Introduction
The National Renewable Energy Laboratory (NREL), located in Golden, Greater Denver Area (CO), Colorado, is the leading laboratory for renewable energy and energy efficiency research and development in the United States and is part of the United States Department of Energy. NREL is committed to developing new forms of energy to create a cleaner and more sustainable future for humanity. As of fiscal year 2018, NREL includes three national research centers: the National Bioenergy Research Center; National Solar Energy Research Center; National Wind Energy Research Center.