battery storage overview storage overvi… · lead-acid battery 100 1 min –8h 6 –40 years 50...

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COPYRIGHT © 2020 by California ISO. All Rights Reserved

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Battery Storage Overview

Brad Bouillon

CAISO

August 18, 2020

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Outline

• Background on Energy Storage Types

• Batteries

– How are they used in energy markets

– How much capacity exists

– What are average build out rates

– Installed cost trends

– Background on actual installations

• Conclusions/Questions

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Classification of Energy Storage Systems

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Energy Storage Technologies

Max Power

Rating (MW)

Discharge

time

Max cycles or lifetime Energy density

(watt-hour per liter)

Efficienc

y

Pumped hydro 3,000 4h – 16h 30 – 60 years 0.2 – 2 70 – 85%

Compressed air 1,000 2h – 30h 20 – 40 years 2 – 6 40 – 70%

Molten salt (thermal) 150 hours 30 years 70 – 210 80 – 90%

Li-ion battery 100 1 min – 8h 1,000 – 10,000 200 – 400 85 – 95%

Lead-acid battery 100 1 min – 8h 6 – 40 years 50 – 80 80 – 90%

Flow battery 100 hours 12,000 – 14,000 20 – 70 60 – 85%

Hydrogen 100 mins – week 5 – 30 years 600 (at 200bar) 25 – 45%

Flywheel 20 secs - mins 20,000 – 100,000 20 – 80 70 – 95%

Characteristics of selected energy storage systems (source: The World Energy Council)

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Storage Technology Deployment

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Pumped-Storage Hydropower

Pumped-storage hydro (PSH) facilities are large-scale energy storage plants that

use gravitational force to generate electricity. Water is pumped to a higher

elevation for storage during low-cost energy periods and high renewable energy

generation periods. When electricity is needed, water is released back to the

lower pool, generating power through turbines.

Comparison between PSH vs. Li-Ion Batteries

According to the Electric Power Research Institute, the installed cost for pumped-

storage hydropower varies between $1,700 and $5,100/kW, compared to

$2,500/kW to 3,900/kW for lithium-ion batteries. Pumped-storage hydropower is

more than 80 percent energy efficient through a full cycle, and PSH facilities can

typically provide 10 hours of electricity, compared to about 6 hours for lithium-ion

batteries

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Compressed Air Energy Storage (CAES)

With compressed air storage, air is pumped into an underground hole, most likely

a salt cavern, during off-peak hours when electricity is cheaper. When energy is

needed, the air from the underground cave is released back up into the facility,

where it is heated and the resulting expansion turns an electricity generator.

Thermal (including Molten Salt)

Thermal energy storage facilities use temperature to store energy. When energy

needs to be stored, rocks, salts, water, or other materials are heated and kept in

insulated environments. When energy needs to be generated, the thermal energy

is released by pumping cold water onto the hot rocks, salts, or hot water in order

to produce steam, which spins turbines.

Lithium-ion BatteriesLithium-ion batteries are by far the most popular battery storage option today and

control more than 90 percent of the global grid battery storage market. Compared

to other battery options, lithium-ion batteries have high energy density and are

lightweight

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Flywheels

Flywheels are not suitable for long-term energy storage, but are very effective for

load-leveling and load-shifting applications. Flywheels are known for their long-life

cycle, high-energy density, low maintenance costs, and quick response speeds.

Motors store energy into flywheels by accelerating their spins to very high rates

(up to 50,000 rpm). The motor can later use that stored kinetic energy to generate

electricity by going into reverse.

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How Batteries help Reliability

• Batteries are versatile devices that can help energy

markets manage operational challenges due to higher

penetrations of renewable resources

– Absorb excess solar supply during the day and help reduce peak

loads in the afternoon and evening

– Respond to alleviate solar ramps

– Firm and fill renewable generation intermittencies

– Provide fast frequency response capabilities

– Utilized through transmission planning as transmission assets

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The ISO non-generator resource (NGR) modelResource can move seamlessly between load and generation

Slide 10

0 MW

20 MW

- 20 MW

NGR Generation Load

Ram

p

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Battery Types

Lithium Ion (Li-Ion) Batteries

After Exxon chemist Stanley Whittingham developed the concept of lithium-ion batteries in the 1970s, Sony and Asahi Kasei created the first commercial product in 1991. The first

batteries were used for consumer electronics and now, building on the success of these Li-ion batteries, many companies are developing larger-format cells for use in energy-storage

applications. Many also expect there to be significant synergies with the emergence of electric vehicles (EVs) powered by Li-ion batteries. The flexibility of Li-ion technology in EV

applications, from small high-power batteries for power buffering in hybrids, to medium-power batteries providing both electric-only range and power buffering in plug-in hybrids, to

high-energy batteries in electric-only vehicles, has similar value in stationary energy storage.

Li-ion batteries have been deployed in a wide range of energy-storage applications, ranging from energy-type batteries of a few kilowatt-hours in residential systems with rooftop

photovoltaic arrays to multi-megawatt containerized batteries for the provision of grid ancillary services.

Lead Batteries

Lead batteries are the most extensively used rechargeable battery technology in the world. They have an unrivalled track record for reliability and safety, which together with a well-

established worldwide supplier base, make them the dominant battery in terms of MWh of production. Lead batteries are widely used in cars and trucks, being used in virtually all

vehicles, supporting increased vehicle hybridization and electrification, all the way from start-stop technology to full electric vehicles. In addition, lead batteries are widely used in

industrial applications, where they provide energy for telecommunications, uninterrupted power supply, secure power, electric traction and for energy storage for utilities as well as

domestic and commercial applications.

Redox Flow Batteries

Redox flow batteries (RFB) represent one class of electrochemical energy storage devices. The name “redox” refers to chemical reduction and oxidation reactions employed in the

RFB to store energy in liquid electrolyte solutions which flow through a battery of electrochemical cells during charge and discharge.

Vanadium Redox (VRB) Flow Batteries

The Vanadium Redox Battery (VRB®)¹ is a true redox flow battery (RFB), which stores energy by employing vanadium redox couples (V2+/V3+ in the negative and V4+/V5+ in the

positive half-cells). These active chemical species are fully dissolved at all times in sulfuric acid electrolyte solutions. Like other true RFBs, the power and energy ratings of Vanadium

Redox Batteries are independent of each other and each may be optimized separately for a specific application. All the other benefits and distinctions of true RFBs compared to

other energy storage systems are realized by VRBs. The first operational vanadium redox battery was successfully demonstrated at the University of New South Wales in the late

1980s and commercial versions have been operating on scale for over 8 years.

Nickel-Cadmium (NI-CD) Batteries

In commercial production since the 1910s, nickel-cadmium (Ni-Cd) is a traditional battery type that has seen periodic advances in electrode technology and packaging in order to

remain viable. While not exceling in typical measures such as energy density or first cost, Ni-Cd batteries remain relevant by providing simple implementation without complex

management systems, while providing long life and reliable service.

Sodium Sulfur (NaS) Batteries

Sodium Sulfur (NaS) Batteries were originally developed by Ford Motor Company in the 1960s and subsequently the technology was sold to the Japanese company NGK. NGK now

manufactures the battery systems for stationary applications. The systems operate at a high temperature, 300 to 350 °C, which can be an operational issue for intermittent operation.

Significant installations for energy storage have been used to facilitate distribution line construction deferral. The round trip efficiency is in the 90% range so provides an efficient use

of energy.

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Battery Types (cont.)

Electrochemical Capacitors

Electrochemical capacitors (ECs) – sometimes referred to as “electric double-layer” capacitors – also appear under trade names like “Supercapacitor” or “Ultracapacitor.” The

phrase “double-layer” refers to their physically storing electrical charge at a surface-electrolyte interface of high-surface-area carbon electrodes. There are two types of ECs,

symmetric and asymmetric, with different properties suitable for different applications. Markets and applications for electrochemical capacitors are growing rapidly and applications

related to electricity grid will be part of that growth.

Iron-Chromium (ICB) Flow Batteries

Iron-chromium flow batteries were pioneered and studied extensively by NASA in the 1970s – 1980s and by Mitsui in Japan. The iron-chromium flow battery is a redox flow battery

(RFB). Energy is stored by employing the Fe2+ – Fe3+ and Cr2+ – Cr3+ redox couples. The active chemical species are fully dissolved in the aqueous electrolyte at all times. Like

other true RFBs, the power and energy ratings of the iron-chromium system are independent of each other, and each may be optimized separately for each application. All the

other benefits and distinctions of true RFBs compared to other energy storage systems are realized by iron-chromium RFBs.

Zinc-Bromine (ZNBR) Flow Batteries

The zinc-bromine battery is a hybrid redox flow battery, because much of the energy is stored by plating zinc metal as a solid onto the anode plates in the electrochemical stack

during charge. Thus, the total energy storage capacity of the system is dependent on both the stack size (electrode area) and the size of the electrolyte storage reservoirs. As such,

the power and energy ratings of the zinc-bromine flow battery are not fully decoupled. The zinc-bromine flow battery was developed by Exxon as a hybrid flow battery system in the

early 1970s.

Source: Energy Storage Association (2020)

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Today California has about 150 MW of storage that is

primarily providing ancillary, not energy, services

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The ISO is developing a tool to ensure that there is

enough energy in storage resources to meet peaks

7.8 GWh

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Cumulative Utility Scale Battery Storage Capacity

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Annual Battery Storage Additions by Region

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Total Installation Cost of Utility Scale Battery Systems

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• Southern California Edison

plans to build seven storage

projects in a total of 770MW

• Pacific Gas and Electric also

plans the 300-megawatt Moss

Landing project, located in

central California, and it will be

the largest battery storage

project in the state, to date

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Questions?

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