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Whenever I have an opportunity to partner with a brilliant technologist to build something special, I do so. A few years ago, Matt Stroud (my brilliant cofounder) set out to rebuild the heat pump. Here is a summary of our company: @Icebox_Energy Problem Statement: We are building an end-to-end cooling solution for data centers using CO2. Why: Next-generation HPC/AI processors produce heat beyond the capabilities of traditional cooling. Only four viable options exist: two-phase immersion cooling (impractical and environmentally hazardous), impinged water jets (complex and leak-risky), two-phase refrigerant cold plates (environmentally concerning), and Icebox Energy’s CO₂-based solution. Our single-loop CO₂ system simplifies design, reduces risks, and significantly lowers costs while providing higher reliability, easier maintenance, and better scalability. Emerging HPC/AI processors produce more heat than can be managed by state-of-the-art air or liquid cooling systems. Future data center builds will require advanced cooling solutions to handle both the extreme heat density of these next-generation processors and rapidly increasing rack power levels—currently around 140 kW and soon reaching 1 MW. Compounding this challenge is limited grid power availability, making it essential that advanced cooling solutions become more efficient—freeing up additional power for computing workloads. There are only four practical cooling options capable of handling these demands: two-phase immersion cooling and three direct-to-chip (cold plate) solutions—impinged water jets, two-phase refrigerant cold plates, and Icebox Energy’s CO₂-based technology. Two-phase immersion cooling is unlikely to scale effectively. Although it delivers impressive energy performance, immersion requires submerging entire servers into sealed vats filled with fluorinated chemicals, making it impractical and posing significant environmental and health risks. This leaves the three cold plate options. Impinged water jet cold plates utilize water, but managing water chemistry and high flow rates for these applications is challenging, and leaks pose serious risks to IT equipment. Two-phase refrigerant cold plates rely on the same fluorinated chemicals (HFOs) used in immersion cooling, though in much smaller quantities. While the environmental impact is reduced, concerns around safety, cost, and long-term regulatory restrictions remain. Both impinged water jet and two-phase refrigerant cold plates require multiple cooling loops, introducing additional points of potential failure and increasing heat losses. Icebox Energy's system transfers heat from the server directly to its heat pump in a single loop. Operating at pressures similar to those in restaurant soda fountains and grocery store refrigeration systems, the direct and pressurized CO₂ approach eliminates numerous components, such as pumps and heat exchangers, significantly reducing the size and complexity of the cooling system. CO₂ can carry 10x the heat compared to water in half the size and is 30x denser than HFOs, allowing smaller return lines. As a result, the system is more compact, uses significantly less coolant, and costs substantially less than systems using HFOs. Our CO₂ system also provides numerous additional advantages, including enhanced reliability, simplified maintenance, and greater scalability. We can support all proposed coolant temps in all climates. Our tech offers the lowest PUE at the best price and highest reliability (5-9s+). Please follow us @Icebox_Energy if you're interested in keeping up to speed with what we are up to.