Plans for the Mongstad energy project (EVM) incorporate a combined heat and power (CHP) station, which will be built to meet a heat requirement of about 350 megawatts at the refinery.
Electricity output will be roughly 280 megawatts, yielding some 2.3 terawatt-hours per year.
Initial energy efficiency of the CHP station is put at about 70%, with opportunities for further improvements and thereby the lowest possible emissions of carbon dioxide per unit of energy.
The facility will have two gas turbines, each linked to an electricity generator and to a section for recovering exhaust gas heat. In addition comes a steam turbine with its own generator.
High-temperature energy recovered from the exhaust fumes will be used to warm up the crude oil stream before it reaches the refinery’s distillation column.
It will also yield high-pressure steam to be used as an energy bearer in the Mongstad process plants.
Emissions to the air
The most important environmental impact of the CHP station will be an increase in carbon emissions to the air from the Mongstad industrial complex.
About 950,000 additional tonnes of carbon dioxide will be released annually from these facilities.
However, the CHP station will reduce the need to import electricity from abroad. Its output is also more efficient than foreign generation, reducing global carbon emissions.
Emissions of nitrogen oxides from Mongstad are unlikely to rise beyond their current level.
Only marginal changes are expected to the volumes of sulphur dioxide, methane and volatile organic compounds released as a result of the CHP station.
Discharges to the sea
Development of the CHP station is not expected to increase discharges to the sea via the Mongstad treatment plant, apart from marginal volumes of drain water.
The latter will largely consist of rainwater which could be polluted by hydrocarbons as a result of normal sweating from pumps and other equipment.
Coolant water discharges to the sea will increase by about 6,500 cubic metres per hour.
