The U.S. electric power grid — the nationwide system of interconnected regional power systems — is a century old and under strain. Long-term power demand has grown steadily since the 1980s, but investments in transmission have lagged behind. Three major blackouts in the past decade have raised concerns about providing electricity reliably. Federal agencies are working with utilities, manufacturers and information technology companies to develop a modernized grid that uses computers to monitor the system. Advocates say this “smart grid” will be able to generate more electricity from renewable fuels and save money for businesses and families. The Obama administration calls the smart grid an urgent priority and is spending billions to help design it. But some experts worry that a digital grid could be vulnerable to cyberattacks or that it will violate consumers' privacy. Others say that promoting energy conservation or building new power plants near population centers would be more effective than building new high-voltage transmission lines.