Despite the emphasis on alternative energy sources in current and proposed government energy policies, the US cannot attain energy independence by 2030, said a majority of oil and gas executives recently surveyed by KPMG LLP’s Global Energy Institute.Most surveyed said mass production of alternative energy simply is not viable in the short term. And while there is a marked shift in their acknowledgement of global warming, the majority does not support proposed regulations to stem carbon dioxide emissions.Since Richard Nixon, US presidents have talked about energy independence. President Barack Obama has called for this country to be independent of crude supplies from Persian Gulf pr...