In a letter to U.S. Energy Department employees today, Energy Secretary Steven Chu announced his decision to not serve a second term. In his remarks he highlighted the tremendous progress of the last four years.

Chu wrote, “Serving the country as Secretary of Energy, and working alongside such an extraordinary team of people at the Department, has been the greatest privilege of my life. While the job has had many challenges, it has been an exciting time for the Department, the country, and for me personally.

I’ve always been inspired by Dr. Martin Luther King, who articulated his Dream of an America where people are judged not by skin color but “by the content of their character.” In the scientific world, people are judged by the content of their ideas. Advances are made with new insights, but the final arbitrator of any point of view are experiments that seek the unbiased truth, not information cherry picked to support a particular point of view. The power of our work is derived from this foundation.”

Chu highlighted several areas where he felt there was great success especially in the country’s move to clean energy. Four areas he noted in which he felt demonstrated tangible signs of success included: in the last four years, the production of clean, renewable energy from wind and solar has doubled; in addition to approximately $25 billion annual budget, also made a $36 billion investment through the Recovery Act to help ensure that the clean energy jobs of tomorrow are being created here in America today; the Department has helped one million low income homeowners weatherize their homes; and administered a loan program that generated a portfolio of loans and loan guarantees to 33 clean energy and advanced automotive manufacturing projects.

You can read his full letter of resignation here.