The grid is rapidly transitioning to low-carbon or no-carbon generation as coal-fired power plants are being retired. Between 2010 and 2022, coal fell from supplying 40% of the nation’s power to around 20% today. About half of that loss has been replaced by renewable generation, the remaining demand (plus recent load growth) has been provided by nuclear and natural gas. As of 2022, natural gas has replaced coal as the primary resource for electric generation, supplying nearly 40% of our nation’s power today.
With baseload projected to increase through 2050, our grid stability and quality of power are as important as ever. Because of the basic physics of transmitting and distributing alternating current (AC) power, rapid swings in load can change the grid voltage, creating the need to either generate or absorb reactive power or load.
One way to control this reactive power or load is through the utilization of synchronous condensers. In electrical engineering, a synchronous condenser is a DC-excited synchronous motor, whose shaft is not connected to anything but spins freely. Its purpose is not to convert electric power to mechanical power or vice versa, but to adjust reactive load or power on the electric grid, thereby affecting power factor – in other words, keeping alternating current and voltage waves properly synchronized on the electric grid.
Some utilities are converting their retired coal units into synchronous condensers, where the generator is decoupled from the old steam turbine and modified for this new functionality. Today, synchronous condensing is also a standard option available on newer aeroderivative gas turbines, a solution many utilities are choosing for their new gas-fired generation projects. These gas-fired generation units are not in competition with renewables, but rather enable their continued growth by providing reliability and stability to the grid in addition to reserve capacity.
Capacity and reliability are underlying themes in recent resource plans of many major utilities. While most headlines revolve around decarbonization and increased renewable capacity, many utilities are simultaneously developing new gas generation projects — including simple-cycle, combined-cycle, and reciprocating internal combustion engine (RICE) plants.