Energy Vault vs ESS, Inc.: Long-Duration Storage Compared
Energy Vault and ESS, Inc. are two distinct approaches to long-duration energy storage. Energy Vault spans gravity, hydrogen, and battery storage, while ESS, Inc. builds iron flow batteries. Here is how they compare.
Quick Comparison
| Attribute | Energy Vault | ESS, Inc. |
|---|---|---|
| Long-duration focus | ✓ | ✓ |
| Iron flow batteries | - | ✓ |
| Gravity storage | ✓ | - |
| Hydrogen storage | ✓ | - |
| Battery storage | ✓ | ✓ |
| Software & operations | ✓ | - |
| Design-build delivery | ✓ | ✓ |
Energy Vault Overview
A major storage company offering battery, gravity, and hydrogen storage options, plus advanced software and operations and consulting services, with a portfolio aimed at flexible, long-duration applications.
Best For:
- Projects exploring non-lithium long-duration options
- Utilities wanting multiple storage technologies
- Buyers who value bundled software and operations
Key Strengths:
- Diverse technology portfolio (gravity, hydrogen, battery)
- Advanced software and operations services
- Configurable, design-build delivery
ESS, Inc. Overview
BESS systems for enterprise and utilities built on iron flow battery chemistry, focused on consistent battery output over prolonged durations.
Best For:
- Long-duration applications needing repeatable cycling
- Enterprise and utility buyers favoring flow chemistry
- Projects prioritizing abundant, non-lithium materials
Key Strengths:
- Iron flow chemistry for sustained output
- Consistent performance over long durations
- Design-build delivery for enterprise and utility scale
Which Should You Choose?
Choose Energy Vault if:
- You want to evaluate gravity or hydrogen alongside batteries
- Bundled software and operations services are valuable
- You need a configurable, multi-technology partner
Choose ESS, Inc. if:
- Iron flow's long, repeatable cycling fits your duration needs
- You prefer abundant, non-lithium materials
- Your project is enterprise or utility scale
Frequently Asked Questions
How do Energy Vault and ESS, Inc. differ technologically?
Energy Vault offers a portfolio that includes gravity and hydrogen storage as well as batteries, while ESS, Inc. specializes in iron flow batteries designed for consistent output over long durations.
Which is better for long-duration storage?
Both target long-duration needs. ESS, Inc.'s iron flow chemistry is purpose-built for sustained, repeatable discharge, while Energy Vault provides multiple long-duration technologies to match different project requirements.
Are these the only long-duration options?
No. Larger lithium-ion systems from providers like Fluence and Wärtsilä can also be configured for longer durations. See our long-duration storage guide for more.
Looking for more options? See our long-duration storage guide or browse all listings.