity use never got much higher than 22,000 MW, as shown in this graph from the ISO report on cold weather operations.

However, in  the cold snap, the LMP prices spent a lot of time between $150 and $300 per MWh (15 cents to 30 cents per kWh). The circled area on the graph below, from the same ISO report.

In short, during the cold snap we used less electricity and paid higher prices than we do now.

Conservation and fuel usage

Using more electricity in New England means making more carbon dioxide and burning more fossil fuels.  So conservation is always good. But is conservation in summer particularly wonderful? Not really.

Right now, we have a fairly clean grid. The fuel mix is mostly natural gas, nuclear,  hydro and renewables.  The grid was running 60% gas, 20% nuclear 16% hydro and renewables.  Pretty good, in terms of emissions!  Here's a recent fuel mix graph.

A fuel mix chart for the grid on July 4

In contrast, in the winter, when natural gas was not available, oil and coal were in heavy use (Oil Kept the Power Grid Running op-ed). During the cold snap, the mix was 30% oil, not "less than 1%" oil, as it is now.  Coal use was higher, also, up around 5%. 

Surplus Capacity

So far, there's no particular reason to conserve right now instead of conserving some other time.  But let's look at something else.  Perhaps, even with natural gas available, the grid is close to maximum capacity in hot weather? Perhaps, if we don't conserve, the grid will fail?

Nope. The grid is doing well.  If you look at the ISO-NE website,  it lists "surplus capacity" right on the front page.  At this moment, as I am writing this, on a very hot day, surplus capacity on the grid is 1,180 MW.  That is the capacity available above the maximum predicted peak power use for today (23, 000MW) and above the grid's operating reserve requirement for today (2,492 MW). You can always check these types of figures in the ISO-NE morning report

Or, you can simply remember that when ISO-NE predicted the possibility of rolling blackouts in the future, ISO was concerned with winter stress on the grid leading to blackouts. They were not concerned with high summer electricity usage. 

 In short, conserving electricity this summer doesn't save more money or more carbon dioxide then it would save at many other times. As a matter of fact, it saves less of both than it would save in a winter cold snap.  Conserving now also doesn't "save the grid" from blackouts.  The grid is operating at high capacity, but nowhere near its capacity limits.

 So why are the utilities pushing conservation right now?

Game of Peaks

The utilities are urging conservation right now because they are playing the Game of Peaks.  It's  a utility game about money. If they play the Game of Peaks well, they can shift some costs from themselves over to neighboring utilities.  Yeah, it's a zero-sum game.  ("I win" can only happen if "you lose.")

 Learn the rules for the Game of Peaks in the next post.

No comments: