Scientists investigate soil as a thermal energy storage solution

When spring arrives and the heating season involves an finish, protecting heat turns into much less of a problem. Nonetheless, scientists remind us that it isn’t only a seasonal necessity—warmth can also be a useful vitality useful resource that may be saved and used when wanted most. Researchers at Kaunas College of Expertise (KTU) have found an modern resolution beneath our ft: utilizing soil as an environment friendly thermal vitality storage system.

KTU professor Dr. Tadas Ždankus and his crew have been investigating how the bottom can serve not just for building functions but additionally as a medium for heat storage. On the core of their analysis is a ground-based warmth accumulator that will retailer excess energy underground and make it obtainable when demand peaks.

“Our goal was to convert heat, which would normally dissipate into the ground as waste, into a useful energy source,” explains Dr. Ždankus. The work is published within the journal Sustainability.

Underground warmth storage potential

Firstly of their analysis, Prof. Ždankus and the crew explored how wind energy could possibly be used to supply warmth as a substitute of electrical energy. As a substitute of a traditional generator, they employed a hydraulic system. The researchers discovered that so-called hydraulic losses, usually seen as inefficiencies, had been really producing usable warmth. “The hydraulic losses we were trying so hard to eliminate turned out to be nothing less than heat generation,” says a KTU professor.

Nonetheless, a portion of this warmth was misplaced earlier than reaching the buildings it was meant to heat throughout colder seasons. “The question became how to not only reduce heat loss to the ground but also store and retain it for future use,” provides Ždankus.

To check this concept, the researchers performed experiments utilizing a man-made warmth supply positioned in floor soil layers. They measured how warmth spreads, how briskly it strikes, and the way lengthy it persists within the floor. In a single take a look at, the soil was heated to the purpose the place moisture started to evaporate—triggering a phase changewherein liquid water turns into vapor.

“Phase change can be an efficient way to store heat. The significantly higher amount of energy can be charged into the soil,” explains a KTU professor.

As vapor travels by the bottom, it distributes warmth over a wider space. “We noticed a sharp temperature rise wherever the vapor flow reached. This means the energy is moving and can be controlled,” says Prof. Ždankus.

Such a system may assist stability district heating networks or alleviate stress throughout energy grid overloads. “It is also attainable to put in thermal accumulators for particular person use—beneath residential buildingsstreets, or parking tons,” he provides.

This analysis demonstrates that underground warmth storage may be much more environment friendly than beforehand believed. As well as, comparable ideas may apply to cooling. “Underground cold or coolness storage is also possible,” notes a KTU knowledgeable.

Turning floor into an vitality cell

As soon as the feasibility of underground warmth storage was confirmed, researchers started exploring its sensible purposes. They wished to see if the soil beneath buildings may passively retailer warmth, making use of the pure downward circulation of warmth from buildings into the bottom.

“We started in the laboratory. A prototype ground energy cell was developed alongside a testing setup to study how heat spreads through the soil. Temperatures were measured at various depths, including at the surface and in the air,” explains Dr. Ždankus.

The crew examined how lengthy the soil retained warmth and the way shortly it returned to its authentic temperature. These findings helped assess the long-term reliability of such a storage technique.

KTU grasp’s college students had been additionally concerned within the challenge. Measurements and calculations spanned a complete yr, which enabled the crew to watch seasonal results and examine outcomes with current climatological information. “The year-long measurements revealed natural seasonal patterns in soil temperature and allowed us to identify several trends,” the professor shares.

Further numerical simulations had been carried out to guage potential warmth losses and the effectiveness of warmth storage beneath buildings. “We found that even the passive use of an isolated soil volume beneath a building can reduce heat loss and increase its energy efficiency. Less heat loss means less energy needed for heating, which in turn leads to energy savings. If that heat comes from burning fossil fuels or biomass, our solution also lowers carbon dioxide emissions,” notes Dr. Ždankus.

To make these ground-based storage programs viable for widespread use, researchers at the moment are creating scaled-down prototypes and refining warmth distribution management strategies. In accordance with the scientist at KTU’s College of Civil Engineering and Structure, the challenge is evolving by collaboration with consultants in varied fields—from geotechnical engineers to vitality system specialists.

“Our immediate goal is to integrate existing solutions, such as boreholes, piles, and other underground heat exchange technologies into a system that can benefit both industry and residential sectors,” he concludes.