Public transportation is the preferred mode of transportation for many people at Boston, especially for broke college students. The Boston subway system, also known as the "T", is the nation's oldest subway system and is plagued by sweltering hot and sweaty conditions for passengers waiting for their often delayed train. These unfavorable conditions caused by system inefficiencies are not only uncomfortable, but also fail to capture revenue-generating energy resources for the city.
What it does:
We have provided a series of implementable recommendations that taps into the otherwise wasted energy generated by arriving and departing trains. Utilizing regenerative braking systems, we can capture the kinetic energy released by trains braking as they pull up into the platform. By storing the energy into flywheel energy storage systems, the energy can be reused immediately to accelerate a nearby departing train. Any excess stored energy can be resold to the local electricity markets, thus generating additional revenue for the Boston MBTA. Our pilot system in Central Square station can generate over $60,000 in direct electricity savings each year and potentially $200,000 in revenues from selling back to electricity markets when prices are high (since the MBTA gets a fixed base rate for buying electricity).
Excess heat as a result of friction during breaking can also be reduced and redirected. 50% of the heat dissipated by trains can be eliminated with the installation of regenerative braking systems. The other 50% of waste heat can be redirected away from the station with the installation of water cooler heat exchanger. This system will absorb the heat trapped in the station and transfer the heat energy to the established steam pipelines currently running underneath Cambridge. Through this system, the unwanted station heat can be transported and sold to nearby Boston hospitals and biotech facilities.
Challenges we ran into:
The most challenging part of this project was designing our system to be feasibly retrofitted into the existing infrastructure of such an old and established subway system. More specifically, figuring out how and where we can install our proposed systems, and also researching what pipelines or other existing infrastructure in the Cambridge/Boston area we can take advantage of in order to minimize construction costs. We carefully assessed current solutions to similar problems in other major cities in order to develop a plan that would best serve the Cambridge/Boston community and increase the energy efficiency of the subway network, making it more sustainable and pleasant for our community.
Accomplishments that we're proud of:
Identifying technologies and tapping into current infrastructure to utilize otherwise wasted energy, allowing us to solve the heat problem in subway systems while also generating some sort of revenue.
What we learned:
Energy storage systems, waste thermal energy, recycling energy
What's next for MiTrain:
Massachusetts has several initiatives and grants dedicated to increasing energy storage. We plan to submit and pitch our proposal to Cambridge City Council.