Those traveling through Benndale recently may have been wondering about the two huge blue box-car-like structures sitting on specialized trailers across from Benndale Superstore. They were Wärtsilä 31SG engines that were moved a short distance up Hwy. 57 to the Cooperative Energy Benndale Site.
Cooperative Energy is a generation and transmission electric cooperative based in Hattiesburg. Cooperative Energy is the wholesale power provider to 11 electric cooperatives across the state of Mississippi, including Singing River Electric and Coast Electric, said Sara Peterson, the company’s corporate communications manager.
“As a not-for-profit electric cooperative, our mission is to provide our members with electricity that is both reliable and economical,” said Jim Compton, Cooperative Energy CEO. “Wärtsilä’s Smart Power Generation plant, which is a great complement to our current generation sources, enables us to achieve this mission and as a result, we are proud to partner with Wärtsilä on this project.”
Most of us turn on our lights and run our air conditioners without giving a thought to where the electricity to power our homes comes from. It is really a remarkable story. As recently as 85 years ago fewer than 1 percent of Mississippians had any electricity at all. Now we take it for granted, in part because of generating stations such as the one at Benndale.
Few of us probably even realized there is a generating station at Benndale.
In 1941, Cooperative Energy, known then as South Mississippi Electric (SME), was formed to provide power to electric companies such as Singing River Electric and Coast Electric. The role of SME was to build transmission lines and buy or generate the power its member electric companies needed for their customers.
As a part of that role the company, renamed Cooperative Energy in 2016, built a natural gas fired 16.2 MW generating unit near Benndale in 1969.
That generating station, used to provide additional power to the transmission system during peak load times, is now being upgraded with the Wärtsilä engines.
The Wärtsilä engines are the world’s most efficient natural gas fired engines, according to Peterson.
The defining feature of the Wärtsilä 31SG is its ability to achieve simple-cycle efficiency levels in excess of 50 percent (compared to around 40 percent with modern gas turbines), which represents a milestone achievement in the energy sector, according to the Wärtsilä website. In addition to reducing emissions, this higher efficiency offers the potential for considerable cost savings to power producers.
Another huge benefit made possible by the Wärtsilä 31SG is the increased flexibility which enables rapid response to continuously changing load patterns, especially within systems having a notable share of solar and wind energy. The engine can be continuously operated at 10 percent load and can reach full load in two minutes from the start command. This flexibility overcomes the challenge created by the daily stops and starts that are inevitable with output from renewable sources.
The 20-cylinder, spark-ignited Wärtsilä 31SG produces 12 MW of power. The specially designed robust engine structure has an unprecedented brake mean effective pressure (BMEP) of 30 bar, allowing it to fully accommodate all the benefits of two-stage turbocharging.
Wärtsilä is a global company building power units for marine and energy companies. It is based in Sweden and began with a sawmill operation in 1834.