Matheus Koengkan holds a PhD in economics from the University of Évora. He is an energy and environmental economics researcher at the Department of Economics, Management, Industrial Engineering and Tourism (DEGEIT), University of Aveiro, Aveiro, Portugal. José Alberto Fuinhas, PhD in economics, is a professor of monetary economics and intermediate econometrics at the Faculty of Economics of the University of Coimbra, Coimbra, Portugal. In addition, he is a researcher of macroeconomics, energy economics, and environmental economics at the CeBER - Centre for Business and Economics Research