The battery system is expected to earn $80,000 per year by providing energy to the local utility during peak summer demand periods, while saving $57,000 per year by reducing the hospital’s own monthly and annual peak consumption.
The Boston Medical Center, New England’s busiest trauma and emergency services center, installed a 572 kW, 1,271 kWh battery storage system manufactured by Tesla. The system is connected to the hospital’s 480 V chiller switchboard.
The nonprofit Clean Energy Group described the project and its expected savings in a report titled “Resilient Power Project Case Study: Boston Medical Center.”
CEG said the project demonstrates the opportunity for hospitals to use battery storage to reduce energy costs, and to reinvest savings to improve patient care.
CEG projected that the battery system, which cost $1.33 million in total, will cut the hospital’s annual electric bill by $131,175. Dividing the cost by the annual savings results in a simple payback period of ten years. But from the hospital’s perspective, because it received a state grant for the project of about $400,000, the simple payback period is projected to be seven years.
Cost savings
Most of the utility bill savings are due to the battery system’s participation in a Massachusetts program that will enable the hospital’s utility to draw on energy stored in the battery during summer peak energy demand events. That program pays $200 per kW made available each summer, with that rate guaranteed for the life of an initial five-year contract. The hospital expects to earn $80,000 per year from participating in the program, suggesting that it expects to commit 400 kW to the program each summer.
The hospital will also use the battery to reduce both its monthly and annual peak usage of electricity. That will reduce the utility transmission and distribution capacity charges it must pay, yielding expected savings of $40,000 per year, based on the current charge, approved by state regulators, of $27.51 per peak kW per month. By reducing the annual peak charges assessed by New England’s regional grid operator ISO-NE, the hospital expects to save $17,000 per year.
The annual operations and maintenance costs for the battery system are expected to be $6,600.
Solar initiatives
The hospital previously contracted for a 26% share in a 60 MW solar facility in North Carolina, which is expected to match the hospital’s annual electricity consumption.
The Boston Medical Center Health System also installed a 356 kW solar system on its administrative building, and uses the system to offer some eligible patients monthly utility bill credits through a virtual net metering program.
Technical assistance
Sandia National Laboratories and the Clean Energy States Alliance, a coalition managed and staffed by CEG, provided technical assistance to the hospital in designing its battery system.
