We Need More Than Transmission Lines
We recently got this from the NRDC, in an article, “We Can’t Let Aging Transmission Stall Clean Energy Progress,” published at CleanTechnica:
“The good news is that there’s an abundance of clean energy waiting to get online. In fact, there are about 2,000 gigawatts of new resources — primarily renewables and storage — waiting to connect to power grids across the country. That’s more than the combined output of all power plants operating in the United States today. The bad news is that as a result of an out-of-date interconnection process, it now takes more than five years on average for new generators to move from application to commercial operation. Most projects never get built, in part because of the delays.”
As much as I respect the NRDC, I think that if we get what we really need most, we might not need more transmission lines.
I want to start with a simple statement that some people think unbelievable: “We cannot power our grid with baseload power alone.” I will admit that it is theoretically possible to power the grid exclusively with baseload plants, but only for a very brief time, perhaps on the order of five minutes.
This is the flip side of the argument against renewable energy: “The sun doesn’t always shine and the wind doesn’t always blow.” It is equally true that baseload power is not sufficient all by itself. Sunshine and wind are incapable of powering the grid all by themselves because of variable or intermittent output. Baseload power plants are incapable of powering the grid all by themselves because they are too inflexible to meet continuous changes in demand.
To manage the grid, it is absolutely necessary to be sure that the demand for electricity and the supply of electricity match as closely as possible. In an extreme case when there is not enough power to meet demand or there is too much power for the demand, critical equipment can get burned out. Either case might best be avoided by shutting down the grid altogether.
The Old Paradigm, Built On Baseload Power
Consider what baseload power is. Wikipedia says, “The base load (also baseload) is the minimum level of demand on an electrical grid over a span of time.” It goes on to say, “Power plants that do not change their power output quickly, such as large coal or nuclear plants, are generally called baseload power plants.” In addition to coal and nuclear, baseload power plants include some kinds of natural gas plants and geothermal plants. Some hydroelectric plants are used to provide baseload power.
Obviously, we cannot power the grid for any length of time using power plants that are intended only to provide only the minimum demand. So there must be other types of plants that are built to cover times when the demand exceeds the minimum, which is almost 100% of the time. The plants providing extra power include load-following plants and peaking plants, historically often fueled by diesel, but these days mostly by gas. Also, some hydroelectric plants can adjust their output within a few minutes, and so are used to follow the load.
There is a reason why baseload power plants were intentionally designed not to follow the load. It was to make the electricity they generated as cheap as possible. Taking a coal-burning plant as an example — the boiler is huge, and while there are ways of changing output quickly in a boiler that size, they are very expensive, so the designs of baseload plants do not include them.
Baseload plants tend to share certain characteristics. Most are near water to cool them, because most are only about 40% efficient, so 60% of the heat they create has to be removed. Combined-cycle gas plants are the exceptions to this, because they can be as much as 60% efficient, so they are slightly easier to cool. Baseload plants can be built so they don’t need water for cooling, but that means expensive investments in such things as cooling towers many people associate with nuclear power. Cooling towers are built at coal and gas plants also.
Baseload power plants typically also need to have easy access to transportation systems that allow them to get fuel. Coal plants usually have access to railheads or wharfs for this reason. Baseload natural gas plants must have gas pipelines.
Since baseload plants only provide a fixed amount of electricity to cover the minimum load, load-following plants and peaker plants that follow changes in demand and cover loads in excess of the minimum are needed, but they produce very expensive electricity. They also do not ramp up or down all that quickly. This means that the system operator has to use some means to adjust the electricity supply to meet demand quickly, which can be done by resorting to such mechanisms as changing the rate at which AC power cycles. This has to be done within a narrow allowable range.
We should observe that peaking and load-following plants are no longer being built much, because the electricity from batteries costs a lot less and provide an ability to change output almost instantly. The cost of battery storage has declined almost continuously. Coal and gas plants need backup, but the best backup might be the cheapest now, batteries.
A Different Paradigm, Built On Renewable Power
Things have changed since a hundred years ago. In some ways, most of that change happened in the last twenty years. The costs of wind power, solar power, and batteries have been declining for a long time at double-digit compound rates. We should think about how these work together.
The sun tends to shine at the times that are the least windy, and the wind tends to blow hardest at the times when the sun is not shining brightly. The wind is strongest at night and in the winter. That means a combination of solar and wind will come closest to providing continuous power. But continuous is best done with some backup, such as a battery.
One thing about distributed power systems based on renewables is that they are scalable. Electric grids can range from being a few solar-powered circuits in a house to large systems providing electricity for broad geographical areas. Furthermore, the broad areas of a grid can include minigrids, and these can be made up of smaller grids, microgrids, which might be made up of even smaller units operating at the household level. And these can all be made to stand alone in the case of failure of the larger grid.
Solar and wind power can be sited more easily than baseload plants. They do not need fuel, so they do not have ongoing needs for special transportation. Since they do not operate by combustion, they do not have important cooling needs. They can go up where they are needed. Whether they do or not is a separate issue.
As the costs of the generating and storage components of the overall distributed system have declined, so has the cost of electricity. NextEra Energy’s June 2022 Investor Presentation had some pretty remarkable material in it. For one thing, it spoke to the idea of “near-firm” solar and wind power. The term means that the resources are very reliable for producing dispatchable energy at peak demand times. In the report, NextEra Energy said it would not invest in thermal plants, whether combustion or nuclear, in the next ten years, but would instead focus exclusively on solar, wind, and energy storage. The graph on page 122 of the report shows why NextEra energy came to the conclusions it did. They foresee new near-firm wind and near-firm solar out-competing anything else, new or already existing.
We should observe that solar and wind, backed up sufficiently with batteries, can not only perform as well as baseload plants, but when backed up with combustion plants, they could do this in a manner that would possibly prevent the grid from going down in a wide-scale blackout, such as we have seen in the past. Furthermore, they could do this at lower cost and without the massive pollution thermal plants make. A lot of people have foreseen these things. But one argument I feel compelled to raise is that this work might be done without any new transmission lines.
One way to avoid transmission lines is to identify geographical areas that can run on self-supporting minigrids or microgrids and develop those systems. This can place generating facilities near enough to where their electricity is needed that transmission lines are not an issue. But also, every time that sort of work is done, it will reduce the load on the existing transmission structures.
The conversion from the old paradigm to such a new one as I have described will require one thing that does not yet exist, which is construction of new batteries. For those who don’t know, one of these is the Form Energy iron-air battery system that has been featured in numerous articles at CleanTechnica, including examples by Steve Hanley and by Tina Casey.
My own conclusion is that we really should not be held up by a lack of transmission lines. In my opinion, that shortfall holds us up only because we think it does. Perhaps that tells us what we have to do: Just stop thinking like we are still in the past, in an old paradigm.
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