The evolution of gas reciprocating engines 

Posted: December 10, 2016 by oldbrew in Energy, innovation
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Experts say reciprocating gas engines can respond faster to load changes than any other prime mover, can compete with small gas turbine systems and also help fill in an efficient way the gap left by the lack of energy storage in most grid systems, as Power Engineering reports.

In southern Minnesota, where wind turbines and ethanol plants are commonplace, two communities have turned to reciprocating engine technology to meet their future power generation needs.

The Fairmont Energy Station, a 25-MW project completed in 2014, and the Owatonna Energy Station, a 38-MW project now under construction, feature highly flexible, quick-starting, low-maintenance reciprocating engines suited for today’s market, which places a premium on rapid-cycling capabilities.

Minnesota is home to about 100 wind power projects and ranks No. 7 in net wind power production in the U.S. That means Minnesota power producers must have reliable backup power to fill the sudden gaps created by growing supplies of intermittent wind power. The $30 million Fairmont plant is well suited for the job, capable of reaching full capacity in just eight minutes. That’s significantly faster than power plants using the latest gas turbine technology.

“We required a more flexible and fast responding power source that could make up the difference,” said Peter Reinarts, manager of Generation and Operation at Southern Minnesota Municipal Power Agency (SMMPA), which owns the Fairmont and Owatonna plants. SMMPA either purchases or operates more than 100 MW of wind power capacity. The four 16-cylinder gas-fired engines provided by Caterpillar for the Fairmont project work in sync with the association’s portfolio of wind power. “The generator sets can be promptly put on or offline to fill in the holes of the current wind generation,” Reinarts said. “These two assets aren’t at odds with each other, but instead work in a dynamic tandem.”

The intermittent nature of renewable generation, low-priced natural gas and advancements in engine technology and flexibility have given reciprocating engines new life in the U.S. as a competitive form of reliable generation. Reciprocating engines are becoming increasingly popular for utility-scale power projects.

Gas engine power plants have several advantages over plants equipped with gas turbines. Perhaps the biggest advantage is flexibility. Gas-engine power plants with multiple modular units are better at scaling their output across a wide range of incremental load without sacrificing efficiency.

For example, 12 generator sets capable of generating up to 10 MW each can deliver output ranging from just a few MW to more than 100 MW in just minutes. By keeping a few units online, the other units can be deployed individually to offset sudden losses of wind power and bring balance to the grid.

“These new generator sets start quickly, like a car engine,” said Bruce Erickson, vice president of Ziegler Power Systems, which supplied the four Cat G16CM34 generator sets for the Fairmont project. “If the grid needs extra power 10 minutes from now – these generator sets can easily adjust to that need.”

In addition to speed and flexibility, gas-fired reciprocating engines can operate at part load – 25 percent or lower – without sacrificing fuel efficiency. Also, reciprocating engines have much lower maintenance costs versus the cost to maintain a sophisticated gas turbine.

What’s more, the output of a modern-day reciprocating engine now exceeds 20 MW, up from 10 MW a decade ago. This has led to the development of more engine-based power plants exceeding a capacity of 200 MW worldwide. Earlier this year, Sky Global One, a 51-MW gas-fired plant about 70 miles west of Houston in the Rock Island community of Colorado County, began commercial operation.

The plant features six 8.6 MW Jenbacher J920 FleXtra gas engines from GE and will supply power to the 18,000 members of the San Bernard Electric Cooperative. The plant can go from zero to full power in just five minutes, a useful feature in a state that leads the nation in wind power production. In addition to providing power on short notice, the power plant – and others like it – uses very little water.

“Reciprocating engines use no water as part of their cycle,” said Andreas M. Lippert, engineering leader for GE’s Distributed Power business. “Our Sky Global power plant in Texas basically uses no more water than an ordinary household.” The J920 Flextra, a two-stage turbocharged engine, has a maximum output of 10.4 MW and can achieve electrical efficiencies of 49.1 percent at 50 hertz.

The 60 hertz version has a capacity of 9.35 MW and can achieve electrical efficiencies of 49.9 percent. The two-stage turbocharging means the J920 can achieve a fuel efficiency rating of more than 90 percent when used in a combined heat and power (CHP) plant that produces hot water, GE said.

Full report: The Evolution of Reciprocating Engines – Power Engineering

See also: Why reciprocating gas engines make sense for Europe’s power industry – PEI

Comments
  1. oldbrew says:

    ‘ Worldwide production of reciprocating internal combustion engines exceeds 200 million units per year.’

    http://energy.gov/sites/prod/files/2016/09/f33/CHP-Recip%20Engines.pdf
    [See: Table 1. Summary of Reciprocating Engine Attributes]

  2. Bitter&twisted says:

    These are Diesel engines.
    What’s new- apart from the insanity of “renewables” that makes them economically viable?
    And don’t they emit NOx, particulates and horror of horrors, CO2?

  3. oldbrew says:

    B&T – No they’re gas engines, but some can also run on diesel.

    E.g. the post says: ‘The plant features six 8.6 MW Jenbacher J920 FleXtra gas engines from GE’

    A dual-fuel reciprocating engine generally runs primarily on natural gas (or propane when pipeline gas is not available). It also needs at least a small amount of diesel fuel to ignite the mixture. A dual-fuel engine can also run entirely on diesel, and typically this is done when limited or no natural gas is available.

    http://microgridknowledge.com/reciprocating-engine-generators-and-microgrids-fuels/

  4. Joe Public says:

    The really interesting bit is at the end of the article:

    But the biggest factor behind the increasing use of reciprocating engines for CHP applications is the prospect for low natural gas prices. According to the Department of Energy, natural gas prices are expected to rise over the next two years but will remain low enough to incentivize the continued construction of gas-fired plants in the U.S. Natural gas prices are expected to average $2.36 per million Btu (MMBtu) in 2016 and $2.95 per MMBtu in 2017. In 2006, the wellhead price of natural gas in the U.S. averaged $6.42 per MMBtu.

    $2.36 per million Btu (MMBtu) is $2.36 per 293kWh!

  5. gwaigau says:

    I worked at a UK government establishment that had previously installed gas-fired reciprocating engines as power generators. Sadly after installation they were mothballed as the cost of maintaining them was prohibitively high. No, no-one thought to check the running costs before installation, but they were installed to reduce the reliance on oil-fired and high-CO2 emitting equipment. So a real win on paper.

  6. oldmanK says:

    Gas engines/diesels have their niche and their advantageous uses. Jenbacher are ideal where one has landfill gases and similar to burn. Or in isolated communities unconnected to a grid system. They are also an important plant addition for emergencies and back-ups (hospitals, hotels, large IT based agencies and banks) -and black start.

    But large/high output installations, its another matter. Service life is low; they have a high maintenance/spares demand; they prefer lube oil to water; and if emissions are to be considered, ammonia for de-noxing. There are other issues.

    In other words study first what plant serves best one’s needs.

  7. oldbrew says:

    Promo vid…2 mins. (no voices).

  8. oldbrew says:

    Re maintenance see section 2.4.6 here:
    https://www.epa.gov/sites/production/files/2015-07/documents/catalog_of_chp_technologies_section_2._technology_characterization_-_reciprocating_internal_combustion_engines.pdf

    Quote: Full maintenance contracts (covering all recommended service) generally cost between 1 to 2.5 cents/kWh depending on engine size, speed and service. Many service contracts now include remote monitoring of engine performance and conditions in addition to allowing for predictive maintenance. Service contract rates typically are all-inclusive, including the travel time of technicians on service calls.

  9. […] Source: The evolution of gas reciprocating engines  […]

  10. oldbrew says:

    ADVANCED RECIPROCATING ENGINE SYSTEM (ARES)

    The ARES program is designed to promote separate, but parallel engine development among the major stationary, gaseous fueled engine manufacturers in the United States.

    ‘With or without the benefit of waste heat recovery, ARES systems
    can result in billions of dollars in savings for the U.S. economy,
    under a variety of operating and market strategies.’ [see pdf]
    http://energy.gov/eere/amo/downloads/advanced-reciprocating-engine-system-ares

  11. catweazle666 says:

    Round and round we go…

    Back in the early 1950s, my grandparents’ house was converted from 120V DC to 240V AC. The DC generator was just down the back street and was a big (looked it to me at that age!) single horizontal cylinder device that ran on good old town gas.

    Plus ca change…

  12. oldmanK says:

    From oldbrew “Quote: Full maintenance contracts (covering all recommended service) generally cost between 1 to 2.5 cents/kWh depending on engine size, speed and service. Many service contracts now include remote monitoring of engine performance and conditions in addition to allowing for predictive maintenance. Service contract rates typically are all-inclusive, including the travel time of technicians on service calls.”

    Those are the general ‘ingredients’. But look carefully at the recipe. Actual maintenance contracts will have plenty of protection to cover the contractor’s back. The initial cost/kWh will climb; the less one looks into the detail, the steeper the climb. gwaigaw’s experience above is quite common; in other instances the experience is worse. (Take the last sentence for example. That is ‘nit-picking’. In a ‘full maint cont’ that’s for the contractor worry on. He is there/paid to deliver not to charge.)

    This is an old work-horse but its needs are just as many and complex as any other plant. It is up to the buyer then to be ‘informed’.

  13. It is interesting that the makers of these large engines minimize the maintenance requirements.

    If the owner of this kit wants to keep it running for a long time, then lots of maintenance is required from skilled engineers.

    Here is a very large reciprocating engine:
    https://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C

    Its specific fuel consumption is 171 grams per kW per h – pretty amazing efficiency!

    An alternate view of this engines internals are here:
    https://web.archive.org/web/20100716202400/http://people.bath.ac.uk/ccsshb/12cyl/index.html.o

    Some of these large engines have been modified to accept either natural gas or heavy fuel oil but with erratic running in some cases.

    Many engine designers have now released brand new designs that run on gas and oil and switch seamlessly between each fuel.

    Here is one that does:
    http://www.wartsila.com/products/marine-oil-gas/engines-generating-sets/low-speed-dual-fuel-engines/wartsila-x92df

    They still need lots of maintenance if you want them to last a long time.

    In a typical vessel you will have at least 3 qualified marine engineers available 24×7 from the time the vessel is built until it is scrapped plus unqualified ‘helpers’ to perform the mundane work.

  14. M Simon says:

    To keep the grid up response time must be on the order of milliseconds.

    And the plant mooted only requires 8 minutes to respond.

    I’d say there was a slight mismatch.

  15. M Simon says:

    In my Navy days we had two back up diesel generators (1 MWe each) for emergencies. I was involved with a reactor scram with the other plant shut down ( a two reactor ship DLG(N)-25 ). It took the two DGs about a minute to start up and get up to speed and another minute to get to the point where significant power was available.

    And no. I wasn’t responsible for the scram. I worked on the hot restart. I helped check the rod position for criticality (a calculation that needed to be done by 3 people independently) and also had a look at the forward DG to make sure it was running properly.

    IIRC we started the DGs once a week to check operational condition. As a reactor operator I didn’t have much to do with DG maintenance.

  16. oldmanK says:

    @ steverichards1984 says: December 10, 2016 at 9:10 pm

    You post very familiar links – but from another era, the RND Sulzer. The father of the 95 was the 105, larger. Here is its resting place of one of its pistons. https://www.flickr.com/photos/kecko/9240580488

  17. In the old days a 50MW coal fired steam turbine could be run at 30% and then turned up to full load in 15-20 minutes.but also with warning it could be cranked up then 30% of capacity load connected. Happened at mines with their own power station.
    Unfortunately, the development of larger gas engines will give ammunition to the Green fools who want to keep installing the ugly wind monsters.
    Should be looking a package nuclear plants which can have output adjusted from 10 to 110% of capacity. I believe South Korea is installing small units in UAE with desalination plants. I read that the units can be up and running in 18 months and have a ;life of 30 years before re-fueling.

  18. Curious George says:

    “If the grid needs extra power 10 minutes from now – these generator sets can easily adjust to that need.” What if the grid needs that extra power NOW? (Batteries, maybe. Or forget the intermittents.)

  19. BoyfromTottenham says:

    When I was a lad (in Tottenham, near the Lea canal) I remember the day I saw my first donkey engine pulling a canal boat instead of the quiet huffing horse. Imagine some bunch of loonies than suggesting only using the donkey engines as backup for when the horses needed a rest. Likewise the same for waterwheels and steam-driven mills during droughts, etc. When is this madness going to end? All one has to do is imagine life without reliable, affordable mains power. I can, and no bl**dy thanks!

  20. oldmanK says:

    BoyfromTottenham :- Quote “Likewise the same for waterwheels and steam-driven mills during droughts”. What is imagined here was a reality elsewhere. The mule driving the water-wheel rested whenever the Chicago air-motor pumped. When the mule retired Petters pumped -and backfired- all through the night, – and day but it wasn’t so bad then. The answer is always adapt to optimal.

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