I'm no expert, but I did find this[1] recent (May 2020) information posted by the U.S. National Renewable Energy Lab that indicates that non-inverted power sour

I'm no expert, but I did find this[1] recent (May 2020) information posted by the U.S. National Renewable Energy Lab that indicates that non-inverted power sources (such as solar and wind) may be able to produce synthetic current frequency in order to maintain grid stability. This technology can be included within large-scale storage batteries. In addition, these inertial techniques ('fast frequency response') are digital and as a result could provide lower-latency and higher-accuracy response compared to mechanical approaches. If I understand that correctly, then eventually these approaches could phase out the need for rotational inertia (no pun intended). [1] - https://www.nrel.gov/news/program/2020/inertia-and-the-power-grid-a-guide-without-the-spin.html https://www.nrel.gov/news/program/2020/inertia-and-the-power... Edit: adding a useful quote from the linked report, below: "In the United States, the Texas grid (the Electric Reliability Council of Texas, or ERCOT) is the smallest of three main grids. ERCOT’s relatively small size, combined with its large wind deployment, has required it to compensate for declining inertia by adopting several low-cost solutions, including allowing fast-responding noncritical loads to respond to changes in frequency. This has enabled ERCOT to achieve increasingly high instantaneous wind penetrations—reaching a record of 58% in 2019—while maintaining reliability."