How inverters can stabilize a renewables-heavy grid

Today's electricity grids are kept stable by the inertia of spinning masses — mostly fossil fuel generators. But what happens when those spinning masses are replaced by inverter-based resources like wind, solar, and batteries? The answer is that inverters must take over the stabilizing job, becoming "grid-forming" rather than merely “grid-following.” I chat with two experts about how grid-forming inverters work, how many are out there, and what the future holds for them.