Water has one of the highest thermal capacities at 4.2 J/(cm3⋅K) whereas concrete has about one third of that. On the other hand, concrete can be heated to much higher temperatures (1200 °C) by for example electrical heating and therefore has a much higher overall volumetric capacity. Thus in the example below, an insulated cube of about would appear to provide sufficient storage for a single house to meet 50% of heating demand. This could, in principle, be used to store surplus wind or solar heat due to the ability of electrical heating to reach high temperatures. At the neighborhood level, the Wiggenhausen-Süd solar development at Friedrichshafen in southern Germany has received international attention. This features a () reinforced concrete thermal store linked to () of solar collectors, which will supply the 570 houses with around 50% of their heating and hot water. Siemens-Gamesa built a 130 MWh thermal storage near Hamburg with 750 °C in basalt and 1.5 MW electric output. A similar system is scheduled for Sorø, Denmark, with 41–58% of the stored 18 MWh heat returned for the town's district heating, and 30–41% returned as electricity.