page_title: Variable renewable energy
section_title: Intermittent energy source
hierarchical_section_title: Variable renewable energy / Intermittent energy source
caption_attribution_description: Workers construct one of a dozen molten salt tanks at Abengoa's Solana Plant. The molten salt tanks will generate clean, renewable electricity with conventional steam turbines.
context_page_description: Variable renewable energy is a renewable energy source that is non-dispatchable due to its fluctuating nature, like wind power and solar power, as opposed to a controllable renewable energy source such as dammed hydroelectricity, or biomass, or a relatively constant source such as geothermal power.
context_section_description: An intermittent energy source is any source of energy that is not continuously available for conversion into electricity and outside direct control because the used primary energy cannot be stored. Intermittent energy sources may be predictable but cannot be dispatched to meet the demand of an electric power system.
  The use of intermittent sources in an electric power system usually displaces storable primary energy that would otherwise be consumed by other power stations. Another option is to store electricity generated by non-dispatchable energy sources for later use when needed, e.g. in the form of pumped storage, compressed air or in batteries. A third option is the sector coupling e.g. by electric heating for district heating schemes.
  The use of small amounts of intermittent power has little effect on grid operations. Using larger amounts of intermittent power may require upgrades or even a redesign of the grid infrastructure.
caption: Construction of the Salt Tanks which provide efficient thermal energy storage[70] so that output can be provided after the sun goes down, and output can be scheduled to meet demand requirements.[71] The 280 MW Solana Generating Station is designed to provide six hours of energy storage. This allows the plant to generate about 38 percent of its rated capacity over the course of a year.[72]
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