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7th March 2014


The J920 largest gas engine, the J920 FleXtra Credit: GE

The largest gas engine yet developed by GE Jenbacher, the 9.5 MW J920 FleXtra, has taken its place in the upgraded municipal cogeneration facility that feeds the district heating system in the city of Rosenheim, Germany.

The new engine generator sits beside four existing Jenbacher engines – three 3.35 MW J620 engines and a 4.4 MW two-stage turbocharged J624 unit – plus an existing waste incineration plant.

Stadtwerke Rosenheim's integrated cogen facility now has an electricity generating capacity of 36 MW and a heat generation capacity of 44 MW. It meets about 40% of the electricity needs and 20% of the heating requirements of the city – which has more than 61,000 inhabitants, and lies 450 metres above sea level in the upper-Bavarian Alpine foothills.

This impressive installation will help meet Germany's goal to increase power from CHP from today's 15% to 25% of the country's power supply by 2020, as part of its larger energy transition (Energiewende) strategy. Germany is already the largest single market for CHP in Europe, accounting for more than 20% of the electricity from cogeneration across the EU-27, but it will need many more new CHP plants to meet the 25% target that was set last year in a new CHP law.

Speaking at the start-up of the expansion of the Stadtwerke Rosenheim plant, the Bavarian minister of state for Environment and Health, Dr. Marcel Huber, stressed the role of local government bodies: 'The energy transition plan, Energiewende, can be achieved only if there is a cooperative effort, including contributions by municipal providers'.

'Investments in innovative, modern power plants create an important foundation for the successful execution of our energy transition plan,' he added

As part of Energiewende, Germany plans to close all nuclear power plants by 2022. To replace the massive amount of low-carbon baseload electricity from the nuclear power plants, the transition plan calls for increasing use of natural gas and renewable energy, and greater use of energy efficiency technologies. GE is also keen for Rosenheim to act as a demonstration of the role of distributed energy, to promote energy security across Europe.

Technology, both flexible, and efficient

The Rosenheim project's centrepiece is GE's largest and newest Jenbacher gas engine, the 9.5 MW J920 FleXtra, which GE calls a flexible power solution. It combines innovation with power and efficiency to help customers address their local energy security priorities, while achieving improved environmental performance.

GE expects to make the engine available in 60 Hz regions of the world in 2014.

The CHP system provides electricity and thermal power (hot water) for local residents and industrial customers. It has a lower-carbon footprint than conventional power plants and boilers, and will assist Germany's effort to reduce greenhouse gas emissions by 40% by 2020. The engine's fast start-up aids Stadtwerke Rosenheim's operational flexibility, to overcome the challenges of intermittency caused by adding wind and solar energy supplies to the electricity grid.

The J920 FleXtra has the highest electrical efficiency in the 10 MW class of gas engines, of 48.7%, and about 90% efficiency in cogeneration mode, depending on heat utilization, says GE. Its two-stage turbocharging design will also help Stadtwerke Rosenheim to meet Germany's goal to improve its energy productivity – related to prime energy usage – by 2.1% annually.

'Our flexible J920 technology offers both high efficiency and reliability levels, which makes it the ideal large gas engine distributed power solution for industrial and grid stabilisation applications, while also minimising the customer's carbon footprint,' said Karl Wetzlmayer, general manager of Gas Engines for Power Generation, GE Power & Water.