The VOSS flywheel: an environment friendly energy storage
Concrete is often criticized because of carbon emissions and sand consumption. This is why we have checked that the use of concrete in our VOSS flywheel was positive for the environment.
In the case of carbon emissions: the VOSS flywheel is much better then other technologies.
The bad reputation of concrete for high carbon emissions is not justified: it results from a confusion between cement and concrete.
It is true that cement fabrication emits a lot of carbon, but cement is only a minor part of concrete (ca. one fifth), so that concrete is mainly made of aggregate (sand and gravel).
Concrete or steel?
Concrete emits ca. 9 times less carbon per kilogram than steel!
Source : https://en.wikipedia.org/wiki/Embodied_energy#Embodied_energy_in_common_materials
We have computed the carbon emissions of the VOSS flywheel (including the prestressing system) and have compared them with the carbon emissions of classic steel flywheels, lead batteries and lithium batteries.
Source : IVL Report N°243 (2017)
The VOSS flywheel is the energy storage technology with the lowest carbon emissions.
Sand consumption: very low
Excessive consumption of sand is a reality, but the sand used to make the VOSS flywheel is good for the planet, as it enables to indefinetely stop carbon emissions that cause global warming.
Moreover, the volume of sand needed for a VOSS flywheel is low. For a house, a storage capacity of ca. 10 kWh is needed to reach full autoconsumption.
The 10 kWh VOSS flywheel uses 1 cubic meter of concrete: this is much lower than for the foundations of the house (10 to 100 cubic meters).
For a solar plant in a desert, concrete aggregate (gravel and sand) will be locally produced because it is abundant there. Solar plants are in rocky deserts, not in sand deserts, whose sand cannot be used in concrete.
A solar plant with VOSS storage will consume roughly the same amount of concrete as a nuclear plant of the same power: ca. One kilogram per watt.