Holmes Western

At a Glance

Project Capacity: 100 MWh

Technology: Rondo Heat Battery (RHB)

Service: 24-hour industrial steam from off-grid solar

Round-Trip Efficiency: >97 %

Temperature Range: >1,000 °C

Integration: Direct steam delivery into existing heat network

Status: Commercial operation as of Sept 2025

Challenge & Opportunity

Industrial facilities across sectors depend heavily on continuous high-temperature heat — typically delivered via gas-fired boilers. But rising fuel costs, carbon regulation, and energy volatility pose risks to both margin and sustainability.

Holmes Western sought a low-carbon, safe, resilient substitute heat source — one that could drop in with minimal disruption and meaningfully cut Scope 1 emissions.
 

Solution: Rondo’s 100 MWh Heat Battery

Rondo deployed its largest industrial heat battery system to date — a 100 MWh RHB — powered entirely by an on-site photovoltaic (PV) solar array. During daylight hours, solar energy charges the battery. Around the clock, the RHB discharges heat, delivering continuous, high-pressure steam to the customer’s existing plant infrastructure, alongside traditional gas boilers, with zero changes to facility operations.

Key technical features:

• Storage and delivery at >1,000 °C
• Ultra-high round-trip efficiency (>97 %)
• Seamless “drop-in” integration with existing steam flanges and boiler systems
• No combustion, no emissions, and no new air permits required

Because Rondo’s system uses only brick and wire as storage media, it leverages abundant, safe, non-reactive materials — designed to eliminate fire risk, no toxic leaks, and uses no exotic or scarce minerals.

Outcomes & Benefits

Reliable, 24/7 Steam from Solar
The system provides constant industrial heat even when the sun isn’t shining, proving renewables can power heavy industry reliably.

Cost Stability
By replacing gas consumption with fixed-cost solar + storage, the system is designed to hedge against fuel price volatility and regulatory exposure.

Significant Carbon Reduction
Eliminating reliance on fossil heat reduces Scope 1 emissions, supporting corporate decarbonization targets and improving product competitiveness in low-carbon markets.

Zero Downtime, Zero Injuries
The project was executed without disrupting plant operations and was completed with zero lost-time injuries.

Scalable & Replicable
The modular, component-based design is ready for deployment across industries and geographies — from cement and chemicals to food & beverage and biofuels.

Key Milestones and Value Drivers:

Record Scale & Efficiency
This is now the world’s largest industrial heat battery in commercial operation — and among the highest efficiency energy storage systems globally.

Seamless Integration:
Deployed in parallel with existing systems, it doesn’t require process redesign or new steam architecture.

Strategic De-risking
Fixed-cost renewable heat mitigates exposure to fuel price swings and carbon regulation shifts.

Simplified Permitting
Because heat batteries emit no pollutants, they avoid air permitting challenges.

Global Deployment Ready
Rondo is already advancing projects across four continents and multiple industrial sectors, using scalable, widely available materials.