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Intermittent renewable energy

What Is Intermittent Renewable Energy?

Intermittent renewable energy refers to forms of electricity generation whose availability fluctuates due to natural, unpredictable factors, rather than being dispatchable or controllable by human operators. This concept is central to modern energy finance and grid management, falling under the broader category of energy systems. The most common examples are solar power, which depends on sunlight, and wind power, which relies on wind speed. Unlike conventional power plants that can provide a steady output or be ramped up/down as needed, intermittent renewable energy sources pose unique challenges for maintaining grid stability and balancing supply and demand within the electrical system.

History and Origin

The concept of intermittent renewable energy gained prominence with the global push towards clean energy and decarbonization in the late 20th and early 21st centuries. As technologies like solar photovoltaic (PV) panels and wind turbines matured and became more cost-effective, their deployment accelerated significantly. However, the inherent variability of these sources quickly highlighted a critical challenge: integrating them into existing electrical infrastructure designed for continuous baseload power from sources such as fossil fuels or nuclear energy.

The International Energy Agency (IEA) has emphasized the need for substantial upgrades to electric grids worldwide to accommodate the growing share of intermittent renewable energy. A 2023 report noted that around 50 million miles of power lines would need to be built or improved by 2040, warning that a failure to enhance grid capacity could severely impede efforts to combat climate change9. Early analyses, such as the IEA's 2017 report "Getting Wind and Sun onto the Grid," highlighted the system integration challenges posed by increasing intermittent generation and suggested measures to maintain cost-effectiveness and reliability as renewable capacity grew globally.

Key Takeaways

  • Intermittent renewable energy sources, primarily solar and wind, produce electricity variably based on natural conditions.
  • Their integration into the power grid requires advanced management techniques and supporting technologies.
  • Battery storage and flexible grid operations are crucial for mitigating intermittency.
  • Overcoming intermittency is vital for the global energy transition and achieving decarbonization goals.
  • Investment in grid modernization is essential to support higher penetrations of these energy sources.

Interpreting Intermittent Renewable Energy

Intermittent renewable energy is interpreted through its impact on the reliability and dispatchability of an electrical energy market. A high penetration of intermittent renewable energy means a greater reliance on variable sources, necessitating robust forecasting, demand response programs, and energy storage solutions to ensure a continuous and stable electricity supply. Without proper management, significant fluctuations in generation from these sources can lead to grid instability, requiring rapid adjustments from other generating assets or, in extreme cases, grid curtailment or outages. Understanding the variability is key for system operators, policymakers, and investors in managing the associated risk management challenges.

Hypothetical Example

Consider a small island nation aiming to source 70% of its electricity generation from solar panels and wind turbines. During a sunny, windy day, these intermittent renewable energy sources might produce more power than the island's immediate demand, leading to excess energy. Conversely, on a cloudy, calm evening, their output could drop significantly, creating a deficit. To manage this, the island could implement large-scale battery storage facilities to store surplus energy from peak generation periods and discharge it during low generation times. They might also employ smart grid technologies to encourage consumers to shift their electricity usage to align with periods of high renewable output (e.g., charging electric vehicles during midday solar peaks).

Practical Applications

Intermittent renewable energy sources are primarily used for large-scale electricity generation, contributing to national and regional power supplies. Their practical application involves integrating them into complex power grids, often requiring sophisticated forecasting models to predict their output. Key applications include:

  • Utility-scale power generation: Large solar farms and wind farms feed electricity directly into transmission networks.
  • Decentralized power: Smaller-scale solar installations on rooftops contribute to local grids.
  • Grid balancing services: When paired with energy storage, intermittent renewable energy can provide services such as frequency regulation and voltage support to maintain grid stability. The U.S. Energy Information Administration (EIA) has highlighted the explosive growth in U.S. battery storage capacity, which plays a crucial role in maintaining grid stability by balancing electricity supply and demand from renewable sources8. Forbes also noted that storage has become an essential player in supporting the grid during normal operations and times of stress7.
  • Meeting carbon reduction targets: Expanding the use of intermittent renewables is fundamental to achieving national and international sustainability goals.

Limitations and Criticisms

The primary limitation of intermittent renewable energy is its inherent variability and lack of dispatchability. This poses challenges for grid operators who must ensure a continuous balance between electricity supply and demand. If the output from solar and wind drops unexpectedly (e.g., due to cloud cover or a sudden decrease in wind speed), other energy sources must quickly compensate to prevent blackouts. This can lead to:

  • Grid instability: Fluctuations can affect grid frequency and voltage, potentially leading to system disruptions. Some experts warn that without sufficient grid infrastructure upgrades, increased reliance on renewables could lead to more widespread blackouts6.
  • Need for backup capacity: Traditional market dynamics often require conventional power plants (e.g., natural gas) or robust energy storage to be available as backup, which can increase overall system costs. This challenge is acknowledged by grid operators, with some stating that fossil fuel generation is retiring faster than renewable resources are entering service, leading to declining reliability margins in certain regions5.
  • Transmission constraints: Regions with abundant solar or wind resources may be far from population centers, requiring extensive and costly new transmission lines. The International Energy Agency has noted that huge amounts of renewable energy capacity globally are awaiting connection to power lines4. Building new transmission infrastructure can be hindered by public opposition and regulatory hurdles3.

Intermittent Renewable Energy vs. Baseload Power

The core distinction between intermittent renewable energy and baseload power lies in their operational characteristics and reliability.

FeatureIntermittent Renewable EnergyBaseload Power
AvailabilityVariable and unpredictable, dependent on natural conditionsConstant and reliable, available 24/7
ControlNon-dispatchable (output cannot be directly controlled)Dispatchable (output can be controlled as needed)
ExamplesSolar, windNuclear, geothermal, some large hydropower, coal, natural gas
Grid RoleRequires balancing mechanisms and storageProvides continuous, foundational electricity supply
ChallengesManaging variability, grid integration, storage needsEnvironmental impact (for fossil fuels), high upfront costs (for nuclear)

While baseload power sources provide a consistent minimum supply of electricity, intermittent renewable energy requires supplementary systems, such as energy storage or flexible conventional generation, to ensure grid reliability and meet demand consistently. The challenge for energy systems is to balance the economic and environmental benefits of intermittent renewables with the stability provided by baseload or dispatchable resources.

FAQs

What are the main types of intermittent renewable energy?

The primary types are solar power (from photovoltaic panels or concentrated solar power) and wind power (from wind turbines). Their output depends directly on the presence and intensity of sunlight or wind.

How is intermittency managed in an electrical grid?

Intermittency is managed through various strategies, including energy storage systems (such as battery storage), smart grids that facilitate demand response, robust transmission infrastructure to balance regional surpluses and deficits, and hybrid systems that combine intermittent renewables with dispatchable sources or other forms of clean energy like hydropower.

Does intermittent renewable energy increase electricity costs?

While the operational cost of generating electricity from sources like solar and wind can be very low once built, the overall system costs might increase due to the need for grid upgrades, backup capacity, and energy storage to maintain reliability. However, the long-term trend shows a significant decrease in the cost of renewable technologies, making them increasingly competitive, especially when paired with storage2.

What is the role of energy storage for intermittent renewables?

Energy storage is crucial for intermittent renewables as it allows excess electricity generated during periods of high output (e.g., sunny midday for solar) to be stored and then released when generation is low but demand is high (e.g., evening peak). This helps stabilize the grid and maximize the utilization of renewable resources. The U.S. Energy Information Administration (EIA) projects record growth in utility-scale battery storage, highlighting its importance for grid stability when used with renewable energy1.