NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE Technical Challenges and Barriers Affecting Turbo-electric and Hybrid Electric Aircraft Propulsion Dr. Ajay Misra Deputy Director, Research and Engineering NASA Glenn Research Center Keynote presentation at ENERGYTECH 2017 conference October 31 – November 2, Cleveland, OH
30
Embed
Technical Challenges and Barriers Affecting Turbo-electric ... · PDF filepassenger 2 –3 passenger 4 passenger 400 Wh/kg ... • 20 passenger hybrid electric aircraft • 335...
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Technical Challenges and Barriers
Affecting Turbo-electric and Hybrid
Electric Aircraft Propulsion
Dr. Ajay Misra
Deputy Director, Research and Engineering
NASA Glenn Research Center
Keynote presentation at ENERGYTECH 2017 conference October 31 – November 2, Cleveland, OH
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Why Electric
• Improve fuel efficiency
• Lower emissions
• Reduced noise
• Low operating cost
• Efficiency of electrical
components significantly
higher than IC engines or
gas turbine engines
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
All Electric Aircraft
3
Power
Converter
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Battery Capability Required for All Electric Urban Mobility Aircraft
4
40
20
60
80
140
120
160
180
200R
ange, M
iles
150 Wh/kg 300 Wh/kg
VTOL
Rotorcraft
2 – 3
passenger
2 – 3
passenger
2 – 3
passenger
4 passenger
400 Wh/kg
4 passenger
Battery Specific Energy, Wh/kg (Pack Level)
Current commercial battery
state-of-the-art: 170 Wh/kg
CTOL
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
All Electric Commuter Aircraft
5
180(Baseline)
Battery Specific Energy, Wh/kg (Pack Level)
Ra
ng
e, M
ile
s
Studies by Happerle (German Aerospace Center)
Dornier 328 turboprop
28 passengers
Baseline range – 750 miles
Speed for electric – 140 – 200 mph
100
200
300
400
500
600
700
800
900
180(Modified aircraft)
360(Modified aircraft)
720(Modified aircraft)
Considering 30 min of reserve
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Series Hybrid Electric Aircraft
6
• Gas turbine/IC engine used either
to charge batteries or provide
auxiliary power to drive the motor
• Battery used during takeoff and
part or all of cruise
• Gas turbine/IC engine used
primarily during part of cruise
• Gas turbine/IC engine can
continuously run at the most
efficient point
• Gas turbine is sized much smaller
Challenge:
• Efficiency of small engines
relatively low (on the order of 30% )
compared to large gas turbine
engines
Range Extender
Battery
Fuel Gas
Turbine
Generator
Power
Converter
Electric
Motor
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE 7
• Degree of hybridization can be
adjusted depending on the
mission
• One option is for gas turbine to
always operate at its peak
efficiency point and to use
battery when power required is
larger than power delivered by
the gas turbine (e.g., during
takeoff)
Challenge:
• Increased complexity of the
mechanical coupling
• Increase in control complexity
as power flow has to be
regulated and blended from two
power sources
Parallel Hybrid Electric Aircraft
Battery
Fuel Gas
Turbine
Power
Converter
Electric
Motor
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Battery Requirement for Commuter and Regional Hybrid
Electric Aircraft
8
Range,
Nautical M
iles
Hybrid electric, 70 Passengers
(Based on Isikveren et.al., ISABE
2015 Paper)
48 passenger turboprop (NASA study)
• For 600 nm, battery pack with specific energy
greater than 500 Wh/kg for total energy to be
less than conventional propulsion
• Battery specific energy must be at least 600
Wh/kg for operating fuel/energy cost parity
with advanced conventional propulsion
Battery Pack Specific Energy (Wh/kg)
Assuming pack specific
energy = 60% of cell
specific energy200
400
600
800
1000
1200
1400
300 400 500 600 700 800 900
RUAG Dornier – DO228NG (Juretzko)
• 20 passenger hybrid electric aircraft
• 335 – 350 miles range with battery specific
energy of 150 Wh/kg
Range for 15% block fuel reduction
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Single Isle 737-Class Aircraft
9
Pompet et.al. (Germany):
• Single aisle 180 passengers, 3300 n
miles base line
• 13 % block fuel reduction for 1500
Wh/kg battery pack
• 6% block fuel reduction for 1000
Wh/kg battery pack
• May not be any benefit for battery
pack with less than 1000 Wh/kg
specific energyLent (UTRC):
• Single aisle 737 class, geared turbofan
• Electric motor used during takeoff
along with gas turbine engine
• Addition of turbogeneartor during
takeoff more effective
• Batteries greater than 1000 Wh/kg
required to be competitive with
turbogenerator
Boeing SUGAR Volt
• Parallel hybrid, ~150 PAX
• 1-5 MW, 3-5 kW/kg, 93%
efficient electric machines
• 60% efficiency improvement
over 2005 baseline aircraft if a
renewable grid is assumedBattery requirement: 750 Wh/kg
Single-aisle 737 class hybrid electric
aircraft will require 1000 Wh/kg or higher
battery specific energy
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Hybrid Electric Helicopters
10
0
50
100
150
200
250
300
350
400
Baseline (no electric)
Hybrid – 290 Wh/kg
Hybrid – 523 Wh/kg
Ra
ng
e, M
iles
Light Utility
(Sikorsky S-
300 C)
Multi-Mission
(Bell 206 L4)
Medium Utility
(Airbus EC
175)
Light Utility Multi Mission
Medium Utility
Specific energy
at pack level
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Battery Chemistry Possibilities
11
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Reduction in Cell-to-Pack Battery Specific Energy
12
CellBattery
Pack
Specific
Ene
rgy (
Wh/k
g)
Typically
40 – 50 %
decrease Reduction in Specific Energy
From Cell to Pack:
• Thermal management
• Battery management
system
• Safety features
• Packing
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Limits on Useable Specific Energy
13
0
100
200
300
400
500
600
700
800
0 100 200 300 400 500 600
Us
ea
ble
En
erg
y D
en
sit
y (
Wh
/L)
Useable Specific Energy (Wh/kg)
Tesla Model S
Nissan Leaf
Gr-NMC622
Li-NMC622
Li-S
Li-O2
J. Electrochem. Soc., 162 (6), A982 (2015),
Energy Environ. Sci.,2014, 7, 1555-1563
Mg-ion
Based on current packaging and integration technologies
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Notional Progression of Battery Capability at Cell Level
14
300 – 350 Wh/kg
300 – 400 Wh/kg
400 – 500 Wh/kg
> 500 Wh/kg,
Si anode, advanced cathode
Li metal anode, advanced cathode
Li metal anode, sulfur cathode
Li – oxygen, Beyond Li chemistries
5 Years 10 Years 15 Years
SOA – 250 Wh/kg at
cell level
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Projected Advances in Battery Technology
15
0
100
200
300
400
500
600
700
800
17 18 19 20 21 22 23 24 25 26 27 28 29 30
Year2017 2030
Sp
ecific
En
erg
y (
Wh
/kg
)
Cell
15 % loss from cell to
pack (current)
32 % loss from cell to
pack
Assuming 8% increase per year at cell level
Innovation required in:
• New chemistries and
materials for cells
• Pack design and
integration
Rate of increase in specific energy is typically on the order of 5 – 8% per year
Specific energy loss from cell to pack is typically 50 to 60%
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Dependency of Evolution of Electrified Aircraft on Battery Advances
16
150-170
Wh/kg400
Wh/kg
300
Wh/kg
500
Wh/kg
600
Wh/kg
700
Wh/kg
800
Wh/kg
2-3
passenger ,
200 miles
2-3 passenger
VTOL, 100
miles
4 passenger
VTOL, 60
miles
4 passenger
VTOL, 100-
120 miles
30 passenger
300 miles
20 passenger
300 miles
70 passenger 800
miles (15% block
fuel reduction)
Light utility
helicopter
1000
Wh/kg
Single aisle
737 class70 passenger
1000 miles
(15% block
fuel reduction)
20 – 30
passenger
> 400 miles
(?)
All Electric
Hybrid Electric
2021 2025 20302028 ??? ??? ??? Timeline
Notional timeline based on optimistic
projections
More system analysis required to identify
requirements
Today
Pack
Level
Wh/kg
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Multifunctional Structures With Energy Storage Capability
17
Electric motor
Battery
Pack
Replace battery with
multifunctional
structural element
Batteries with some load bearing capability or structure with energy storage capability ????
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Application of Fuel Cells
18
X-57 FUELEAP System
Using Solid Oxide Fuel Cell:
Power output: 120kW
(161hp) max continuous,
158kW (209hp) peak
• Specific power: 314 W/kg
(0.19 hp/lb)
• Efficiency: 62% (10k ft, std
day)
Solid oxide fuel cells
• High efficiency
• Low power density at system level
• Potential range extender for small hybrid electric aircraft
• Durability, thermal cycling
PEM fuel cell:
• Needs hydrogen
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Turboelectric Aircraft
19
Benefits of Turboelectric Propulsion:
• Enables new aircraft configurations
• Decoupling of speeds of turbine and fan
• Multiple fans can be driven by one gas
turbine, providing high propulsive
efficiency due to higher bypass ratio
(BPR)
• Can enable boundary layer ingestion
capability Boundary Layer Ingestion Testing at
NASA GRC
Challenge:
• Development
of distortion
tolerant fan
NASA GRC • RESEARCH AND ENGINEERING DIRECTORATE
Advanced Single Aisle Turboelectric Concept
20
Single-aisle Turboelectric Aircraft with Aft Boundary
Layer Ingestion (STARC – ABL)
• Conventional single aisle tube-and-wing configuration