The Advantage of Paraffin-based Latent Heat Storage

Thermic energy can be stored in various ways. Latent heat storage is not only an environmentally conscious but also a very energy efficient solution.  The pilot of Lendava by our project STORE4HUC will introduce a paraffin-based latent heat storage in the local library building. This project is a unique undertaking in Slovenia, as it will be realised in combination with the installation of a geothermal district heating system.

Historic sites and energy-efficient transformation

Due to the higher percentage of renewable energies, the demand rises for high-performance heat storages. A special challenge at historical urban sites is to comply with the legislations regarding the appearance of the building. Most countries in Europe have legislations specifically concieved for historical monuments. Those regulations only allow minor changes or even non-changes on the protected premises. Therefore, the smaller the impact is on the building, the more advantages it brings. A latent heat storage allows to reduce the costs and makes a sustainable renovation possible. Thus, the choice of latent heat storage is highly attractive for protected areas. In  comparison to water buffer tanks, they have a three time’s higher volumetric energy density. The smaller containers of latent heat storage save money and make it possible to renovate historical premises sustainably. 

How do latent thermal storages work?

How can paraffin-based storage increase its energy density by a factor of three? The reason for that is the principle of change phases in material. During the process of phase changes, a high amount of energy can be stored. Most latent thermal storages are based on the melting and solidification processes between solid and liquid phases. An example of the principle of the latent heat storage is a hand-warming pad. They are heated up in boiling water or microwave but only release the heat if they are kinked or bruised, and they are slowing become solid again. The principle of the change phase has a second advantage. With this technology, the heat can be stored longer and is more efficient than in conventional heat storages. 

Paraffin-based solution explained

We are returning to the hand-warming pads to further explain the principle of the paraffin heat storage. During a higher temperature, the paraffin is melting and absorbs the heating energy. This happens with boiling hand-warming pad in boiling water until it is fluid again. The heat energy is stored as long as the temperature does not fall below the solidification temperature of the material. If this happens, the paraffin becomes solid and releases the heat back to the environment. Therefore, this principle can be used in a reversed way with cooling effects. 

Advantages and disadvantages

To sum up, the advantage of the latent paraffin storage is first the higher energy density and secondly the effectiveness of long-term storage of the heat. Nevertheless, the small disadvantages are the higher prices for this technology. On the other hand, especially for historical urban sites, the advantage of the size of the storage is valuable. Due to the less adjustment and changes in the building, it makes it easier to comply with the regulations regarding historical sites. 

Read more about this Pilot here.