Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 °C or 147 °F). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in 1948. Solar energy can also be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store <answer>1.44 terajoules (400,000 kWh)</answer> in its 68 cubic metres storage tank with an annual storage efficiency of about 99%.
How much energy was the Solar Two able to store using salts?
1.44 terajoules (400,000 kWh)