Is Intermittency a Problem for Renewable Energy?
Exploring how wind and solar deal with variability—and why the reliability of grids is more complex than fossil fuel advocates claim.
The transformation toward renewable energy depends heavily on technologies like wind and solar. These sources are often criticized for their intermittency: the sun doesn’t always shine, and the wind doesn’t always blow. Traditionally, this variability has fueled doubts about the grid reliability of renewables. But is intermittency truly an unsolvable problem for a clean energy future? This article dissects the realities, misconceptions, and modern solutions shaping the role of intermittency in renewable power.
Understanding Intermittency in Renewable Power
Intermittency refers to the variable and sometimes unpredictable output from energy sources such as wind and solar. Unlike conventional power plants that burn fuel or split atoms to generate continuous, predictable electricity, renewables depend on the volatility of weather and time of day. However, this variability is neither new to power systems nor as crippling as some critics suggest.
- Wind turbines generate electricity only when wind speeds fall within certain ranges.
- Solar photovoltaics (PV) produce power during daylight, peaking at midday and falling to zero at night or under heavy clouds.
- Tidal and wave energy are also intermittent, though typically more predictable because of their links to lunar cycles.
Misconceptions: Does Intermittency Equal Unreliability?
Detractors of renewable energy often claim that intermittent sources are inherently unreliable for a stable energy grid—emphasizing moments when renewables underperform or overproduce. However, this is a mischaracterization of how power systems work in practice.
- No power generator is available 100% of the time. Even coal and nuclear plants undergo planned maintenance and unplanned outages.
- Grid reliability comes from system diversity, not from each individual generator running nonstop.
- Historically, power grids have been designed to accommodate variability—including changes in demand and random outages of conventional plants.
As the Stanford Law Review points out, the tension between renewable energy and reliability is often overstated. Many failures attributed to renewables are more frequently due to other grid issues, including weather-related disruptions impacting all types of generation.
How Power Grids Manage Variability
Grid operators already balance constant fluctuations in supply and demand, dispatching resources to match minute-to-minute needs. Intermittency from renewables is just another form of variability, and grids are evolving to handle it efficiently.
- Dispatchable generators (like gas, hydro, or batteries) can quickly ramp up or down to fill in when renewable output dips.
- Geographic diversity spreads risk: Wind or solar may be variable at a single site, but across a wide area, these variations are smoothed out.
- Grid interconnections and large-scale transmission lines allow regions with surplus renewable generation to help those experiencing shortfalls.
- Demand response programs incentivize consumers to shift their usage according to supply, subtly aligning demand with variable generation.
Case Study: Wind Power Across Regions
A study of wind generation in the U.S. Midwest found that distributing wind farms over wide geographic areas drastically reduced the chances of producing zero power at any given moment. Even with intermittent sources, system-wide variability becomes manageable with spatial diversity.
What others are reading
Renewables in Practice: Recent Lessons
Some high-profile blackouts, such as Texas’s Winter Storm Uri, have been incorrectly attributed solely to renewable intermittency. In reality, the failure of gas infrastructure and a lack of system-wide resilience played larger roles. No generation type is immune to extreme weather, mechanical failure, or resource constraints. The core lesson: reliability is a function of entire grid architecture, not any single technology.
Proven Solutions for the Intermittency Challenge
The world’s transition to higher shares of wind and solar is pushing innovation in grid management, energy storage, and flexible consumption. Here are the principal strategies addressing intermittency:
- Energy storage: Batteries, pumped hydro, and emerging storage technologies can shift renewable power supply over hours or even days, covering lulls and soaking up excesses.
- Flexible generation: Hydropower, biogas, and even some fossil fuel generators can provide adjustable backup capacity.
- Grid expansion: Building new transmission lines connects disparate regions, enabling the sharing of renewable electricity and smoothing variability.
- Demand-side management: Smart appliances, electric vehicles, and pricing incentives reshape consumption patterns to match renewable output.
- Diversification: Combining different renewable technologies (wind, solar, geothermal, hydro, tidal) ensures that lulls in one source can be covered by others.
Why Intermittency is Not the Roadblock Many Imagine
Contrary to early doubts, real-world evidence now shows that high proportions of intermittent renewables can power modern economies reliably—provided the grid is modernized.
- Countries like Denmark, Germany, and Spain regularly operate with wind and solar providing 30-50% or more of annual electricity. Grid reliability statistics in these countries rival or exceed those in fossil-dependent systems.
- Studies confirm that technology already exists to ensure grid stability at much higher renewable penetrations than traditional grids were designed for.
- Even critics who note that wind and solar can’t ramp like fossil or nuclear admit that modern grids don’t rely on individual generators, but on diversity and integration.
Common-Mode Failure: A Unique Challenge
One specific risk for renewables is “common-mode failure,” where weather fronts can impact many wind turbines or solar panels at once. Grid operators mitigate this with:
- Long-range weather forecasting
- Regional resource sharing
- Flexible imports and exports through interconnections
By reacting to meteorological events across hundreds of sites, system managers ensure this risk remains manageable.
Intermittency in Context: The Bigger Picture of Grid Reliability
| Generator Type | Typical Availability | Nature of Outages | Role in Grid |
|---|---|---|---|
| Coal/Nuclear | 85%-95% | Mechanical failure, maintenance | Base load, dispatchable |
| Natural Gas | 80%-90% | Supplies, mechanical, fuel disruptions | Peaking, load following |
| Wind | 25%-50% (capacity factor) | Weather-driven, predictable with forecasting | Variable, non-dispatchable |
| Solar | 15%-25% (capacity factor) | Night, clouds, weather | Variable, non-dispatchable |
| Hydropower | 40%-80% | Seasonal, drought | Dispatchable and variable |
Note: All generators, regardless of type, require backup and integration to maintain grid reliability.
Does Intermittency Increase Costs?
Another concern is that managing intermittency will drive up the cost of electricity. However, falling prices for wind, solar, and storage have already offset system integration expenses. System operators report that grid costs for renewables are modest compared to the long-term savings from low fuel prices and reduced environmental impacts.
- Upgrading transmission and adding storage incurs up-front expenses, but these are dwarfed by ongoing fuel and climate costs avoided through renewables.
- Flexibility and integrated planning create a more robust, cost-effective grid over the long run.
Looking Forward: Building Resilient, Clean Power Systems
Intermittency is only part of a broader conversation about the future of energy. As climate change increases extreme weather events and system stresses, all grid technologies—fossil or renewable—must adapt. The best strategies include:
- Investing in infrastructure upgrades and digitalized control systems
- Developing distributed energy resources such as rooftop solar and community batteries
- Adopting market reforms that reward flexibility and resilience, not just raw output
The ultimate goal is a clean, reliable, and affordable grid that leverages technology to overcome old limitations. Intermittency is real—but no longer the barrier it once was.
Frequently Asked Questions (FAQs)
Q: Are renewables as reliable as fossil fuels?
A: Reliability is achieved at the system level, not by individual generators. Modern grids with high shares of renewables utilize backup, storage, and geographic diversity to match and sometimes exceed the reliability metrics of fossil-based systems.
Q: What happens when renewables aren’t producing enough power?
A: Grid operators dispatch other available sources, draw on stored energy, or import power from connected regions. This is no different from solutions used during fossil fuel plant outages or supply disruptions.
Q: Can storage solve all of renewables’ intermittency problems?
A: Storage—mainly in the form of batteries and pumped hydro—greatly helps, but works best as part of an integrated system with flexible generation, smart grids, and diversified renewable sources.
Q: Are blackouts linked to renewable energy growth?
A: Major blackouts are almost always due to broader system failures—such as extreme weather, inadequate infrastructure, or poorly maintained backup—rather than renewable intermittency alone.
Q: Is it possible to have a 100% renewable grid?
A: While challenging, studies suggest that with the right mix of technology—storage, demand response, grid interconnections, and a diverse energy portfolio—it’s technically feasible to run reliable grids entirely on renewable power.
References
Similar Articles
Read full bio of Sneha Tete
