TY JOUR TI ECONOMIC EFFECTS OF HYDROGEN TRANSFORMATION OF THE RUSSIAN GAS TRANSPORTATION SYSTEM KW hydrogen KW natural gas KW Russian gas transmission system KW macroeconomic effects KW energy transition KW hydrogen exports KW decarbonization KW European hydrogen market KW inter-fuel competition JO MOSCOW ECONOMIC JOURNAL AU Verpahovskiy, G.A. PY 2025 IS 10 PB Electronic science