The Energy Information Administration (EIA) reports the United States had a 4.5GW total capacity of energy storage by the end of 2021. The wellspring of storage development has come in response to a variety of beneficial grid services storage can provide, especially when paired with renewable energy. In fact, EIA reports more than 60% of upcoming battery capacity will be co-located with solar PV systems.
Energy storage duration refers to the amount of time a battery or other energy storage system can dispatch energy from a full charge until it is depleted. Most batteries on the grid today range from an hour or less to four-plus hours, and there are some outliers that can provide continuous power for 12 hours or more.
Duration has largely been found to be tied to the function the storage system provides, according to EIA. EIA categorizes battery functions in two main buckets: grid services and electrical load shifting. Grid services, which entail dispatching power for brief periods, sometimes for minutes or even a few seconds, help maintain grid stability and reliability. Electrical load shifting involves shifting electricity from times of low demand to times of high demand. This service is particularly important when paired with the diurnal generation of solar energy.
The grid services-only segment averages 1.15 hours in duration. Hybrid, dual-service storage averages 2.95 hours, and electric load shifting-only batteries average 4.15 hours.
More than 40% of US battery energy storage can perform both grid services and load shifting activities. About 40% performed load shifting activities, and the remaining 20% performed only short-duration grid dispatch services.
In the late 2010s, the bulk of the energy storage added to the grid was focused on short-duration services, but as solar energy becomes an increasing feature of the grid, longer-duration load shifting services are coming under focus. Most co-located solar and energy storage systems feature a battery with durations of four hours or more.
Innovation and growth outlook
EIA forecasts that by the end of 2023, energy storage deployment across the nation will have more than doubled from current levels to about 10GW. With this growth comes a host of innovative opportunities.
In the US, lithium-ion batteries are the dominant source of both short and long duration storage, but other chemistries and designs are being actively considered, especially in the long duration use case. pv magazine has covered developments in lithium-ferro-phosphate batteries, sodium-ion batteries, flow batteries, and other atypical designs like compressed air energy storage, iron-air energy storage systems that rely on oxidation, and gravity-based energy storage towers.
At last November’s COP26 climate summit, a long-duration energy storage consortium was formed. The consortium estimates between 85 and 140 terawatt-hours of LDES deployment will be required to achieve a net-zero grid by 2040. The council also estimates a need of 1 TWh of LDES deployment by 2025 to pace for decarbonization by 2040.
These deployment projections would entail a $1.5 to $3 trillion investment. The council said renewable energy stored in these technologies could eliminate 1.5 to 2.3 Gigatons of carbon dioxide emissions, or about 10-15% of global power emissions.
If these emissions reduction targets are to be achieved, there must be carbon-free energy charging the batteries. The world will need 5.2TW of solar power generation capacity by 2030, and 14TW by mid-century, to have any chance of limiting global average temperature rises this century to 1.5 degrees Celsius, according to the International Renewable Energy Agency (IRENA).
The world will have to install 450GW of new solar capacity each year – most of it utility scale – for the rest of this decade, with China and India to lead Asia to a roughly half share of the world’s installed PV capacity in 2030, the report’s authors estimated.
Based on current deployment levels, IRENA director-general Francesco La Camera, recently wrote, “Progress across all energy uses has been woefully inadequate.”
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