Abstract
Behind-the-meter generation from variable renewable energy is a potential pathway for new data centers to obtain power more quickly and more sustainably than interconnecting to existing electrical grids. Energy storage is needed to accommodate the variability of wind and solar energy across multiple timescales. Hydrogen from electrolysis and ammonia made from this hydrogen can be used as fuel for dispatchable power generation while offering lower $/MWh storage costs than batteries. In this work, we analyze the economics of using hydrogen, and/or ammonia along with batteries in hybrid energy storage systems to enable data centers to be powered by 100% renewables. We perform this analysis using an optimization model for the selection, sizing, and coordinated hourly operation of constituent energy storage technologies toward minimizing the levelized cost of energy (LCOE). The model uses an hourly resolution scheduling horizon of five years to account for hourly, seasonal, and interannual renewable variability. We use this model to specifically analyze the economics of to 5 MW, 50 MW, and 500 MW sustainable data center energy systems in three relevant American locations. We find that including ammonia energy storage in hybrid systems with batteries and hydrogen enables lower LCOE across all scales and locations by reducing energy storage capital investments despite deploying an order-of-magnitude more storage capacity while also enabling less investment in renewable generation. Ammonia is used for seasonal and interannual energy storage and its inclusion in these hybrid storage systems is most advantageous for larger-scale data centers in locations with high wind potential.