Chicago Transit Authority Energy Initiatives Energy Storage Association April 19, 2017

Big Challenges with Energy Storage at CTA Location, location, location. ROI CTA’s electricity is cheap – 7 cents/KWh Equipment and infrastructure is expensive and complex (but getting cheaper and easier) Energy savings and revenue opportunities not a sure thing

The Case for Wayside Energy Storage System (WESS) When there are no accelerating trains, regenerative braking energy dissipates as heat. WESS can capture excess braking energy and discharge it to the third rail, provide voltage support, or participate in grid ancillary markets. To estimate ROI, two issues need to be addressed first: The opportunity from “breaking events” Physical space WESS

CTA WESS Feasibility Study (Consultant: Mott McDonald) 1. Load flow analysis – a model of power flows along the entire Red Line and connecting sections How much electricity is being captured from regenerative braking trains today? How much more electricity could be captured if we installed WESS? Where are the best locations to install WESS to capture and reuse the most electricity? 2. Site surveys – physical assessment of high-potential WESS locations Are high-potential locations accessible and physically fit for the installation of a WESS? Load flow analysis data inputs: Rail car data – motor characteristics, mass, length, power, regenerative braking characteristics Signal data – line layouts, stations, junctions, gradients, speed limits Traction power data – substation connections, substation equipment ratings Planning data – train schedules, passenger loads, dwell times at stations

CTA Rail Stats Getting people around Infrastructure 1,400 rail cars 239 million passengers in 2016 78 million miles run in 2016 Infrastructure Runs on continuous electrified (“third rail”) network 8 lines 145 stations 66 substations 1,400 rail cars 700 cars with regenerative braking deployed on Red, Green, Purple, Yellow, and Pink Lines in 2010-2015 (“5000” series) 700 without regenerative braking (“2600” & “3200” series) to be replaced beginning in 2020 About 430GWh in consumption, annually, costing $30M WESS modeled on Red Line (red arrows) 5000 trains also deployed on Green, Pink, Yellow, and Purple Lines (blue arrows).

Regenerative Braking Performance 5000 series trains weigh more than older cars and have additional electric features. A single 5000 car uses more electricity than an older car, but… In live simulation in 2010, a group of 5000 series cars running on the same segment of track used 20% less electricity than older cars. Since the full 5000 series deployment, electricity consumption is 10% lower than predicted—and that’s with only half the fleet with regenerative braking.* Wow! *Validated by regression model forecasting energy consumption and load flow study.

Load flow analysis data inputs: Rail car Signal Traction power Planning Motor characteristics Mass Length Power Regenerative braking characteristics Line layouts, Stations Junctions Gradients Speed limits Substation connections Substation equipment ratings Train schedules Passenger loads Dwell times at stations

Modeling Results 6 candidate substations identified. Model simulated electricity savings with various configurations of one, two or three WESS units in substations. One WESS achieved 436MWh in annual savings; adding a second only produced 7% more and adding a third resulted in no additional benefit. A single WESS saved 80-150KWh per hour but… There was only 20-80KWh savings for the system as a whole. CTA’s network and third rail composite mean regen energy can flow two miles or more. WESS ends up intercepting energy that would go to other trains, making other substations work harder.

Payback Estimate for Single WESS Unit Specs 2000 Amperes Rated between 6 and 8 KWh storage capacity ROI Cost of $600-700K up front $30K in energy savings per year 20-year payback period Does not include revenue from ancillary markets like Frequency Regulation, but capacity for participation likely to be low, intermittent.

Other CTA Energy Initiatives: E-buses Progress 2 in service, 20-30 in planning stage Existing 2 are charged in garage—slow charge New cohort would charge in route—quick charge Expect savings on energy, maintenance Challenges Buying E-buses is easy; installing charging stations is hard. Limited number of locations have space and optimal electric utility interconnection Concerns about service delays due to charging time when there is bad weather, constructions, or accidents. There is little margin for error with a tight route schedule.

Other Energy Initiatives: Solar Cook County sponsoring “community solar business case studies” funded by Department of Energy grant Array placed on government-owned land Electricity generated sold to surrounding neighborhood. CTA’s rail maintenance facility one of 15 sites selected out of 110 applicants. Study will determine feasibility, potential ROI

Questions? Pete Ballard Chicago Transit Authority 773-960-4016 pballard@transitchicago.com