Renewable energy sources in the Region of Warmia and Mazury in north-eastern Poland Janusz Piechocki, Maciej Neugebauer, Joanna Hałacz, Aneta Skotnicka-Siepsiak and Andrzej Lange E3S Web Conf., 154 (2020) 07002 Published online: 09 March 2020 DOI: 10.1051/e3sconf/202015407002