ABB technology powers North Sea platform from land

By Editorial services

The world premiere is the Troll A offshore platform in the North Sea which is now fed by direct current electricity produced on the mainland 70 kilometers away.

The inaugural event in Bergen, Norway from October 3 to 6 continues with about 60 customers from the transmission and distribution and oil and gas sectors.

The delegation was led by Samir Brikho, who spent his first working day as head of ABB Power Systems talking with journalists. The highlight of the event was a helicopter flight to the Statoil-operated Troll A gas platform, and a guided tour of the HVDC Light system and the Very High Voltage (VHV) Motor operating on the platform.

ABB's two 40 megawatt VHV Motors on Troll A produce 110,000 horsepower and drive compressors that maintain Troll A's gas-delivery pressure and compensate for falling reservoir pressure.

Troll A’s power needs are met via ABB's cable-wound, VHV Motor and generator on the platform; power is transmitted from shore through HVDC Light cables on the seabed. Most of the materials in the VHV Motor can be easily recycled.

Presenting Troll A
Technical presentations were complemented by another field trip for both media and customers to the gas processing station at Kollsnes on the Norwegian coast, which featured the sending end of the HVDC Light converter, the control room, and many other of the project's technology components.

Nils Harald Sellevold, Statoil’s project director, presented details of the Troll A precomperession project.

"With a height of 472 meters, Troll A is the tallest structure ever moved by mankind," he said. "Over the next 60 to 70 years, it will exploit 47 percent of Norway's gas reserves, and satisfy 10 percent of the entire gas demand of Europe."

In Kollsnes, "up to 120 million standard cubic meters of gas are processed every day," he added. "A key factor for Statoil was finding the most environmentally attractive solution, and actually the ABB system at Troll avoids 230,000 tons of CO2 and 230 tons of NOX, emissions - equivalent to the pollution of 75,000 cars."

Avoiding tax on CO2 emissions also cuts costs, while carbon trading supported by the Kyoto protocol creates added value (CO2 currently trades at more than 20 Euros per ton on the European Energy Exchange).

LEFT: Samir Brikho (center) showing journalists how an HVDC Light cable works. RIGHT: The onshore gas treatment plant at Kollsnes. Transmitting power from shore to the Troll A platform via HVDC Light cables eliminates annual emissions of some 230,000 tons of CO2 and 230 tons of NOx.

Zero emission mindset
Sellevold said ABB's HVDC Light power-from-shore solution was chosen over low-pollution gas turbines as the most competitive solution, despite slightly higher initial investment costs. “This is a key contribution to Statoil’s zero-emission mindset.”
Safety is an integral part of Statoil's management principles. Everything starts with ensuring proper HSE (health, safety and environmental conditions), which is another reason for choosing an HVDC Light system.

Said Lars Stendius, ABB's Troll project manager: "The project has brought us to a higher level of HSE understanding, and that includes ABB and all of our sub-suppliers."

Core component of ABB's HVDC Light system are valves which consist of millions of high power semiconductors. The valves are shielded and suspended from the ceiling in an extremely compact converter module. The semiconductor design allows less than one failure per 10 million operating hours. HVDC Light is a unique and proven power transmission system, specially designed to transmit power underground and underwater.

“It is a tremendous technological achievement, and demonstrates ABB's ongoing commitment to the oil and gas industry, and our ability to deliver state-of-the-art technologies that increase productivity and power reliability, while lowering environmental impact,” said Brikho.

Sandy Taylor, the head of ABB's oil and gas business unit, said energy demand is expected to rise by 60 percent in the next 25 - 30 years, and meeting this demand will require an investment of $568 billion per year from 2003 to 2030.

"Oil and gas represents about 40 percent of this total investment, and ABB is well-positioned to take advantage of this investment opportunity."

LEFT: Pipes in Troll A recieving gas from the platforms Troll B and Troll C, as well as export lines to the treatment plant at Kollsnes. RIGHT: The very bottom of Troll A (364 meters), where pipes enter/exit the shaft.

Troll A’s power needs are met via ABB's cable-wound, VHV Motor and generator on the platform; power is transmitted from shore through two pairs of HVDC Light cables on the seabed.
ABB's key technologies on Troll A are:

• Two 40-megawatt high-voltage ABB VHV Motors that drive the compressor units, with associated utilities. The VHV Motor can be used in any application where conventional synchronous machines are used, both onshore and offshore. It can be linked with high-voltage input, without a step-down transformer.
• HVDC Light, a power system designed for underwater and underground transmission. HVDC is used mainly for bulk power transmission and for the interconnection of independent power grids. HVDC lines cannot be overloaded, ensuring reliable power.

The Troll A gas platform is the first offshore platform in the world to be powered by a direct current (DC) electricity link originating on land. On the platform ABB has deployed two key technologies - HVDC Light and a Very High Voltage Motor - as well as other solutions to help power the two 40-megawatt compressor units on the Troll A platform without any local power generation. This adds up to major emission savings and lower costs.