Fading has special significance in power supply systems. It describes any action that reduces the amount of electricity produced to maintain the balance between supply and demand – which is essential to avoid blackouts.
Recently, the restriction has made headlines in states like California and Texas which add a lot of wind and solar energy. On very windy or sunny days, these sources can produce more electricity than the grid can absorb. System operators therefore reduce production to manage this excess supply.
It may be a lost opportunity. Solar and wind electricity, as well as that from existing nuclear power plants, is inexpensive and emits less greenhouse gases than fossil fuelsit may therefore be in society’s interest to keep these generators running.
A particular surplus
Consumers experience shortages and surpluses of the goods they buy. Shortages mean buyers can’t get this PlayStation 5 for Christmas – or, more importantly, bread, the water Where baby formula they need.
Surpluses look different, like unsold books categorized as remains or 80% off Easter candy at local pharmacies on Monday mornings.
But electricity is not like these goods. On today’s electrical grid, shortages and surpluses can lead to exactly the same thing: blackouts.
The North American grid transmits electricity alternating current that changes direction back and forth, like water ebbing and flowing from a vintage hand pump as the handle is pushed up and down. Modern power grids require precise frequency levels – the back and forth movement of power – to function properly.
The network is designed to operate at 60 hertz, which means the flow of electrical current moves back and forth 60 times per second. This is achieved, in part, by ensuring that the amount of electricity generated at any given time equals the amount of electricity used. If too little electricity is generated, the system frequency drops. If too much electricity is produced, the frequency increases.
Modern power plants are designed to operate in a relatively narrow range around 60 hertz. If the actual frequency on the network is outside this range, the panel can disconnect from the system. If enough plants do this, it causes a power outage.
In parts of the United States, primarily the southeast and west, the same companies generate electricity and deliver it to customers. When power plants in a utility’s territory produce more electricity than customers use, the company will simply produce less electricity from its most expensive power plant or shut it down temporarily.
But other states have have restructured their electricity markets so some companies generate electricity and others deliver it to customers. In these competitive markets, reduction poses complex problems. Power producers stay in business by generating and selling electricity. So when demand drops, network operators need a system to ensure they make fair curtailment decisions.
Often, the first tool to choose the plants to reduce is the the prices that producers are paid. When supply increases or demand decreases, the price of electricity falls. Some generators may decide they are unwilling to produce electricity below a certain price and give up if it reaches that level.
If there is still a surplus of energy, the organization operating the network steps in to manually reduce generators. They can either do it via signals in the network data system or by contacting the generators directly through phone calls. Power can be off for five minutes or five hours, depending on how quickly the system returns to normal.
Overall, the United States needs more low-emission electricity to help reduce air pollution and slow climate change. Curbing is therefore not a good long-term strategy for managing excess electricity. It’s somewhat comparable to the early days of the COVID-19 pandemic, when supply chain disruptions forced producers to throw huge amounts of food even as grocery stores struggled to stock their shelves.
One solution is to extend energy storage so that generators can save excess energy for a few hours instead of sending it directly into the grid. Another option is build more transmission to transport electricity to areas that need it. Both types of investments can reduce the need to curtail generation and forgo producing clean, affordable electricity.