Gas turbines provide peak performance

Paul Boughton

Gas turbine technology is at the heart of major investments in new generating plants. Eugene McCarthy reports.

The improved efficiencies that new technologies are bringing to generating plants all rely on gas turbines and their associated technologies. So turbine manufacturers are winning substantial orders.

Take for example Alstom, which has just won two new turbine contracts. The first is to provide two 900 MW units for the largest coal-fired power plant in Poland.

The company has signed contracts worth approximately EUR1.25 billion with Polimex, Rafako and Mostostal Warsawa, members of the consortium in charge of the supply of two 900 MW units to major Polish utility PGE. This project concerns the units five and six for a new ultra-supercritical (USC) coal-fired power plant in Opole, south-western Poland. Once operational, it will be the country's largest coal-fuelled facility, and will supply electricity to the equivalent of two million homes. Unit five is due to enter commercial operation in 2018 and unit six in 2019.

Ultra-supercritical technology

Alstom's scope includes the provision of its proprietary ultra-supercritical technology including the supply of boiler islands, the steam turbine generator islands, including the turbine hall equipment, the air quality control systems as well as some balance of plant systems. Alstom will be responsible for overall project management and general design for this part, and also support the consortium members in their scope of work and contribute to the construction and commissioning of the plants.

The use of USC, which gives higher electrical output while burning less coal, will enable PGE to reduce its environmental impact and meet regulatory requirements. This is particularly important in Poland, where around 90 percent of fuel for electricity generation is coal or lignite.

Alstom previously retrofitted units two, three and four at Opole to uplift their efficiency, and successfully completed last year the USC unit 14 at Benchatów, Poland's most efficient coal-fired unit.

Alstom's second contract, worth EUR85million, has been awarded Bharat Heavy Electricals Limited (BHEL) to supply two 800 MW supercritical boilers for Darlipalli super thermal power project (STPP) located in Sundergarh, in the State of Odisha, India.

This project forms part of NTPC bulk 800 MW tender. Under the scope of the contract, Alstom - the sole licensor for BHEL supercritical technology - will design the 800 MW supercritical boilers and supply identified pressure parts along with windboxes, pulverisers and airpreheater components. The group will also assist BHEL with technical advisors during the erection and commissioning of the units. The units are expected to be commissioned starting in 2017.

Combined-cycle power plant

An Germany, the Erfurt municipal utility has put the extension of its Erfurt Ost combined-cycle power plant into operation. At the core of the plant is a Siemens SGT-700 industrial gas turbine.

Siemens also supplied an SGen5-100A generator and was in charge of the commissioning of the turbine and the generator. The company will also be responsible for service for the major components in the coming years.

The SGT-700 industrial gas turbine has an electrical capacity of up to 31MW. The thermal energy that is generated is also utilised for steam generation with operation of the existing steam turbine.

In addition to electricity, the extension of the Erfurt Ost combined-cycle plant will supply district heating for the city of Erfurt. Substantially higher fuel efficiency, here natural gas, is achieved through this co-generation of heat and power.

The power plant also remains extremely flexible thanks to the use of a heat accumulator and to the rapid start-up and shutdown times for the SGT-700. This gas turbine can provide full capacity within 30minutes of a hot start. This enables the power plant to be used both as a peak-load power plant and to function as a back-up for renewable energy sources (Fig.1). This expansion of the power plant will enable the municipal utility to cover nearly the entire electricity demand for Erfurt.

Strategic partnership

In March, Mitsubishi Heavy Industries and Ata Kombine Çevrim Santrali Elektrik Uretim Anonim Sirketi, a member of the Urundul Group based in Istanbul, Turkey, signed a co-operation and strategic partnership agreement to invest in 520MW natural gas combined cycle gas turbine (CCGT) power plant to be built in Kirklareli province.

The power plant will be built by a consortium consisting of contractors Mitsubishi Hitachi Power Systems and Mitsubishi Hitachi Power Systems Europe. Construction is expected to be completed within approximately 30 months and the power plant is scheduled to be put into operation in 2016.

The partnership with Urundul Group represents Mitsubishi Heavy Industries' fourth investment into an overseas power generation project.

The three previous investments were the independent power producer AES Energia Cartagena of Spain, Kaliakra Wind Power of Bulgaria, and Pocheon Power of Korea.

US gas-fired plant challenged on environmental grounds

The Salem Harbour power station run by Dominion in Salem, Massachusetts, USA, currently burns coal but it due to shut down in June and be replaced with a gas-fired plant following the state's approval of the plan.

However, environmental advocates are challenging this approval in the Massachusetts supreme judicial court under a 2008 state law aimed at reducing greenhouse gas emissions.

As a result, the operator of the region's power grid is warning that a delay in completing the new Salem plant over the next two years could lead to electricity shortages, and possibly rolling blackouts.

According to a report in The Boston Globe, environmental advocates say converting the 1950s plant will not do enough to curb greenhouse gas emissions.

The Conservation Law Foundation, the Boston advocacy group bringing the case, says governor Deval Patrick's administration failed to adequately consider its own climate change law when state energy officials approved the Salem plant. Compared with coal, natural gas produces far lower levels of greenhouse gases, environmentalists acknowledge, but the state won't meet the aggressive pollution reductions mandated by the law if it continues to rely on fossil fuels for energy.

"This is the place where we decide whether or not we are going to make good on our promises on climate, or whether we are going to continue doing more of the same. If we don't get this right now, there is no way we are going to meet our climate mandate," Shanna Cleveland, a senior attorney with the group, told the newspaper.

Recent Issues