Massachusetts Bay Transportation Authority – Philip Picotte – 2016

Goals 

The Massachusetts Bay Transportation Authority enlisted EDF Climate Corps fellow Philip Picotte to find energy and cost savings by reducing peak demand across its electric distribution system. The MBTA operates the nation’s fifth busiest public transit system and is the largest electric user in Massachusetts. Because the Authority’s traction power systems and built infrastructure consume up to 80 megawatts during peak periods, strategies to reduce, shift or cycle major electric loads means saving millions of dollars in demand charges every year.

Solutions

Picotte analyzed a year’s worth of hourly interval data to better understand key drivers behind the MBTA’s electric demand. He found that powering trains and electric busses, and keeping passengers comfortable, accounts for 75% of electric load variability, but 25% remains unexplained. Philip identified innovative opportunities for demand response at the Authority’s maintenance facilities and considered the potential of load-reducing distributed generation. In particular, wayside energy storage offers a low-carbon approach to reduce peak demand by capturing energy from trains’ regenerative braking systems that would otherwise be wasted.  From supercapacitors to flywheels, Picotte researched storage technologies and calculated the financial benefits. The analysis found that wayside energy storage would pay for itself at various substations across the MBTA’s power network, while improving voltage stability and the agency’s resiliency to blackouts.

Potential Impact

Over a decade, five installations of 1 MW wayside energy storage could reduce the MBTA’s peak demand charges by $17 million, while also capturing 32 million kWh from regenerative braking. This accounts for 2,090 metric tons of carbon dioxide and $2 million in wholesale energy savings. Picotte’s work enables the MBTA to proceed with procuring energy storage and consider options for demand response and distributed generation.