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Dynamic Wireless Power Transfer

Grid Impacts Analysis

Tony Markel, Andrew Meintz, 

and Jeff Gonder

EPRI EV IWC Meeting

Atlanta, GA

November 19, 2015

NREL/PR-5400-65449
2

Electrified Roadways Implementation Benefits

• Electrified Roadways Opportunity 

o Expand vehicle utility and value 

o Integrate with renewable resources and grid operations

• Electric Vehicles (EVs)

o Roadway electrification extends operable range

• Plug-In Hybrid Electric Vehicles (PHEVs)

o Fully electrified operation possible even with a mediumsize battery

• Hybrid Electric Vehicles (HEVs)

o Fuel displacement from a more-electrified operation
3

Background Analyses

• Electrified roadway grid impact analysis builds on NREL's previous incremental inmotion wireless power Transfer (WPT) rollout evaluation for urban areas [1]. 

• Used 2010 Census Combined Statistical Area (CSA) geographic boundaries to 

analyze road segments and vehicle miles travelled (VMT) within region.

• Datasets from NREL's Transportation Secure Data Center [2] were paired with a 

specific CSA in multiple regions to investigate applications to seven CSA regions.

• Work concluded that if 1% of the road miles within a geographic region were 

electrified, 25% of the fuel used by the “fleet” could be displaced. 

• Simulated hourly loads to show some alignment with renewables generation and 

potential curtailment reduction.

https://www.youtube.com/watch?v=gqfih5swB8Q

Source: NREL
4

Multi-Platform Analysis Completed

• Heavy Truck Simulations

o Target moderate- to high-grade roadway segments

o 100-kW WPT on 1.5% or greater grade allows engine 

downsizing and 9% fuel savings

• Light-Duty Vehicles

o Target urban areas and highly utilized roads show 

1% of roadway cuts consumption by 25%

• Transit Bus Analysis

o Minneapolis route data used to select 

charge points and battery sizes

o For same net present value as HEV 

solution, WPT bus achieves 50% cut 

in consumption from conventional
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ARC: 2011 Regional Travel Survey

• Down select of Atlanta CSA from the 

previous analysis – consistent fullweek data for vehicles in the study

• Focus on most used roadways in the 

incremental in-motion WPT rollout 

provides scenario for initial 

deployment 

• Roadway segments (green network on 

the map) and the ARC travel data 

generate weekly time distribution for 

vehicle miles travelled (graph below) 

ARC - Atlanta Regional 

Commission [3]

HPMS – Highway Performance 

Monitoring System

Previous analysis roadway (green) to selected roadway 

from 2013 HPMS (black) with the 2010 Census CSA 

Boundary (blue dashed) and 2013 CSA boundary 

(orange)

Hourly distribution of VMT on 

selected roadways for a "typical" 

week of travel
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Electrified Roadway Load Forecasting

Electrified roadway grid 

load for a "typical" week 

on the designated roads 

as a percent of total 

HPMS defined VMT 

• The Federal Highway Administration's HPMS 2013 data set was used on the road 

segments highlighted in black on the map to produce daily VMT for the proposed 

electrified roadways

• The grid power used by these roads for various levels of total VMT is shown in the 

graph below using the weekly distribution from the ARC 2011 study 

• Grid power has been calculated to 484 Whr per VMT based on the 2014 RAV4 EV 

(similar 26 mpg as the production-weighted MY2014 car and truck EPA fuel economy) 

Representative of fleet consumption
7

Seasonal Load Scenarios – Fall

• Atlanta region grid load determined from the power consumed within the 2013 

Atlanta CSA (orange line on map) taken from NREL 2013 Eastern Renewable 

Generation Integration Study (ERGIS) [4]

• The grid load for the four seasons has been determined by averaging the hourly 

load throughout a week for each hour within the season

• Graphs show hourly load growth with electrified roadway load over the baseline at 

from each fractional VMT scenario (colored text indicates the percent) 

Electrified Roadway Scenarios added to Typical Fall Grid Load

Vehicles : Grid

5% = 0.76%

10% = 1.52%

25% = 6.17%

...
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Seasonal Load – Winter & Spring

Electrified Roadway Scenarios added to Typical Spring Grid Load

Electrified Roadway Scenarios added to Typical Winter Grid Load

Vehicles : Grid

5% = 1.16%

10% = 2.32%

25% = 5.80%

...

Vehicles : Grid

5% = 1%

10% = 2%

25% = 5%

...
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Seasonal Load – Summer & Highest Week

Electrified Roadway Scenarios added to Typical Summer Grid Load

Electrified Roadway Scenarios added to Highest Week Grid Load

Vehicles : Grid

5% = 0.70%

10% = 1.17%

25% = 4.28%

...

Vehicles : Grid

5% = 0.62%

10% = 1.24%

25% = 3.10%

...
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Result Discussion

• The findings indicate that electrifying 5% of all VMT on high-capacity roads in the 

Atlanta area could increase peak hour grid demand by a little over 100 MW, which 

is a little less than a 1% load increase

• 5% electrification of VMT is the lowest roadway electrification case examined in 

the preceding grid analysis

o Represents an aggressive penetration of WPT-enabled vehicles 

o HEVs have been commercial for over 15 years, but still account for less than 3% of new 

car sales [6] 

Absolute and incremental 

percentage load impacts 

from the 5% of light-duty 

VMT electrified roadway 

scenario added to the 

baseline highest yearly 

grid load week 
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Results

• Not included here

o Stationary charging of the vehicles along with electrified roadway power

o Differences in powertrain implementations’ ability to utilize roadway

– All EVs: fully functional

– HEVs/PHEVs: should have large enough e-drive system to maintain highway speeds

o System layout and its impacts on power delivery and quality

o Integration of both light-duty and heavy-duty utilization profiles

• Future analysis and testing should consider other WPT implementation 

challenges

o Fall and winter midday trough accentuated with electrified roadway loads

o Infrastructure and load profile differences depending on the class of vehicle 

(light, medium, heavy-duty) and powertrain to be served (EV, PHEV, HEV)

o The ability to charge batteries rather than just meeting the instantaneous 

driving load

o Data presents “hourly” average power and its impact 

– Analysis by Highways England in [7] has shown that sub-hour maximum power flow is 

influenced by the design and layout of the WPT system 
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Highways England Report – System Layouts

Example DWPT System- Layout 1 [7] Example DWPT System- Layout 2 [7]

Power demand per mile of motorway for 30% light vehicle and 50% 

heavy vehicle penetration at 55 mph, DWPT system layout 1 [7]

Power demand per mile of motorway for 30% light vehicle and 50% 

heavy vehicle penetration at 55 mph, DWPT system layout 2 [7]

DWPT – dynamic wireless 

power transfer
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Simulated Power Flows Impacted by Speeds and Headway 100 kph, 50 kW, 55-m headway 40 kph, 50 kW, 27-m headway

Dynamics 

of 0-150 

kW in 

0.1s

Even higher 

at lower 

speeds
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Discussion – Roadway WPT Scenarios

Transmission Line

Positive 

Grade

Transformer

Central Inverter

Local Inverters

Group of Primaries

A roadway WPT system based on [8];

buffering infrastructure limits impact on power systems

Many WPT mechanization concepts for dynamic power transfer, one example is shown 

in the image below 

Many open questions as to what should be the design criteria for such systems

• How should the spacing of primaries along the roadway be optimized for power 

delivery to various load sizes? 

• What is the minimum power level that 

secondary receivers on light-duty and 

heavy-duty vehicles need to provide the 

infrastructure flexibility?

• How does traffic impact peak power 

required by the grid and what limitation 

should be placed on transients? 

• Would the use of integrated energy 

storage with the daily / weekly traffic 

patterns become a valuable grid device?
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Potential Impacts to Vehicle Adoption

• ORNL analyzed 

several regions 

for vehicle 

preferences

• Roadway WPT 

vehicle 

capabilities add 

5-20% to 20yr 

adoption 

potential [9]

SF=San Francisco

SD=San Diego

AVG=Average SF/SD

Bat10=10% lower cost

5% 

increase

20% increase
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Testing and Demonstration Activities

• Multi-unit testing for grid integration

o Three 3-kW units on a distribution grid with varied 

DC sources and level 2 AC chargers

• NREL campus shuttle application

o 1.5-mi loop; 60–75 circuits per day; 2–3 charging 

locations

• Future opportunities

o Target airport shuttles with fixed routes

o Medium-duty delivery routes 
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References

1) Burton, E.; Wang, L.; Gonder, J.; Brooker, A.; Konan, A. "Fuel Savings Potential from Future InMotion Wireless Power Transfer." Proceedings of the 3rd Conference on Electric Roads and 

Vehicles (CERV), February 2015, Park City, UT. www.nrel.gov/docs/fy15osti/63758.pdf

2) Transportation Secure Data Center, www.nrel.gov/tsdc (2015). National Renewable Energy 

Laboratory. Accessed 9/22/2015.

3) Atlanta Regional Travel Commission, Regional Travel Survey: Final Report, November 2011.

4) Eastern Renewable Generation Integration Study, 

http://www.nrel.gov/electricity/transmission/eastern_renewable.html . National Renewable 

Energy Laboratory. Accessed on 11/3/2015.

5) U.S. Energy Information Agency. "Annual Energy Review, Table 8.12A." Accessed on 

September 2015. http://www.eia.gov/totalenergy/data/annual/showtext.cfm?t=ptb0812a

6) Cobb, J. Jan. 6, 2015. “2014 December 2014 Dashboard.” HybridCars. Accessed on 

09/01/2015. http://www.hybridcars.com/december-2014-dashboard/

7) Highways England. “Feasibility Study: Powering Electric Vehicles on England’s Major Roads.” 

07/28/2015. http://www.highways.gov.uk/knowledge/publications/1902/

8) Chen, Liang; Nagendra, G.R.; Boys, J.T.; Covic, G.A. "Double-Coupled Systems for IPT Roadway 

Applications," IEEE Journal of Emerging and Selected Topics in Power Electronics vol. 3, no.1, 

pp. 37, 49, March 2015.

9) Zhenhong Lin; Jan-Mou Li; Jing Dong. “Dynamic Wireless Power Transfer: Potential Impact on 

Plug-in Electric Vehicle Adoption.” SAE 2014-01-1965.