Tankers are extremely energy efficient. A round trip journey from Reykjavik to Shanghai would consume about 90 kg of fuel per ton transported. Since 2 tons of alumina is converted to about 1 ton of aluminum, the round trip cost for aluminum is 135 kg of fuel, which generates about 420 kg of CO2. If the aluminum were produced using electricity from coal it would generate about 14,000 kg of CO2.
Of course, China wouldn't have to use coal if they chose not to, and cargo ship bunker fuel produces some very nasty pollution besides CO2, but in the world we live in it is far better for carbon emissions and probably for the environment in general, to use Iceland as the aluminum smelting hub.
Of course, China wouldn't have to use coal if they chose not to, and cargo ship bunker fuel produces some very nasty pollution besides CO2, but in the world we live in it is far better for carbon emissions and probably for the environment in general, to use Iceland as the aluminum smelting hub.