Demand Base Load
What it is:
The U.S. Energy Information Administration (EIA) defines base load as “The minimum amount of electric power delivered or required over a given period of time at a steady rate.” LINK
Figure 1 shows an example of Demand Base Load vs. Demand Peak Load for a typical Grid.
Source (Demand & Capacity Factors): Open-Electricity (AEMO)
And what Demand Base Load is NOT:
Demand Base Load does not refer to a specific type of generator; any generator can contribute to it. Typically, Demand Base Load generators maintain constant output and do not adjust to follow demand fluctuations.
It is Important to understand the difference between Demand Base Load and Demand Peak Load and how this insures a stable and responsive grid.
Definition of Dispatchable Generation: Refers to a generator that actively regulates its output based on real-time grid frequency measurements at its busbar. Grid frequency serves as a proxy for the balance between electricity supply and demand, which must be maintained continuously to prevent blackouts or grid failure. The generator adjusts its governor to increase or decrease output, stabilizing frequency in response to deviations.
Imagine every generator on the grid operating in dispatchable mode, where output adjustments are solely governed by frequency response. Each generator’s reaction to frequency changes would create multiple feedback loops, destabilizing the grid.
Generators have varying governor response characteristics, leading to inconsistent reactions to frequency deviations. These differences amplify feedback loop variations, increasing grid instability.
As demand fluctuates, some generators will be pushed outside their control envelopes, operating from zero to maximum output. This exceeds design limits, further exacerbating feedback-driven instability.
Operating Base Load generators at constant output significantly reduces the number of dispatchable generators. This minimizes feedback interactions and ensures dispatchable generators remain within their control envelopes, enhancing grid stability.
On a real-life functioning grid, Operational Base Load is constantly optimized by grid operators who monitor overall performance on a minute-to-minute basis.
Why is Demand Base Load assumed to be a type of generation?
In a legacy power grid relying on hydroelectric and hydrocarbon generation, Operational Base Load is typically assigned to generators with slow response times to output changes. Historically, coal-fired power plants have been used for this role due to their operational characteristics.
However, many have incorrectly conflated Generator type with Demand Base Load, assuming they are identical. This is a misconception, as Demand Base Load refers to the minimum level of electricity demand on the grid and is independent of the generator type.
Figure 3 shows a typical Legacy Grid differentiating between Demand Base Load and Operational Base Load.
Transition to Renewables
The integration of wind and solar into the grid introduces part-time, highly variable, unpredictable, and uncontrollable generation. As a result, these sources cannot serve as dispatchable resources.
Contrary to the belief that adding wind and solar renders Demand Base Load obsolete, the opposite is true. Both Demand Base Load and Operational Base Load become even more critical in maintaining dispatchable generation within its operational limits for a stable and reliable grid.
Figure 4 illustrates how Operational Base Load must adapt to accommodate increased grid variability.
Transition to a 100% Low-Carbon Grid
Increasing wind, solar, and energy storage to achieve a 100% low-carbon grid with minimal emissions underscores the critical role of both Demand Base Load and Operational Base Load in ensuring grid stability and reliability.
Figure 5 illustrates a 100% low-carbon grid with all hydrocarbon generation eliminated.
Energy storage is essential and must function as a dispatchable resource 100% of the time. It must also provide inertia and other grid services to fully replace the functions currently supplied by thermal generation (i.e. Inertia).
Thanks for a very clear exposition of this difficult topic.
I see the powers that be are now (re-)committing to nuclear, presumably because of the arguments you present above, despite the past 'incidents' and the anti-nuclear lobbies.
Changing horses in midstream never was a good idea.
This isn't true though. You already have grids that operate reliably without baseload. See figure 2 here. H
https://prismbysugandha.substack.com/p/sunshine-state
Gas peakers balance RE but they're not "always on" (which is the defining feature of baseload).