Q2 net profits for 2012 totalled US$95 million compared with US$185 million for the same period in 2011.
The world's fourth largest aluminium smelter saw its gas supply costs soar by US$0.75 per million British thermal units to US$2.25/mmbtu on January 1 this year.
During Q2 one of Alba's main priorities was to secure a long-term price and availability deal on gas for the company's planned US$2.5 billion expansion plans.
While sales remained stable, production for Q2 was up by 1.7%
A proposed new line, which should be completed by early 2015, will add 400kt annual capacity to Alba's current 881kt per annum.