Energy giant Total has tested what it claims to be the world’s longest subsea high-voltage AC power cable that will supply a newly developed oil and gas field with renewable electricity to cut greenhouse gas emissions.
The 163km long HVAC cable supplied by ABB stretches between the town of Kollsnes, on the coast of west Norway, and the Martin Linge oil and gas field in the North Sea.
“The cable will allow us to supply power to the field from the shore instead of installing large offshore gas turbines,” explained Nico van-Luijk, lead electrical engineer at the Martin Linge project.
“We did an assessment based on the economics and also on the environmental impact and found that if we provide power from the shore it will be more efficient and cost-effective for the project.”
As a result, the firm said, the field - discovered in the 1970s, but not developed due to its difficult accessibility - will be producing almost zero CO2 emissions during its normal operations.
Moreover, as 99 per cent of Norway’s electricity comes from hydro-power, the field will be mostly powered by renewable energy.
Total’s engineers successfully tested the cable earlier this month.
“The longest cable before was about 100km,” explained van-Luijk. “Once you go above that you start running into issues because of quite large reactive power that we have to compensate for. There is also the effect of quite significant voltage changes on the platform because of the cable.”
A substation in Kollsnes transforms the 300kV high voltage power from Norway’s national grid to 100kV to be transmitted to the field.
Total further enlisted the help of Siemens to develop technology that would compensate for the reactive power.
“This is done by fast-acting regulators that can inject quite large amounts of reactive power or absorb it,” said van-Luijk. “It is a standard product of Siemens, but we are one of the first using it for a cable this long.”
The Martin Linge oil field, estimated to hold about 190 million barrels of oil equivalents, is scheduled to start operating by the end of 2016.
Total said it will be the first field in the Norwegian Shelf to be run entirely from an onshore control room.
The remote control will be carried out via fibre optic cables that are part of the 163km-long HVAC power cable, with the controllers to be based in Stavanger, southern Norway.
Total said supplying power from the shore will also reduce maintenance demands and result in less noise and vibration on the platform.
According to calculations, the solution will cut local carbon emissions by 200,000 tonnes per year.