Who was the Department of Energy under Obama?

Excuse me, could you please clarify your question? It seems that you're asking about the identity or composition of the Department of Energy during the Obama administration, but phrased in a manner that's a bit unconventional. The Department of Energy, or DOE, is a federal agency responsible for advancing the nation's energy security, environmental quality, and economic vitality. It has existed under various presidential administrations, including the Obama administration. So, when you ask "Who was the Department of Energy under Obama?", I believe you might be referring to the leadership or key personnel of the DOE during that period. If that's the case, the Secretary of Energy during President Obama's first term was Steven Chu, a Nobel Prize-winning physicist, who was succeeded by Ernest Moniz in Obama's second term. However, if you're looking for a more comprehensive overview of the DOE's operations and achievements under the Obama administration, that would require a more detailed explanation of its policies, programs, and initiatives during that time.