; (2) achieve reductions in global greenhouse gas emissions at a pace and level sufficient to avoid dangerous interference with the Earth’s climate; and (3) advance and protect the economic and national security interests of the United States. I RENEWABLE ENERGY 101. National renewable energy standard Title VI of the Public Utility Regulatory Policies Act of 1978 is amended by adding at the end the following: 610. National renewable energy standard (a) In general The Secretary shall promulgate regulations requiring that— (1) beginning in calendar year 2020, the percentage of electric energy generated from renewable sources that is sold at the retail level in the United States shall increase each year; (2) in calendar year 2030 and each subsequent calendar year, such percentage shall be not less than 40 percent of the total electric energy sold at the retail level in the United States