INTRODUCTION TO GRID ENERGY STORAGE Roger Lin NEC Energy Solutions [email protected] August 2017

Tampa Convention Center • Tampa, Florida Topics Covered

• Grid Energy Storage Introduction – Why grid energy storage? – What is it and what are the different types? – Where is it used today? • Understanding Energy Storage – The Fundamental Equation – Battery Based Energy Storage Systems – The Importance of Controls & Integration – SOC vs. DOD – Cycles, Degradation, & Useful Life – What’s the Best Battery? • Energy Storage Economics – Understanding Energy Storage Costs – Understanding Energy Storage Value

Energy Exchange: Connect • Collaborate • Conserve Why do we need energy storage on the grid? Why Energy Storage for the Grid?

• Adding flexibility, efficiency, and reliability • Today’s grids require more flexibility to address: – Increased renewable generation • Compensating for variable energy resources – Changing load patterns • Generation now distributed to load centers (PV) • EV chargers are shifting consumption patterns – Aging transmission and distribution network • Infrastructure is aging and needs reinforcement • Upgrades in urban environments can be difficult • Energy storage in the grid is a powerful tool – Increase flexibility of the system – Improve capacity utilization for generation, transmission, and distribution infrastructure – Can be placed almost anywhere in the network

4 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• What is Energy Storage? Note: We will use the • In our context, Energy Storage refers to the ability to hold term Energy Storage but electricity safely, reliably, and economically for future use. discuss specifically Electricity Storage, which – If Energy Storage were cheap and abundant, it would change is one type of Energy the grid dramatically by: Storage. Other forms of Energy Storage include • Mediating between variable sources and variable loads. fossil fuels like oil/natural gas/coal, • Decoupling production from consumption. thermal storage, or • Reducing price volatility. power-to-gas, which will not be covered here. • Enabling 100% renewable generation. • Making the grid more efficient. • Increasing reliability. • Today, only about 2.2% of electricity is stored world-wide(1)

Adapted from: Introduction to Bulk Power Systems, B. Kirby, EUCI course, Jun 8-9 2009, Washington DC (1) Source: “Annual Electric Generator Report”, 2011 EIA – Total Capacity 2009; US Energy Information Administration, Form EIA-860, 2011.

5 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• What is Energy Storage?

• Energy Storage moves energy through time • With Energy Storage, the grid does not have to instantly balance generation with consumption • It fundamentally changes system resource adequacy and the system planning paradigm • It provides System Operators a powerful new tool for system security • It is a game-changer for the electricity grid…

With Energy Storage, we need to think about the electricity grid in new ways!

6 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• What is Energy Storage?

• There are many types of energy storage that can be Other types of Energy Storage: used in the grid Fossil Fuels – Pumped Hydroelectric Storage (PHS) Probably the most abundant and well known form of energy storage – – Compressed Air Energy Storage (CAES) chemical energy storage in the form of oil or gas. – Flywheels Thermal Energy Storage – Batteries! Storing Heat or Cold in molten salt or • Lead acid ice to either generate electricity or provide useful heat or cooling. • Lithium ion Power-to-Gas (PtG) • Sodium beta alumina Using electricity to create hydrogen • Flow batteries gas, with possible methanization step, and feeding it into the gas grid Note: These types will not be covered in this training module.

7 Energy Exchange: Connect • Collaborate • Conserve Pumped Hydro Energy Storage

Pumped hydro storage constitutes close to 99% of the worlds energy storage. Due to each facility’s sheer size and scale there are significant hurdles; it takes a lot of money and time to install. They are typically very high energy and can run for tens of hours, and can have a low per unit energy storage cost, but require special geologic conditions to build. There are about 132GW of pumped storage installed around the world as of 2012*. Europe: 48.3GW Japan: 26.7GW Americas: 23.5GW China: 21.0GW RoW: 8.0GW

*Source: “International Energy Statistics”, www.eia.gov, Accessed Jan 14 2015.

8 Energy Exchange: Connect • Collaborate • Conserve Compressed Air Energy Storage

Compressed air energy storage, or CAES, uses large reservoirs of high pressure air to store energy. Electricity runs pumps that pressurize the reservoir. When needed, the air is expanded to run generators. CAES requires thermal management since lots of heat is created upon compression and needed back upon expansion due to thermodynamics – sometimes natural gas is burned to provide this heat. Typically high energy capability, and large scale (hundreds of MW). Installations Huntorf, Germany Built 1978 321MW, 4 hours McIntosh Alabama Built 1991 110MW, 26 hours There are only 2 commercially operating bulk CAES systems in the world today!

9 Energy Exchange: Connect • Collaborate • Conserve Flywheel Energy Storage

Flywheel systems consist of a rotating wheel, storing kinetic energy. Motors speed up the Notable Vendors flywheel to store energy, and a generator slows it down to release energy. Beacon Power was the leader in this area, with two large plants in the US but is now defunct. Flywheels have very high power capability, but very low energy storage capability. Two commercial facilities in operation today: Stephentown, New York, USA Built 2011 20MW, 15 minutes Hazel, Pennsylvania, USA Built July 2014 20MW, 15 minutes

10 Energy Exchange: Connect • Collaborate • Conserve Battery Energy Storage

General layout of a battery energy storage system for the grid Battery Energy Storage Systems need power conversion equipment to connect to the grid and do not make use of any turbine or other generating equipment, unlike PHS or CAES. While the transformers, power conversion systems, breakers and switches are all fairly common, the differentiating characteristics are primarily in the storage device, and in system design, which ties all the major components to the storage device in a seamless, safe and reliable system. There are many battery energy storage sites in operation today as both pilot projects and commercial revenue projects… but more on that later. The next slide will detail the different types of battery technologies.

11 Energy Exchange: Connect • Collaborate • Conserve Battery Energy Storage

• Many types! A word on various battery types While this tutorial will not contain an in-depth comparison of various vendors’ • Lead Acid technologies, the generalizations below provide an introduction to each type of battery. • Lithium Ion Nickel manganese cobalt (NMC) Lead Acid – Poor cycle life, power, and energy density, but excellent cost per kWh. However – Nickelate (LNO) poor deep discharge capabilities limit versatility. ‘Lead carbon’ variants improve upon performance but price also increases. Vendors include Ecoult/East Penn Mfg – Nickel cobalt aluminum (NCA) (using Furukawa technology), Enersys, GS Yuasa, and Axion Power. Iron phosphate (LFP) – Lithium Ion – Manganese spinel (LMO) Many types; LMO and NMC are most common, generally, but LFP and LTO have taken share in grid applications also. High power, efficiency (up to 90%), versatility – Titanate (anode) (LTO) (15 min to 4+ hrs) and maturity (used in many applications outside grid), but cost can Sodium Beta Alumina be high as power to energy ratio decreases. Requires cell balancing electronics. • Good to excellent cycle life. Majors include Samsung, LG, Panasonic/Tesla, BYD. – Sodium sulfur Sodium Beta Alumina – Sodium nickel chloride Major vendor is Japanese company NGK with their NAS battery. All operate at high temperatures (~300°C) and require 4-6 hours of energy storage per unit power. • Flow Good round trip efficiencies depending on operational profile, up to 85%, but drops – Vanadium redox if batteries must sit idle – heaters required to prevent ‘freezing’ will consume power constantly. Good to excellent cycle life. – Zinc bromine Flow Batteries – Iron chromium While many types of flow batteries, low energy density and requirement to pump liquid electrolyte complicates operation for all. Low round trip efficiencies (60-70%). Exceptional cycle life, and good cost for high energy low power configurations. Technology improving but high cost currently. Vendors include Sumitomo, ViZn, Prudent, Primus, Redflow, Gildemeister, and UET.

12 Energy Exchange: Connect • Collaborate • Conserve Where is grid energy storage used today?

• The vast majority of energy storage on the grid is in the form of PHS – About 2.2% of electricity is stored world-wide, mostly in pumped storage(1). • Only two CAES sites in operation today in revenue service • Lots of battery energy storage projects today; many in revenue service – Most in California in the United States – Lithium ion batteries as a category make up the largest group; sodium beta alumina is the next • Find out more at: – United States Dept of Energy’s Global Energy Storage Database – http://www.energystorageexchange.org/ – Contains a comprehensive listing of many storage projects with details on each, along with other resources on energy storage! – One can submit projects or corrections to projects to the Database administrator for inclusion. • Some example projects follow… Interior of a battery energy storage container from NEC Energy Solutions showing energy storage racks

(1) Source: “Annual Electric Generator Report”, 2011 EIA – Total Capacity 2009; US Energy Information Administration, Form EIA-860, 2011.

Energy Exchange: Connect • Collaborate • Conserve 11 MW, 4.3 MWh Battery Energy Storage System

Image courtesy of NEC Energy Solutions ©2017 NEC Energy Solutions, Inc. – Used with Permission

14 Energy Exchange: Connect • Collaborate • Conserve 2 MW, 3.9 MWh Battery Energy Storage System

Image courtesy of NEC Energy Solutions ©2017 NEC Energy Solutions, Inc. – Used with Permission

15 Energy Exchange: Connect • Collaborate • Conserve 6 MW, 6 MWh Battery Energy Storage System

Image courtesy of NEC Energy Solutions ©2017 NEC Energy Solutions, Inc. – Used with Permission

16 Energy Exchange: Connect • Collaborate • Conserve 4 MW, 2 MWh Battery Energy Storage System

Image courtesy of NEC Energy Solutions ©2017 NEC Energy Solutions, Inc. – Used with Permission

17 Energy Exchange: Connect • Collaborate • Conserve The future of energy storage?

• There are many emerging technologies that have not been proven yet… some of these include: – aqueous sodium ion – liquid metal – zinc air – magnesium ion – lithium air – lithium solid polymer electrolyte – lithium sulfur • All promise various improvements in cost, cycle life, energy density, and/or safety, but market validation of all these technologies is still underway

Energy Exchange: Connect • Collaborate • Conserve Understanding Energy Storage

Adapted from: M. Hardin “Making Cents of Energy Storage”. Energy Storage North America Conference, Oct 2014. Some Basic Terminology

• Duration • Power • Power to Energy Ratio • Energy • Response Time • Charge • Internal Impedance/Resistance • Discharge While you don’t need to understand all of these terms just yet, some are important • Duty Cycle • C-Rate • Cycle Life • State-of-Charge • Calendar (storage) Life • Energy Density • Round Trip Efficiency • Power Density • Levelized Cost of Energy (LCOE) • Depth-of-Discharge • Usable Energy

Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

21 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

Power x Time = Energy

22 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

Watts x Hours = Wh

23 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

• Power is the RATE of energy delivered – Joule (J) = unit of energy – Watt (W) = Joule per second (J/sec) – 1 Hour (h) = 3600 sec

• Therefore: (J/sec) x (3600 sec) = W x 1 h = Wh

24 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

How much Energy is Delivered?

10 MW

5 MW

30 min 60 min 90 min 120 min

25 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

How much Energy is Delivered?

10 MW 10 MW x 60 min/(60 min/h) 5 MW = 10 MW x 1.0 h = 10 MWh

30 min 60 min 90 min 120 min

26 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

How much Energy is Delivered?

10 MW

5 MW

30 min 60 min 90 min 120 min

27 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

How much Energy is Delivered?

10 MW

5 MW 5 MW x 120 min/(60 min/h) = 5 MW x 2.0 h = 10 MWh

30 min 60 min 90 min 120 min

28 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

Why the confusion?

29 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The fundamental equation

Why the confusion? • Energy Markets sell in 1 hour increments – 50 MW x 1 h = 50 MWh

• Power (50 MW) = Energy (50 MWh) – Both Power and Energy values are “50” – No difference between MW and MWh – No requirement to understand the difference

30 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The Water Tank Analogy

• Amount of water able to be Valves stored depends on size of tank (Control System)

• Time required to fill/empty the tank dependent on size of pipe Size of Tank

• The rate of water flowing in and (Energy out is controlled by the valves Capacity)

Q: How long does it take to fill the tank if: Inlet Pipe Size Outlet Pipe Size Tank is empty and holds 20 gallons – (Charging Power) (Discharging Power) – Pipe allows flow rate of 10 gal/min – The valve controls inlet to 5 gal/min – No water exits

31 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The Water Tank Analogy

• Amount of water able to be Valves stored depends on size of tank (Control System)

• Time required to fill/empty the tank dependent on size of pipe Size of Tank

• The rate of water flowing in and (Energy out is controlled by the valves Capacity)

Q: How long does it take to fill the tank if: – Tank is empty and holds 20 gallons Inlet Pipe Size Outlet Pipe Size (Discharging Power) – Pipe allows flow rate of 10 gal/min (Charging Power) – The valve controls inlet to 5 gal/min – No water exits

A: 20 gal/ (5 gal/min) = 4 min

32 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The Water Tank Analogy Energy Storage System WATER TANK (ESS)

Note: We will be using the term “ESS” as a generic acronym for any energy storage system. This is similar in letter but different in meaning from NECES’s GSS™ product family.

Water Tank Energy Storage System Definition Water Tank Energy Storage Capacity Total energy (Wh) system can store Water Level State of Charge (SOC) % of Energy Storage Capacity available Inlet/Outlet Pipes Power Conversion System (PCS) Converts power between storage and grid Valves Control System Controls charging and discharging rates

33 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Battery-based Energy Storage Systems (ESS)

34 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The importance of Controls and System Integration

Battery & Enclosure

35 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The importance of Controls and System Integration

Power Conversion System

Battery & Enclosure

36 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The importance of Controls and System Integration

Power Conversion System

Battery & Enclosure

Control System Hardware

37 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage The importance of Controls and System Integration

System Integration & Controls SW

38 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Key Takeaways

Energy (Wh) = Power (W) x Time (h)

An ESS requires a storage medium, PCS, control system, and system integration

An ESS is greater than the sum of its parts

39 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage C-rate, Power:Energy Ratio, and Round Trip Efficiency

• What do these terms refer to?

• Why are they important?

40 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• C-rate

• “C-rate” refers to a battery’s discharge rate in amps in relation to its capacity (Ah). It is a way to compare different size batteries on a proportional basis. – C-rate of “1C” means that if the battery capacity is 100Ah, the discharge rate is 100A. – C-rate of “2C” means that the discharge rate is 200A. – C-rate of “C/4” means that the discharge rate is 25A. • A related term “Rate Capability” is the ability to discharge faster and still deliver expected capacity. This is important to understand. – For instance if I discharge a 100Ah battery at 2C, how long will it last? • It depends on the battery type:

100Ah Battery A discharges at 100A and lasts 1 hr, but 100Ah Battery B discharges at 100A and lasts 1 hr, but at 200A lasts 15 minutes (not 30 minutes as you might at 200A lasts 29 minutes. expect)! 1C delivers 100Ah 1C delivers 100Ah 2C delivers only 50Ah 2C delivers 97Ah Battery B has a higher Rate Capability.

41 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• C-rate key takeaways C-rate is a metric to compare energy storage devices of different sizes in a proportional way

Discharging at 2C will not always give you 30 minutes of runtime!

C-rate does not take into account the energy delivered, only the Amp-hours delivered

*Depending on cost per unit power and energy, of course! 42 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Power:Energy ratio

• What is Power:Energy ratio? – Essentially a measure of discharge power (W) compared to energy storage capacity (Wh); a rating of the maximum discharge power you can achieve while receiving substantially all of the energy stored in the device. – However unlike C-Rate, it takes into account the voltage at which each amp is delivered, and thus the amount of useful work that can be performed and is a better metric for energy storage. • Why is this important? – Say you need a 1MW energy storage system. – Option A: Lithium ion with 1MW of power capability, and 1MWh of energy storage capability. • It cannot do 1MW with less storage because the underlying device is not capable of discharging at that power level. It simply does not have the “body weight” to generate that much power. – Option B: Lithium ion with 1MW of power capability, and 250kWh of energy storage capability. • It can do 1MW with only 250kWh because it has a higher Power:Energy ratio. It is stronger per unit “body weight”. It can also be said that it has a higher Rate Capability. – Let’s say Option A is $600/kWh and Option B is $2,000/kWh. Which one is better?

43 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Power:Energy ratio

– Do the math: • Option A: $600/kWh x 1,000kWh = $600,000 • Option B: $2,000/kWh x 250kWh = $500,000 – Option B is better even though the unit price is more than 3x of Option A! • Now let’s say you again need a 1MW energy storage system. – But this time, you need at least 1 hour of energy storage (1,000kWh)! • Which one is better? – Do the math: • Option A: $600/kWh x 1,000kWh = $600,000 • Option B: $2,000/kWh x 1,000kWh = $2,000,000 – Option A is better by far since the application requires more storage capacity.

44 Energy Exchange: Connect • Collaborate • Conserve Energy Storage Costs Vary By Technology

ModifiedSimple cost Cost per per kW kW (Power) (Power) vs vs Duration Duration (Energy) (Energy) 2000• Some more economic for power applications,

1800 some for energy

1600

1400

1200

1000 $/kW

800 Energy storage costs are coming down, but they vary in capability. Some are good for power, others for energy. Choose the right tool for the job! 600

400 Green and blue curves are both the same capability, same C-rate, but one is more expensive than the other. Always choose the blue curve? Maybe not! 200 Depends on performance over time. Consider… levelized cost of STORAGE.

0 0 30 60 90 120 150 180 210 240 270 300 330 360 Duration (minutes)

45 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Power:Energy ratio key takeaways Power:Energy Ratio is important to match applications with the best battery technology

A high power application would benefit from a high Power:Energy ratio battery*

A high energy application would benefit from a low Power:Energy ratio battery*

*Depending on cost per unit power and energy, of course! 46 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Round Trip Efficiency

• Round Trip Efficiency (RTE) refers to the amount of energy (Wh) that can be returned after being stored. • It is never 100% - there is always some loss in the storage of energy. – Storing and returning energy results in some of it being lost in heat or side reactions – Power to Energy Ratio and Rate Capability are good indicators of the RTE capability • Lower internal resistance means higher RTE; less wasted energy – Operating at higher power and higher C-rates will lower RTE and vice versa; RTE can fluctuate in the same system depending on operating parameters. • RTE% impacts the operational cost of an energy storage device, because for every Wh you put in, you only get a fraction of it back out! – This means that, on a net basis, all energy storage devices consume energy. – This energy consumption can be considered a “storage fee”. – Lower RTE means you pay higher storage fees!

47 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• RTE key takeaways

Round Trip Efficiency is never 100%

You want higher RTE’s since it will lower your “storage fees”

Energy storage type, system design, and operating parameters can impact RTE

*Depending on cost per unit power and energy, of course! 48 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

SOC vs. DOD • What’s the difference?

• Who uses which metric and why?

• Which is more important for an ESS?

• Why should you care?

49 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

SOC vs. DOD • Depth of Discharge (DOD) = % of energy removed

• State of Charge (SOC) = % of energy remaining

0% 25% 50% 75% 100%

75% SOC 25% DOD

SOC% = 100% - DOD%

50 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

SOC vs. DOD • Depth of Discharge (DOD) = “air in the tank”

• State of Charge (SOC) = “water in the tank”

0% 25% 50% 75% 100%

25% SOC 75% DOD

SOC% = 100% - DOD%

51 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

SOC vs. DOD: Key Takeaways

SOC% = 100% - DOD%

SOC measures % energy remaining DOD measures % energy removed

Battery Suppliers use DOD, but SOC more important in understanding ESS

52 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life

So… how long will the batteries last?

53 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life # Cycles vs. Capacity Degradation 100%

95%

90%

85%

80% EOL @ 80% Remaining Capacity

% % Capacity Remaining 75%

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 ±1C at 25°C # Cycles @ 80% DOD What does this mean?

54 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life • Cycle – when a battery is discharged and recharged from an initial SOC and back

• Degradation – the loss of battery energy storage capacity over time which reduces the available % remaining capacity (also known as capacity “fade”)

• End of Life (EOL) – the point at which a battery degrades enough to reach a % remaining capacity which the manufacture defines as the end of its useful life 55 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life

• “Battery Life” depends on a number of factors including but not limited to: • Total nameplate energy capacity • Operating temperature • Power required per battery • Total energy charged + discharged during use • Operating SOC range • % Remaining capacity at End of Life

56 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life # Cycles vs. Capacity Degradation 100%

95%

90%

85%

80% EOL @ 80% Remaining Capacity

% % Capacity Remaining 75%

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 ±1C at 25°C # Cycles @ 80% DOD

• Most of the technical specifications required are provided • But we still must convert life cycles to energy throughput 60 Energy Exchange: Connect • Collaborate • Conserve Cycles, Degradation, & Useful Life

• What if car warranties were based on 1,000 road trips of 18 miles each way?

61 Energy Exchange: Connect • Collaborate • Conserve Cycles, Degradation, & Useful Life

• What if car warranties were based on 1,000 road trips of 18 miles each way?

• Total miles = 1,000 x 18mi/trip x 2 trips = 36,000mi

62 Energy Exchange: Connect • Collaborate • Conserve Cycles, Degradation, & Useful Life

• What if car warranties were based on 1,000 road trips of 18 miles each way?

• Total miles = 1,000 x 18mi/trip x 2 trips = 36,000mi

# Cycles kWh/Cycle Total Energy Throughput

63 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life # Cycles vs. Capacity Degradation 100%

95%

90%

85%

80% EOL @ 80% Remaining Capacity

% % Capacity Remaining 75%

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 ±1C at 25°C # Cycles @ 80% DOD For example only Assuming an ESS has 1 MWh nameplate energy, lifetime energy throughput can be calculated as: 6,000 cycles x 80% DOD x 1 MWh x 2 trips/cycle Throughput = 6,000 x 0.8 x 1 x 2 = 9,600 MWh

64 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life

# Cycles vs. Capacity Degradation

100 %

95%

90%

85%

80%

% Remaining % Remaining Capacity EOL @ 80% Remaining Capacity

75%

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 ±1C at 25°C # Cycles @ 80% DOD For example only How many miles per year do How many MWh/year are you need to drive the car? required to be charged and discharged in the energy storage application?

65 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life

# Cycles vs. Capacity Degradation

100 %

95%

90%

85%

80%

% Remaining % Remaining Capacity EOL @ 80% Remaining Capacity

75%

500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 ±1C at 25°C # Cycles @ 80% DOD For example only Throughput = 6,000 x 80% x 1.0 MWh x 2 = 9,600 MWh Assuming application requires 960 MWh/year 80% nameplate capacity remaining in year 10 (high level estimate)

66 Energy Exchange: Connect • Collaborate • Conserve Introduction to Grid Energy Storage

• Cycles, Degradation, & Useful Life

Battery life depends on a number of factors

The impact of most factors can be minimized if the ESS is properly sized and controlled

Use cycle life data to calculate lifetime energy throughput & compare to application needs

67 Energy Exchange: Connect • Collaborate • Conserve What Can Energy Storage Do?

• Lots of possibilities!

94 Energy Exchange: Connect • Collaborate • Conserve Thank you!

Contact me for more information

Roger Lin Senior Director, Product Marketing NEC Energy Solutions, Inc. 155 Flanders Rd Westborough, MA 01581 +1 (508) 497-7261 [email protected]

Energy Exchange: Connect • Collaborate • Conserve