Two Nerd Ideas from the Nerd Conference

As I mentioned previously, I spend the first half of last week in Detroit at a conference for those of us in the power and energy part of electrical engineering. There were many interesting topics discussed, two of which I thought might be interesting to the general public.

The first is not something that is actually a new idea but rather one expressed in a new-ish way. About a year ago it first came to my attention that people outside the electrical power industry probably don't realize that there is virtually no energy storage in our power system. (There are a few exceptions but not enough to matter much.) No energy storage means that whenever you turn on a light in your house, some generator somewhere has to produce a tiny bit more power immediately. There is no way to produce a bunch of energy ahead of time and serve it up as needed later. My professor said it this way: "The electrical energy industry is the only manufacturer whose goods are consumed the instant they are produced."

Using this manufacturing analogy, you can think of any time a light is turned on or an air-conditioner starts up as an "order" being placed to the electrical company for some energy. Unlike every other manufacturer, though, the delivery of the good must be made immediately. None of us would accept a situation where a light switch is flipped and the light turns on minutes, hours, or days later. When we want energy we want it now. Thankfully, physics also makes the same requirement and the energy will either flow immediately or not at all. We'll never get an email from the power company confirming our energy order to run our air conditioner with an estimated delivery date of next week (or the ability to pay extra for two-day shipping).

It is actually possible for the electrical energy companies to fail to provide the right amount of energy in two ways: undersupply and oversupply. Undersupply is something we've all experienced in some way as brownouts and/or blackouts. Actually, a true blackout due to a lack of energy being produced is fairly rare; most of the time when our houses loose power its due to other event like damage to equipment due to a storm. This past winter, though, Texas had some customers in blackout due to a combination of unexpected down-time on some of its generators and unusually cold weather causing customers to turn up their electric heaters.

On the other end of the spectrum are oversupply situations which may not seem as bad. What does it matter if the generators produce more power than we use? The answer to this is a tiny bit technical and it relates to the frequency of the system operation. Without worrying about the details, I'll simply say that all the generators are designed to run at 60 Hz and everything we plug into an outlet expects power at 60 Hz and if more energy is generated than used, the frequency begins to drift up and bad things begin to happen. 60 Hz is the standard and deviation from that standard isn't good for anybody.

All of this I've laid out so far can be summarized in one sentence: at all times, electrical energy supply (from generators) must match electrical energy demand (by consumers). This is the definition of stable system operation. Balancing supply and demand turns out to be very complicated for many reasons, not the least of which is that demand by consumers varies throughout the day and year and that demand can change suddenly. There is much effort being made to predict the amount of electrical energy that will be needed but theses efforts will always be imperfect. (Here's a graph for the California system showing the predicted and actual demand for the day showing this imperfection.) The result of this is that electrical system operators need to always have generators standing by to pick up any extra demand that may suddenly appear. These generators have to be able to respond instantaneously (not in a minutes, or fifteen seconds, or even five seconds) to changes in demand which means they have to be fully up and running responding quickly as the demand on the system changes. What's more, there have to be still other power plants that are not fully online but able to ramp up their output quickly if even larger changes in demand begin to form.

All of this say one simple thing: there are many many more generators in our electrical system than are needed for most days of the year. Many of these generators are not regularly used or do not produce their full output power most of the time. In fact, some of them may only be used during the peak demand for the year, during the hottest days of the summer. Going back to our factory analogy, this is the equivalent of building a factory so that it is able to produce enough goods during the peak Christmas season even though the rest of the year much of the factory will be idle. It all comes back to the fact that there is no energy storage in our system. There is no ability to produce a bunch of energy and put it in a warehouse to be shipped out when needed.

This leads to the second idea I heard at the conference: electric vehicles and their batteries. As these vehicles become more popular and affordable, we are going to start seeing the introduction of non-trivial energy storage introduced to our electrical energy system via the large battery packs in these cars. There is a lot of talk concerning the use of the battery packs in the cars to provide backup power for your house or even electric utility companies paying the car-owners to use that energy for whatever needs the grid may have at a given point in time. There are many interesting ideas floating around out there and all of them will help the system run more efficiently but there are still a lot of details to be worked out; I'm not going to discuss any of them.

I'm going to talk about what we do with the batteries once they have reached the end of life for use in cars. Again, due to physics (and in this case chemistry) batteries that are useless for electric vehicles are far from dead. The figure I heard thrown around was 80%; battery packs in electric vehicles will be removed once, when full charged, they only have 80% of their original design capacity. This means these batteries still have a lot of life left in them, just not for transportation purposes. Many smart people are considering a second-life use for these batteries as distributed energy storage in neighborhoods going by the name "community energy storage" (CES). If these batteries can be repackaged and assembled economically into large battery banks, they could be put out in neighborhoods and act as energy storage distributed all over the grid. From the utility's perspective there are many things that could be done with these battery packs, most of which we as normal people don't care that much about. What we do care about is not losing power and these battery packs could solve that problem; we would have neighborhood-wide battery-backup with the potential to have virtually uninterrupted power.

The other implication of this second life for car batteries is that it may help lower the cost of electric vehicles. If there is a well-established market for "used" electric vehicle batteries, when the time comes to replace those batteries, the car owner may get 80% of the value of a new battery pack by selling the old one. Using made up numbers, if a battery pack costs $10,000 when new but can be resold when its "dead" for $8,000, the net cost to the care owner is only $2,000 for the battery pack in his or her electric car. Batteries in electric cars are a significant cost-driver and having a way to recoup those costs could make electric vehicles more affordable.