4B: Intermittent Energy, Storage, and a Diverse Resource Mix

Tim Kowalchik | Chapter Four: Energy

Forge Research Site, Milford, UT | Aaron Fortin

TAKEAWAY

Only a diverse mix of energy generation will effectively meet Utah’s needs. Intermittent resource plus storage are insufficient alone.

Terms to Know

Intermittent energy generation: Energy produced only when resources like sun or wind are available.

Peaking energy generation: Power plants run briefly to meet highest electricity demands.

Baseload energy generation: Power plants that run continuously to supply steady electricity.:

Intermittent electricity resources, such as solar and wind, are essential to Utah’s growing energy portfolio but present unique challenges when considering their contribution to system-wide capacity. Unlike on- demand generation, their output is tied to variable conditions like sunlight availability or wind speed that cannot be controlled to match demand. This means a solar plant rated at 200 megawatts of capacity may only deliver a fraction of that during peak evening hours. Demand won’t wait for morning or sunshine. The entire grid must match demand and generation to operate and must be planned around the greatest predicted demand. The inherent variability of intermittent resources reduces the certainty that installed capacity translates to useable electricity during peak demand.

When properly applied, energy storage, like batteries, can help shift surplus generation from intermittent sources to peak demands. However, implementing storage at the scale required to meaningfully offset intermittency and provide reliability is technically challenging and capital-intensive. Current battery technologies, while rapidly improving, face limitations in duration, lifecycle, and material availability. Long-duration storage options, such as pumped hydro or advanced thermal systems, have their own challenges. This is further complicated by the electricity market, which rewards short duration storage, not long-term reliability.

A diverse generation mix is a healthy generation mix. To meet the growing demand of the future, integrating storage alongside healthy proportions of intermittent, peaking, and baseload generation will be essential. Doing so will require careful planning, diverse technologies, and accompanying transmission investment to ensure that generation is always ready to meet demand.

Properly applied, energy storage, like batteries, can help shift surplus generation from intermittent sources to peak demands.

Figure 4.B.1 Daily Energy Production and Allocation Example

A graph showing daily electricity generation and allocation over a 24-hour period. The x-axis represents a 24-hour timeframe from midnight through 6:00 am, 12:00 pm, 6:00 pm, and back to midnight, while the y-axis represents electricity generation in megawatts (MW), moving from base demand at the bottom to peak demand at the top. Layers of color represent different energy sources: blue for geothermal and coal (baseload generation), green for natural gas and hydro (firming generation), orange for solar and wind (intermittent generation), and pink for battery and thermal storage. During midday, intermittent solar and wind generation rises sharply, exceeding demand and storing surplus energy. In the evening, stored energy and firming generation cover the peak demand as intermittent generation declines. The pattern illustrates how baseload generation runs continuously, intermittent sources fluctuate with daylight, and stored and firming sources balance supply with demand throughout the day.

References

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