The Denver startup plans factory-built supercritical carbon dioxide systems designed to recover gas turbine exhaust heat.
Denver-based American Supercritical has come out of stealth with $8 million in pre-seed funding to commercialize factory-built supercritical carbon dioxide (sCO2) power blocks. The units are designed to recover exhaust heat from gas turbines already in operation and turn it into electricity.1
The company is focusing first on simple cycle installations. Those units have taken on much of the recent growth in U.S. power demand from data centers, electrification and onshored manufacturing, but they lose a large share of their fuel energy as exhaust heat.1
"Our first goal is to make wasteful simple cycle gas turbine installations obsolete," said Simon Shuham, co-founder and chief executive, in a press release. "Our sCO2 power block converts any gas turbine into a combined cycle plant. We upgrade turbines running today instead of replacing them."
Silent Ventures led the round. Riot Ventures, Harpoon, Reveille VC, Hillwood, Mana Ventures, Climate Capital, Alumni Ventures and several angel investors also participated.1
The system mounts at the turbine exhaust and acts as a bottoming cycle. In a conventional combined cycle plant, a heat recovery steam generator and steam turbine perform that role.
American Supercritical says its unit can raise output by up to 50% without additional fuel, turbine modifications or re-permitting. The company also says the package is about one-tenth the size of a comparable steam system.1
These are company projections. The announcement did not include test results, a pilot site, or a delivery schedule.
The company estimates that about 140 gigawatts of small gas turbine capacity runs in the U.S., representing tens of gigawatts of recoverable output. It also estimates that converting that fleet would avoid roughly 20 million tons of carbon dioxide a year, or about 10% of the natural gas sector's emissions.1
Neither figure has been independently verified.
Speed to capacity has driven much of the recent turbine demand. Combined cycle plants still account for most U.S. natural gas-fired generating capacity.
However, very little new natural gas capacity came online in 2024. Developers have planned 18.7 gigawatts of combined cycle additions through 2028, of which 4.3 gigawatts were under construction as of mid-2025, according to the U.S. Energy Information Administration.3
"Compressed timelines pushed operators toward simple cycle turbines. Wasting fuel was never the goal," said Matt Carlson, co-founder and chief technology officer, in a press release.
Carlson has worked on sCO2 systems for about a decade at Sandia National Laboratories, Heliogen and Kairos Power.
In sCO2 cycles, carbon dioxide held above its critical point replaces steam as the working fluid. This allows for more compact turbomachinery and heat exchangers.
The largest demonstration to date is the 10-megawatt Supercritical Transformational Electric Power pilot plant, known as the STEP Demo, at Southwest Research Institute in San Antonio. The $169 million project is led by GTI Energy with GE Vernova and the Department of Energy's National Energy Technology Laboratory.2
In 2024, the STEP Demo completed its first test phase in a simple cycle configuration. The next and final phase is intended to raise efficiency and output.2
Using sCO2 to recover heat from turbine exhaust also has commercial precedent. Echogen Power Systems developed the EPS100, a heat engine of roughly 7.5 to 8 megawatts designed for gas turbine and industrial exhaust streams.
The company began offering it commercially in 2019 and planned an initial deployment in Alberta.4
American Supercritical is at an early stage. It has not disclosed pricing, prototype performance data or customers.
Whether re-permitting can be avoided will likely depend on the jurisdiction and the site. Operators evaluating any bottoming cycle retrofit typically consider exhaust back pressure, part-load behavior on units that start and stop frequently, and cooling requirements.
The company says the same platform could eventually serve small modular reactors, geothermal plants, concentrated solar and industrial waste heat. It puts the recoverable power from those sources at tens of terawatt-hours a year.1 For now, work is starting at a 25,000-square-foot facility in Denver for testing and low-volume production.
The team includes alumni of Sandia, Echogen, Hanwha, Blue Origin, Southwest Research Institute and Google X. The company is hiring engineers in turbomachinery and power electronics.1
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