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18 May 2026
What is an energy crisis and why does it occur?
The closure of the Strait of Hormuz has triggered the largest disruption to oil supply in history, according to the IEA. We explain what an energy crisis is, why it occurs, how it impacts the global economy, and what mechanisms Spain has in place to respond.
An energy crisis is a mismatch between the supply and demand of energy resources (oil, natural gas, electricity, or petroleum products) caused by geopolitical conflicts, production failures, or climatic factors. This causes price spikes and threatens the security of supply for households, industries, and entire economies.
Understanding what causes them is the first step in anticipating their impact and evaluating responses.
What is an energy crisis?
An energy crisis is the system's inability to balance energy production with consumption needs at affordable prices.
It affects primary energy (crude oil, natural gas, coal, uranium) and petroleum products (electricity, refined fuels like diesel or kerosene, industrial heat).
The impact varies depending on each country's position in the global energy chain:
- For net importing countries like Spain: a crisis occurs when the demand for primary energy or derived fuels exceeds the available supply on international markets, sending import costs and final consumer prices soaring – from petrol to electricity bills.
- For exporting countries (such as members of OPEC, the Organization of the Petroleum Exporting Countries): it can arise from an oversupply that causes prices to collapse, threatening the viability of their economies, or from signs of accelerated depletion of their reserves.
Why does an energy crisis occur? The four main causes
1. Imbalance between energy supply and demand
This occurs when demand growth, driven by economic expansion, industrialisation, or climate change, is not accompanied by a parallel increase in production.
There is an inevitable structural lag between the decision to invest in a new oil field, power station, or regasification plant, and its entry into commercial operation, which can take between 5 and 10 years.
2. Geopolitical tensions
Much of the world's oil and gas is produced in or transits through geopolitically unstable areas. When a conflict breaks out in a key producing region or a strategic transit route is blocked, millions of barrels can disappear from the market overnight.
3. Raw material shortages and external dependence
Many countries rely on importing the oil, gas, and other raw materials they need. When supply is interrupted, there is no immediate substitute: without gas, there are no fertilisers; without naphtha, there are no plastics; and without critical metals, there is no renewable technology.
4. Climatic and environmental factors
Prolonged droughts that reduce hydroelectric generation, heatwaves that send air conditioning consumption soaring, storms that can damage production or transport infrastructure, or very cold winters that increase heating demand are all factors that can trigger situations of energy stress.
According to the Global Energy Review 2026 by the IEA, in Europe the combination of a cold winter with low availability of hydro and wind power in 2025 drove up the demand for natural gas for electricity generation, even in a context of already high gas prices.
Current energy situation: the 2026 context
The global energy scenario in 2026 is defined by the conflict that began on 28 February 2026, which led to the almost complete closure of the Strait of Hormuz, through which 20% of the world's oil and 20% of its refined products, as well as 18% of liquefied natural gas (LNG), transit.
According to the IEA's April 2026 Oil Market Report, in the first days of April, the volume of oil and fuels crossing the Strait each day dropped to 3.8 million barrels per day, compared to over 20 million barrels per day in February. In other words, it went from channelling 25% of global maritime oil trade to moving less than 4% of global supply.
The impact on global supply was immediate, dropping drastically in March: over 10 million barrels per day stopped reaching the markets. Behind the collapse? Attacks on energy infrastructure in the Middle East and the effective blockade of the Strait of Hormuz. The result? The largest oil supply disruption recorded to date, according to the IEA.
How does an oil shortage impact the wider economy?
Oil is behind almost everything we produce, transport, and consume. Its shortage or price increase cascades through the economy via several channels, which international organisations have accurately documented in the context of 2026.
When oil becomes scarce or expensive, the consequences are felt across the economy: the cost of transporting any good rises, airlines adjust flights and raise fares, plastics and chemical factories reduce production due to lack of raw materials, and food becomes more expensive because producing and distributing it costs more.
According to the IMF, such events drive up prices, destabilise supply chains, reduce household purchasing power, and simultaneously slow economic growth.
Examples of past energy crises
Since its foundation in 1974, the International Energy Agency has intervened on six occasions to stabilise oil markets by releasing emergency reserves from its member countries.
The five interventions prior to 2026 took place in 1991 (Gulf War), 2005 (Hurricane Katrina), 2011 (Libyan Civil War), and twice in 2022, both in response to the Russian invasion of Ukraine. This conflict sent natural gas prices in Europe soaring to record highs, exceeding €300/MWh in August 2022, and forced the EU to implement an emergency 15% reduction in gas consumption.
IEA members hold over 1.2 billion barrels in emergency reserves, alongside a further 600 million barrels under government obligations.
How can the pressure of an energy crisis be alleviated?
In the face of any supply crisis, reducing demand can act faster and more cost-effectively than increasing production. According to the IEA, the following measures are effective:
- Working from home where possible to reduce car journeys.
- Reducing motorway speed limits by at least 10 km/h to cut fuel consumption in cars and lorries.
- Promoting public transport over private car use.
- Implementing traffic restrictions based on number plates in large cities to reduce congestion and fuel consumption.
- Cutting back on air travel when alternatives exist to ease pressure on the aviation fuel market.
- In industry, substituting petrochemical derivatives with available alternatives wherever possible.
Is Spain prepared for an energy crisis?
In the electricity sector, the Ministry for the Ecological Transition and the Demographic Challenge (MITECO) is the authority responsible for managing responses to potential supply disruptions through the Risk Preparedness Plan in the Electricity Sector (PPR), drawn up in accordance with European Regulation 2019/941.
To do this, it analyses the most likely crisis scenarios, defines the conditions for declaring an energy crisis, and establishes coordination protocols between all involved bodies. The plan applies throughout Spain.
When a crisis occurs, the plan outlines two types of response:
- On the supply side: Activating facilities that were idle or operating below their maximum capacity, which can be brought online quickly to offset the supply deficit, as well as tapping into strategic reserves of the affected products.
- On the demand side: Implementing measures to reduce consumption.
In the context of the 2026 crisis, according to Red Eléctrica's 2025 Spanish Electricity System Report, renewables covered 56.6% of the electricity mix in 2025, allowing Spain to cushion the impact of the crisis on electricity prices better than other importing countries.
This situation confirms that renewable development is not just a climate policy: it is a tool to reduce external energy dependence.
Understanding what an energy crisis is and why it occurs is key to being able to respond effectively, both individually and collectively – from reducing daily consumption to triggering the emergency mechanisms available to governments and international organisations.