U.S. Energy Secretary Steven Chu announced in a letter Friday he will step down from his position at the end of this month.
In his time as U.S. Energy Secretary, Chu pushed for growth in renewable energy and clean tech innovation.
Chu led the department during President Barack Obama’s stimulus package. The department divvied up about $3.5 billion in the Pacific Northwest.
Much of the money went to projects that helped develop energy efficiency and smart grid technologies.
But a major portion went to the environmental cleanup at the Hanford Site, in Richland, Wash.
Chu has slowed construction at the site’s waste treatment plant. That’s as engineers worked to fix some of the design’s technical problems.
President Obama has not yet nominated a replacement.
Former Washington Governor Chris Gregoire is on the list. She has also been mentioned as a top candidate to fill the Interior Secretary and Environmental Protection Agency positions.