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The Batteries are Coming!

Desert Peak Energy Project

by Tom Spiglanin, Director of Education
Palm Springs Windmill Tours

We’ve known about it for a while, but the Desert Peak Energy Center project in Palm Springs broke ground a week ago. When completed next year, it will be visible from our tour location, so we will undoubtedly answer many questions. Perhaps the most important is, “Why are batteries so crucial to the future of California’s grid?”

Let’s start with the basics.

What is the grid?

The electric grid is a system of high-voltage wires that distribute electrical energy around the state, connecting power sources with consumers. Operating the grid is a complex process, but we can simplify our understanding by considering the basics of supply and demand.

• Demand is the amount of energy being pulled from the grid by consumers.
• Supply is the amount of energy being added to the grid by producers.

Unmet demand leads to blackouts, but excess supply goes to waste. Batteries could store this surplus energy, but this alone doesn’t explain the need for large-scale batteries.

The thing about electricity is that supply must always match the demand, energy flowing in from producers and flowing out to consumers, for the grid to work. The grid operator’s job is to ensure this balance. They know the electric production capability at any given time and predict consumer needs based on history, weather, population data, and many other factors.

For example, consider the accompanying figure representing an instant in time reported by California Independent System Operator that manages California’s grid.


Electricity demand on California’s grid, as reported by CA ISO.

Ideally, when demand goes up, the grid operator turns up supply. When electricity use falls, they lower it. The obvious challenge is to ensure that the current production capacity (shown above as 42,953 MW) exceeds the highest projected demand.

The renewable challenge

California’s electric supply today is made from natural gas, coal, nuclear, and renewable sources, along with electricity imported from other grids. The grid operator uses these tools to ensure enough energy to meet demand.

Nuclear, coal, and many natural gas power sources operate full-time. Their steady output is always a part of the electricity supply when running. They are a base supply, so demand consistently exceeds what they produce. Large hydroelectric plants also supply reliable, steady base supply when running, but drought and other situations sometimes limit their use.

The two lowest-cost energy sources on today’s grid are renewable: solar and wind. They represent a significant fraction of the electricity generated in California, but they share a common characteristic: neither is dispatchable. When the sun is shining, solar panels produce electricity. When the wind spins turbines, they make electricity. They can’t be turned on or up when needed, but they are desirable: they are inexpensive, and the resource is renewable.

Power Knob

Fortunately, CA ISO has excellent experience managing this asset and makes every effort to use all renewable energy. After the sun sets, however, the real challenge rears its head. People return home from work, and businesses remain open—electricity demand peaks around the same time the solar energy resource stops producing, and the demand doesn’t subside until after 9 PM.

The grid operator needs a knob that dispatches more energy during peak hours. Until recently, this knob has been natural gas power plants distributed throughout the state. So-called peaker plants are activated to meet peak energy needs, reaching full operational capacity in about ten minutes. Unlike conventional power plants, they are also shut down when not needed and stand ready to operate again when needed.

While clean among fossil fuel sources, natural gas plants still generate substantial amounts of CO2, and natural gas prices have soared. California has long sought a solution to replace these plants to meet its environmental goals while meeting the growing needs of consumers.

Bring on the batteries

Energy storage using batteries is growing throughout California’s electric grid. The typical battery project charges during the day when energy is plentiful and releases energy to meet peak demand in the evening. CA ISO reports a 500% growth in battery storage in California since May 2020, with many projects replacing aging natural gas peaker plants.

Most grid-connected batteries store enough energy daily to deliver their rated power for about four hours. A 400 MW project like Desert Peak will power about 400,000 average California homes for four hours in the evening after the sun sets and consumer demand peaks. Such battery systems, distributed around the state, are the low-carbon knob the electric utilities need.

We welcome the Desert Peak Energy Center to Palm Springs and are excited to watch it develop and come online. Be sure to stop by Palm Springs Windmill Tours, where we’ll be happy to share our knowledge and discuss the project’s importance to Southern California.

The look forward

Desert Peak Energy won’t be our area’s last energy storage. Throughout the state, much more is coming, and we’re thrilled. One of the more exciting is a new category of energy on California’s grid, so-called hybrid power systems. These combine battery storage with solar electricity generation.

Unlike separate solar and battery systems, hybrid power systems’ solar and storage components will work together within the power plant to charge batteries during the day and make the energy available to the grid as a dispatchable resource. Generated power doesn’t leave the facility unless needed to fill gaps in the grid. We’ll talk more about them in a subsequent article.

Thanks for reading!

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