6Th International Conference on Energy and Environment Research (Iceer) - Energy and Environment - Challenges Towards Circular Economy, Date: JUL 22-25, 2019, Location: Univ Aveiro, Aveiro, PORTUGAL, Sponsors: Polytechn Porto, Inst Super Engn Porto, SCIEI, CESAM, CIETI, LEPABE Res Labs, Climate, Energies & Sustainabil Journals, Host: Univ Aveiro