The Challenge

Bullitt County, Kentucky has experienced tremendous growth over the last few decades. As a result, the Bullet County Central Library needed a larger facility to support the many functions and purposes of the library’s main branch. The new Central Library is a 45,000-square-foot building displaying a green architectural design. Some of the environment-friendly features include geothermal heating, LED lighting, a 240 kilowatt (kW) solar array, and a 110-kW energy storage system (ESS). Being such a large facility, the new location was placed on a demand charge heavy electric rate. Louisville Gas & Electric’s Time-of-Day Secondary (TODS) service rate includes three separate demand charges, totaling almost $21/kW. Rate TODS also entails several demand ratchets, or billing minimums, that would undoubtedly add to each month’s demand charge expense.

The Solution

A Delta LG Chem 110-kW ESS, equipped with ETB Controller and Acumen AI™, was installed at the new library. The system was configured for demand charge management, with Acumen AI dynamically forecasting load and optimizing dispatch in real time to shave peaks and reduce utility charges. By leveraging dynamic economic dispatch, the system becomes increasingly efficient as more interval data is collected. Now that the facility is operating at full capacity and energy requirements are established, the fully integrated solar and energy storage system also enables a rate switch to further decrease demand costs.