Battery-Electric Buses 101

Speaker: Erik Bigelow, Senior Project Manager, Center for Transportation and the Environment,

Atlanta, GA

Battery Electric Buses 101APTA 2017 Sustainability Workshop

Minneapolis, MN

Erik BigelowSenior Project Manager

Center for Transportation and the Environment

About CTE

• Mission: To advance clean, sustainable, innovative transportation and energy technologies

• 501(3)(c) non-profit

• Portfolio - $400+ million

– Research, demonstration, deployment

– Alt. fuel and advanced vehicle technologies

• National presence

Atlanta, Berkeley, Los Angeles, St. Paul

3

CTE Activity Roadmap

Over $217 million active project portfolio

CURRENT PROJECTS TRANSITMEMBERS PAST PROJECTS

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CTE Zero Emission Bus Projects

More than 140 ZEB’s with over 30 Transit Agencies5

Overview & Agenda

• Why switch to electric buses?

• Battery electric bus history

• Understanding batteries

• Charging overview

• Driving range

• Electric rates and fuel cost

• Planning for your fleet

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Warming Up the Batteries

• Where are you from?

• What is your experience with zero emission buses so far?

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Electric Bus Fleet Trivia

• Where is the current largest US Zero Emission Fleet?

• Where is the longest (in years) running battery electric bus operation?

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What do you want to hear about?

• Key concerns?

• Open questions?

• Getting started?

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Key Terms

• ZEB – Zero Emission Bus

• BEB – Battery Electric Bus

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Why Electrify Buses Now?

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Why Electrify Buses Now?

• Currently a global movement to electrify transportation underway

Volvo

“Every Volvo from 2019 on will have an electric motor”

Toyota

“All cars will be only battery electric or fuel cell by 2050”

France & UK

Planning to ban sales of combustion engines by 2040

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Why Electrify Buses Now?

• Transportation GHG is now above power generation for the first time

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Local Pollution Control

• Most bus emissions are concentrated where people are most concentrated

• Shifting energy production to centers outside of cities, or to zero emission, reduces impacts on population

14LA, Nov 2015 - from LA Times

Overall Energy Efficiency – “Well to Wheels”

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Source: California Fuel Cell Partnership. Air Climate Energy Water Security.https://cafcp.org/sites/default/files/W2W-2016.pdf

Fuel Production Fuel Consumption

Regulatory Environment

• Increasing complexity of Emissions Controls

• Zero Emission Bus Mandates

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Modern diesel emissions controlTechnology• DOC• DPF• DEF• SCR• AOC• EGR

Zero emission buses are quiet

• Quieter interiors are more comfortable

• Quieting city centers makes transit more desirable

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Key Current Challenges

1. Initial Capital Cost

2. New Operational Requirements

3. Procurement Hurdles

4. Charging Interfaces/Standards

5. Long Term Energy Needs

18Adapted from UITP eBus Training Program, June 2017

Hydrogen Fuel Cell vs. Battery Electric

• Both are all-electric drivetrains

• Both are zero point source emission

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Battery Electric Vehicle

Charger

Hydrogen Fuel Cell vs. Battery Electric

• Both are all-electric drivetrains

• Both are zero point source emission

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Fuel Cell Electric Vehicle

Fuel Cell

Hydrogen Refueling

• Vehicle fueling is similar to CNG

• Station fuels buses in ~15 minutes, which are then ready for the next pull out

• Sufficient range for most transit service

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Hydrogen Fuel Cell Buses

• Pro: Simpler logistics and fueling

• Con: Higher capital and operating cost

• Costs are coming down rapidly

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Calendar Year Price

2008 $3.2 mm

2010 $2.2 mm

2016 $1.1 mm

2019 Under $1 mm

40’ Fuel Cell Transit Bus Price History

Battery Electric Bus History

• Similar history to light duty vehicles– Technology has been generally available for decades, but the

right combination of affordability and capability are here

• Earliest electric buses were before gasoline vehicles were reliable

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1915 1974 1992

Understanding Batteries

High capacity batteries are the key enabler of modern electric buses

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Key Topics to Discuss

• Battery Chemistries

• System Architecture

• Safety

• Units of Measure

Battery Chemistries

• All batteries in new buses today are variations of Lithium Ion batteries

• Different battery chemistries offer different strengths and benefits

• Typical Chemistries:

– NMC - Nickel Manganese Cobalt

– LiFe – Lithium Iron Phosphate

– LiTo – Lithium Titanate

25

Energy Storage Architecture

Cell –> Module –> String -> Pack3VDC 30VDC 400-600VDC

Note: manufacturers may use different terms26

Source: Alexander Otto, “Battery Management Network for Fully Electrical Vehicles Featuring Smart Systems at Cell and Pack Level.”

Energy Storage Architecture

• A battery energy storage system is comprised of components:

– Battery cells

– Packaging – mechanical, thermal management

– Safety – fusing, ground fault detection

– Battery Management System

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Battery Capacity Terminology

• State of Charge (SOC)– Percent of total energy currently in batteries

• State of Health (SOH)– Measure of degradation from BOL

• Beginning of Life (BOL) Capacity– Energy storage capacity when new

• End of Life (EOL) Capacity– Energy storage capacity when useful limit, or warranty

condition, is reached

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Batteries Units of Measure

• kW and kWh measure very different things

Unit Describes what?

Conventional Equivalent

Example

kW Power Horsepower (hp) This battery pack can provide 230 kW (308 hp)

kWh Energy Gallons of diesel This bus stores 300 kWh (7.9 gallons diesel)

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Battery Capacity Terminology

Beginning-of-Life Batteries

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Battery Capacity Terminology

End-of-Life Batteries

31Note: Batteries all lose capacity through use and aging

Safety

• Different batteries have different safety related characteristics, effective cell management is the most critical

Any energy storage that can move a bus (diesel, CNG, or battery) can lead to a hazard in

the wrong conditions

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New vs. Similar Bus Systems

• Many onboard systems will be identical to diesel counterparts

• New Systems– Electric Heating and Air Conditioning

– Electric Accessories: Power Steering, Air Compressor

– Electric drivetrain: Batteries, Motor, Controls

• Vehicle Charging Interface

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Charging Infrastructure Installation

• Installation can be a significant infrastructure project

• We typically budget around 1 year for the entire process for on-route infrastructure

• Identify how this fits in to longer range plans if possible

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Charging Option Overview

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On Route Charge

• Conductive

– Static

– Dynamic – trolley style

• Inductive

– Static

– Dynamic – early research

• Conductive

Depot

Charge

Zero Emission Buses & Infrastructure

– Large battery pack

– 70 – 300 mile range

– 50 – 120 kW charger

– Recharge in 3-7 hours

– Fast chargers may be an option in the future

Depot Charge – Conductive

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Zero Emission Buses & Infrastructure

• Pros– On site infrastructure (chargers at depot)

– Takes advantage of lower off-peak electricity rate

– Flexibility for route selection and route changes

• Cons– Must be taken out of service to recharge

– Larger, heavier battery packs

– Scalability at the depot can be a challenge

Depot Charge – Conductive

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Zero Emission Buses & Infrastructure

– Smaller battery pack

– 20 – 50 miles range

– 300 – 500 kW charger

– Full charge in 5 - 15 mins.

On-Route Charge – Conductive Stationary

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Zero Emission Buses & Infrastructure

• Pros

– Charging while on-route, 24/7 operation possible

– Smaller Battery Pack

– Distributed demand may minimize grid impacts

• Cons

– Higher cost of charging infrastructure

– Overhead systems may require dedicated/restricted pull-off

– May require change to service schedule to charge

– Costly to modify routes in the future

On-Route Charge – Stationary Conductive

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Zero Emission Buses & Infrastructure

• Profile:

– 50 kW charger• 200-250 kW in development

– Can be primary charger with 250 kW version

On-Route Charge – Inductive Stationary

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Zero Emission Buses & Infrastructure

• Pros– Can remain in service while charging on-route

– Extends range of depot-charged BEB

– Smaller on-route infrastructure footprint

• Cons– At current power level, cannot be used as sole source

– Infrastructure and cost for on-route charging system

– Costly to modify routes in the future

On-Route Charge – Inductive Stationary

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Range – Onboard Energy Capacity

• It depends!

• Different bus models will have different installed energy capacity

– All else being equal, usable range depends directly on capacity

• Larger battery packs are heavier

– Causes slight efficiency penalty

• Headlights are not a big draw

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Range – HVAC Impacts

• Heating and cooling will cause the single largest impact on useable range

• In most of the US, heating on the coldest days will have a larger impact than AC on the hottest days

• Vehicle planning needs to include varied HVAC impact

• Diesel fired heaters are typically available for cold climates

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Range Impacts – How is the Bus Used

• The next largest impact to efficiency is sitting in the driver’s seat

• Regenerative breaking recovers significant energy

• Hard braking will increase overall energy use

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Range Impacts – How is the Bus Used

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OEM Brochure CTE Model

Route A (summer, no passengers) 1.7 – 2.0 1.72

Route A (summer, avg. passengers) 1.7 – 2.0 2.11

Route A (summer, max passengers) 1.7 – 2.0 2.46

Route A (winter, no passengers) 1.7 – 2.0 1.91

Route A (winter, avg. passengers) 1.7 – 2.0 2.64

Route A (winter, max passengers) 1.7 – 2.0 3.10

Route B (fall, no passengers) 1.7 – 2.0 1.68

Route B (fall, avg. passengers) 1.7 – 2.0 2.06

Route B (fall, max passengers) 1.7 – 2.0 2.20

Worst Route, Worst Case 6.17

kWh/mile consumption

Understanding Electric Fuel Cost

Electric rates are typically a combination of:

1. Consumption charges– Varies with amount of energy used

2. Demand charges– Based on the highest power draw that month

3. Fees– Fixed and variable

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Understanding Electric Fuel Cost

Actual electric fuel cost can be higher or lowerthan existing fuel costs based on:

• Baseline - Existing conventional fuel price

• New Fuel Cost - Electric rate structure

• Usage - Bus use and recharging pattern

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Time of Use Rates (TOU)

• Time of Use Rates have a varied cost structure depending on the time of day to match grid supply and demand

• Consumption and demand charges can vary significantly over the day

• Highest costs during highest demand

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Charging Standards

• Charging system standards will allow common hardware between different manufacturers

• Standards are currently in development

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How Do You Add Electric Buses?

• Electric buses are operationally different than conventional buses – how do you get started?

Go for it!

Go for it, conservatively!

Strategy, Planning, Implementation

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Life Cycle

Cost

Modeling

Annual FuelCosts

Capital Costs

MaintenanceCosts

12 YearCost

Analysis

Energy ConsumptionAnd Charging

Profile

Bus & Route

Modeling

Electricity

Modeling

RouteRequirement

ProposedBus/Charger

Electricity Rate Schedules

• Determine which technology is right for your routes

– Bus Modeling & Route Simulation

• Estimate Operating Costs

– Rate Modeling & Fuel Cost Analysis

• Establish the Business Case

– Life Cycle Cost Analysis

– Risk Assessment

Key Elements for ZEB Deployment

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Bus Modeling and Route Simulation

Service Requirement• Route Logistics

– Length

– Duration

– Schedule

– Frequency

• Duty Cycle

– Speed

– Accel/Decel

– Grades

– Passenger Load

– Auxiliary Load

– Deadhead

• Operating Environment

– Traffic Congestion

– Climate53

- Autonomie™ Simulation Software

(developed by Argonne National

Lab.)

- GUI utilizing MATLAB & Simulink

software package

- Quick assembly of complex ZEB

specifications:• Vehicle weight

• Battery chemistry and energy

capacity

• Motor power output and energy

requirements

• Rolling resistance

ZEB Modeling Methodology

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Typical Route Model Results

Battery SOC Charge Rate

LayoverBus Speed

Model

route databus specifications

operation plan

expected energy useaverage bus efficiencycharging requirements

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Rate Modeling & Fuel Cost Analysis

• Battery Electric Charging

– Energy Consumption estimate from Route Modeling

– Charger Specifications

– Charging Profile

• Charge Rate, Duration, Time of Day

– Utility Rate Schedules

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Key Performance Indicators

Track & Analyze Performance - Take Corrective Action - Realize Benefits - Repeat

0

10

20

30

40

50

60

70

80

-

1.00

2.00

3.00

4.00

5.00

6.00

Sep

-13

Nov

-13

Jan-14

Mar-14

May

-14

Jul-1

4

Sep

-14

Nov

-14

Jan-15

Mar-15

May

-15

Jul-1

5

Sep

-15

Nov

-15

Jan-16

Mar-16

May

-16

kW

h/m

ile

Electric Fleet kWh/Mile vs. Avg. Temp

kWh/Mile

Temp (F)

$0.20

$0.30

$0.40

$0.50

$0.60

$0.70

$0.80

$0.90

$1.00

Sep

-13

Oct-

13

Nov-13

Dec-13

Jan

-14

Feb-14

Mar-14

Apr-14

Ma

y-14

Jun

-14

Ju

l-14

Aug

-14

Sep

-14

Oct-

14

Nov-14

Dec-14

Jan

-15

Feb

-15

Ma

r-15

Ap

r-15

May-15

Jun

-15

Jul-15

Aug

-15

Sep

-15

Oct-

15

Nov-15

Dec-15

Jan

-16

Feb

-16

Ma

r-16

Ap

r-16

May-16

Jun

-16

$/M

ile

Monthly Average Cost/Mile

Non-Electric Elec Total Fleet

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

20.00

Se

p-1

3

Oct-

13

Nov-1

3

Dec-1

3

Jan-1

4

Feb-1

4

Mar-

14

Apr-

14

Ma

y-1

4

Jun-1

4

Jul-14

Aug-1

4

Sep-1

4

Oct-

14

Nov-1

4

Dec-1

4

Ja

n-1

5

Fe

b-1

5

Mar-

15

Apr-

15

May-1

5

Ju

n-1

5

Jul-15

Au

g-1

5

Se

p-1

5

Oct-

15

Nov-1

5

Dec-1

5

Ja

n-1

6

Fe

b-1

6

Mar-

16

Apr-

16

May-1

6

Ju

n-1

6

Monthly Miles/DG(E)

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Fleet Introduction Planning

• Training

– Maintenance

• New technologies and diagnostics

• Safe handling

– Operators

• OEMs aim for seamless experience, some familiarization is needed

• Charge docking, if on-route charging

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Fleet Introduction Planning

• Schedule Adjustment, if needed

• Safety Planning

– BEB: Similar training requirements as diesel electric hybrids for high voltage

– Hydrogen Fuel Cell: Combination of requirements similar to CNG and hybrid safety

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What’s next for your fleet?

Zero Emission Buses work!

• Define your agency goals

• Create deployment strategy

• Start operating Zero Emission Buses

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Questions?

Erik Bigelow

CENTER FOR TRANSPORTATION & THE ENVIRONMENT

erik@cte.tv

www.cte.tv