Energy transition to zero-carbon economy: Estimation of investment costs Kirill Degtyarev, Sophia Kiseleva, Liudmila Nefedova, Mikhail Berezkin and Oleg Sinyugin E3S Web Conf., 407 (2023) 03003 Published online: 02 August 2023 DOI: 10.1051/e3sconf/202340703003