Coming Together at the Seams

James McCalley, London Professor of Power Systems Engineering in Iowa State’s Department of Electrical Engineering, has spent more than a decade working with the National Renewable Energy Laboratory to evaluate methods of effectively connecting the main US power grid systems to allow efficient transfer of renewable energy from coast to coast. Dr. McCalley recently sat down with Factor Analysis to explain the challenges and obstacles, as well as the benefits of this study.

 

Announcer
Welcome to Factor Analysis, an in-depth conversation of engineering knowledge from the classroom to the field, and topical issues surrounding work and life from an engineer’s viewpoint.

Travis Ballstadt
I’m Travis Ballstadt, and I’m going to be your host for this episode of Factor Analysis.

Travis Ballstadt
When plugging in our chargers or flicking on the lights, we probably don’t think much about what it takes to power our devices and light up our homes. In reality, electricity is the lifeblood for nearly everything we do from accessing the Internet to cooking a meal. James McCalley London Professor of Power Systems Engineering has been working with his student researchers, industry partners and the US Department of Energy to explore how best to connect the eastern and western power interconnections. These grids comprise the electricity network Americans rely on to power their everyday life.

Travis Ballstadt
The study is an important piece of the National Renewable Energy Laboratory’s work to modernize the American grid system. The Iowa Governor’s Wind and Solar Coalition has also been highly supportive of the project.

James McCalley
Actually, this work started about 10 years ago just with a student of mine and myself and we just started thinking about it and we had a little money to work on it. And we asked the question, you know, what if what if the future look like this would big transmission look good? And we did a few you know, cursory studies and and the result was yes. And so the more times we got a yes answer to that, the more time we started putting into it. And three years ago, NREL, National Renewable Energy Laboratory in Golden Colorado, one of the National Labs, called me up and said, we want to look at this closely and we want Iowa State involved, you know, to do this part of the work.

James McCalley
That study was referred to as the Interconnection Seam Study, the word “seam” to focus on the boundary between the Eastern and the Western Interconnection.

Travis Ballstadt
So, what exactly is the United States power grid? And how does it work?

James McCalley
Mainly three different sectors. One is generation and easy to get your mind around that what the power generation resources look like, big, thermal power plants that burn coal or oil, natural gas, and in some cases, nuclear, and then there’s a whole new set of them coming in the past 10 years and as we speak, are energized from wind and solar resources. And then of course, there’s hydro. So there’s a few other things but this is the basics of the generation sector.

James McCalley
And then there’s a transmission sector, which interconnect those, the larger of those generation resources to the load centers, and transmission is typically on the order of 69,000 volts upwards in the United States to 765,000 volts. So that’s the range of AC transmission.

James McCalley
The third sector, which we refer to as the distribution sector, some people think of the entire transmission in the lower voltage sector as being distribution. But in the terminology, we separate it, the lower voltage distribution is, in this country is 34,500 volts and below all the way down to 120v that you see at the outlet that you use in your homes. So, this is the electric power system or electric power grid.

Travis Ballstadt
Throughout the United States, there are three interconnections that make up the power grid. One begins at the western border of Nebraska and extends to the Atlantic seaboard. The second portion spans the western side of the country. And the third piece of the grid is most of the state of Texas.

James McCalley
So those are the three asynchronous grids that are operating separately from, one from the other. But within each one of those, the grid is interconnected. So if you live in Florida, and you look at the voltage waveform, it will look exactly the same as the voltage waveform that you see in Duluth, Minnesota.

Travis Ballstadt
So why would these electricity hubs not be connected? McCalley says it’s due to a variety of factors that can be explained by geography and economics.

James McCalley
Several reasons, some of which are historical. As the grid originally grew in the early part of the last century, you know, of course, we didn’t have any grid and so slowly, but surely, transmission facilities started to be built. And, you know, there was a difficulty and it provided a disincentive from connecting west to east and that was the Rocky Mountains. So you had sort of a natural boundary there and the motivation needed to be strong because to do it, one of the requirements that you have when you interconnect two large grids with what we refer to as AC transmission, which is the sinusoidal wave form that you think about when you think about 60 hertz, AC transmission in order to connect to large scale grids you require a lot of it, basically. We refer to the problem that results if you don’t interconnect with enough AC you have stability problems. It’s difficult to maintain one side in synchronism with the other side. So the only way that you can really do it is through DC interconnections.

Travis Ballstadt
McCalley says the technology for connecting the grids became available in the 70s. But it was only recently that people have begun to explore the possibilities.

James McCalley
Even though over the past, really, hundred years, people have thought about it from time to time, it was only maybe in the past 10 years that, that thoughts start to get really serious in a way and, and the motivator was essentially the reliance on wind and solar. Before, you built your thermal power plants based on fossil fuels reasonably close to the load center, because you could, and then you move the fuel to the power generation facilities. And so this largely defined you know that the transmission didn’t need to be necessarily extensive. Although we do have a good transmission grid on both sides of the country.

Travis Ballstadt
Compared to other forms of energy, wind and solar are not as mobile. Unleashing the full potential of renewable energy can be done through efficient transmission. This would bring the best solar from the west, and the best wind from the Midwest to other parts of the US.

James McCalley
With wind and solar, you know, those resources are location specific, so you can’t really move the fuel in these cases, for obvious reasons, right? The best wind is in the Midwest. There’s some good wind in other places, but a broad general assessment would result in the conclusion that the best wind resources are in Iowa, Kansas, Oklahoma, Dakotas, Minnesota and so forth. The best solar tends to be in the West and the best wind is east of the dividing line between the eastern and western interconnection. If you want to use the best solar on the east coast, you can’t, and if you want to use the best wind on the west coast, you can’t, today.

Travis Ballstadt
So why do we need to send wind to the west and solar to the east? You may already be thinking that the sun isn’t always shining and the wind isn’t always blowing. The power from renewable energy ebbs and flows, and solar and wind energy can work hand-in-hand to fill each other’s voids.

James McCalley
The resources are complimentary in a way. Even though you would think you get wind all the time, you really don’t, even for a widely dispersed wind resource. You know, there’s times of the day where you tend to get more wind and other times of the day, primarily in the night. And solar, I think it’s pretty clear that you know, you only get it from 7am to 7pm or so there’s a little bit of a complimentary issue there that it’s good to have both, they reinforce each other and that’s with respect to energy.

Travis Ballstadt
Wind and solar are good energy resources, but they’re not good capacity resources. For wind and solar, peak demand occurs at different times in different parts of the country. The ability to borrow capacity through transmission saves a lot of money nationwide.

James McCalley
The other part of this is related to the ability to use, at any given moment, the most economic resources. Even though you think you know, it’s a long ways from west of the Rockies to the east coast, and you know, vice versa, electrically, it’s not. From a time point of view, it’s almost instantaneous. But from a loss point of view, when you send electricity over a wire, you know, there’s some resistance, so you do lose a little bit, but transmission is pretty efficient. So the loss is not huge. So having the ability to move large blocks of energy from one side of the country to the other enables you to take advantage of, at any given moment, the most economic resource, and this is done today, but only on a regional scale.

Travis Ballstadt
Interconnected electricity can’t be harnessed within state lines. Like many other state and federal issues, McCalley says connecting the grids will come with some inherent political and economic challenges.

James McCalley
When I build generation, it creates jobs. If I’m on the East Coast, why should I build out generation in Iowa and create all those jobs for them and then bring the energy here using transmission, transmission doesn’t create many jobs. So from an economic development point of view, people sort of like to have it in their own backyard. So there’s kind of a tension here about, you know, how will go and ultimately, I guess, you know, there’s gonna have to be some meeting of the minds and agreement and probably leadership from you know, the federal level.

Travis Ballstadt
While transmitting renewable energy to other parts of the country is efficient, there’s another reason it’s attractive – economics. Investing in the macro grid will lead to lower energy prices and benefit the overall economy.

James McCalley
Fossil fuels are going away, no matter what. Whether you have this macro grid or not, and it has nothing to do with carbon. It’s purely economics. Today, the most economic resource in the country is wind and solar. They outperform even natural gas and coal and nuclear, assuming you build the wind and solar in the richest locations. So with that thought in mind, the benefit of the macro grid could be perceived as accelerating the retirement of thermal resources.

James McCalley
By and large, the technology is there. And it’s not that expensive. If I gave you a number you would raise your eyebrows. But from an infrastructure investment point of view, an $80 billion investment is about what it would take to build what I would refer to as a macrogrid that would span the country and enable energy and capacity sharing from different parts of the country and gain the benefits that I’ve been talking about. That’s a very rough price tag, which you know, when you compare it to the federal budget is not that big, really.

Travis Ballstadt
Beyond improving energy efficiency, connecting the power grid and using renewable energy provides stability and resilience. Following the devastation of Hurricanes Katrina and Rita in 2005, McCalley said 80% of natural gas resources in the Gulf of Mexico were lost and gas prices skyrocketed, and this effect propagated through to electricity due to the heavy reliance of electricity on natural gas.

James McCalley
The electric lines in Texas, we brought those back within weeks. But the gas wells, it took months for some of those to come back, and so it was really, that price spike in August of 2005, early September, a dramatic spike, almost within like a one or two week period. And then it gradually came down over the next six months. But it was a full half-year before the prices of electricity and the prices of natural gas came back to where they were pre-Katrina. That’s a huge impact on our economy. And if, I’ve sort of done this work, if you were to have had the macrogrid in place at that time, it would have mitigated by over 50% the economic impact of that disturbance, let’s call it, of that event.

James McCalley
It really creates strength, you know, in our country in lots of interesting and important ways. Large-scale, high-capacity transmission all over the country essentially makes any resources, anywhere, available to anywhere else. And that provides redundancy and backup to all of these kinds of things that we hope won’t happen, but inevitably do.

James McCalley
Thinking like this is fun for me. It’s a lot of, a lot of implications in engineering, a lot of implications in policy implications in sort of just daily life, gross national product, economics, and so forth.

Travis Ballstadt
McCalley says the best way to connect the power grid is to do so little by little, small increments of progress can ultimately bring the macrogrid to life.

James McCalley
People are just tentative it’s it’s a new, big thing, and who’s first? There’s this natural human tendency, and there may be other you know, reasons, but one of the strategies is to, you know, don’t try to build it all. Just build one, just build one segment, and then build the next one, and then the next one, etc.

Travis Ballstadt
Just as small steps lead to big progress with connecting the power grid, we challenge you to catch up on the latest stories from Factor Analysis one episode at a time.

Travis Ballstadt
Thanks for listening. Don’t forget to click subscribe wherever you listen to podcasts. I’ll talk to you again soon on another episode of Factor Analysis.

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Factor Analysis is produced by Iowa State University’s College of Engineering. For a list of ways to keep up with the college including more podcasts, social media and apps go to engineering.iastate.edu. Music by Lee Rosevere and used under Creative Commons license.