As much as 13 GW of wind hybrids is in interconnection queues in the US, and 160GW of solar. Half of the wind capacity is to be co-located with storage, the other half with solar, while most of the solar backlog is co-located with storage, said Will Gorman, a researcher at the Lawrence Berkeley National Laboratory (LBNL).
A decline in the costs for each component is pushing growth of these projects, Gorman said during a panel discussion on hybrid project opportunities on the second day of the Clean Power 2021 virtual summit.
Key drivers are falling battery costs, as well as growth in non-dispatchable renewables, such as wind and solar. The investment tax credit (ITC) can also now be applied to co-located storage systems.
Gorman said that there can be, on average, a $10/MWh value loss for storage co-located with wind or solar. That is compared with storage located at the more valuable nodes, where market prices are most volatile. But averages can be deceiving, an LBNL study found, and both co-location and independent siting of batteries makes sense.
By 2025, installed storage capacity in the US will increase four-fold, according to research consultancy Wood Mackenzie. Rocio Herrera, a project manager in wind at consultancy DNV GL, cited a prediction by the Energy Information Administration (EIA) that the US will see 250TWh of storage by 2050.
Siting remains a challenge, for co-location of wind-solar, as does interconnection to the grid. The wind is not necessarily at its strongest in the sunniest places — though Texas and other parts of the US’s south-west do offer both strong wind and solar resources, said panellists.
Interconnection queues can be lengthy. Wind and solar power may or may not need to be offloaded at the same time. Modelling of the interconnect loads is further complicated by the fact that the storage is newer and has often not been incorporated into the original models.
Incentives need to be made complementary, including in terms of the construction schedules. Wind traditionally benefits from the production tax credit (PTC), which is offered for the first ten years after building is complete. In contrast, solar and storage — the latter is eligible only if it is co-located — benefit from the investment tax credit, which is upfront and based on the capital investment.