What is Seasonal Thermal Energy Storage (STES)

How would you feel if you could store-up thermal energy for use when the need arises? Dazzled right? Well, technological advancements in the energy sector have made this seemingly impossible task feasible. Seasonal Thermal Energy Storage (STES) is used to refer to the technologies which make this possible. You can now heat up your home during winter and cool it off in summer using the thermal energy collected throughout the year. This way, you can reduce your energy bills substantially without causing any discomfort to the occupants of your home. It is a very good example of a win-win situation.

The concept which instigated the introduction of these technologies is the huge amount of heat and cold available during certain seasons of the year. Besides the natural provisions of heat, it can be collected from industrial waste and stored for later use. The earth’s rather slow rate of heat loss is one of the contributory factors responsible for the success of this concept. You can store surplus heat underground without worrying about losing all of it before it is needed. Still unsure of how this works? Perhaps a more descriptive explanation will help.

The earth has been proven to be a poor conductor. But the big question on the lips of many has been how to exploit this reluctance of our planet to heat loss? Fortunately, many firms with adequate insight on thermal energy have done some research on the topic and came out with some astonishing results.

The first challenge dealt with was collecting the heat. Some experts utilized the rapid rate of heat absorption shown by asphalt. They placed water pipes just beneath the black road leading to schools, car parks, and a host of other places. To transport heat, you need a medium and water was the most suitable in this scenario. The heat collected, is channeled to the designated stores in the earth. Usually, the heat stores are built underneath buildings to warm specific living spaces in the winter season. However, this not always the case since these heat stores can also be placed in distant locations.

To make use of the heat, specialized computer-like units have been designed. But getting the earth to give up what’s within its depth isn’t just about ‘tickling it with a feather’, it involves some complex kind of fluid dynamics which only a specialized few are well-informed about. The result is an increase in the value of these set of individuals which causes a significant rise in the cost of their services.

Do you remember when you enjoyed your warm coffee regardless of when it was made since you kept it in a vacuum flask? Yes, the seasonal thermal energy storage uses our planet in the same manner. And frankly, the earth does a better job than your vacuum flask.

Theoretically, the sun’s energy is capable of heating the water used in the STES project to as much as 90°c. This is below the boiling point of water which could complicate the situation. Since water is the means through which the heat collected is stored for use at a later date, there is the need to ensure its thermal heat content and conductivity matches the precursors needed in a project of this nature. The indices of just our planet wouldn’t be enough. Since soil content from different parts of the earth varies, knowledge of the part of our planet which would provide support to this heat storage facility is required. The content of the soil including water, its structure, and density has to be understood. This could help in calculating its heat transfer coefficient and its capacity.

Human beings are warm-blooded. This explains the huge demand for heat, especially in the winter season. Many homes use a furnace powered by electricity or the more traditional fireplace and its characteristic release of smoke elements to the atmosphere. Both have their flaws. While the former is known to increase your energy bill greatly, the latter plays a huge role in the notorious greenhouse effect. The greenhouse effect is responsible for the depletion of the ozone layer – which protects the earth against penetration of unwanted radiation.

Using the STES approach wouldn’t leave you with huge energy bills. Also, you don’t have to worry about carbon emission which is one of the components of the greenhouse effect.

Denmark, a country with a temperate climate has a surging need – to warm up its population during the cold winter season. The Nordic country has gone ‘big’ on its STES project. The Danish government has built one of the largest heat storage facilities in the world. This has helped their citizens stay warm in the winter season without having to depend on a furnace or fireplace.

While the earth doesn’t lose too much heat over a long period of time, there’s still the problem of heat loss when it is been used in heating spaces within properties. Heat pumps are utilized to salvage the situation. They can get the heat out from the storage tanks underground to where warmth is needed. But they need power. Ground source water pumps consume substantial power. So, how is this economical compared to a furnace or fireplace? With just enough power, they can deliver enormous heat. Consider it as a trade. However, this is only feasible if all the indices are near perfect. The heat within the storage tank has to be evenly distributed including when the ground source heat pumps are working. This is almost impossible. Heat travels in the ground at a much slower pace compared to what’s obtainable elsewhere. The result is increasing the work done by the heat pumps in supplying the required warmth. On the plus side, a few establishments have been able to overcome this catastrophic problem by increasing the heat of the underground storage unit and reducing the work done by the heat pumps. This positively affects the economic deficits as described earlier.

In conclusion, jumping into the use of the seasonal thermal energy storage involves engaging individuals with the required technical know-how. It will only be economically viable if the design is fail-proof. You will need to pay attention to a lot of indices which increases its overall cost.

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