Sembcorp Second Co-Generation Plant, Singapore

Sembcorp Industries, a leading energy, water and marine group based in Singapore, is building an 800MW gas-fired combined cycle co-generation power plant in the Tembusu sector of Jurong Island in Singapore. Estimated to cost €500m, the project will provide electricity and steam to petrochemical plants on the island.

The new plant is the second co-generation plant being developed by Sembcorp. It will be operated by the company under a power generation licence granted by the Energy Market Authority (EMA) of Singapore.

The project is part of a capacity expansion programme that is expected to double Sembcorp's generation capacity to 1,600MW. It will be funded by a mix of bank loans and internal cash resources.

The company owns an 815MW co-generation plant in the Sakra sector of Jurong Island.

The plant was commissioned in 2001 and billed as Singapore's first co-generation plant.

Sembcorp plant details

The new 800MW plant will be constructed in two phases of 400MW each. Construction is expected to begin in the second quarter of 2011, with the first phase scheduled to come online in the third quarter of 2013. Phase I will generate 400MW of power and 200t / hr of steam.

Each phase will feature Alstom's GT26 gas turbine, a steam turbine, a turbo generator and a heat recovery system. The ALSPA Series 6 integrated control system will be installed to regulate the plant's working mechanism.

The new plant will use natural gas and liquefied natural gas (LNG) as fuel. Natural gas will be transported through pipes from Indonesia, while LNG will be supplied by Singapore-based BG Group under a long-term agreement.

Development of the Sembcorp plant

The engineering, procurement and construction contract was signed with Alstom Power Singapore and Alstom (Switzerland) for a total value of €500m (S$900m).

The order for the first 400MW was signed in February 2011. The single contract is worth €300m and calls for the supply of the entire unit and associated equipment. It also includes an 18-year maintenance clause.

GT26 turbine technology

The GT26 turbine design is based on the sequential combustion technique. It can perform at a 60% efficiency level in a combined-cycle operation. An operating range of 40% and below while keeping low NOx levels allows the plant to meet the necessary power demands.

The GT26 technology is flexible and can operate on a single cycle and a combined cycle. Features such as a low inlet temperature, a uniform annular temperature profile, a welded rotor, and a simple and robust Environmental Vortex burner help to increase the reliability and availability of the turbine.

The sequential gas turbine provides lower kilowatt hour costs without reducing availability. The concept exhibits high power density in a gas turbine.

GT26 has five rows of small dimensional blades, arranged in the form of fir-tree slots. A combination of film and convection cooling techniques cools the high pressure turbine stage and the first three low-pressure turbine stages through the air coming from the compressor.

Fuel in the turbine is burnt in two dry NOx combustors at low fire temperatures. These burners are capable of using combination of fuel such as natural gas, LNG, medium or low calorific gasses or light oil, which eliminates dependency on a single fuel.

Singapore power market

As per 2008 estimates, Singapore produced 39.21 billion kilowatt hours of electricity, of which 37.11 billion KWh were consumed.

More than 60% of the electricity generation is fuelled by natural gas. With the increase in electricity demand there has been a strong uptake of LNG by power companies in Singapore, resulting in the construction of a third LNG terminal on Jurong Island, which is scheduled to come online in 2013.

In first quarter of 2010, six power companies entered into long-term contracts with EMA for the supply of 2mtpa of LNG.

This reflects the demand for gas to fuel power generation capacity. As of the first quarter 2011, Singapore had approximately 3,600MW of new gas-fired power plants in the planning or construction stages.