We are in the full swing of summer! As such, I thought it would be fun to talk about HEAT! Specifically, I am referring to thermal storage. This is, by no means, a new technology. In fact, the concept has been around for some time. However, in recent years, we have seen an increase in its application because many believe that technologies such as these will help usher us into our carbon-free future. Here are some examples of thermal storage applications and technologies:
Ice Storage Air Conditioners In past Technology Tuesdays, we discussed ice storage air conditioning, which is a form of thermal storage albeit cold storage. The idea is to shift the energy usage away from peak times between 4 PM and 9 PM for use later.
An ice storage air conditioner uses its energy to create ice overnight (or whenever your electricity rates are the cheapest) and uses the ice during the day to cool the air inside your building. This method shifts most of the energy usage away from peak times when the electricity grid is most strained and when electricity rates are the highest. This load shifting results in sizable energy and money savings.
Listen to a 2.5-minute description of ice storage air conditioning here.
Heat Pumps One of the most common types of thermal storage technologies is heat pumps. In the simplest of terms, heat pumps transfer heat from one place to another. For example, an air-source heat pump absorbs heat from the surrounding air and uses it for heating water or space heating. A ground-source heat pump transfers heat between the air and the ground. Ground source heat pumps are also known as geothermal heat pumps.
Over the last 24 months, we have been obsessed with heat pump water heaters. We see them as the first easy step in electrifying non-residential facilities. Heat pump water heaters also work much more efficiently than regular natural gas water heaters and are preferred to tankless units due to their ability to participate effectively in demand response events. Heat pump water heaters can heat water during the hours preceding a demand response event and maintain their minimum water temperature throughout the event to achieve energy savings and relieve stress on the grid.
Other Thermal Storage Applications:
Sensible Heat Storage Sensible heat storage is defined as “the shifting temperature of a type of storage medium without changing its phase” (Science Direct). A heat storage medium can be any number of items such as water or various rock-type materials. In a utility-scale application, the medium can be molten salts, synthetic oil, liquid metals or powders.
Latent Heat Storage The method by which thermal energy storage or release occurs during a material's phase change. Some examples of materials used in this application include paraffin compounds, fatty acids, salt hydrates, and eutectics. Latent heat is stored when melting or cooling a particular material.
Thermochemical Storage Thermochemical storage uses a chemical reaction created from strong chemical bonds to store as energy chemical potential (Science Direct). This type of thermal storage can be found in nuclear power plants, concentrated solar power plants, industrial processes, and in transportation applications.
Advantages and Disadvantages Thermal storage, in its many forms, is an amazing technology with potential for seemingly endless applications and technologies. Its advantages perfectly align with our energy goals. For example, thermal storage plays an important role in integrating renewable energy sources into our energy mix, relieving stress and energy peak demand on the grid by enabling energy load shifting, and helping us realize cost savings.
On the other hand, we still have a way to go before many thermal storage technologies make financial sense in some real-world applications. For example, it can be expensive, there are challenges in maintaining steady temperatures to maximize potential energy savings, and the space required to make some applications worth while.
These are just some of the challenges. However, technological advancements occur daily. We won’t give up on thermal storage because it has so much potential.
