Solar and wind energy are expanding quickly across the U.S., making up 19% of electricity generation today and projected to exceed 40% by 2030. However, their intermittent nature presents a challenge for grid reliability, as they generate power only when the sun shines or the wind blows. This intermittency means backup sources are crucial to bridge energy gaps, and natural gas is currently the most practical and affordable option for this purpose. Many anticipate that as renewables grow, they will fully replace fossil fuels, but in reality, natural gas will remain essential for maintaining a stable and reliable grid for the foreseeable future.
The issue lies in the nature of variable renewable energy (VRE). Solar and wind have predictable limitations, such as solar’s absence at night or reduced power during winter. Yet, they also face unpredictable issues, like prolonged cloudy weather or wind droughts, which can reduce energy production for days or even weeks. This becomes especially challenging as VRE accounts for a larger share of the grid. Short-duration batteries, like lithium-ion, are currently used to meet daily fluctuations, providing power for a few hours during peak demand. While valuable, these batteries are insufficient for longer VRE deficits, such as those caused by prolonged adverse weather conditions.
To fill these longer gaps, the grid relies heavily on natural gas. Gas plants, especially “peaker” plants, which operate on a single cycle, can be activated on demand to address spikes in energy needs when renewable generation dips. Although peaker plants are less efficient than combined cycle gas turbines (CCGTs), they are only used in emergencies, making them an economical solution to meet peak demands without excessive costs. As renewables grow, more of this backup capacity will be needed, and the Department of Energy (DOE) projects that peaker plant capacity will likely increase during the clean energy transition to prevent blackouts during extended VRE shortfalls.
Alternatives to natural gas for long-duration energy storage, such as hydropower, green hydrogen, and compressed air, all face limitations. Hydropower is established and efficient but constrained by geography and environmental considerations, with fewer dams being built than removed in the U.S. Green hydrogen, while promising, suffers from high costs, low efficiency, and transport challenges. Compressed air storage also has efficiency constraints and requires significant investment. Therefore, natural gas remains the most reliable and flexible backup option during prolonged renewable deficits.
As VREs increase, the role of natural gas will evolve. CCGT plants, traditionally used as baseload power, will increasingly serve as insurance, providing power when renewables fall short, similar to the current role of peaker plants. Over time, we may reduce reliance on gas through advances in storage technologies, carbon capture, or emerging energy sources like geothermal or even fusion. Yet, until these technologies become viable and affordable, natural gas will remain a crucial part of the grid, enabling the shift to renewables while maintaining reliability.
For the U.S. to achieve decarbonization, a balanced approach that acknowledges gas’s transitional role is essential, ensuring reliable energy today while investing in the technologies of tomorrow.