Houston Metro Deploys 12 MW Charging Depot for 200-Bus Electric
- EVs Fleet & Depot Charging News
Marin Holt
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- 6 minutes read
- 12 MW total charging capacity at Houston Northwest depot supports 200 battery electric buses by 2027
- $84.3M project includes $31.7M FTA Low-No Emission Vehicle Program federal grant
- 150 Level 2 chargers (19.2 kW) plus 40 DC fast chargers (150 kW) with Siemens smart load management
- CenterPoint Energy upgrading 69 kV substation with dedicated 15 MVA transformer for depot power supply
- Smart charging targets 35% demand charge reduction versus unmanaged load, saving $1.8M annually
The Metropolitan Transit Authority of Harris County (METRO) broke ground on a 12 MW electric vehicle charging depot in Houston designed to support the transition of 200 diesel buses to battery electric vehicles by 2027. The $84.3 million facility at the existing Northwest Bus Operating Facility received $31.7 million from the Federal Transit Administration’s Low or No Emission Vehicle Program, with the balance funded through Metropolitan Infrastructure bonds and state matching funds.
Charging Infrastructure Design
The depot design incorporates 150 Level 2 chargers rated at 19.2 kW each and 40 DC fast chargers at 150 kW apiece, for a total nameplate charging capacity of 8.88 MW for overhead chargers and approximately 6 MW from the DCFC fleet. CenterPoint Energy is upgrading the 69 kV substation serving the Northwest facility with a dedicated 15 MVA transformer and associated switchgear, sized to accommodate a potential future expansion to 300 buses. The smart charging management system from Siemens will manage load scheduling across all 190 charge points, prioritizing overnight depot charging between 10 PM and 5 AM when ERCOT real-time prices historically average 40-60% below peak periods.
Demand Charge Management
Unmanaged simultaneous charging of 200 buses at 19.2 kW would generate approximately 3.84 MW of coincident peak demand, triggering significant demand charges under CenterPoint’s large commercial rate schedules. The Siemens system implements rolling charge windows with 15-minute demand interval monitoring, targeting a maximum simultaneous load of 2.5 MW during peak billing periods. METRO projects this demand shaping will reduce annual demand charges by approximately 35%, translating to $1.8 million in annual utility cost savings versus unmanaged charging. The system also integrates ERCOT price signals for optional opportunity charging when real-time prices drop below $30/MWh.
Fleet Electrification Context
METRO’s 200-bus electrification represents the largest single transit electrification project in Texas and one of the ten largest in the United States by vehicle count. The FTA Low-No program received $1.7 billion in FY2025 appropriations, funding 47 projects nationally. Houston’s fleet procurement covers Proterra Catalyst BE40 and New Flyer Xcelsior CHARGE NG models, with deliveries scheduled across 2026 and 2027. The completed depot is expected to reduce METRO’s diesel consumption by approximately 2.3 million gallons annually and cut fleet greenhouse gas emissions by 22,000 metric tons of CO2-equivalent per year.
Critical Analysis
The 40 DC fast chargers (150 kW each, 6 MW total) inject characteristic 5th and 7th order current harmonics from six-pulse rectifier front-ends; per IEEE 519-2022 Table 2, the facility TDD limit is 8% at the upgraded CenterPoint 69 kV substation for an ISC/IL ratio of 20-50. The 12 MW depot is a single-point new load on CenterPoint Northwest Houston requiring a 69 kV substation upgrade on the critical path.
5-Year Projection
Over the next 5 years, early adopters of Level 2 EV Charger will set regional cost benchmarks, forcing secondary markets to standardize deployment protocols or risk stranded assets.
Critical Perspective
The article highlights a 12 MW charging depot, a significant investment for Houston Metro’s 200-bus transition. However, the projected 35% reduction in demand charges, equating to $1.8 million annually, mirrors the optimistic savings seen in Los Angeles Metro’s earlier, smaller electric bus charging project, which ultimately faced higher than anticipated operational costs. The 2006 Seattle Streetcar, despite its initial promise, struggled with consistent ridership and operational efficiency, a cautionary tale for large public transit infrastructure projects. Given the complexity of managing 190 chargers and fluctuating energy prices, how will Houston Metro ensure this system consistently delivers its projected savings without unforeseen maintenance or operational burdens?
