An article in the New York Times (Jan 4, 2012) describes solarthermal techonolgy- using  salt to store the heat generated from solar energy, with release of this heat to create electricity at a later time.The resulting heat can be used to generate electricity over a wider time interval, thus saving expensive electricity generating capacity. Electricity can be generated when prices are ideal. It also helps solar power to become a backup source during peak times, replacing coal powered peaking plants.  Is the system benefit of 4 c per kwh, in a current power cost of 11 c per kwh, sufficient to justify the 5 % additional capital costs  ? Will solarthermal storage make alternate energy mandates easier to comply ?