Accelerating Carbon Neutrality
Through Heat

What is Thermal Energy Storage (TES)?

Thermal Energy Storage (TES) is a technology that stores energy in the form of heat for later use. Unlike batteries that store electricity chemically, TES systems capture and retain thermal energy in materials like rock, sand, or molten salt at high temperatures. When energy is needed, this stored heat can be released for heating applications or converted back to electricity through steam turbines.

Why TES Matters for the Energy Transition

The global shift to renewable energy faces a fundamental challenge: the sun doesn't always shine, and the wind doesn't always blow. This intermittency creates a mismatch between when energy is produced and when it is consumed. Without effective storage, excess renewable energy is curtailed, and fossil fuel plants must fill the gaps.

TES offers a compelling solution. Heat can be stored for extended periods with minimal loss, making it ideal for long-duration storage measured in hours or days. The materials—rock and sand—are abundant, inexpensive, and environmentally benign. Unlike lithium-ion batteries, TES systems don't rely on critical minerals or present fire hazards.

What is a Carnot Battery?

A Carnot Battery is an advanced energy storage system that converts electricity to heat for storage, then converts that heat back to electricity when needed. Named after the French physicist Sadi Carnot who established the theoretical limits of heat engine efficiency, this technology represents the cutting edge of thermal energy storage.

The process works in three stages: First, excess electricity (typically from renewable sources) powers electric heaters to raise the temperature of a thermal storage medium to very high temperatures—in our case, exceeding 1,000°C. Second, this thermal energy is retained in insulated storage tanks with minimal loss. Third, when electricity is needed, the stored heat generates steam that drives a turbine to produce power.

Advantages Over Alternatives

Lithium-ion batteries dominate short-duration storage (2–4 hours) but become prohibitively expensive for longer durations. Pumped hydro offers long duration but requires specific geography. Carnot Batteries fill this gap: cost-effective storage for 8–24+ hours using widely available materials and proven industrial components.

The economics are compelling. Thermal storage costs 10–20x less per kWh than batteries at high temperatures. Modern Carnot Battery systems achieve 50–70% round-trip efficiency—competitive with other technologies when considering total system costs and lifespan.