How the TVA prepares for energy demand in the hotter months

There's a high demand for energy from the TVA this summer.Demand has peaked above 31,000 megawatts in June and July of this summer, and there's still a month left to go. Those peaks are a bit higher than last year's peaks for June and July, which were around 30,900 megawatts and 30,600 megawatts, respectively.Before the summer demand period, which runs from June through August, TVA crews walk through generating sites to check for things that might cause units to unexpectedly shut down."Whenever we get to these peak periods, we want to have every available generating unit ready to come online as quickly as possible," said TVA spokesperson Scott Brooks. "So [there are] manual walk downs, making sure there's any adjustments that need to be made."Some of the units being checked are "peaking units" reserved by the TVA for when demand, well, peaks. Those units are typically smaller and fueled by natural gas."Last week, we were running just about every available generating unit because we had demands around 31,000 and 32,000 megawatts," said Brooks.TVA systems are built to generate around 32,000 megawatts in energy during the summer, according to Brooks.The TVA puts contracts in place with utilities in surrounding areas in case demand breaches that point to about 32,000 megawatts, and the TVA needs to buy power elsewhere, he said."We make sure that we have contracts in place with these neighboring utilities, where [if] we need to come to them and say, 'We need 100 megawatts an hour from now,' we have a firm guarantee with those utilities that we can purchase that power as needed," he said.The TVA has a team of meteorologists on staff so they can have their own heads up on extreme weather or extreme temperatures ahead of time. If there are several consecutive days of 90 degree weather on the horizon, TVA uses that information to prepare for more people trying to stay cooler.Heat itself poses less of a strain on TVA units, whether it's a natural gas or nuclear unit."Almost all the components are built with extreme temperatures and extreme heat in mind, because those are just different ways to boil water, to produce steam, to turn turbines so that that naturally involves a heating process," said Brooks."Extreme heat in the 90s really is not as big an issue as extreme cold was for a while."When we show up in our homes, sweaty and seeking refuge in the air conditioning, it may seem like those energy systems are working overtime to keep us cool — but there can be even more demand from the TVA when the winter comes.That's what was shown by the all-time record set earlier this year, when demand reached 35,319 megawatts. That's the highest power demand in the 91-year history of the utility.Summer electricity use across the country has increased overall since the 1970s, but has relatively leveled off in recent years, according to EPA data.When the TVA makes requests for people to cut down on their energy use, it's not always because of the demand created by high heat. Sometimes it can be because a unit is out of service or another source of power is unavailable at the time."We could get up to 90, between 95 and 100 degrees, and still not have to issue that request," said Brooks. "But there may be a period where we have, for example, a nuclear unit that's offline for whatever reason. That's 1,100 megawatts that we don't have.""If we put out a voluntary request for conservation, that could make up that difference pretty quickly."