How Energy is Produced:
Understanding Electricity Generation
How old is the power running your blender or light bulb? This may sound like a strange question… but when compared to other utilities like water and natural gas, it is a reasonable thing to ask. Traditionally, the power grid has relied on power generation to meet all electrical demand – electricity is made as it is needed!
Unlike water or gas which can be stored in tanks or reservoirs, electricity has historically been produced at the time it is to be consumed. As a result, load balancing has meant that we rely on a variety of different types of power plants – some which handle base loads and some which can rapidly turn on or off to handle temporary peaks.
Today we’re going to look at how power is produced, how generation is scaled to meet demand, how the grid is changing as we incorporate more renewable sources into it, and even how your home’s EV charging system might one day be the secret ingredient that makes a renewable energy grid possible.
Meeting Energy Demand: A Moving Target
If power demand across the country was steady – it would be easy to figure out how many, and what type of power plant we needed. Simply build exactly as much generation as there is demand, and maybe work in some extra margin for unexpected problems, right?
However, it isn’t that simple. In fact, power demand is highly variable, with one or two peaks per day which vary by season and region.
Here in the Midlands, peak demand during the summer is weekdays from 6pm to 10pm – corresponding to the time where most people are home and using air conditioning to cool their homes. In the winter, we see two peak times: the first from 6am to 9am, and the second from 6pm to 10pm. These line up with when people are home and are heating their homes.
However, while these daily peaks and troughs are fairly consistent – heat waves, blizzards, holidays, and even sporting events can cause actual demand to rise or fall.
Because of this variability our power grid has different types of power generation – some which provide a base level of power to meet the minimum demands, and others which can be turned on and off quickly to meet peak demands.
How Electricity is Produced
The US power grid is amazingly interconnected and includes everything from nuclear power plants to biomass fuel facilities. It can look confusing – why are there so many different types of plant in use? Surely we should have simply found the ‘best’ one and built lots of that, right?
In part, the variety comes from a developing understanding of environmental concerns, but also has a lot to do with the fact that each type of power production has its own benefits and limitations. For example, nuclear power plants provide plenty of clean energy but cannot be quickly turned on or off – making them a poor choice for meeting peak demand.
Let’s take a closer look at the most common sources of power generation:
Image Credit: https://www.nrc.gov/reactors/power/pwrs.html
Nuclear: Slow and Steady
Percentage of US Power Generation (2023): 18.6%
Percentage of South Carolina Power Generation (2022): 55%
Nuclear energy may conjure up images of disasters like Chernobyl or Three Mile Island, but in reality has proven itself to be the safest power source by any standard.
These plants do, however, take a very long time to build (*and occasionally don’t get built at all) and once built the reactors are expected to operate nearly continuously throughout their service life – only taking occasional breaks for maintenance.
A reason for the infrequent breaks is that nuclear power plants are time consuming to restart – requiring 12 or more hours to start producing power again.
As a result, nuclear power generally provides ‘base’ power – delivering enough energy for off-peak hours and requiring supplemental power generation during peak hours.
*The Difficulty in Building Nuclear Plants:
A little less than a decade ago South Carolinian’s got to see first hand how difficult construction of nuclear power really is with the political and financial fallout (no radioactive fallout!) of the Virgil C. Summer Nuclear Generating Station’s so-called “Nukegate” scandal.
The Virgil C. Summer plant had been in operation for decades when the then-owners South Carolina Electric & Gas (SCE&G) and the South Carolina Public Service Authority (Santee Cooper) launched a $9 billion expansion of the plant. However, the upgrade which began in 2013 quickly encountered delays and the estimated price soared to $25 billion. The job was poorly managed and was described as suffering from “incompetence at every level” and a total lack of oversight.
The project’s deathknell came when the contractor hired to build and construct the plant, Westinghouse, filed for chapter 11 bankruptcy. The end result was billions of dollars wasted, a few indictments for fraud and conspiracy, and a merger between the beleaguered SCE&G and Dominion Energy.
So, while nuclear plants are incredibly safe to operate – their construction is expensive, time consuming, and arguably financially risky.
Coal: The Former King of Power
US Power Generation (2023): 16.2%
South Carolina Power Generation (2022): 14%
Coal was the undisputed king of power production up until 2015 – when natural gas overtook it. Coal plants have been progressively phased out in response to environmental concerns – although modern coal plants are far cleaner today than at any other time in history.
Even though these modern plants are much cleaner than they were in the past, they still lag behind natural gas plants and many coal plants are slated to close. Dominion Energy is planning on closing most of their South Carolina coal-fired plants by 2030, transitioning their capacity to natural gas plants instead.
Like nuclear power plants, coal plants have lengthy restart times – routinely exceeding 12 hours. Thus, the few coal plants that remain in use are almost always used to meet base power demands.
Natural Gas: The Current King of Power
US Power Generation (2023): 43.1%
South Carolina Power Generation (2022): 24%
Currently natural gas is the dominant fuel for power generation in the United States. The plants are relatively affordable and quick to build, debatably environmentally friendly, and can be turned on and off quickly. The biggest downside is that the fuel costs can be high, they still produce greenhouse gasses, and combustion plants are quite inefficient.
There are two main types of natural gas power plants: combined cycle plants and combustion plants. Combined cycle plants are by far the more efficient of the two and require up to an hour to generate power. These plants are most commonly used to meet base, as well as predicted peak demands – but are less suited for unexpected surges. Combustion plants are very responsive and can produce power within minutes, but due to their high running costs they are reserved for meeting momentary peak demands.
Photovoltaic Solar & Wind Power: Fully Renewable, Highly Variable
US Power Generation (2023): 3.5% PV Solar / 10.2% Wind
South Carolina Power Generation (2022): 3% PV Solar
Photovoltaic (PV) solar and wind power get a lot of well-deserved attention, but still only represent a small fraction of the total power generation in the United States. However, with the price of solar panels falling year after year and increasingly tough limits on greenhouse gas emissions, these power sources will continue to gain ground on their fossil-fuel counterparts. One big problem posed by both of these sources is that they are not on-demand power sources and their output varies based on conditions. When there are clouds or a calm, breezeless day, power output will fall. Similarly, it can be difficult to handle a glut of power production when demand is low. However, what ultimately makes up for these downsides is their incredibly tiny environmental impact and affordability. Wind and solar are the two cheapest sources of energy in the United States per megawatt, undercutting even the most modern, fuel-efficient natural gas plants.
Hydroelectric: Renewable & On-Demand Source
US Power Generation (2023): 5.7%
South Carolina Power Generation (2022): 2%
Hydroelectric power plays an important role in the US power grid as it offers the ability to increase output with very little lead time. Typically these plants deliver a constant, low-level of output (in order to maintain reservoir water levels), and then flow to turbines is ramped up to help meet peak demand.
While these plants provide renewable energy, dams are subject to the vagaries of nature and prolonged drought can result in decreased power generation.
Moving Towards a Renewable Future
The trend towards renewable energy is set to continue – both for the environmental benefits it offers as well as the cost savings over fuels like natural gas. With unsubsidized costs significantly lower than even the most efficient natural gas plants, it just makes sense to see more of these environmentally friendly options built.
However, an obstacle remains: power must be generated at the time it is destined to be used and photovoltaic solar and wind energy produce power only when mother nature decides they will.
So the question arises: Is there some way to store the excess power they generate so that these renewable sources can power our homes 24/7?
Battery Storage / Vehicle to Grid
One option that makes sense at first glance is large batteries. However, modern lithium batteries are expensive and lithium is already a scarce resource so it seems unlikely that utility scale battery storage will become common. But, there are already millions of lithium batteries that each have enough capacity to power an average American home… and one might already be in your garage.
Here in the south, the average home consumes 43 Kilowatt/hours of electricity daily. Ford’s battery-powered F150 comes standard with a 98 KW/hr battery – meaning that its battery could power a typical home for more than 2 days. While it isn’t yet commonplace to see vehicle to grid (V2G) power solutions in use, it would not be a problem to implement V2G systems using current technology. Of course, homeowners wouldn’t be expected to offer the use of their EVs for free, and utility companies would likely offer compensation plans similar to those currently available for home solar generation. The result could be millions of homeowners providing invaluable support to the grid – their cars charging when renewable sources are available, and then returning some of that power to the grid when necessary.
Pumped Storage Hydroelectric
Another solution, which is more in line with how utility companies currently operate, is pumped hydroelectric power.
These plants already exist today – for example the Bad Creek Pumped Storage plant in Salem, South Carolina provides enough stored energy to power 1 million homes.
The plants operate almost exactly the same as traditional hydroelectric plants, except that electrically operated pumps are used to fill them instead of natural water sources.This means that these plants actually end up using more energy than they produce.
But, if the reservoirs are filled using excess power generated by renewable sources then the wasted energy is of less significance than the availability of on-demand energy from the reservoir.
Why the Grid Matters to Homeowners
The reason we all should know more about the grid is simple: it is too important to get wrong. However, the power grids have been chronically underfunded for decades while growing in size and complexity. This, in combination with more extreme weather events like heat waves, hurricanes, and winter storms, leads to a greater risk of power outages.
Ultimately, the issues plaguing the power grid are incredibly complex as there is no single governing body which controls it. Instead, it includes hundreds of companies and must comply with varying municipal, state, and federal regulatory bodies. While it is hard to say exactly what a path forward needs to look like, the first step is being able to recognize there is a problem which needs to be solved – particularly since the demands on the power grid will only continue to grow.
Preparing for the Future
The grid serves an essential role, keeping our homes and offices illuminated and ensuring that modern life can continue without interruption. However, improvements to the grid are slow in coming and are made more complicated by its distributed nature and the numerous entities responsible for its upkeep and development.
As a homeowner, it’s essential to be aware of these potential problems so you can make informed decisions about everything from who you choose for municipal elected positions to whether or not a whole-home backup generator is right for you.
