Blackstart: How the Grid Gets Restarted & Why It Matters

Whenever there’s a power outage, the first concern that comes to mind is when will the lights come back on.

In fact, when the grid will be restarted is typically the only question that gets asked. Most people don’t even consider how the grid gets restarted, who is involved in that process, and why it matters. But it’s crucial for the average person to have a better understanding of blackstart, which is the process of restoring electrical power after an outage of the electrical grid. Let’s take a closer look at this process and why people must understand this.

A System of Backups

Perhaps the first question to address is why blackstart isn’t more commonly known. This is likely because power losses aren’t that common, especially the types of power losses that keep homes and businesses in the dark for long periods of time. Obviously, this doesn’t happen by accident. Electrical grids are designed in a way that there are always backup plans, as well as backup plans for the backup plans. It’s essentially a system of redundancy that’s designed to prevent prolonged power outages in virtually every scenario and all conditions.

Under normal conditions, there will always be enough sources for power generation and transmission capacity to meet the electrical needs of the entire system. Even if there’s one power plant that’s incapacitated or transmission lines that are damaged, there are backup resources that can fill in the gaps and avoid any major disruptions. Providers will almost always have contingency plans in place, even for the worst-case scenario, so that the electrical needs of the entire grid can be met. This is why it takes something catastrophic for there to be a long-term and widespread disruption to electrical power, such as a black sky disaster. 

At the end of the list of backup systems is where you’ll find blackstart. When all else fails, blackstart is the option to help restore power as quickly and as widely as possible. In a way, that makes blackstart the most important backup option.

When is Blackstart Required?

As mentioned, blackstart is often the final backup plan or the last line of defense, but when is it needed? The most common answer is during large-scale failures, often as a result of natural disasters. In these situations, it can take days or weeks to restore electricity to every home and business affected by the disaster. But, with a blackstart, this time is reduced drastically to a matter of hours. 

But large-scale catastrophes aren't the only example of blackstart being needed. On a much smaller scale, power can sometimes be difficult to restore on islands or in rural areas due to access issues. In these types of areas, utility companies must reach these areas first to diagnose and fix the problem, leading to longer periods without electricity. Those who rely on radial transmission lines can also experience delays in getting electricity back after outages, creating the need to have blackstart capabilities and use them in the event of power outages.

What is a Blackstart?

To put it simply, a blackstart is the process of restarting electrical components during a blackout using designated units that don’t need an existing power supply to get started. It utilizes on-site auxiliary generators to help restore power to the rest of the electrical grid via the transmission system. Transmission lines are used to connect power stations, ultimately getting the entire system back online after the power outage as efficiently as possible. In other words, small sources of power are used to get larger sources of power back online, essentially scaling upward from small to big until the entire grid is back to normal.

Needless to say, there are several steps involved in a blackstart. Unfortunately, the lights don’t just magically light up right away for everyone without power as soon as the blackstart is initiated. It’s very much a gradual process, albeit one that can be effective if those conducting the blackstart are prepared and understand the procedure. 

As an example, battery power might be used to start a small diesel generator. That diesel generator will be used to bring one generating station back to full operation. Through transmission lines, that one generating station can supply energy to similar locations. Before too long, other power plants that are connected to the same system will be able to restart. Ultimately, there will be enough power to start distributing electricity to homes and businesses experiencing a blackout. 

Again, this will be a gradual process. Even once power is ready to be distributed to the entire grid, that is something that will happen at a modest pace. The demand for power could be too great if the entire grid comes back online at the same time. There may not be enough of a supply available to meet the demand, causing power outages all over again and forcing the process to start from the beginning. This is particularly common during periods of extreme weather conditions when all buildings will have either a high demand for heat or air conditioning as soon as power is restored.

When a blackstart is required at a massive scale, it’s possible for there to be several starting points. These are sometimes called “islands” of generating power. They might start to supply power to localized areas before several islands become synchronized, connecting to one another to put the entire electrical grid back together. This also helps to explain why some areas will have their power returned sooner than others during a blackstart. Of course, the islands used at the beginning of the blackstart need to be able to handle significant increases in power needs as more generating stations restart.

One of the fascinating elements of a blackstart is that it can be initiated in a variety of ways depending on the specific needs of a particular power source. As mentioned, batteries and small diesel generators are a common way to commence a blackstart. But open-cycle gas turbines, hydroelectric dams, compressed air storage, and similar power sources can sometimes be used as one of the first steps in a blackstart. The exact method that’s used for a blackstart is largely dependent on the resources available in a particular area, how connected various power-generating locations are to one another, the complexity of the blackstart, and the cost of using one method as opposed to another. This makes every blackstart a new and unique process.

Blackstart and Renewable Energy Sources

Given the need for alternative sources of energy in today’s world, it's important to understand the relationship between a blackstart and renewable energy sources. For instance, hydroelectric plans need some electrical energy to get started after a power outage because they need to open intake gates and adjust the speed of hydraulic turbines. Likewise, wind farms might need to adjust the direction or blade pitch of their turbines, requiring a small amount of electrical power to accomplish.

On the other hand, hydroelectric stations can also play a critical role early in blackstart operations because they only require a small amount of electrical power to get back online. If there are transmission lines between a hydroelectric station and power stations that operate on nuclear power or fossil fuels, they can play a critical role in restoring power to the rest of the grid. Meanwhile, solar panel systems that have battery storage can continue to supply power even during a blackout, making them useful to have when the electrical grid goes down. 

The Need for Blackstart

Finally, it’s important to reiterate the need for the average person to understand blackstart and the process of bringing electricity back to the power grid. People need to know about blackstart because events that require a blackstart are becoming more and more common and will continue to happen. The need for a blackstart occurs somewhere in the world roughly every two years. In 2003, there was a major blackout throughout the Northeastern U.S. and parts of Canada, not to mention a separate incident that same year in Italy. In 2019, there was a transmission that left roughly 50 million people across several South American countries without power. It was only a few months later that a few Central American countries experienced a similar blackout.

These types of events aren’t ancient history, nor do they seem to be slowing down any time soon. With more and more severe weather events occurring and the world’s political turmoil, it’s clear that society must be prepared for anything. These events also show vulnerabilities in critical infrastructure. Serious weather events like hurricanes and wildfires also have the potential to leave millions of people across massive areas without power. If not for blackstart capabilities, these power outages would last much longer and have more serious consequences for those affected. In short, there’s a good chance a blackstart will impact everyone’s life directly sooner or later, making it all the more important that we understand what is happening, why, and what to expect when the lights go out.