What is energy security?

Energy security is the uninterrupted physical and economic availability of energy at a price that is affordable while respecting environmental concerns. The IEA defines energy security through four dimensions — the '4 As': (1) Availability — physical existence of energy resources (reserves, production capacity); (2) Accessibility — geopolitical and logistical ability to access those resources (trade routes, infrastructure, supplier relationships); (3) Affordability — economic accessibility at prices that do not damage growth or social welfare; (4) Acceptability — environmental and social sustainability of the energy system. Energy security operates at multiple timescales: long-run (investment in energy infrastructure, reserve development), medium-run (supply diversification, stockpiling, strategic reserves), and short-run (real-time system balancing, emergency response).

How did the Russia-Ukraine war affect European energy security?

Russia's February 2022 invasion of Ukraine triggered Europe's most significant energy security crisis in decades. Before 2022, Europe depended on Russia for approximately 40–45% of its natural gas imports (via Nord Stream 1, TurkStream, and Ukrainian transit pipeline), ~25% of oil imports, and ~45% of coal imports. Following the invasion: (1) EU imposed phased bans on Russian coal (August 2022), oil imports (December 2022, with pipeline exceptions), and curtailed Russian gas purchases; (2) Russia cut gas flows via Nord Stream to ~20% capacity (summer 2022) before the pipeline was sabotaged (September 2022); (3) Europe reduced Russian gas dependence from ~155 bcm/year (2021) to ~25–30 bcm/year (2025) by: building LNG import terminals, increasing Norwegian and Algerian gas imports, accelerating renewable deployment, and implementing demand reduction. The crisis accelerated REPowerEU — the EU's plan to eliminate Russian energy dependency — and permanently reshaped European energy security strategy.

What is the energy trilemma?

The energy trilemma is the challenge of simultaneously achieving three policy objectives that are often in tension: (1) Energy security — reliable supply, diversity of sources, resilience to disruptions; (2) Energy equity (affordability) — access to affordable, reliable energy for all citizens and businesses; (3) Environmental sustainability — reducing emissions, minimising environmental impact of energy systems. The trilemma, popularised by the World Energy Council, captures why energy policy is difficult: maximising one dimension often compromises another. Example tensions: coal power provides affordable baseload security but harms sustainability; renewable energy improves sustainability but creates intermittency challenges for security; gas is a cleaner transition fuel but creates geopolitical import dependencies; carbon taxes improve sustainability but reduce affordability. The Russia-Ukraine crisis was a stark example of security-sustainability tension — Europe's rapid LNG import build-up and extended coal plant life sacrificed short-term sustainability for security.

Energy Security

The uninterrupted availability of energy at affordable prices — and the geopolitical, infrastructure, and market dimensions that determine how secure an energy system truly is.

Published 1 October 2026 · Updated 22 October 2026

Definition

Energy security is the reliable, affordable, and sustainable supply of energy to support economic activity and social welfare. The IEA frames energy security through four dimensions — the "4 As":

Dimension	Definition	Examples of risk
Availability	Physical existence of energy resources	Reserve depletion; production decline; resource nationalism
Accessibility	Geopolitical and logistical access to resources	Pipeline disruption; sanctions; Strait of Hormuz closure; Houthi shipping attacks
Affordability	Energy prices that households and businesses can bear	Price spikes; subsidy removal; regressive energy poverty
Acceptability	Environmental and social sustainability	Climate change; local air quality; community opposition to infrastructure

European energy security: before and after 2022

The pre-2022 European energy security model Before 2022, Europe operated under a model of "energy through trade" — accepting high dependence on Russian gas (~40–45% of EU gas imports), Russian oil (~25% of EU oil imports), and Russian coal (~45% of EU coal imports) on the basis that commercial interdependence reduced conflict risk and market mechanisms would ensure supply. This model was supported by Germany's Ostpolitik — the belief that economic engagement would moderate Russian behaviour. The European gas price framework based on long-term pipeline contracts with Gazprom provided pricing predictability but created structural dependency. For context on the LNG market that Europe pivoted to, see our CERAWeek 2028 preview.: Before 2022, Europe operated under a model of "energy through trade" — accepting high dependence on Russian gas (~40–45% of EU gas imports), Russian oil (~25% of EU oil imports), and Russian coal (~45% of EU coal imports) on the basis that commercial interdependence reduced conflict risk and market mechanisms would ensure supply. This model was supported by Germany's Ostpolitik — the belief that economic engagement would moderate Russian behaviour. The European gas price framework based on long-term pipeline contracts with Gazprom provided pricing predictability but created structural dependency. For context on the LNG market that Europe pivoted to, see our CERAWeek 2028 preview.
REPowerEU and the European energy security pivot REPowerEU (May 2022) was the EU's emergency energy security plan — targeting elimination of Russian fossil fuel dependence by 2027. Key measures: (1) LNG imports: 10 new FSRU (floating storage and regasification units) deployed in Germany, Netherlands, Italy — adding ~50+ bcm/year LNG import capacity by 2024; US, Norwegian, Qatari, and Australian LNG displaced Russian pipeline gas; (2) Norwegian gas surge: Norway increased pipeline gas exports to ~120 bcm/year (2022–2023) from pre-crisis ~110 bcm, via new fields and capacity; (3) Renewable energy acceleration: EU fast-tracked solar, wind, and heat pump deployment; (4) Demand reduction: EU achieved ~15% gas demand reduction vs 2019–2021 average by 2022–2023; (5) Gas storage: EU mandated 80%+ gas storage by November 1 each year. Russian gas fell from ~155 bcm/year (2021) to ~25–30 bcm/year (2025). See our EU Energy Week 2026 for current EU energy policy.: REPowerEU (May 2022) was the EU's emergency energy security plan — targeting elimination of Russian fossil fuel dependence by 2027. Key measures: (1) LNG imports: 10 new FSRU (floating storage and regasification units) deployed in Germany, Netherlands, Italy — adding ~50+ bcm/year LNG import capacity by 2024; US, Norwegian, Qatari, and Australian LNG displaced Russian pipeline gas; (2) Norwegian gas surge: Norway increased pipeline gas exports to ~120 bcm/year (2022–2023) from pre-crisis ~110 bcm, via new fields and capacity; (3) Renewable energy acceleration: EU fast-tracked solar, wind, and heat pump deployment; (4) Demand reduction: EU achieved ~15% gas demand reduction vs 2019–2021 average by 2022–2023; (5) Gas storage: EU mandated 80%+ gas storage by November 1 each year. Russian gas fell from ~155 bcm/year (2021) to ~25–30 bcm/year (2025). See our EU Energy Week 2026 for current EU energy policy.
Energy security and the energy transition: tension and alignment The energy transition creates both new energy security vulnerabilities and new security opportunities: New vulnerabilities: (1) Critical minerals — EVs, batteries, and wind turbines require lithium, cobalt, nickel, rare earths; supply concentrated in China and few other nations creates new dependency risks analogous to oil import dependency (see our critical minerals 2026 analysis); (2) Grid security — higher renewable share requires more grid flexibility, storage, and interconnection; cyber and physical attacks on electrical infrastructure are a growing concern; (3) Hydrogen supply chains — if green hydrogen import dependency replicates gas import dependency, the security problem is not solved. New security benefits: (1) Domestic renewable generation — solar and wind are domestic resources not subject to geopolitical supply disruption; (2) Electrification reduces oil import dependency for transport; (3) Energy efficiency directly reduces exposure to volatile fuel prices.: The energy transition creates both new energy security vulnerabilities and new security opportunities: New vulnerabilities: (1) Critical minerals — EVs, batteries, and wind turbines require lithium, cobalt, nickel, rare earths; supply concentrated in China and few other nations creates new dependency risks analogous to oil import dependency (see our critical minerals 2026 analysis); (2) Grid security — higher renewable share requires more grid flexibility, storage, and interconnection; cyber and physical attacks on electrical infrastructure are a growing concern; (3) Hydrogen supply chains — if green hydrogen import dependency replicates gas import dependency, the security problem is not solved. New security benefits: (1) Domestic renewable generation — solar and wind are domestic resources not subject to geopolitical supply disruption; (2) Electrification reduces oil import dependency for transport; (3) Energy efficiency directly reduces exposure to volatile fuel prices.

Energy security tools and mechanisms

Tool	Purpose	Examples
Strategic petroleum reserves (SPR)	Buffer against supply disruption; IEA coordinates releases	US SPR (~365 mb capacity); EU member state 90-day minimum stock obligations
Gas storage mandates	Winter supply security in gas-import-dependent countries	EU gas storage regulation (80% fill by Nov 1)
Supply diversification	Reduce single-supplier dependency	EU LNG import terminal buildout; pipeline diversification (Interconnector, TAP, TANAP)
Long-term supply contracts	Price and volume certainty	LNG SPAs (Sale and Purchase Agreements); pipeline take-or-pay contracts
Domestic production incentives	Increase self-sufficiency	US shale support; Norwegian tax regime; UK North Sea windfall tax debate
Demand reduction	Reduce exposure to supply risk	EU 15% gas demand reduction target; efficiency mandates; price signals
Energy interconnection	Share emergency capacity across borders	EU electricity interconnection targets; LNG terminal sharing

For energy security as discussed at CERAWeek — the world's leading industry forum for this debate — see our CERAWeek 2028 preview. For how fuel subsidies intersect with energy affordability security, see our fuel subsidy glossary entry. For Africa's energy security challenges, see our Africa Energy Forum 2027.

Frequently asked questions

What is energy security? Energy security is the reliable, affordable, and sustainable supply of energy. The IEA's "4 As": Availability (physical resources), Accessibility (geopolitical/logistical access), Affordability (price levels households and businesses can bear), and Acceptability (environmental sustainability). Energy security operates across timescales: long-run infrastructure investment, medium-run diversification and stockpiling, and short-run emergency response.: Energy security is the reliable, affordable, and sustainable supply of energy. The IEA's "4 As": Availability (physical resources), Accessibility (geopolitical/logistical access), Affordability (price levels households and businesses can bear), and Acceptability (environmental sustainability). Energy security operates across timescales: long-run infrastructure investment, medium-run diversification and stockpiling, and short-run emergency response.
How did the Russia-Ukraine war affect European energy security? Russia supplied ~40–45% of EU gas, ~25% of oil, ~45% of coal pre-2022. Following the invasion, Europe rapidly diversified: built 10+ FSRU LNG import terminals, increased Norwegian/Algerian gas, accelerated renewables, and implemented demand reduction. Russian gas fell from ~155 bcm/year (2021) to ~25–30 bcm/year (2025). REPowerEU targets full independence by 2027. The crisis permanently shifted European energy security strategy away from pipeline dependency.: Russia supplied ~40–45% of EU gas, ~25% of oil, ~45% of coal pre-2022. Following the invasion, Europe rapidly diversified: built 10+ FSRU LNG import terminals, increased Norwegian/Algerian gas, accelerated renewables, and implemented demand reduction. Russian gas fell from ~155 bcm/year (2021) to ~25–30 bcm/year (2025). REPowerEU targets full independence by 2027. The crisis permanently shifted European energy security strategy away from pipeline dependency.
What is the energy trilemma? The energy trilemma is the challenge of simultaneously achieving: (1) Energy security — reliable, diverse supply; (2) Energy equity/affordability — accessible prices for all; (3) Environmental sustainability — low emissions. The World Energy Council uses this framework to explain why energy policy is difficult — optimising one dimension often compromises others. The 2022 European energy crisis demonstrated the security-sustainability tension: rapid LNG buildout and coal plant extensions sacrificed near-term sustainability for security.: The energy trilemma is the challenge of simultaneously achieving: (1) Energy security — reliable, diverse supply; (2) Energy equity/affordability — accessible prices for all; (3) Environmental sustainability — low emissions. The World Energy Council uses this framework to explain why energy policy is difficult — optimising one dimension often compromises others. The 2022 European energy crisis demonstrated the security-sustainability tension: rapid LNG buildout and coal plant extensions sacrificed near-term sustainability for security.