Replacing natural gas with green heat

Heat battery replaces fossil fuels for companies in GreenLab

In an announcement at the Breakthrough Energy Summit, Danish GreenLab and Rondo Energy proudly announced financial closing (FID) on a large-scale thermal heat storage project. With Rondo’s heat battery technology, the green industrial park GreenLab will be able to replace fossil fuels tied to heat consumption for its site partners and offer CO2-neutral heat, or “green heat”, at cost parity.

Green heat at cost parity to fossil fuel alternatives 
GreenLab is a pioneer green and circular industrial park in Denmark that works to demonstrate how energy waste can be reduced in industry. They do that by directly connecting renewable energy to industrial consumption, integrating energy flexibility solutions, and by applying a circular approach to the energy resources in the park via their unique SymbiosisNet platform.  

Today, GreenLab announces that they have signed a long-term agreement for a 100 MWh heat battery from Rondo Energy. The battery will add high temperature thermal storage to GreenLab’s energy mix and will be directly connected to the 84 MW hybrid wind and solar park adjacent to GreenLab. It will use electricity from the hybrid energy park during low price periods, convert it to heat and store it as heat, and distribute the heat to GreenLab’s site partners as and when they need heat. This will deliver green heat for the tenants in the industrial park at cost parity to fossil fuel-based heat. 

The first of its kind 
GreenLab CEO Christopher Sorensen explains: “Industry accounts for 25% of energy-related carbon pollution globally, and 74% of industrial energy use is tied to heat. At GreenLab, we work to reduce industrial energy waste and CO2-emissions by demonstrating new green technologies at scale. That is why Rondo’s heat battery is a perfect match for our industrial park. On a global level, serving industrial heat with renewables and heat batteries can cut annual CO2-emissions drastically, and we are happy to pioneer the solution in our park in this first-of-its-kind fully commercial project”.   

Sector integration and a step towards zero emissions  
Rondo Energy’s groundbreaking heat storage technology turns electricity from renewable sources into  high-temperature heat and stores it, delivering the heat when it is needed. Using intermittent renewables as the source of energy for heat replaces natural gas and other fossil fuels. The Rondo heat battery delivers heat to industrial processes at any required temperature and pressure, such as superheated water or steam. This solution creates sector integration between electricity and industrial heat and brings benefits to the industrial sector: green heat at low costs thanks to increasingly low-cost renewables.  It also brings benefits to the electricity sector: large and very flexible energy storage, at a time when flexibility is more and more critical for the electricity sector.  

As a first step, this Rondo Heat Battery will supply GreenLab’s site partner, GreenLab Skive Biogas, with green heat, reducing their CO2-emissions by up to 80%.  In a larger perspective, Rondo’s technology is an extension of GreenLab’s unique SymbiosisNet™ – an intelligent infrastructure of data and energy that allows companies to share their excess resources.  The SymbiosisNet showcases sector integration in action and provides an opportunity to displace fossil energy with green hydrogen, syngas, and now also high-temperature heat. 

A pivotal step in GreenLab’s journey 
“This collaboration marks a pivotal step in our journey toward a sustainable and integrated energy system at GreenLab, and we are proud that Rondo Energy and Breakthrough Energy chose GreenLab as their European showcase” says Christopher Sorensen, CEO at GreenLab. “Rondo Energy’s heat battery increases our robustness and resilience to price volatility from a single energy source and makes GreenLab an even more attractive location for energy intensive companies”. 

Rondo Energy has strong partners, including Bill Gates' green investment company, Breakthrough Energy, and is committed to providing competitive green heat and energy for large industrial processes. “ 

“We are thrilled to support GreenLab in their mission to demonstrate the economic advantage in green industrial hubs.  The Rondo Heat Battery at GreenLab will be built in our green-CHP configuration, by pairing a Rondo Heat Battery with a steam turbine to deliver continuous heat and dispatchable clean power, all with 95% energy efficiency. In this way, we will bring the full value of thermal storage to GreenLab’s energy intensive industrial park customers and to Denmark’s electricity network. We are proud to work with GreenLab who not only see clearly where the real economic opportunities in the energy transition lie, but act on them.” says, Eric Trusiewicz, CEO at Rondo Energy. 



  • GreenLab has signed an agreement for a 100MWh heat battery from Rondo Energy
  • The system provides 100MWh ceramic heat storage system with the capability to operate at temperatures up to 1500°C 
  • Rondo’s system will be directly connected to the 84 MW hybrid wind and solar park adjacent to GreenLab

The thermal battery storage facility is expected to become operational in 2025 and when completed will be one of the largest in Europe. 

Eric Trusiewicz, CEO at Rondo Energy and Christopher Sorensen, CEO at GreenLab at the announcement at Breakthrough Energy Summit in London.

Rondo Heat Battery - Pilot project in Calgren, California