1MW/4 Hour Battery Storage Installation at CSU Dominguez Hills
As campuses increasingly adopt energy efficiency and renewable energy from photovoltaic systems, battery storage is becoming a key approach for lowering utility costs and creating grid-responsive campuses. The central plant team at CSU Dominguez Hills recently completed a 1MW/4-hour battery storage project that is expected to provide significant savings through peak demand reduction. The project is one of the largest “behind-the-meter” storage projects in Southern California, occupying space of less than 2000 ft2 while saving approximately $3,000 to $7,000 in demand-charge fees per month.
Creative financing allowed the project to be installed with little or no initial costs to the campus, saving up to $80,000 annually, and lowering the campus carbon emission by reducing the peak demand.
Although battery storage systems do not reduce total energy consumption, they can reduce the peak demand from the grid, helping utilities avoid the use of costly and less efficient ‘peaker’ plants, and effectively reducing the total greenhouse gas emissions resulting from campus operations. The central plant team at CSUDH estimated that approximately 60 percent of total utility costs are impacted by the monthly peak load. An evaluation of past energy bills reveal that demand charges have more than doubled over the past ten years, while the increase in energy charges has remained minimal.
Installation of the battery system adjacent to the central plant.
Because large-scale battery storage is an emerging and competitive market, the campus team was able to evaluate competing battery system providers to identify the best alternative in terms of cost and functionality. However, as with any new technology, this required the campus to navigate unfamiliar challenges related to permitting, construction and financing the project. The campus ultimately decided to partner with power integrator Stem, using batteries provided by Tesla, with a contract that required little upfront investment from the campus. The campus utility provider, Southern California Edison, partnered with the campus in creating an agreement that would work in concert with other utility programs. Under the agreement, Stem is paid mainly by SCE, with the campus receiving the benefits from reduced peak demand charges. The campus has also pledged to further reduce peak loads during demand response events by shedding building loads wherever possible.
The battery systems were ordered for delivery in October of 2017, taking advantage of Tesla’s production capacity before a set of large international orders came online. The equipment was stored on site until construction could take place a few months later, directly adjacent to the campus central plant. The installation was scheduled to coincide with a cooling tower replacement; though school was in session the work caused little disruption to campus operations.
An overhead view showing the compact footprint of the battery system.
The battery system uses Athena, artificial-intelligence software that predicts weather patterns and campus loads, automatically controlling battery charging to take place during low load times and ensuring that batteries are fully charged when needed to offset peaks. Athena provides a real-time visual display of campus energy use and the impact of the battery storage system when it kicks in. Charting the campus energy use (below) shows the grid-supplied energy peaks being capped at a consistent level as the battery system fills the gap between the peak load and the predetermined utility maximum.
This battery and software solution is projected to save the campus approximately $80,000 per year in time-of-use utility charges, based on a 4.8 MW annual reduction, multiplied by the current utility peak demand rate of $18.21. Battery storage provides additional benefits, for example, the flexibility to adapt to potential utility rate changes, and may add to the value of solar, fuel cells, and other on-site generation. Beyond this project, Stem now manages a system of over 800 storage systems, creating a ‘virtual power plant’ that helps SCE and other utilities to stabilize the power grid. As these storage systems expand, they may be used to counter the challenges resulting from solar energy trailing off as evening demand ramps up, commonly referred to as the ‘duck curve.’
Screenshot of the system interface shows the total campus load in orange, and the utility-supplied power in green. Daily temperatures are shown on the red line at top.
The campus has used the project for outreach, and features it on campus tours for classes, faculty, students and staff. The ability to view data from the battery storage as it executes a drop in the campus utility load is useful for faculty integrating energy concepts into their classes.
As an early adopter of aggregator-funded battery storage, CSUDH was one of the first to negotiate the complex agreement between a utility, a private vendor, and campus entities. Through this process the campus team developed best practices that may serve as a model for campuses considering such technology. For example, PG&E has approached CSUDH about using the campus for a course on microgrids, and widely sharing this innovative approach as a best practice in order to advance the adoption of campus-scale energy storage.
Images courtesy of CSU Dominguez Hills.