World's most efficient engine becomes a colossal clean energy generator

World's most efficient engine becomes a colossal clean energy generator
Wärtsilä 31SG-H1 hydrogen-ready engine
Wärtsilä 31SG-H1 hydrogen-ready engine
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Wärtsilä 31SG-H1 hydrogen-ready engine
Wärtsilä 31SG-H1 hydrogen-ready engine
Wärtsilä 31H2 engine hydrogen powered power plant concept
Wärtsilä 31H2 engine hydrogen powered power plant concept
Wärtsilä 31H2 hydrogen engine
Wärtsilä 31H2 hydrogen engine
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One of the world's largest engines becomes a clean generator. Originally designed to burn diesel, dual-fuel, or gasoline for tankers and container ships, the Wärtsilä 31 marine engine gets a new life generating clean, renewable electricity.

The Wärtsilä 31 engine is in the Guinness Book of World Records for being the most efficient 4-stroke marine engine ever made in its class. It also boasts the highest power per cylinder in engines of equivalent bore size. It can be configured in 8 to 16 cylinders and with a power output ranging from 4.6 MW to 10.4 MW at 720 and 750 rpm.

This Finnish company is best known for making the world's largest combustion engines – notably the 89 ft (27 m) tall, 44 ft (13 m) long, 110,000 horsepower RTA96-C. The Wärtsilä 31 engine is a fair bit smaller, maxing out at 15.4 ft (4.7 m) high and 28.8 ft (8.7 m) long, and running on fossil fuel, it can crank out up to 13,142 horsepower (9.8 MW).

The cylinder bore and stroke (12.2 x 16.9 inches, or 31 x 43 cm) sound enormous if you're coming from the auto/moto world, but compared to some of the company's bigger engines, which have cylinders big enough to walk into, they're relatively compact.

Converted to a generator, the hydrogen-ready 31SG-H2 version can run on natural gas, or a blend of natural gas and 25% hydrogen – or it can be upgraded to run on 100% hydrogen. There's also a flexible-fuel 31H2 designed to run natively on full hydrogen, but also accepting natural gas or blended fuels.

Both promise to be the world's largest hydrogen-powered generators when rolled out – assuming there's enough hydrogen available to run them.

The hydrogen power station is designed for firming up a renewables-based grid, quickly ramping up or down to support intermittent clean energy sources such as solar and wind, with no minimum up or downtime and the ability to ramp up and synchronize with the power grid in as little as 30 seconds with the push of a button. By using hydrogen, Wärtsilä can generate electricity 100% carbon-free.

Wärtsilä 31H2 engine hydrogen powered power plant concept
Wärtsilä 31H2 engine hydrogen powered power plant concept

Anders Lindberg, President of Wärtsilä Energy stated, "We must be realistic that natural gas will play a part in our power systems for years to come. Our fuel-flexible engines can use natural gas today to provide flexibility and balancing, enabling renewable power to thrive. They can then be converted to run on hydrogen when it becomes readily available, future-proofing the journey to net zero."

Wärtsilä's power plant concept has been phase 1 certified by TÜV SÜD, an organization focused on protecting people and the environment and ensuring regulatory compliance. It must pass two more certifications before ground can be broken. Its hydrogen-ready engines are expected to be available for delivery by 2026.

World’s first large-scale 100% hydrogen engine power plant | Wärtsilä

With over a million running hours and over 1,000 MW of installations so far, Wärtsilä has a proven track record of reliability. We're interested to learn what kind of efficiency this massive machine might run at, and how it might compare in terms of industrial-scale, long-term economics against a large fuel cell type of operation, which could convert the hydrogen directly back into electricity and water.

Source: Wärtsilä

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"The Wärtsilä 31 engine is in the Guinness Book of World Records for being the most efficient 4-stroke marine engine ever made in its class."
And just how efficient is that, I wonder? Oh... 50% (

So, fully half your (no doubt 'green') H2 (generated at 30% max efficiency) is just being thrown down the drain, then.
It seems more of a clean energy hoax. 97% of hydrogen comes from reformed fossil gas with all the GHG emission of burning it directly. Green hydrogen, you ask? Well it's scarce and made from renewable electricity, so why would you want to squander it on hydrogen's losses and the poor efficiency of an ICE just to make more electricity? However, you are right about the colossal part.
Expanded Viewpoint
What a bunch of hooey! Just how hard of a knock on the head does it take to get people to buy into this fallacy of creating efficiency by going to Hydrogen as a fuel source? Where does all of that Hydrogen come from, since it isn't provided to us by Nature? Oh, that's right, Man has to intervene in the equation and introduce some complexity to the mix, complexity which adds SIGNIFICANT costs and losses in efficiency! Or does someone open up the Sorcerer's bench book and say a few incantations over the process, to make it all turn green?
White Rabbit
@martinwinlow - You seem to have neglected to consider your citation (and proceeding argument) into context.
"The average efficiencies of power generation are 35% for coal, 45% for natural gas and 38% for oil-fired power generation. What this means is that 35% of the energy in coal results in electric power, the rest goes 'up the stack' as heat." (
So 50% looks pretty good by comparison!
A 5% increase from the 45% efficiency of natural gas is a change of 11.11%, and in the case of coal the increase is 15%, which is 43% better!
Another greenwashing. H2 takes 4x the energy to make a kwh this way than just using the energy used to make, store the H2.

Their engines have always used many fuels with just an intake change including gasified biomass/syngas, which is H2 and CO.
The only logic I can see considering the comments from others is using it as a reserved for when green’ methods of producing electricity are not producing sufficient power which is why I presume they boast the speed at which this can be turned on. The only logic in using pre ious Hydrogen or bio fuel for that matter.
Fix the title guys "clean energy" is not natural gas, and not hydrogen either (95%+ of which comes from natural gas itself). Combustion engines burn fossil fuels, and by the time you've moved it from the engine to a house, it's already lost all the efficiency accolades is started with anyhow. A regular car engine at the end of busy neighborhoods would be more efficient.
It's competitor is the Combined Cycle gas turbine - I believe that attains a similar efficiency only after a couple of hours running to get its heat exchangers working fully.
However this engine would seem a step up in terms of complexity.
My money is on battery storage beating hydrogen to the lead in grid level energy storage.
Tony Field
A beautiful engine, but a colossal waste of hydrogen. Hydrogen is a nightmare to store and transport, even if you have a lot of it, and is more efficiently used in a fuel cell. No doubt this engine will be popular with some eager people with more money than sense, or stupid politicians trying to prove their environmental credentials using taxpayer money. If we are forced into a hydrogen economy, watch the energy prices skyrocket.
Robin Gordon
Your "clean" hydrogen is made from processing methane, that process is dirtier than using natural gas. Or h2o electrolysis, which uses as much electricity as it creates. Yall gotta stop calling hydrogen "clean".
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