Multi-Year Energy Storage for a Resilient Future 🔥

: ; ; ; ; ; ;

How storing synthetic liquid fuels across years strengthens energy security under climate uncertainty — and why it matters for the future of Energy Storage.

Published November 22, 2025 By EngiSphere Research Editors
Energy Storage. Storage Tank of Synthetic Fuel © AI Illustration
Energy Storage. Storage Tank of Synthetic Fuel © AI Illustration

TL;DR

A recent research shows that storing renewable energy as synthetic liquid fuels across multiple years can dramatically boost energy security, cut fossil imports, reduce costs, and reliably protect net-zero energy systems against unpredictable climate-driven shortages.

Breaking it Down

🌍 When Weather Meets the Energy Transition

If the energy transition was a movie, weather would be the unpredictable villain—sometimes calm, sometimes chaotic, and always influential. As Europe and the world push toward net-zero systems powered by renewables, the big question arises:

How do we keep the lights on when the wind stops blowing, the sun hides for months, or a multi-year drought reduces hydropower?

Short-term fixes like batteries ⚡ and demand shifting help for hours or days. But climate-driven energy droughts can last months or even years. That’s where this research steps in.

In the paper “The Liquid Buffer: Multi-Year Storage for Defossilization and Energy Security under Climate Uncertainty,” researchers from ETH Zurich and the University of Oslo propose a breakthrough strategy:

💡 Use synthetic liquid hydrocarbons—made from renewable electricity—as a massive multi-year storage buffer for Europe.

It’s like creating an energy savings account that you can dip into during tough years.

🔍 What Problem Are the Researchers Solving?
🌬️ Renewable energy is amazing… and unpredictable

Wind and solar power fluctuate not only daily or seasonally, but also year to year. For example:

  • A cold winter with low wind = huge demand + weak supply 😨
  • A year of heavy rain produces abundant hydropower; a dry year doesn't 😕

These long-term mismatches can cause what researchers call energy droughts — prolonged periods where renewable generation is insufficient.

Europe already experienced a mini-version of this during the recent winters when low wind and high heating demand strained grids.

🧩 The missing piece: Multi-year energy storage

Most energy planning today assumes we only need to shift energy across hours or days. But the research argues that:

We must prepare for rare but extreme multi-year deficits caused by climate uncertainty.

However, direct modeling of 50,000+ potential climate years would be computationally impossible… until this paper introduces a smart, scalable method.

The authors create a stochastic (probabilistic) model that captures long-term climate uncertainty while staying computationally tractable.

🛢️ The Big Idea: Synthetic Liquid Hydrocarbons as “Liquid Batteries”

Here’s the groundbreaking insight:

Instead of wasting renewable energy during surplus years…

Convert excess power → hydrogen → synthetic liquid hydrocarbons (like synthetic oil).

…and store these fuels for years

These multi-year liquid energy reserves become Europe’s strategic buffer against bad-weather years.

In the same way nations store crude oil in giant tanks and caverns, we can store renewably made liquid fuels—but now as a climate-friendly backup.

Why liquids? Because:

  • They’re dense in energy
  • Easy to store over long periods
  • Compatible with existing infrastructure
  • Achieves superior economic viability at a massive-scale compared to both hydrogen and battery solutions.

The authors call this giant reserve the Liquid Buffer.

📊 Key Findings: What the Research Reveals
1. Multi-year storage cuts system costs by 4.1%

That equals €13 billion saved per year across Europe.

In energy-systems research, shaving off even 1% is huge—so 4.1% is a big deal.

Why does it save money?

  • Less need for fossil imports
  • Less curtailment (wasting surplus renewable energy)
  • Less need to overbuild wind/solar
  • More efficient heating electrification
2. Fossil fuel imports drop by a staggering 86%

With multi-year storage:

  • Oil imports drop from 486 TWh → 51 TWh
  • Gas imports drop from 111 TWh → 24 TWh

This reduces exposure to geopolitical shocks and price volatility.

3. Renewable curtailment drops 60%

Today, much renewable energy gets wasted because it can’t be stored. With multi-year storage, this energy is saved, converted, and used in future years.

4. Europe needs 525 TWh of liquid hydrocarbon storage

This sounds massive, but:

🛢️ When considering combined oil and gas reserves, the EU currently holds four times that volume in its existing storage facilities.

So achieving this is realistic using existing approaches.

Additionally:

  • Hydrogen storage requirement: 116 TWh
  • Seasonal storage (batteries, pumped hydro) still plays a role
5. System reliability becomes extremely high

Unserved energy (power shortages) drops to 0.0035‰, well below the standard target of 0.02‰.

Meaning: Almost no blackouts — even in bad climate years.

6. It reduces reliance on flexible imports

Fuel imports are often unreliable during crises (as 2022 proved).

Multi-year storage provides “local insurance” against external shocks.

🧠 How the System Works (Simplified)

Here’s the intuitive flow:

During good years (surplus ➕):

🌞 Lots of sun
🌬️ Steady wind
🌧️ Strong hydro inflows

Instead of curtailing:

  1. Electricity powers electrolysis → hydrogen
  2. Hydrogen + captured carbon → synthetic oil
  3. Synthetic oil goes into multi-year storage tanks
During bad years (deficit ➖):

🌥️ Months of low wind
❄️ High heating demand
💧 Low hydropower

The system:

  1. Retrieves synthetic oil
  2. Converts it back to electricity & heat
  3. Reduces the need for fossil backup
  4. Maintains security even in multi-year droughts
🧩 Why Liquid Hydrocarbons, Not Hydrogen Alone?

Hydrogen gets all the attention—but for multi-year storage, liquids are better:

FeatureHydrogenSynthetic Liquid Fuels
Energy densityLowHigh 🔥
Storage costHigh (caverns needed)Low
InfrastructureLimitedExtensive & proven
Long-term storageChallengingEasy ✔️
TransportRequires new pipelinesShips, tanks, rails already exist

This explains why the researchers see synthetic oil as the cornerstone of Europe’s climate-secure energy future.

🧮 A Clever Modeling Breakthrough

To handle 51,840 climate years, the researchers developed:

  • A probabilistic method that samples 32 representative climate months
  • A combinatorial stochastic approach to generate millions of possible year combinations
  • A robust optimization framework that balances storage over multiple years without needing full scenario trees (which would be impossible to compute)

This technique could become a new standard for energy security modeling.

🔧 What Changes in the Energy System With Multi-Year Storage?
🌀 More wind & solar

Because surplus isn’t wasted anymore.

  • Wind ↑ 138 TWh
  • Solar ↑ 162 TWh
💧 More hydrogen production

Electrolyzers run harder during good years.

🔥 Less need for fossil backup

Thermal plant operation drops by more than half.

🧊 Heating becomes cheaper

Air-source heat pumps replace more expensive alternatives, thanks to improved winter electricity availability.

🔭 Future Prospects: Where We Go from Here
🌐 1. Europe-wide energy resilience

This research shows Europe can secure reliable supply without relying on uncertain fossil imports—even under extreme climate variability.

🧪 2. Expansion of synthetic fuel technologies

Expect growing investment in:

Synthetic fuel hubs may become the new backbone of the EU’s energy security.

🌱 3. Integrating negative emissions smartly

In deficit years, the system allows temporary positive emissions.
In good years, DAC removes extra CO₂ to compensate.

This provides carbon flexibility and operational resilience.

⚙️ 4. Better long-term forecasting techniques

Future studies may incorporate:

  • Climate trend projections
  • Decadal oscillation patterns
  • Improved hydrology models
  • Biomass supply variability

The modeling framework can adapt to these future insights.

🏗️ 5. Infrastructure development

To store and refine 525 TWh of synthetic oil, Europe will need:

  • Massive storage facilities
  • Upgraded refineries
  • Expanded hydrogen networks
  • Cross-border liquid fuel logistics

Many of these already exist for fossil fuels — a major advantage.

🤝 6. Policy incentives

Governments may:

  • Subsidize synthetic fuel production
  • Set minimum strategic green-fuel reserves
  • Support multi-year storage R&D
  • Encourage integrated modeling for national grids
🎯 Closing Thoughts: Climate Uncertainty Is Manageable

This paper’s core message is powerful:

Climate uncertainty is not a barrier to renewable-based, net-zero energy systems.
Multi-year storage—especially through synthetic liquid fuels—can provide affordable, reliable energy security.

By converting surplus renewable energy into storable liquid fuels, Europe can:

🌟 Cut fossil imports
🌟 Reduce costs
🌟 Boost energy independence
🌟 Slash curtailment
🌟 Maintain near-perfect reliability
🌟 Build resilience against multi-year climate swings

The Liquid Buffer could become one of the key pillars of Europe’s long-term energy strategy — and a model for the world.


Terms to Know

🔋 Energy Storage - A way to save energy now so we can use it later — like a battery for the whole energy system. - More about this concept in the article "Long Duration Energy Storage 🔋 Cracking the Code".

💨 Renewable Energy - Energy from natural sources that constantly replenish, such as sun, wind, and water. - More about this concept in the article "Forecasting the Future of Renewable Energy: Smarter, Faster, Better! ⚡☀".

🌬️ Wind Power - Electricity generated by turbines that capture the kinetic energy of moving air.

☀️ Solar Power (PV) - Electricity produced when sunlight hits photovoltaic panels and frees electrons.

💧 Hydropower - Energy created from moving water, usually using dams or river flows.

❄️ Energy Drought - A long period (months or even years) when renewable energy generation is unusually low because of weather conditions. - More about this concept in the article "Energy Resources vs Droughts ⚡ Building Weather-Proof Power Systems".

🔁 Curtailment - When we waste renewable energy because the grid can’t use or store it fast enough.

🛢️ Synthetic Liquid Fuels - Man-made fuels (like synthetic oil) produced using renewable electricity, hydrogen, and captured carbon.

⚗️ Electrolysis - The process involves the application of electrical energy to separate water, yielding distinct streams of hydrogen and oxygen. - More about this concept in the article "Powering a Net-Zero Future: The Circular Economy of Solid Oxide Cells ♻️⚡".

🚰 Hydrogen Storage - Saving hydrogen gas in special tanks or underground caverns so it can be used later for electricity or fuel.

🧪 Direct Air Capture (DAC) - Technology that pulls CO₂ directly from the air — like a giant air purifier for the planet. - More about this concept in the article "Powering Profit 💨 Direct Air Capture in Volatile Markets".

🧮 Stochastic Modeling - A mathematical approach that handles uncertainty by analyzing many possible future scenarios.

🌦️ Climate Uncertainty - The natural unpredictability in weather patterns from year to year, affecting renewable energy production.

🌡️ Heat Pump - A device that moves heat from one place to another (like a fridge in reverse) to warm or cool buildings efficiently.

🔥 Thermal Generation - Electricity produced by burning fuels (like gas or oil) — typically used as backup when renewables dip.

🌐 Energy System Security - Ensuring a region always has enough energy, even during extreme weather or supply disruptions.


Source: Leonard Göke, Jan Wohland, Stefano Moret, André Bardow. The Liquid Buffer: Multi-Year Storage for Defossilization and Energy Security under Climate Uncertainty. https://doi.org/10.48550/arXiv.2511.13513

From: ETH Zurich; University of Oslo.

© 2025 EngiSphere.com