From the Document: "The electric grid is collection of generating facilities that produce electricity, customers that use it, and intermediate power lines and other equipment that deliver it to those customers. The vast majority of the threats it faces are localized and handled by the grid's operators with minimal disruption for customers. But some threats to the grid might cause a widespread and long-lasting outage. Threats of that scale are the topic of this report, along with potential approaches to improve the grid's security against those threats. [...] The Congressional Budget Office has identified some key considerations for policymakers by examining two approaches in detail: deploying new space-based sensors to warn of solar storms and thus better enable operators to prevent or limit damage to the grid and increasing the stock of large transformers to aid recovery if significant damage occurs. Those considerations include determining the appropriate role for the federal government, deciding what factors to weigh, and comparing the advantages and disadvantages of federal intervention amid uncertainty."
Congressional Budget Office: http://www.cbo.gov/