Falling battery prices and the growth of variable renewable generation are driving a surge of interest in “hybrid” power plants that combine, for example, wind or solar generating capacity with co-located batteries. While most of the current interest involves pairing photovoltaic (PV) plants with batteries, other types of hybrid or co-located plants with wide-ranging configurations have been part of the U.S. electricity mix for decades.
A newly released briefing from Lawrence Berkeley National Laboratory tracks and maps existing hybrid or co-located plants across the United States while also synthesizing data mined from power purchase agreements (PPAs) and generation interconnection queues to shed light on near- and long-term development pipelines. This work follows earlier Berkeley Lab research that analyzed the motivations and options for deploying hybrid plants within the bulk power system, as well as the value of co-locating hybrid plant components relative to siting them independently.
The scope of this data summary includes co-located hybrid plants that pair two or more generators and/or that pair generation with storage at a single point of interconnection, and also full hybrids that feature co-location and co-control. ‘Virtual’ hybrids that do not include co-location are excluded. The focus is on larger, 1 MW+ systems; smaller (often behind-the-meter) projects are also increasingly common, but are not included in this data synthesis. This briefing is accompanied by two data visualizations, one focused on online projects and the other on those in interconnection queues.
Based in part on Form EIA-860 data, there were at least 226 co-located hybrid plants (>1 MW) operating across the United States at the end of 2020, totaling more than 30 GW of aggregate capacity (see map below). Among these operating plants, the most common configuration is PV+storage (with 73 projects totaling 992 MW of PV and 250 MW of storage), followed by several different fossil hybrid categories (34 fossil+PV, 29 fossil+hydro, and 21 fossil+storage plants—each dominated by the fossil component) and 14 wind+storage plants (with 1,425 MW wind and 198 MW of storage). But there are roughly a dozen other configurations as well, each numbering in the single digits and including wind+PV, wind+PV+storage, biomass+hydro, geothermal+PV, and others.
Among the existing generator+storage hybrids, the storage:generator capacity ratios and storage durations are highest, on average, when storage is paired with PV. This suggests that PV+storage hybrids are used to serve arbitrage and capacity needs in addition to delivering ancillary services. Storage paired with wind and fossil assets, meanwhile, has largely been intended to meet ancillary service needs, to date.