Cold recovery: Utilizing untapped process cooling energy

In the world of heat transfer, heat recovery is a well-known principle: capturing and reusing waste heat. But did you know that you can also harness and reuse the cooling capacity of a process? This is known as cold recovery: recovering and reusing cold energy that would otherwise go to waste.

What is “cold” actually?

From a thermodynamic perspective, cold does not exist as a separate form of energy. Instead, it indicates that an object or medium has a low temperature. In theory, only heat exists, because cold itself cannot be transferred. For example, when an ice cube is placed in a glass of water, the water is warmer than the ice cube. Heat flows from the water to the ice cube, causing the water to cool down and the ice cube to warm up.

In cold recovery, we make use of the cooling potential available in processes where cold fluids, such as LNG (liquefied natural gas, approximately −162°C), are warmed and vaporized. We are not literally recovering “cold” as a form of energy but rather making effective use of the available cooling capacity.

This requires a different way of thinking. During the import or transportation of cryogenic fluids such as LNG (-162°C) and ammonia (-33°C), heat is required to warm them up. This can be supplied through electric heating or steaming, but also by using a readily available medium such as seawater.

Looking at it from the opposite perspective, there are also locations that require cooling. This is especially true in places where excess heat occurs, such as cold storage facilities, data centers, and residential buildings.

How can you heat and cool at the same time?

You may already see where this is heading. By linking a process that requires heat with a process that requires cooling, heat can be transferred from one process to the other. In this way, the handling of cryogenic fluids can be integrated with processes where excess heat needs to be removed. As a result, both the demand for dedicated chiller systems and overall energy consumption can be significantly reduced.

Cold recovery in practice

Our partner Vahterus has already implemented cold recovery in the port of Barcelona: LNGenius: Clever Cold Energy Recovery in Spain’s Ports | Vahterus.

The port operates a system that recovers the residual cooling capacity released during the vaporization of LNG and distributes it through a district cooling network to industrial facilities, offices, and residential buildings. In practice, however, it can be helpful to look at the process from the opposite perspective: heat from buildings is used to warm the LNG. As a result, heat is removed from the buildings, causing them to become cooler.

Ports are particularly interesting locations for cold recovery applications. Commodities such as ammonia and LNG are imported and processed there, while ports and their surrounding areas often host industrial facilities, logistics centers, and buildings with significant cooling demands. This creates opportunities to intelligently match cooling supply with cooling demand, maximizing energy efficiency and reducing overall energy consumption.

A look into the future

As global temperatures continue to rise and the demand for cooling increases, energy efficiency is becoming more important than ever. Cold recovery offers an opportunity to make better use of existing process energy while reducing the need for dedicated cooling systems.

When we think about heat transfer, we often focus on recovering heat. However, by also considering the cooling capacity available within processes, new opportunities emerge.

After all, why use energy to heat something when you can utilize heat that needs to be removed elsewhere?