The Challenge of Industrial Heat

The industrial sector is a massive energy consumer, with heat accounting for a substantial portion of that demand. Processes like steelmaking, cement production, and chemical manufacturing rely heavily on consistent, high-temperature heat, traditionally supplied by burning fossil fuels. Replacing these fuels with renewable alternatives has proven challenging due to the energy density, reliability, and cost-effectiveness of conventional methods. However, industrial heat is responsible for approximately 18 percent of global greenhouse gas emissions and over 20 percent of global energy consumption, making it a crucial area for innovation. The World Business Council for Sustainable Development highlights the urgency of addressing this overlooked piece of the decarbonization puzzle.

How Rondo’s Thermal Battery Works

Rondo’s system tackles this challenge by converting surplus renewable electricity – particularly from solar and wind – into heat and storing it for later use. The core of the technology lies in its unique design, described by John O’Donnell, Rondo Energy’s chief innovation officer, as a “3D checkerboard of brick and open chambers.” Electricity heats iron wires, which in turn warm hundreds of tonnes of refractory bricks to temperatures reaching 1,500 °C. This stored heat can then be discharged as either hot air or steam, providing a clean and emission-free heat source for industrial applications. The system’s agility, allowing for rapid charging and consistent temperature delivery, is a key differentiator. “We can turn charging circuits on and off as fast as you can turn your toaster on and off,” O’Donnell explains.

First Deployment: Enhanced Oil Recovery in California

Rondo’s initial commercial project involves supplying heat to an enhanced oil recovery (EOR) facility operated by Holmes Western Oil Corp. in Kern County, California. The battery, powered by a dedicated 20-MW solar array, generates steam injected into oil wells to improve oil flow. Previously, this process relied on a gas-fired boiler. Rondo estimates this switch will save nearly 13,000 tonnes of CO₂ emissions annually, while also reducing costs for Holmes Western Oil. This initial application, while reducing emissions, has sparked debate due to its connection to fossil fuel extraction.

Beyond Rondo: A Growing Field of Thermal Energy Storage

Rondo isn’t alone in pursuing thermal energy storage solutions. Several other companies are developing innovative technologies to address the demand for clean industrial heat. Antora Energy is pioneering carbon-block heat batteries capable of reaching extremely high temperatures, with pilot projects underway. EnergyNest is focusing on concrete-based thermal modules and collaborating with Siemens Energy for European expansion. Calectra is developing ultra-high-temperature systems, while EarthEn Energy offers modular low-temperature heat batteries. These diverse approaches demonstrate the growing recognition of thermal energy storage as a vital component of a sustainable industrial future.

The Role of Renewable Energy Prices

The economic viability of thermal batteries is closely tied to the cost of renewable energy. As solar and wind power become increasingly competitive, and in some cases even cheaper than fossil fuels, the economic argument for thermal storage strengthens. In locations with abundant renewable energy, grid operators sometimes face the challenge of curtailing excess power, even resulting in negative electricity prices. This creates an ideal scenario for thermal batteries, allowing them to store surplus energy when it’s cheapest and discharge it when demand – and prices – are higher. California, for example, generated almost as much electricity from solar as from gas plants in 2024.

But what challenges remain in scaling these technologies? Do you believe thermal batteries represent a viable long-term solution for decarbonizing heavy industry, or are there other approaches that hold more promise?

Frequently Asked Questions About Thermal Batteries