“The model today is that of big centralized power plants feeding electricity out to all of these end destinations, and 60% of transmission lines in the U.S. are already at or past their life expectancy,” says Thomas Healy, founder and CEO of electricity-producing technology company Hyliion. “Our vision is, why don’t those end destinations actually just make the electricity they need on site?”
Hyliion’s Karno Power Module is enabled by the Karno Core, an array of four synchronous shafts with 3D printed metal parts providing the thermal performance needed to efficiently generate power from heat. Source: Hyliion
Hyliion is going to market with a solution to enable this vision, using additive manufacturing as a primary production technology. Dubbed the Karno Power Module, Hyliion’s core product is a standalone generator about the size of a pickup truck bed that is designed to generate up to 200 kilowatts of power at the point of use. That’s enough to power a big-box store like a Home Depot completely off the grid, round the clock. Rather than an emergency or backup generator, the Karno Power Module is intended to be a primary, continuous power source that generates electricity precisely where it is needed — and at lower cost and higher efficiency than the conventional grid.
The technology behind the Karno generator is an idea that is two centuries old, which has now come to life due to advances in underlying manufacturing technology. I visited Hyliion’s Cedar Park, Texas, facility in September to see the production floor and learn how the Karno Power Module is not just being enhanced, but enabled by additive manufacturing. Metal AM provides the critical components that unlock the generator’s performance, making it not only more efficient than standard grid electricity, but commercially viable in the first place.
The Road to New(?) Generator Technology
Hyliion founder and CEO Thomas Healy shows a model of the current facility, with current machines in green and those still to come in white. Source: Additive Manufacturing Media
Hyliion was founded in 2015 with the intention to develop electrified semitrucks for more sustainable transportation. The Karno technology was acquired from GE Additive in 2022 and was originally intended as a second-generation powertrain for a line of “Hypertrucks” capable of running on a range of fuel types. But two years ago, the company pivoted away from trucking to focus on developing the Karno as a standalone and primary product focused on the power generation market.
The Karno Power Module, Hyliion’s flagship product, is a four-shaft linear generator system. It generates electricity using heat from fuel oxidation in an external reactor (or other heat sources) to move a linear piston system back and forth inside a sealed chamber.
The technology is based on the Stirling engine, a design developed by Robert Stirling more than 200 years ago, whereby a motor is driven by the cyclical expansion and contraction of a gas. While Stirling engines have seen limited use over the last two centuries, difficulties in manufacturing heat exchangers have held back the practicality of the design and restricted its effectiveness.
“Yes, you could make Stirling engines, but the efficiency was probably only 20 to 30%,” Healy says. “We’re moving that up towards 50% efficiency, really because of additive.”
Two of the 3D printed components of each Karno Core shaft. On the left, a cutaway version of the reactor where fuel and air mix to generate heat. On the right, the fins of the heat exchanger that transmits the heat of the reaction to the working gas in the next chamber. Source: Additive Manufacturing Media
Additive at the Core
Within each shaft assembly, six out of the seven major metal components are produced with laser powder bed fusion (LPBF). This metal 3D printing technology enables the highly complex and effective heat exchangers that make electricity from the Karno cheaper and up to 15% more efficient than that from the conventional grid.
Here’s how it works, in simplified terms: A reactor on one end of the shaft assembly oxidizes fuel to heat helium in an adjacent but separate chamber. As the helium expands, it pushes the piston and the shaft connected to it toward the other end of the assembly. A similar process on the opposite side of the linear piston shaft pushes the piston back. As the shaft traverses back and forth, permanent magnets mounted on the piston shaft move linearly across a series of copper coils, generating electricity.
Source: Hyliion
Excess heat is stored and reused within the system effectively using a thermal battery, a key additively manufactured component that enables the Karno Power Module to achieve high efficiency.
The design brings several notable benefits:
- Fuel flexibility. The Karno Power Module is a heat engine with an external reactor (versus internal combustion), which means that the exact fuel source is not important. “As long as you can react a fuel and make heat out of it, we can likely run on it,” Healy says. The technology has been tested with multiple fuels, including natural gas, propane, diesel, hydrogen and kerosene, letting end users choose the fuel infrastructure that is most accessible to them. It can even be used with flare gas or other contaminated fuel.
- Reduced emissions. The generator’s reactors use a technique known as “flameless oxidation” which Healy describes as a “super-efficient, low-emissions way of reacting the fuel to make heat.” Fuel is oxidized at a lower temperature that allows it to more fully react, resulting in lower NOx emissions and reduced CO levels as well.
- Low maintenance. The piston shaft floats on gas bearings, negating the need for lubrication, and the linear motor assembly is completely sealed off from external fuel oxidation so that it cannot be contaminated. “The only thing that gets transferred in the sealed chamber is heat,” Healy says. “That allows us to not have to worry about gumming up O rings and pistons, because the fuel or oxidation byproducts never go in there.”
Power Up for Production
Since the pivot to power generation two years ago, Hyliion has continued the development of the Karno Power Module and additive manufacturing process at its R&D facility in Cincinnati, Ohio. Meanwhile the ,company has been revamping its Cedar Park, Texas, facility for scale additive manufacturing and assembly of the modules.
Because of the Karno technology’s origin and history with GE, Hyliion is entirely a Colibrium shop (GE Additive’s new-ish moniker). When I visited in September, the company was printing cobalt chromium and aluminum superalloys on about two dozen laser powder bed fusion machines, and expecting a delivery of several more in the near future.
Hyliion’s Texas facility currently has more than 20 Colibrium laser powder bed fusion 3D printers, with more on the way. The M Line and X Line machines feature swappable build modules, enabling more efficient production. Source: Hyliion
The exact models are a mix of two-laser, 400-watt M2 (build size 245 by 245 by 350 mm); four-laser, 1,000-watt M Line (500 by 500 by 400 mm); and two-laser, 1,000-watt X Line (800 by 400 by 500 mm) machines. Each has its strengths and weaknesses, says Joe Davis, technologist, additive at Hyliion.
“The M2s have the best optics. We use them for parts with very tight, fine details,” he says, like the previously mentioned thermal batteries. Meanwhile, the X Line machines offer less detail, but higher-powered lasers for greater productivity and larger build space to accommodate multiple parts such as the chillers. With the greatest number of lasers available, the M Line 3D printers will be the primary production machines to churn out taller parts like the reactor four at a time. Both the M Line and X Line machines provide the added advantage of swappable build modules that enable operators to unload and depowder one build while the next begins to print.
Completed builds from one of Hyliion’s Colibrium Additive X Line 3D printers. A system of colored cones indicates the status of each part. Source: Additive Manufacturing Media
While additive manufacturing is a crucial enabler of the Karno Power Module, Healy says it has also been a critical factor in determining its size and output.
“If we went one millimeter larger, we couldn’t fit four parts to a build in the M Line, and we couldn’t fit a full part in an M2,” he says. Printing parts at the absolute limits of the machine in some cases has dictated the size of the piston assembly, and therefore the 50-kilowatt output of each shaft assembly.
A Karno Power Module in progress. The systems are constructed, and many of the components are produced, in this Texas facility. Source: Additive Manufacturing Media
3D printed parts are further depowdered using systems from Solukon, and proprietary techniques that Hyliion has developed for its complex parts. Postprocessing was a hurdle “for almost everything,” Healy says, but investing in discovering the best techniques has enabled the company to “unlock” further functionality from parts that can now be even more complex because it is possible to effectively depowder them. Final machining is performed by an external machine shop, and then parts are returned to Cedar Park for assembly into the final product.
While the production space in Texas is dominated by metal 3D printing and generator assembly, it’s worth noting that other significant components of the Karno system are produced here, too. Hyliion builds its own linear electric motors and assembles its own battery packs from purchased lithium-titanate cells in this space — not necessarily by choice, but by necessity.
“It would be nice to buy these, but no one makes a battery like this,” Healy says. As a result of some selective vertical integration, most of the Karno Power Module is made in one place. And, Hyliion is prepared to scale that production as generator sales begin in earnest.
On Demand, Distributed Power
Hyliion began field trials for Karno Power Modules starting in early 2025, and has previously announced a goal to deliver 10 by the end of the year. In 2026, the company plans to move into commercial launch and begin delivering the modules to customers.
“We have nonbinding LOIs [letters of intent] for almost 500 units,” Healy says. Early customers will include data centers, EV charging stations and prime power for large industrial users, as well as mobile solutions. The company was also selected by the U.S. Navy as a power plant option for unmanned surface vessels (USVs) that require efficient, low-maintenance power.
Hyliion has also clearly set its sights on a product beyond the 200-kW Power Module it expects to bring to market next year. “Today we are also working on a 2-megawatt variant, which is really intended for C&I [commercial and industrial] and O&G [oil and gas] sites,” Healy says. The multi-megawatt systems will combine multiple shaft assemblies into a larger generator housed inside a shipping container-style enclosure.
“We recently announced a data center company that signed an LOI with us for up to 70 megawatts of power,” Healy says. “That would be 35 of these electric boxes upon execution of a definitive agreement.”
A cutaway of the chiller portion of the shaft assembly. Water cooling is used to reduce the temperature of the hot helium, forcing it to contract. Source: Hyliion
Looking forward, Healy sees potential future demand for lower wattage generators as well. Generators supplying 20 to 25 kW could be useful for noncommercial users and various military applications. There’s also the potential to integrate Karno Power Modules with renewable and other types of energy sources.
“It’s really an enabling technology because it’s fuel agnostic,” Healy says. “We could run off of nuclear, for example. We just need heat.”
As power demands grow, finding more options to generate electricity with greater efficiency will need to be top priority. Hyliion believes it is well-positioned to enable a less centralized, more resilient power grid.
“Everyone agrees that we’re going to use a lot more power with AI and data centers,” Healy says. “Either we’ve got to go build big power plants and then build out all the transmission lines, or we need a distributed model. Just like every facility has an air conditioning unit sitting outside, we want them to have one of these power modules to make their own power.”
Credit: Source link
