ARPA-E Act of 2018 This bill amends the America COMPETES Act to require the Advanced Research Projects Agency-Energy (ARPA-E) in the Department of Energy (DOE) to overcome the long-term and high-risk technological barriers in the development of transformative science and technology solutions to address energy, environmental, economic, and national security challenges. (Currently, ARPA-E must overcome barriers in the development of energy technologies.) The bill expands the goals of ARPA-E to include the development of energy technologies that: provide transformative solutions to improve management of radioactive waste, improve the efficiency and reduce the environmental impact of energy production, and address other challenges within the mission of DOE. The bill expands the responsibility of ARPA-E to accelerate novel early-stage research to include nonenergy research. ARPA-E must: include a strategic vision roadmap in each annual report on energy technology projects or advanced technology projects, and ensure that it does not fund an advanced technology project unless the prospective grantee has demonstrated that it has sufficiently attempted to secure private financing or that such project is not independently commercially viable. Specified categories of proprietary information collected by ARPA-E from award recipients shall be considered privileged and confidential and not subject to disclosure under the Freedom of Information Act.