Dutch gas plants designed to cope with fluctuating renewable power

Siemens Energy has completed two combined cycle power plants (CCPP) Hemweg 9 and Diemen 34 in the Netherlands. Dutch utility Nuon, a part of Vattenfall, has officially inaugurated the 440MW Hemweg 9 located in the Westport district to the west of Amsterdam's center and 435MW (260MW thermal capacity) Diemen 34 CCPP situated to the east of Amsterdam about 15km from Hemweg.

Siemens built the two power plants on a turnkey basis and equipped each facility with a F-Class gas turbine, SGT5-4000F gas turbine, SST5-5000 steam turbine, hydrogen-cooled SGen5-2000H generator, the complete electrical equipment, and SPPA-T3000 I&C system.

The new unit, Hemweg 9 is a combined cycle steam turbine that gives Hemweg-9 electrical efficiency 59 percent and will supply 440 MW to about 750,000 households. It was planned technology for capturing nitrogen oxides (NOx).

The start-up for the full conversion operation for both power plants was June 20, the operator Nuon confirmed. Both the power plants have been operational in the Dutch market since mid-2012, but the existing capacity at the Hemweg Plant, which consists of units Hemweg 7 and Hemweg 8, is being decreased and replaced with a more efficient turbine.

Fifteen kilometres away, Diemen-34 is a combined cycle power plant tasked to supply heat to 25,000 households in the area of Amsterdam. The new power plant complex will also supply heat, which will allow an increase in total plant efficiency to over 59 percent, and increases in yield.

Hemweg 7 unit to be shut down next year

The capacity that is being replaced is the gas turbine at the Hemweg 7 unit, with 511 MW capacity, generated by equipment which dates from 1979 and a gas turbine installed in 1988. The gas turbine at the Hemweg 7 unit will be shut down next year but will remain in operation for the supply of peak-hour capacity, Nuon said. In contrast, the coal-fired unit Hemweg 8, which dates from 1994, will remain in operation.

Siemens has signed an engineering procurement and construction contract and a long-term maintenance contract for the project. The Hemweg 9 and Diemen 34 combined cycle power plants are supplied with an F-Class gas turbine, which has an efficiency of approximately 60 percent.

Unfavourable market conditions and persistent policy uncertainty has reversed growth in the Dutch CHP sector following a period of rapid growth in the 1990s. The Dutch CHP sector used to be "one of the best-performing in Europe", with 51.8 percent of the total generated electricity coming from CHP plants in 2011.