One subject that renewable advocates are averse to discussing is asset utilization and I can understand why. Capacity factors, which are a measure of asset utilization, plummet when renewables enter the picture. As a typical example look at Red Eléctrica de España (REE). In 2024, it had capacity factors for wind, solar, and natural gas of 22%, 17%, and 16%, respectively. In essence, REE possessed three expensive assets that were grossly underutilized. If it discarded the wind and solar, the natural gas capacity factor would rise to 64%.

Moreover, even with the price of natural gas being four times (4x) more in Spain than in Texas, it is still 1.3 times more expensive for REE to operate with solar, wind, and natural gas than with natural gas alone. My calculations are here. Now that would not even be too bad, if the system were reliable, but we know otherwise now. However, the REE grid is about to get a lot more expensive. To save face, the Spanish government will pour billions more into the grid scheme to bolster its resilience. The money will go into building more synthetic inertia to keep it going when times get tough.

Synthetic inertia refers to the ability to mimic the stabilizing effect of traditional, large rotating generators. Grid-forming inverters in conjunction with dedicated batteries substitute for the rotating generators, providing a fast, controlled response to changes in grid frequency, and helping to maintain stability and resilience. This is achieved by rapidly injecting or absorbing power when the grid frequency deviates from its nominal value, essentially mimicking the inertial response of a spinning generator.

Will REE succeed in creating a resilient system without spinning generators? It’s hard to say. Engineers can be very resourceful. However, it won’t come cheap. I had some direct experience with this type of technology in my earlier engineering days on the Tokamak Fusion Test Reactor (TFTR) at Princeton Plasma Physics Lab (PPPL). We stored energy in massive flywheel mechanisms called motor-generators and then shaped the output into a pulse with power thyristors and capacitors before dumping it into the reactor coil. Essentially, with enough ingenuity and money, one can play all sorts of games in transforming energy.

However, this begs the question. Why bother? We have a perfectly good way of producing electricity at present that is affordable, reliable and accessible. I say don’t rock the boat, it’s liable to tip over.

Image generated by AI.