Clean Air:

Acid precipitation is caused by sulphur and nitrogen compounds released to the air, where they react chemically with water vapor to create sulphuric and nitric acids. These substances can be transported over long distances to fall as acid rain or snow, damaging freshwater fish stocks as well as forests and other vegetation. Areas of southern Norway have low tolerance to acidification, which has particularly reduced fish populations.

Challenges:

Nitrogen oxides: These substances are created when burning fossil fuels. The Group facilities on land and offshore consume gas and some oil to fuel their operations, and accordingly give off these substances. The bulk of its products are used as automotive fuels or for energy generation, which also yield nitrogen oxide emissions. How much of these gases is released depends primarily on combustion temperature. Their emission can accordingly be reduced with technologies which burn cooler. Scrubbing exhaust fumes to remove nitrogen oxides offers another approach

Sulphur oxides: These compounds form when sulphur is present in the fuel, and their volume can accordingly be reduced by cutting the sulphur content in Group's products. Natural gas contains very little sulphur. North Sea crude is also low on this substance (sweet), but Group's refineries must reduce the content even further before their products can be sold. Sulphur has a negative effect on the catalytic converters which reduce nitrogen oxides and other pollutants in car exhaust fumes. This has prompted a steady reduction in the proportion of sulphur permitted in petrol and diesel oil.

Measures:

The Group has installed facilities for lowering the sulphur content in automotive fuels at all its refineries in good time before the European Union makes this compulsory. One in five turbines on the group's offshore platforms is now a low nitrogen oxide type, and turbines and burners at its land-based plants are being steadily upgraded to this technology. Other ways of releasing fewer nitrogen oxides are also under consideration, particularly where it would be difficult or disproportionately expensive to use "traditional" low nitrogen oxide technology. The Group is the first operator on the nation continental shelf to charter two new supply ships fuelled by natural gas rather than diesel oil. Such third-party measures could be a good environmental and financial alternative to action at its own facilities.

Results:

Adopting low nitrogen oxide turbines on platforms reduces emissions by about 85 per cent, corresponding to roughly 300 tons per year per turbine. Taken together, these units cut annual emissions of nitrogen oxides from inshore and offshore turbines by several thousand tons. The Group's refineries remove about 17 000 tons of sulphur every year which would otherwise have been released when their products were burnt. And the Group's facility has installed a plant to produce ammonia thiosulphate for fertilizer in order to reduce emissions to the air.