Integrated Energy Systems Act of 2019 This bill directs the Department of Energy (DOE) to establish an integrated energy systems program to (1) maximize energy production and efficiency; (2) develop energy systems involving the integration of nuclear energy with renewable energy, fossil energy, and energy storage; and (3) expand the use of emissions-reducing energy technologies into nonelectric sectors to achieve significant reductions in environmental emissions. DOE must establish quantitative goals and milestones for the program.