Wärtsilä Introduces Gas-Fueled Version of ‘World’s Most Efficient 4-Stroke Diesel Engine’

Wärtsilä 31SG coming off the factory line in Vaasa, Finland. Photo credit: Wärtsilä

Finnish technology group Wärtsilä has introduced a gas-fueled version of its Wärtsilä 31 marine engine, which is recognized by Guinness World Records as the world’s most efficient 4-stroke diesel engine.

The engine, dubbed the Wärtsilä 31SG, builds on the efficiency of the successful Wärtsilä 31 engine, but with added flexibility and efficiency compared to its conventionally-fueled and dual-fuel predecessor.

“The defining feature of the Wärtsilä 31SG is its ability to achieve simple-cycle efficiency levels in excess of 50 % (compared to around 40 % with modern gas turbines), which represents a milestone achievement in the energy sector,” according to Wärtsilä. “In addition to reducing emissions, this higher efficiency offers the potential for considerable cost savings to power producers.”

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, explains Wärtsilä.

“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 company says.

Re: “The engine can be continuously operated at 10 percent load, and can reach full load in two minutes from the start command.”

That’s interesting.

Diesel generators have long been used in multiple locations in New York City, and, I assume, in other densely populated areas.

Natural gas would would be optimal if they could build a pipeline from the tight shale formations in the northern Appalachians directly into NYC.

Thanks for posting. This is an amazing technical achievement -- hitting 50% thermal efficiency in a simple cycle engine is not trivial. As more wind and solar is deployed, these engines are critical to making the entire power system work and be stable.

I still believe that the true economics of wind and solar are awful. You have to build the core wind and solar plant, then you have to build backup at the same capacity for the times the wind isn't blowing and the sun isn't shining. That means huge battery storage, supercapacitor storage, pumped storage, or huge internal combustion engines such as these. You are effectively paying for TWO complete power plants where you only use one at a time - in other words, your plant Capacity Factor is terrible. What a waste of resources to fix a hoax.

For marine applications, these engines could really contribute to cleaning up the air in harbors. The Wärtsilä site says their 20DF is also optimal for harbour genset application for a wide range of vessel types. There's a big push to reduce harbor emissions and I won't be surprised if LNG powered harbor craft are going to be a big part of that.

Some may be asking about the meaning of Brake Mean Effective Pressure of an internal combustion engine (I had to look that up). It isn't a real pressure reading at all. It's a metric to describe engine performance that happens to work out to units of pressure, so it is called "Pressure" even though it isn't. Very good explanation at: What is the Mean Effective Pressure (MEP) of an engine ?. "The mean effective pressure can be regarded as an average pressure in the cylinder for a complete engine cycle. By definition, mean effective pressure is the ratio between the work and engine displacement. There are different “flavors” of mean effective pressure:"

• indicated mean effective pressure (IMEP)
• brake mean effective pressure (BMEP)
• friction mean effective pressure (FMEP)

Re: “Well that’s cool but Sako and Valmet rifles, The Winter war the anti Tank Lahti? Metal Rock Church Mass, Hot chicks and even Lingonberrys beat that. Wigwam! Hanoi Rocks LOL.”

What's Wigwam?

I can only think of Wigwam socks, but that's an American company.

Anyway, you forgot the most important thing...

98% of religious Finns are Lutheran!

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