Elena Bilheimer, EcoNews Journalist
Although the electrical grid is not always at the forefront of conversations about energy, understanding how electric energy is distributed is arguably just as important as understanding how it is generated and produced. Part of the reason that the grid is not more commonly discussed is because the science underlying it is extremely complex, making it difficult for any individual person to fully understand all the various aspects that go into it.
Each topic addressed in this article could be a book by itself, but hopefully this overview is enough to spark interest in learning more about these different threads, especially as the development of renewable energy sources in Humboldt makes this an especially timely and salient topic.
How the Grid Works
To put it simply, the point of the grid is to provide an electromagnetic linkage between the generators (where power is produced) and the loads (anything that uses or consumes electricity). If that sounds overwhelming already, Peter Alstone, an Associate Professor in the Engineering Department of Cal Poly Humboldt, has a useful analogy to better understand the physics involved. “Electricity is not stuff,” said Alstone. “There’s no substance to it. So it’s not as though the generators manufacture electricity and put it into the wire and it kind of flows through like water. I think that’s what a lot of people imagine.” Alstone recommends thinking of electricity transmission like a bike chain, so when someone uses their energy to push the pedals, the gears on the bike begin to crank and transfer the force through the chain to make the back wheels move. Similarly, when energy is produced at a power plant, the grid transfers the force from the generators to the loads where it will be used.
This process begins with spinning electrical generators at power plants. These generators are usually powered by turbines that spin because of the steam created by burning coal, oil, biomass, and natural gas, or through the process of nuclear fission. Inside the generator, there are many electrically amplified magnets that spin past big coils of conductive wire. The coil of wire interacts with the magnetic field to “induce alternating currents and voltages capable of performing work over time, which is also known as power,” according to the US Department of Energy. More simply, thanks to some very cool physics (also known as electromagnetic induction), when a magnet is spun past a coil of wire, it pushes the electrons through the coil of wire. These electrons are moved by the magnet through circuits that are connected to loads, creating a flow of electricity. Although this is the “conventional” way to generate power, it is also possible to use inverters, which is the technology that solar panels and batteries use. According to Alstone, inverters use power electronics with high speed switching to apply force in a way that is similar to the spinning generator.
Metal is used in this process to transmit power because of its conductive nature, meaning that it has a lot of free electrons that can be thought of as loosely bound in the substance itself. Because of this, when an electrical force is applied, the electrons are more easily able to flow and transport energy. If that is confusing, it is helpful to go back to the bike chain analogy, where all the links in the chain are moving due to the external force applied from someone pushing on the pedals. However, the links in the chain are never added or subtracted, even if someone decides to stop riding the bike. Similarly, electrons used to transmit electricity are neither created nor destroyed, just used to transmit electromagnetic work from a power generating station to the load. The electrical power flow is instantaneous and finite, illustrated by the bike chain that immediately stops moving once there is no more outside force. While batteries are improving, energy cannot be stored in the wires, meaning that most of it is used immediately after it is created.
To get electricity from a power plant hundreds of miles from someone’s house, the electrical power flow moves through the system of poles and wires that make up the modern alternating current (AC) power grid. Aisha Cissna, the Regulatory and Legislative Policy Manager at Redwood Coast Energy Authority (RCEA), provided another useful analogy for understanding grid infrastructure. At the highest level, there are the transmission lines, which can be thought of as the highways of the grid (these are the huge steel towers most everyone is familiar with). The electricity that is being transferred through the transmission lines is extremely high voltage, meaning that the electrons in these lines carry more energy and can travel for longer distances. Once this electricity has traveled where it needs to be, the voltage must be stepped down to make it manageable for the distribution system and keep people safe.
In order to lower the energy (step down) or increase the energy (step up) of the voltage, electricity moves through substations, or off ramps and interchanges in Cissna’s analogy. To enable this a piece of technology called a transformer is used. Alstone described a transformer like an iron magnetic doughnut with wire wrapped around two of the sides. The ratio of the number of windings for the two wires determines the voltage change. If it is ten to one, (for example, if one side of the doughnut had wire wrapped around it 100 times, and the other side had wire wrapped around it ten times), the transformer would change the voltage by 10x. In this example, when electricity moves through the transformer, the voltage would automatically change from 100 volts to ten volts. This is also true for higher voltages, so 100,000 volts would become 10,000. While there are large transformers at substations, they can also be spotted on top of power poles near homes and businesses (looking similar in size and shape to garbage cans), where they step down to the power to safe voltages for use in buildings.
Once the voltage has been stepped down, transmission lines become distribution lines. Although these distribution wires are the city streets and country roads in Cissna’s analogy (the electricity has almost made it to somebody’s home!), they are still really high voltage — around 12,000 volts — meaning they would kill someone instantly if they touched it. In order to make it usable and safe, the electricity is stepped down again so that the wires in peoples’ houses have only a few hundred volts. These wires can be protected with normal wire insulation, and at this voltage it’s possible for a person to accidentally come in contact with them and not die.
Once the electricity is at a voltage that could be used in a home, when a light in someone’s house is off, it is an open circuit and there is nothing connecting the light and the rest of the grid. According to Alstone, when the switch is flipped, suddenly there’s a full connection with potential for the electricity to flow through the light bulb and complete the circuit. “One of the key facts about the grid is that at every moment, like every second, the load in the generation on the grid is exactly in balance,” said Alstone. “So the amount of force or power that’s being provided by the generators, is exactly matched up with all of the loads that are out there. All the light bulbs and all the washing machines, the factories with industrial motors, they’re all lined up. And so if there’s a motor that turns off, then somewhere out in the world some generator turns down a little bit instantly. And then if you turn on a motor or if you put in a piece of toast in your toaster, somewhere, there’s a little subtle shift and some of the generators ramp up a little bit to match that new load.”
History of the Grid
In 1882, Thomas Edison unveiled the country’s first central power station on Pearl Street in New York City. The generators at his power station created electricity that could travel about one square mile and light up rooms in homes and businesses for the very first time. Unsurprisingly, the grid started out serving industry and the wealthy, creating fragmented little pockets of electricity service. In the late 1800s, Edison’s sometime rival Nikola Tesla — the person, not the car company — helped develop the technology of the transformer, which revolutionized the ability to transmit power long distances. However, it wasn’t until Franklin D. Roosevelt created the Rural Electrification Administration in 1935 that electricity access became more commonplace, rather than just a luxury for wealthy people living in dense, urban areas. This Act led to the development of three main grids in the United States: the Eastern Interconnection, the Western Interconnection, and the Texas Interconnection. In 2021, there were over 600,000 miles of transmission lines and 5.5 million miles of local distribution lines bringing electricity to people all across the country.
The Grid in Humboldt
In Humboldt, the grid grew along with the timber industry. Nowadays, the local grid infrastructure is made up of four 80 to 100 miles long transmission circuits. Two of these lines are 115-kV (kilovolt) circuits following Highway 299 and 36 along an east-west corridor from the Cottonwood Substation, with an additional 60-kV circuit that runs along a similar route (see visual). There is also one 60-kV circuit that runs north-south from the Mendocino Substation. These lines are part of Pacific Gas & Electric’s (PG&E) transmission system and provide supplemental power from outside the region. Power is also procured locally from a variety of sources, including hydropower, biomass from the Humboldt Redwood company, utility-scale solar, and natural gas from PG&E’s Humboldt Bay Generating Station. The Humboldt Bay Generating Station is especially important when there are any outages related to the transmission lines coming from out of the area, including PG&E’s Public Safety Power Shutoffs (PSPS). When outages happen, the county becomes an island and the Generating Station is the only thing that is able to keep the tri-city area powered.
In addition to PG&E, another entity helps manage power procurement and delivery in the county. In 2002, a law was passed that allows local governments to form a Community Choice Aggregation (CCA) program, which has local control over what resources are used to provide energy. The Redwood Coast Energy Authority launched in 2003 with the intention to “to develop and implement sustainable energy initiatives that reduce energy demand, increase energy efficiency, and advance the use of clean, efficient and renewable resources available in the region for the benefit of the Member agencies and their constituents,” according to its website. In order to do this, RCEA collects rates for electricity generation and uses those funds to procure energy for its customers. RCEA is responsible for the generation of electricity, while PG&E is responsible for billing and maintaining the transmission and distribution infrastructure to deliver the energy.
Challenges the Grid Faces
According to Cissna, one of the main issues in Humboldt is that there isn’t a large capacity for importing or exporting electricity into or out of Humboldt County. This limits the development of things like affordable housing projects and critical facilities such as hospitals, as well as electrification efforts to reach climate action goals. With the upcoming development of large-scale offshore wind, serious upgrades to the interconnecting transmission lines will be required in order to utilize, and export, the power that would be produced. “I think it’s safe to say that the challenges for the community members are reaching our climate action goals,” said Cissna. “Whether that’s installing charging stations or electrifying our homes and businesses, those really grind to a halt when you consider there are places in Humboldt County that don’t have any additional distribution capacity.”
Beyond the challenges already mentioned in Humboldt, there are other issues facing the grid at large. In 2021, the US Department of Energy made the goal of having net-zero carbon emissions by 2050. Following this prediction, Princeton estimated that this would lead to a 40-60 percent increase in peak electricity consumption. Increasing consumption at this rate puts a large strain on a grid that is already vulnerable. In addition to most power lines currently exceeding their life expectancies, extreme weather caused by climate change is posing a serious risk. Wildfires are a serious problem, particularly in California, as exemplified by the Camp Fire in 2018 that was caused by a combination of old, faulty PG&E equipment and extreme drought.
Additionally, although considerable progress has been made in growing renewable energy power sources — 2021 was the first time renewables (solar, wind, hydropower) accounted for the largest portion of new generating capacity — transmission issues like the ones in Humboldt have sometimes resulted in there being more electricity than there is capability to transport it. Renewable energy sources are often more site-specific than fossil fuels (a solar array in a typical Humboldt winter doesn’t work very well), meaning that upgrading transmission lines is a necessity in order to more fully integrate them into the grid. Unfortunately, the permitting process for transmission projects is extremely lengthy and costly, which creates delays for important projects.
The Future of the Grid
Although the grid faces many challenges, there are efforts being made to mitigate these issues. In Humboldt, Cissna mentioned that there has been legislation this year that’s been seeking to truncate the timelines associated with transmission projects. The California Independent System Operator, whose job it is to manage the grid and schedule energy to make sure supply meets demand, has put together a transmission plan for high priority projects in California. California State agencies are planning to have the transmission capacity built for the Humboldt offshore wind project around 2030, and May 2024 is when the Board of Governors is supposed to vote on the transmission plans for these projects. This means that between now and May, these agencies are going to be studying what a transmission project should look like for Humboldt offshore wind, giving stakeholders an opportunity to engage. In the near future, workshops and opportunities for public comment will be available, allowing for community members in Humboldt to expand their knowledge and share their opinions.
While Princeton estimated in 2021 that it could cost 2.5 trillion by 2030 to decarbonize the power grid, studies have found that it would still be cost effective, and high upfront investments would be offset by lower energy costs. Other solutions could include investing in microgrids, weatherproofing existing infrastructure, and creating better storage capabilities. “There’s no free lunch, unfortunately,” said Alstone. “ Renewables are not, you know, a pure good and have their own impacts. I think it’s important to have a good public process and make the best choices about when and where to develop them. I think a key thing though, is that doing nothing means embracing the status quo of burning fossil fuels. So it’s kind of about remembering that as we’re considering all the different options for renewable energy, remembering that the system marches on as it is today.”
In order to stay up to date on the transmission projects in Humboldt, visit redwoodenergy.org.
To learn more about the physics behind the grid