Complex sentence: Its annual energy consumption was 29.6 quads, for an Energy Intensity of 20,676 kJ/$(more than twice the US value), largely due to harsh climatic conditions in most of Eastern Russia and the country's vast territorial space.
Split into simpler sentences: Its annual energy consumption was, for an Energy Intensity of per dollar, or more than double that of the US. This may be due to harsh climatic conditions in most of Eastern Russia and the country's vast territorial space.