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LiquidPiston receives $8.2M award to integrate XTS-210 heavy-fueled rotary engine into compact 10 kW genset for US Army

LiquidPiston, a developer of efficient engine technology and hybrid power systems, has been awarded an $8.3-million contract by Parsons Corporation to integrate its recently launched high-performance rotary X-Engine, the XTS-210 (earlier post), into a lightweight, compact 10 kW generator set to be field-tested by the Army, delivering unmatched power flexibility and portability to the warfighter.

The XTS-210 is a 25 horsepower, two-stroke, supercharged, liquid-cooled 210cc X-Engine variant currently under development that reduces size and weight by nearly 80% over diesel engines with comparable power output while targeting an SFC of less than 350 g/kwh at maturity.

The XTS supercharger adds up to 1 bar boost while operating on a 2-stroke cycle, producing 6 combustion events per revolution of the rotor, to deliver smooth power from a minuscule package.


XTS-210 engine core (left) compared to 25 hp Kohler KDW1003 (right).

The LiquidPiston generator set (genset) will be approximately one-quarter the size and weight of the currently fielded Advanced Medium Mobile Power Source (AMMPS) generator system. Given its smaller footprint and inverter type operation, LiquidPiston’s new genset could replace multiple existing generator power classes with a single genset platform, greatly simplifying Army genset procurement and logistics.

Leveraging LiquidPiston’s patented High Efficiency Hybrid Thermodynamic Cycle (HEHC) and compact, heavy-fueled rotary engine, the new genset will offer several key benefits:

  • Lightweight: 75% lighter and smaller than the currently-fielded AMMPS

  • Easy to transport: can be man-portable, instead of requiring a truck, trailer, or forklift

  • Space-efficient: occupies only ~9 cubic feet of space

  • Fuel-efficient: targeted to use up to 8% less fuel

Current military mobile generators are too heavy and inefficient for modern use cases, which also makes them a potential hazard. A 2009 report commissioned by the Army Environmental Policy Institute (AEPI) developed a methodology for calculating casualty factors for fuel and water resupply convoys in theater operations. The authors demonstrated the methodology based on historical data from the wars in Iraq and Afghanistan. Casualties calculated include Army soldiers and civilians killed or wounded while transporting fuel or drinking water to consuming units and forward operating bases in theater.

The report found that the casualty factor for fuel resupply in Afghanistan was 0.042—i.e., 0.042 casualties for every fuel-related resupply convoy or one casualty for every 24 fuel resupply convoys in Afghanistan. For Iraq, the fuel casualty factor was 0.026.

The report estimated that in 2007 there were 5,133 required fuel convoys for Iraq and 897 required fuel convoys for Afghanistan—or 170 casualties (132 in Iraq, 38 in Afganistan) from fuel convoys in 2007 alone.

With the power density of LiquidPiston’s 10 kW genset, nearly 4x the power could be deployed to the battlefront for the same transport volume as currently-fielded gensets; this would reduce the frequency of refueling and therefore the risk to the troops.

Imagine the possibilities that are created when soldiers no longer have to haul a massive and inefficient generator on a towed trailer. This generator can have a revolutionary impact on the lives—and the mission success—of our armed forces. This award demonstrates a deep commitment by the Army to help LiquidPiston develop an ultra-light and portable power generation system, first for military applications and later for a range of commercial applications in the over $4-billion global portable generator market.

—Dr Alec Shkolnik, co-founder and CEO of LiquidPiston

LiquidPiston’s award supports an existing $14.9-million Other Transaction Award (OTA) prime contract for US Army Expeditionary Intelligent Tactical and Expeditionary Power that was awarded to Polaris Alpha Advanced Systems, a Parsons Company, by the Department of Defense Ordnance Technology Consortium (DOTC) in 2022. Through this contract, Polaris Alpha Advanced Systems is providing research and development to deliver reliable, adaptable, and reconfigurable power that meets extended power needs for the growing number of tactical electronic devices utilized in increasingly complex and remote battlegrounds.

LiquidPiston’s generator solution is the result of decades of engine research and development, coupled with more than 10 contracts secured with the US Department of Defense and more than $20 million awarded in development funding over the past 24 months, including a $9-million DEVCOM Army Research Laboratory award for a Compact Efficient Rotary Engine announced last fall and a $8.3-million award from DEVCOM C5ISR Center for the development of a Light Weight High Efficiency Generators. It will serve as a building block that will yield a family of modernized Tactical Electric Power (TEP) sources with similar efficiency and size reduction benefits.



I don't quite get this.
It certainly is smaller, but it is only 8% more fuel efficient than existing generators.
They say: "With the power density of LiquidPiston’s 10 kW genset, nearly 4x the power could be deployed to the battlefront for the same transport volume as currently-fielded gensets; this would reduce the frequency of refueling and therefore the risk to the troops."
So you could bring 4x the number of gensets, but presumably you only have to done this once, when setting up a base. After that, you are transporting fuel, but you now need 8% less fuel.
Which is good, but hardly earth shattering.
Is this a bait and switch, or am I missing something?
+ what are the yellow things sticking out of it - spark plugs?
If you include those, and the leads, the volume gets a lot bigger.

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