Let's talk a little bit about storage. We're going to talk about storage metrics; how you measure, and define, and talk about storage. It's a little confusing because storage it's not really supply, it's not really demand, it's in some fuzzy gray area in between. This is how storage has been evolving, I say. But there's two aspects of storage, like there is two aspects of power plants. There's the power side, the clean and jerk or sprint aspect; how much power can be delivered by storage? Typically, if you see measurements of storage or you're looking at a battery system for sale, it's going to be in terms of kilowatts or even megawatts, probably megawatts for a large system. If you look at cost, it'll be dollars per megawatts. That's how much it can deliver, essentially all of a sudden or all at once. You can imagine if you have, let's say, a large power plant and you want to be able to provide power even when there's something wrong with the power plant, you need a really big battery, big in the power sense. That's the power aspect of storage, same as a power plant. There's also an energy aspect of storage, how long it can provide electricity. Again, the length of time is different than power plants because power plants will generally keep going as long as there's fuel. But batteries are different. You can think of a battery or storage generally, but largely in the context of batteries now as how big it is, is how big the bucket is. The storage is a big old bucket of electrons, obviously not literally plus we want to think about it. You could design that bucket so you could turn it upside down quickly and get a whole bunch of power, in essence, for a short period of time, or so you could keep it slowly, it would not be very much all at once, but it'll last a long time. That's the only way to think about those two attributes. Now ideally you want both, but then you need an enormous bucket. I guess, you turn upside down and drain it for a long time, that's expensive. When sizing, or buying, or specifying storage systems, one thing is about both the power and their energy aspects of the battery. Now the fourth good news on battery storage is prices are coming down as there's more investment. This graph shows a standard or typical pattern for cost reduction, where for example, there are new applications for batteries, there's research and development. There may be new materials, there may be more field experience, which informs research and development and the output of this R&D is better batteries. Better could be in part, lower prices. Lower prices opens up new applications. New applications increases demand and increases production. This pattern is not specific to batteries, but generally how technologies improve over time due to R&D, due to market pressures, and that's currently happening with batteries. What's happening in the battery field, is the numbers are growing rapidly. As of 2016, global, what the [inaudible] calls electro-chemical, what I'll call battery storage capacity was 1.6 gigawatts. It's quite a bit higher than that by now, 2020. By the time you watch this, it's increasing as well. It's still nowhere near where we are with pumped hydro, but turn its way, you can see the very rapid growth. This graph shows how the technology mix is changing. As I mentioned few videos ago. But if you go back not long ago, 10 years, a whole bunch of different technologies, it's not clear what would dominate, but what has happened through 2016 and more or less since then, is the lithium-ion technology for batteries, it's dominating. Again, there's no guarantee that will continue, but other technologies, zinc air, flywheels, compressed air, not really dominating new installations. Again, there's always uncertainty with technologies. We're seeing more batteries, lithium-ion seems to be dominating. We're seeing more and more evidence, again, as of 2020, that batteries are just starting to make a difference. Here's some data from the California electricity system, the CAISO, showing battery charge and discharge on a typical day. This happened to be one November, 2020. You can see batteries were charging at negative. Below the zero value on the y-axis means the batteries were taking in energy and it oscillated over the course of the day, I'm guessing because the winds were up and down or more likely partly cloudy. At times, solar PV generation was high, the batteries took some in, otherwise they provided. Just looking at the data, it was probably a partly cloudy day, but you can see what you would expect for California with the highest battery discharge was to meet the peak demand, which as you recall in California is late in the day. You can see by 1800, I900 hours, 6:00 or 7:00 PM, batteries we're discharging close to maximum, about 100-150 megawatts, which California system is maybe 30,000 megawatts, 30 gigawatts. This is not a high percentage, but it's not trivially there, it's just that well captures for batteries are, that they're just starting to make a difference. Though that will end our discussion of storage.
