“…The problem is that sustainability and environmental friendliness of energy are multifaceted, which makes it difficult to quantify them Popkova and Sergi, 2021;Shabaltina et al, 2021;. To date, many indices have been calculated that directly or indirectly reflect the sustainability and environmental friendliness of energy (Sisodia et al, 2020;Štreimikienė et al, 2022;Teichmann et al, 2020), as well as many individual statistical indicators, but a systematic understanding of it has not yet been formed (Gallo et al, 2020;Ratner et al, 2021;Ratner et al, 2022).…”