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Though often an afterthought apart from paying the monthly utility bill, the US electric grid’s influence on the average American’s day-to-day life is near infinite—from brewing the first cup of coffee in the morning to fuel the day to streaming a movie with the family to relax. While the current grid is remarkable in its own right, industry experts project a surge in demand by 2050, posing significant challenges for renewable energy developers, such as Green Development LLC, that will have far-reaching and long-term consequences.

In this two-part educational series, Green Development LLC’s Director of Project Management Matt Ursillo summarizes the history of the energy grid in the United States, challenges associated with the rapid growth of renewable energy sources, how change or lack thereof will impact US energy consumers, as well as the framework that is shaping the future of the grid.

1. How would you describe the design of the current electric grid in the United States to a non-technical audience?

The modern US electric grid is composed of a series of the interstate, federally regulated, bulk power transmission circuits (the grid), which transport the power generated from massive power plants. These bulk circuits feed a wide variety of regulated, unregulated, and smaller distribution circuits, which in turn deliver electricity to end-users.

One of the technical problems we run into today is that this system was designed to be a one-way transaction. It’s similar to a factory supply chain that makes a product and ships it around the world to distributors in large quantities. These distributors then sell the product to stores in smaller quantities, which then sell it to you, the end-user. If something happens in that supply chain to disrupt the transportation process, the end-user may never receive the intended product.

The difference if we substitute electric power as the product in the previous example is that our society has become critically dependent on both availability of electricity and the specific quality of it. Our electronic devices are designed to operate at a particular voltage (electric pressure), current (flow rate of electricity), and alternating current (AC) frequency. The fragility of the current system is such that deviations of those constituents can result in, at best, our electric devices not operating correctly and, at worst, the whole system crashing. Either situation could quite literally be the difference between life and death for millions of Americans.

With the current one-way system, grid operators have quite a bit of control over both the availability and quality of the electric power. However, as you start to add in many smaller power plants distributed throughout the entire system, operated by many owners, the grid becomes multidirectional, with power being imported and exported in many different directions and at various times of the day. Grid operators must ensure the quantity and quality of the power, despite losing centralized control by a limited number of companies.

2. Why and when was it designed this way?

In the late 19th century, the early US electric grid was developed to utilize direct current (DC) electricity. In the typical business model, a utility business enterprise would construct a DC power plant, typically in a densely populated area with many potential customers, and distribute the DC power to those customers locally. With the advent of AC electricity and the introduction of the AC transformer, which could inexpensively increase the voltage of the electricity, long-distance transmission became more viable. Utility owners maintained the same business plan, but instead, they were able to serve very large areas and increase the number of customers served.

To accommodate the increased demand for electric power, utilities began to construct even larger, controllable, fossil fuel burning, AC power plants and distribute the power over very long distances to more customers. As the availability of electric power spread, system reliability became a critical need. Some of these utilities started tying their electric networks together (interconnecting) to share power in case the load in one region exceeded the available power generation. To do that, utilities had to ensure that their AC circuits were operating at the same voltage and precisely the same frequency—because they must be synchronized. Today we have very large grids such as the Eastern Interconnection and Western Interconnection, which are overseen and managed by Independent System Operators (ISO’s) to ensure that the systems maintain reliability.

3. What are some of the general challenges faced by grid operators with the aging of the grid infrastructure?

The biggest challenge is reliability. As mentioned, the system maintains a fragile balancing act between electric producers and users. The rotational nature of AC electricity is such that the frequency needs to be consistent across all power plant generators that interconnect to the grid. Also, the existing grid equipment can handle only certain voltages and currents without sustaining damage.

With only a limited number of utilities producing power within an interconnection region before the proliferation of distributed energy sources, such as hydropower, solar, and wind, coordination was simplified. Now with many, smaller power producers utilizing the same transmission and distribution equipment, grid operators need to delicately balance the power being produced, the load requirement of users, and the equipment limitations between the two.

An additional complication is that most renewable energy sources are not considered dispatchable. Unlike a fossil fuel burning power plant, they produce power only under certain environmental conditions regardless of the need for power being there. Energy is only available when the sun is shining, and the wind is blowing, making the balance for grid operators even more difficult.

4. How have these issues impacted US energy consumers and/or the country, in general?

While having a limited number of utility companies generating and distributing power simplified control over the quality of power, it also created powerful business monopolies in which consumers were beholden to whichever utility served their area. By breaking up those monopolies, the market received a healthy boost of competition, which, in general, lowered consumer electric rates and improved availability. However, the system’s complexity has also increased, and there is a higher cost to maintain the balance. At the end of the day, though, the environmental, public health, and economic benefits of renewable sources have the most significant long-term gain to the consumers.

5. What are some of the specific challenges faced by grid operators with the rapid growth of renewable energy sources, such as solar and wind farms? At what point in time did these issues emerge?

As stated earlier, the previous one-way system allowed for abundant and controlled generation, transmission, and distribution of electricity. The generation of electricity was mostly accomplished by burning carbon-based fossil fuels of various sorts. That system was very controllable: Burn more fuel, get more power, and vice versa. However, this combustion process’s byproducts include a multitude of gasses released in the surrounding atmosphere, including carbon dioxide, sulfur oxides, nitrogen oxides, mercury, chlorides, and fluorides. It also generated solid wastes in the form of fly ash, bottom ash, and slag, all of which also contain hazardous chemicals.

Because of these polluting byproducts, which are released in the area surrounding large generating plants, fossil fuel plants have historically been built in remote locations or in lower-income areas. However, the long-distance transmission and distribution grids enable this power to be transported to commercial, industrial, and other residential areas far away from where the power is produced.

With renewable energy such as solar and wind, the traditional model is disrupted. Smaller power plants can be sited closer to populations that need it, without the effects of harmful combustion products. However, due to the varying availability of power from these sources, grid operators now need to contend with managing the distribution of power from areas where there is excess to areas with a deficit, while still maintaining the quality of the power being delivered.

About Green Development:

Green Development LLC is the leading developer of utility-scale renewable energy projects in Rhode Island, specializing in wind, solar, and battery storage. The company delivers significant energy savings to municipalities, quasi-public entities, nonprofits, and other qualified entities through the virtual net metering program while providing long-term lease payments to landowners and farmers.

Since 2009, Green Development has been instrumental in transforming the energy mix in Rhode Island to clean, reliable energy. The company has developed more than 70 MW in solar and wind capacity, with plans to add 111 MW in 2021. Green Development is devoted to preserving farmland, reducing water and air pollution, increasing energy security, and creating local jobs. Current wind and solar sites reduce carbon emissions equivalent to using 8,091,141 gallons of gas each year.