Pictures of the Future    Fall 2006

Gas on the Go

Natural gas is steadily gaining in importance in the energy mix. But because it often travels thousands of miles from production fields to consumers, powerful compressors are needed to keep it moving at the highest possible speed.

The city of Erlangen, Germany, is proud of its new, ultra-modern combined cycle power plant. Now that Siemens Power Generation (PG) has modernized the facility, its CO₂ emissions will be reduced by 10 %, or about 70,000 t per year. The power plant covers 30 % of the city’s energy requirements and supplies an additional 3,000 households with district heating. And it’s highly efficient. It utilizes up to 90 % of the energy contained in the natural gas. Communities worldwide are increasingly turning to natural gas. The International Energy Agency estimates that associated investment requirements will reach $500 billion for site development and transportation systems by 2030.

The most common way of transporting gas, sometimes over enormous distances, to densely populated urban centers is the pipeline. The Jamal-Europe Pipeline, for example, is 4,000 km long—extending from the Jamal Peninsula in western Siberia to eastern Germany. Gas needs just under a week for the journey. Compressor stations are installed every 200 km because the gas loses pressure as a result of friction. The stations compress the gas up to 90 bar—90 times the pressure of air—so that it can flow through the pipes quickly. Turbo compressors, in which up to three runners are positioned one behind the other on a shaft, are used in pipelines that require particularly high throughput. They are driven by a gas turbine or powerful electric motors. Siemens supplied 21 gas turbine compressor lines with 25 MW each for the Jamal Pipeline, which is operated by the Russian company Gasprom, among others.

Another company that has used Siemens technology is BASF subsidiary Wingas. It equipped its compressor station in Eischleben, Germany (completed in 2005) with two Siemens compressor strings. These are powered by SGT-700 gas turbines, each with 30 MW of mechanical coupling output. When the gas turbines were ordered, there weren’t any references yet for this series’ performance in practice. "A key reason for deciding in favor of the SGT-700 was the fact that it bore the Siemens name," says Klaus Haußmann of BASF, project manager for the technical planning of several Wingas facilities. "The machines have been running to our full satisfaction from the start of operations." The same is true of the control system, which was also made by Siemens.

Natural gas is often converted to liquefied natural gas (LNG) close to the source and shipped by tankers. Here, the trend is toward bigger facilities. "The larger the amounts produced, the lower the specific investment costs," explains Manfred Ramdohr, who is responsible for LNG business development at PG. That requires huge, multi-casing compressors. The single casings are up to seven meters long, weigh up to 220 t, and have an output exceeding 100 MW. Beginning in 2007, Siemens will be able to test up to six of these giant compressors at full load—including drives—at the same time in a test center that is being built in a huge hall in Duisburg. "That way we can fulfill the customer’s specific requirements exactly, all the way through to assembly and test," says Dr. Peter Langer, head of the compressor business. In addition to gas and steam turbines, Siemens also makes electric motors that operate as drives. It is thus in tune with the trend toward fully electric LNG systems. "Due to routine maintenance, gas turbines are not in operation 20 to 30 days per year. Electrically driven compressors, on the other hand, can run 350 days and more per year," says Ramdohr. The first fully electric LNG facility will enter service in Hammerfest, Norway, at the end of 2007. Siemens’ Dynamo plant in Berlin furnished 65-MW electric motors for this project—the most powerful that have ever been built.

Environmentally Friendly Diesel. Synthetic GTL (gas-to-liquid) fuels represent another market for natural gas. They are created through the transformation of methane, the main constituent of natural gas, into diesel, kerosene, naphtha (raw gasoline), lubricating oils and paraffins. GTL diesel is considered to be environmentally compatible, as it contains very low levels of sulfur and aromatic hydrocarbons. The fuel produced by Shell in Malaysia is already improving air quality in Bangkok and Athens, and Shell is planning a 140,000-barrel per day mega-facility in the Emirate of Qatar.

"As Siemens can also supply management systems, process controls and plants for waste water treatment and power generation, it can provide unique solutions for the oil and gas industry from one source," says Peter Adam, sector manager for oil and natural gas.

Companies such as Shell are also eyeing untapped natural gas fields under the ocean. But pumping the gas out is a challenge. Until now, development has been held back because of a lack high-performance compressors for maintenance free, deep-sea operations. However, engineers from Siemens PG are working with underwater specialists from FMC Technologies to develop a compressor capable of operating at depths of up to 3,000 m.
                                                                                                                       Ute Kehse