Frequently Asked Questions

We are happy to answer your further questions at info@storasol.com.

What are the reasons for the widely reduced investment costs of the STORASOL-HTTESS compared to molten salt or battery storage system?

The main difference regarding the investment costs compared to other energy storage systems is the much cheaper storage material rock/gravel (approx. 6 - 12 €/t compared to e.g. solar salt approx. 500 - 800 €/t). An additional point is the wide use of standard components that can be bought under market conditions (Heat exchangers, fans, storage vessel, etc.). Therefore STORASOL is able to follow a multisourcing strategy reducing costs for the main components.

What is the reason for the low operational costs of the STORASOL-HTTESS?

The operational costs for the storage systems are mainly depending on the electricity demand of the fan. Based on the innovative arrangement of the storage material (Increasing of the surface area ==> decreasing of the necessary air velocity ==>exponential decreasing of the pressure loss) the power consumption of the fan (and therefore the electricity demand) is at low level.

To what extent the maintenance costs for the STORASOL-HTTESS are to be?

The use of relative simple standard components is resulting in low maintenance costs. Based on our experience these costs can be estimated in a range of 0.2 - 0.6 % of the investment cost of the overall HTTES-system.

What is the reason for the low pressure loss over the rockbed with about 5-15 mbar?

Dies liegt hauptsächlich daran, dass der Luftstrom nach dem Einströmen in ein Modul eine große Fläche anströmt und dabei stark verlangsamt wird (von ca. 25 - 40 m/s auf 0,5 - 1,5 m/s). Der Zusammenhang zwischen Druckverlust und Strömungsgeschwindigkeit ist quadratisch, d. h. der Druckverlust steigt deutlich überproportional bei höheren Geschwindigkeiten. Weiterhin werden immer nur einzelne Module durchströmt, sobald diese aufgeladen sind wird auf das nächste Modul umgeschaltet. Die Optimierung der Strömungen innerhalb der Module sowie die konstruktive Ausführung stellt ein wesentliches Know-How-Merkmal von STORASOL dar.

Which range of temperature could be achieved by the STORASOL-HTTESS ?

In principal the STORASOL-HTTESS can cover a temperature range of approx. 50 - 650 °C with the current setup (compared to molten salt approx. 270 - max. 560 °C). Regarding the storage material, the possible temperature range could be extended to temperatures above 1.000 °C.

Why is the STORASOL-HTTESS system not yet available in large scale on the market?

Recent projects with a high investment volume of more than 100 Mio €, including a commercial scale high-temperature storage system, are usually financed by banks. High scale project financing by banks is only possible for projects using exclusively state-of-the-art technology. To reach this status, the construction and successful operation of demonstration plants is required. With additional positive due-diligence of the technologies (regarding technical functionality and operational capability) it is possible to finance, build and operate the technology in a commercial scale. The STORASOL system has been successfully in operation in a megawatt demonstration facility at the University of Bayreuth since 2015.

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