This research optimizes the design and operation of compressed air energy storage (CAES) in Southern Ontario’s salt caverns, identifying the most stable cavern shape and safest pressure range to enable efficient, long-term underground energy storage.
As the world races toward cleaner energy, engineers are digging deep—literally—to solve one of renewable energy’s biggest challenges: storage. 🌞💨 Renewable sources like solar and wind are amazing, but they don’t always deliver electricity when we need it most. That’s where Compressed Air Energy Storage (CAES) steps in, and believe it or not, salt caverns deep underground might be our golden ticket! 🧂🏞️
A new study by researchers from the University of Waterloo dives into how Ontario’s underground Unit B salt formations could be optimized for CAES. Let’s unpack this salty science and see how we might store tomorrow’s energy—today! 🔋🇨🇦
CAES works like a giant energy bank. 💰 When there's excess electricity (like on a windy night), we use it to compress air and shove it into underground caverns. When we need power again, we release that air to drive turbines and generate electricity. ⚙️💨⚡
Salt caverns are perfect for this because:
Southern Ontario’s Salina B Formation is loaded with high-quality halite (rock salt) 🧂—a perfect host for these storage systems.
This study wasn’t just about saying “yep, this might work”—the team wanted to know how to optimize it. 🧠✅
They asked:
To answer these, they used detailed geological data, simulations in COMSOL 6.2, and rock mechanics models like Drucker–Prager (a go-to for underground stress analysis) and Norton’s Creep Law.
They tested two main shapes:
Each shape was “grown” in simulations with different diameter-to-height ratios: from tall and narrow to short and wide.
✅ Simple to leach and control
🧱 Stress builds up at corners, especially the roof and floor
🤏 Best stability when diameter = 1.5 × height
✅ Less stress at corners due to smooth shape
⚠️ BUT more deformation in shale interlayers, which are weaker and could fail over time
⚠️ Harder to predict shape due to irregular leaching paths
🥇 Winner: Cylinder with a 1.5 diameter-to-height ratio. This design offered great capacity + long-term stability, making it the top pick for real-world use.
Air pressure is the heart of CAES. But too little pressure means wasted space; too much can cause damage or leaks. 🧨
Researchers tested various pressure levels, ranging from 30% to 80% of the vertical ground stress. Here’s what they found:
So, think of it like a car tire—you want it inflated enough to roll well, but not so much it explodes! 🚗💨💥
Energy storage isn’t a sprint—it’s a marathon. 🏃♂️💨 So, the team simulated 10 years of real-world operation:
Their findings:
Ontario’s Salina B Formation is part of the Michigan Basin—formed in the Silurian age (~400 million years ago! ⏳).
It’s divided into three “layers” or subunits:
👉 The team focused on SQ2 + SQ3, using a combined 65-meter depth for cavern modeling.
They also modeled real-world shale interlayers, which are important for predicting leaks and structural risks. The 3D simulation cube was 200 m wide, 100 m tall, and included real rock data from wells in the area. 🧱📊
🌍 As the world gets more wind and solar farms, we’ll need massive, affordable energy storage to smooth out the power supply. CAES in salt caverns could play a huge role.
This research proves that:
Governments and utilities in Canada (and beyond!) could start developing these caverns as part of national renewable energy strategies.
✅ Compressed Air Energy Storage is a powerful, clean way to store energy at large scale.
✅ Ontario’s salt caverns, especially in the Salina B unit, are ready for action—with the right engineering.
✅ Cylindrical caverns with a 1.5 diameter-to-height ratio and operating pressures between 0.4 and 0.7 times vertical stress are the gold standard for safety and efficiency 🥇
✅ With further development, CAES could help Canada (and the world) reach net-zero goals without sacrificing grid reliability ⚡🌎
📢 Engineers, researchers, and policymakers—it's time to go underground for a cleaner future! 💪🔋⛏️
🛠️ Stay tuned with EngiSphere for more simplified deep dives into cutting-edge engineering research!
⚡ Compressed Air Energy Storage (CAES) - A way to store electricity by using it to compress air into underground spaces—later released to make power when needed. - This concept was also discussed in the article "Reengineering the Future 🌍 How Engineers Are Tackling Climate Change One Innovation at a Time 🌱".
🧂 Salt Cavern - A huge underground space formed in rock salt, often made by dissolving salt with water—perfect for storing gas or air because it's naturally tight and self-sealing.
🧱 Halite - The scientific name for rock salt—it’s the same stuff as table salt but in big underground chunks.
📐 Cavern Geometry - The shape and size of an underground storage space—affects how safe and efficient it is.
⛓️ Stress Field - The invisible “pressure map” underground caused by the weight of rocks above and around a cavern.
📉 Von Mises Stress - A way engineers measure if a material (like rock) is getting close to breaking under pressure. - More about this concept in the article "🔧 Supercharging Seatbelt Safety: AI-Driven Design Slashes Weight by 77%".
🔄 Creep Deformation - Slow, steady bending or shifting of rock over time—especially important in salt, which flows under stress like silly putty.
🧪 Plastic Strain - Permanent changes in shape when rock gets squished too hard—basically, damage that doesn’t bounce back. - Gain a better understanding of this concept using our "Interactive Stress-Strain Curve Generator ⚙️ 📈📉".
🧯 Sealability / Tightness - How well the cavern holds in air without leaking—super important for pressure and energy storage!
📊 Operating Pressure - How much air pressure is pumped into the cavern—must be high enough to store energy but not so high it cracks the rock.
Source: Huang, J.; Yin, S. Compressed Air Energy Storage in Salt Caverns Optimization in Southern Ontario, Canada. Energies 2025, 18, 2258. https://doi.org/10.3390/en18092258
From: University of Waterloo.
