Billie Christen joined the National Renewable Energy Laboratory (NREL) as the Project Coordinator for the Biomass Program in 1999. She was then promoted to Business Manager for the Biomass Program in 2007. In 2008, the Project Management Center (PMC) was moved to the U.S. Department of Energy Golden Field Office. Christen then became the liaison with Contracts and Business Services for the Biomass and Biosciences Centers. She is responsible for overseeing the management, administration, and placement of subcontracts for both centers, ensuring that the objectives are met and that the deliverables are received in a timely manner. Christen works closely with the center's financial analyst to develop budgets for subcontracts and makes sure the subcontracts are properly initiated and closed out in accordance with NREL procedures. She also helps staff members prepare the statements of work, sole source justifications, and other documentation needed for placing a subcontract. More recently her primary focus has been on supporting the members of the Biorefinery Analysis Section.