PlanItMetro

Net Zero Water Treatment Facility

Near the Largo Town Center Metrorail Station, Metro is constructing a water treatment facility that features a modular green roof system and rain garden to filter stormwater. The facility will manage subsurface water from the track bed and has been designed with photovoltaic panels and battery storage system to achieve net zero energy specifications. Designing the facility to net zero means the building will produce as much energy as it needs on-site, without drawing power from the electric grid, to perform the entire subsurface water treatment process.

Currently, in accordance with State of Maryland requirements, track bed water at the station is treated to balance acidity and sulfate solids prior to being discharged into the storm sewer system. New regulations require Metro to undertake more comprehensive stormwater treatment to remove also remove iron and suspended solids. Initially, expanding the current underground water treatment facility at the site was considered. However, the existing location did not have sufficient space to allow the new requirements to be met and a new treatment facility was necessary. The new treatment facility will utilize three large submersible pumps to transport the stormwater to the surface for treatment. Pumping the water to the surface presented new process load requirements, but to address these the facility has been designed with a gravity feed system that uses less energy over the life of the project to perform the water treatment process. In addition, the facility also showcases a host of operating cost reducing green building technologies, including: Read more…

Wayside Storage Battery Power System

For more than 20 years, Metro’s rail cars have captured and reused some of the electric energy that would otherwise be wasted when they brake through a process called regenerative braking. This process converts the excess kinetic energy, as the vehicle slows, to electric energy which can be stored and reused for propulsion power. Building on this technology, Metro recently completed tests to capture and utilize even more of the energy during braking through wayside battery storage.

The pilot project tests the energy storage efficiency and return on investment of a wayside Battery Power System (BPS). The BPS uses an innovative nickel-metal hydride battery that is characterized by low internal resistance. As a consequence, the battery can charge and discharge in a matter of seconds, making it perfect for wayside applications where rapid storage and discharge of propulsion power is required. Through this BPS storage system, the kinetic energy that would previously have been dissipated as waste heat can now be productively reused to power railcars and reduce overall energy consumption. Read more…