»
Energy Storage
In this case , the silo of sand sits above ground but PNE is also exploring possibilities for large-scale underground storage in disused mines and quarries . Source : Polar Night Energy
Pekka Passi , Managing Director of Vatajankoski says of the project : “ We are actively developing our energy production portfolio towards a 100 % sustainable and emission-free future . Polar Night Energy provides a perfect solution for our needs .” There have been many reports claiming that the Polar Night Energy sand battery system could be installed below ground , an attractive concept for very large-scale applications , but Markku is keen to clarify that although possible , underground energy storage would pose another challenge . “ For the Kankaanpää case , the sand is stored in a silo above ground because it was relatively easy to build . When you start looking at below-ground options , you have to tackle water leakage . A small amount of water in the sand storage would obviously just evaporate , whilst taking up energy from the unit . But if you have a large amount of water , it will compromise the whole system .” He explains that the heat transfer system could easily be transferred to an underground space , but that water protection would make the purposely simple concept more complicated . However , PNE is already exploring future possibilities in this regard . “ Certain spaces would be ideal , such as quarries , as they are already dry . The storage would then be hidden and you ’ d be saving the cost of the steel housing ,” Markku confirms . “ Water presents a big issue , but underground
Why sand ?
This current sand-based solution is around three times more efficient than water , and can store far more energy than a water tank of a similar size . Sand is therefore a space-saving and versatile approach to energy storage , and can be used in a vast arrange of industrial applications . “ The heat storage is not very sensitive to sand grain size ,” the company states . “ We prefer high density , low-cost materials that are not from scarce sources . Someone else ’ s dirt could be our heat storage medium . We prefer to use materials that are not suitable for the construction industry .” Associated cost comes less from the storage medium , sand , but rather from the pipes and related equipment . However , PNE believes that the global reliance on combustion as an energy production method has a limited life expectancy ahead of it . “ More than 90 % of energy generated in industry to heat our buildings is made by burning something : wood chips , natural gas , oil , peat ,” says Markku . “ We need to replace almost all of it if we want to have any chance of meeting our climate goals .” The company believes that , in the future , the cost of combustion will rise significantly meaning that burning will no longer be such a financially attractive option – the lower relative cost of renewable energy production and storage will be far more popular .
www . heat-exchanger-world . com Heat Exchanger World September 2022
35