Back in 2004, the number was predicted to be about $165 billion. The new estimate is based on a steady deployment of smart grid technologies between 2010 and 2030. The increase in cost is apparently due to more advanced technologies as well as a "more expansive vision" for the grid.
While the number seems to be outrageous, the EPRI also said that the benefits could reach about $2 trillion. The benefits are measured in lower cost for energy delivery, greater energy capacity that is achieved through greater efficiency and fewer outages, enhanced security, improved quality of life, safety as well as greater consumer productivity.
So, who is going to pay for a clever power system? The EPRI suggests that "society" should bear the costs of the upgrade - "and paid directly, bundled with other goods and services or otherwise included by the utility in its cost of service."