Editing Electricity (section)

=== Transmission and storage ===
The invention in the late nineteenth century of the [[transformer]] meant that electrical power could be transmitted more efficiently at a higher voltage but lower current. Efficient [[electrical transmission]] meant in turn that electricity could be generated at centralised [[power station]]s, where it benefited from [[economies of scale]], and then be despatched relatively long distances to where it was needed.<ref name="Patterson_p44-48">
{{citation |last=Patterson |first=Walter C. |title=Transforming Electricity: The Coming Generation of Change |pages=44–48 |year=1999 |publisher=Earthscan |isbn=1-85383-341-X}}
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{{citation |last=Edison Electric Institute |title=History of the Electric Power Industry |url=http://www.eei.org/industry_issues/industry_overview_and_statistics/history |archive-url=https://web.archive.org/web/20071113132557/http://www.eei.org/industry_issues/industry_overview_and_statistics/history |access-date=2007-12-08 |archive-date=November 13, 2007 |url-status=dead}}
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Normally, demand for electricity must match the supply, as storage of electricity is difficult.<ref name="Patterson_p44-48" /> A certain amount of generation must always be held in [[Operating reserve|reserve]] to cushion an electrical grid against inevitable disturbances and losses.<ref>{{Cite journal |last1=Castillo |first1=Anya |last2=Gayme |first2=Dennice F.|author2-link=Dennice Gayme |date=2014 |title=Grid-scale energy storage applications in renewable energy integration: A survey |url=https://www.sciencedirect.com/science/article/pii/S0196890414007018 |journal=Energy Conversion and Management |language=en |volume=87 |pages=885–894 |doi=10.1016/j.enconman.2014.07.063 |bibcode=2014ECM....87..885C |issn=0196-8904}}</ref> With increasing levels of [[variable renewable energy]] (wind and solar energy) in the grid, it has become more challenging to match supply and demand. Storage plays an increasing role in bridging that gap. There are four types of energy storage technologies, each in varying states of [[Technology readiness level|technology readiness]]: [[Electric battery|batteries]] (electrochemical storage), chemical storage such as [[hydrogen]], thermal or mechanical (such as [[Pumped-storage hydroelectricity|pumped hydropower]]).<ref>{{Cite book |url=https://energy.mit.edu/wp-content/uploads/2022/05/The-Future-of-Energy-Storage.pdf |title=The Future of Energy Storage |publisher=Massachusetts Institute of Technology |year=2022 |isbn=978-0-578-29263-2 |pages=xi-xvi}}</ref>