Powering the Dream_ The History and Promise of Green Technology - Alexis Madrigal [130]
So engineers came up with logical workarounds to sell their product. They built the entire energy system around balancing load and demand. Most plants run most efficiently when they’re left on all the time, so it became important to smooth the amount of light and power used throughout the twenty-four-hour day, even if people didn’t need it. As a result, the engineering properties of the turbines and electricity drove the creation of entire social systems. When the traction companies had excess nighttime capacity because they ran more trolleys during the day, they built amusement parks at the end of the line and extravagantly lighted them to suck up the extra juice. Utilities also invented (wasteful) uses of energy like electrical resistance heating to help balance the increase in load from air conditioning. Thus, the inability to store their product has shaped the entire industry from top to bottom.
In modern systems, entire classes of power plants are switched on only a few days a year, when they make some of the dirtiest and most expensive power. They’re like fireworks stands that remain empty all year and then make all of their cash in the two weeks around the Fourth of July. The electricity business is the ultimate just-in-time delivery game.
Conversely, compressed air has completely different properties. Air is a mix of gases. It might not be quite as easy to store as a liquid like oil, but decades of natural gas storage have proved that it’s possible to do so—and cheaply. At any given moment, something like 1.7 trillion cubic feet of natural gas are stored underground in the caverns and sandstones of America.7 That’s enough to fill 1.1 billion cargo containers, or the Sydney Harbor sixty times over.
In the ’90s, after the McIntosh plant proved that compressed air storage could be done, there were high hopes that many utilities might jump on board and build their own. “We expect the CAES plant technology pioneered in Alabama to lead to widespread application in this country,” said Robert Schainker, the manager of the Electric Power Research Institute’s Energy Storage Program. “Three fourths of the United States has geology suitable for underground air storage. At present, more than a dozen utilities are evaluating sites for CAES application.”8
But they didn’t. Nakhamkin said that the tiny Alabama Electric Cooperative was in a unique position. During the day, they had to purchase expensive peak power and run their coal generators, but at night, they had to switch off their power plant, which is very inefficient.9 They needed something to suck up nighttime power. Unlike bigger utilities, they couldn’t balance their loads as well. Other utilities could have saved money by building similar plants, but it was not “critical savings,” Nakhamkin maintained. “Rich people don’t talk about how to save five dollars or ten dollars.”10
Because the McIntosh plant was specifically optimized for the situation in Alabama, it was not very flexible. It could take power from the grid only in 50 megawatt chunks, for example. Its startup time was also long, which decreased utilities’ interest in the technology.11 Nakhamkin said that his next generation designs will provide plants that can fit more utilities’ needs.
But what’s really brought CAES roaring back is Zahner’s “distant, yet hithero unavailable sources of power.” In the United States, that’s turned out to be wind electricity, which has led alternative power additions to the grid for the last several years. Quick-to-deploy, cheap, and with less carbon risk than other alternatives, more wind than coal is slated to be added to the grid from now until 2030.12
The importance of compressed air storage is not only that it would make it easier on utilities to accept gigawatts of wind power on their transmission grids, but also that it would allow wind to compete directly with coal. To balance the amount of generation and load on the