[ { "id": 730, "name": "Helion Energy", "slug": "helion-energy", "former_names": [ "Helion" ], "small_logo_thumb_url": "https://bookface-images.s3.amazonaws.com/small_logos/b5119e7d1a685052ca06d144fde031fb2c13baf4.png", "website": "http://helionenergy.com", "all_locations": "Seattle, WA, USA; Everett, WA, USA", "long_description": "Helion is creating the world’s first fusion power plant, enabling a future with unlimited zero-carbon electricity. ", "one_liner": "Building the world's first fusion power plant", "team_size": 150, "industry": "Industrials", "subindustry": "Industrials -> Energy", "launched_at": 1400927949, "tags": [ "Fusion Energy", "Hard Tech", "Climate", "Energy" ], "tags_highlighted": [], "top_company": false, "isHiring": false, "nonprofit": false, "batch": "Summer 2014", "status": "Active", "industries": [ "Industrials", "Energy" ], "regions": [ "United States of America", "America / Canada" ], "stage": "Growth", "app_video_public": false, "demo_day_video_public": false, "app_answers": null, "question_answers": null, "url": "https://www.ycombinator.com/companies/helion-energy", "api": "https://devasheeshg.github.io/yc-api/batches/summer-2014/helion-energy.json", "year_founded": 2013, "city": "Seattle", "country": "US", "linkedin_url": "https://www.linkedin.com/company/helion-energy/", "x_url": "https://twitter.com/helion_energy", "fb_url": "https://www.facebook.com/helionenergy/", "cb_url": "https://www.crunchbase.com/organization/helion-energy", "github_url": null, "logo_url": "https://bookface-images.s3.amazonaws.com/small_logos/b5119e7d1a685052ca06d144fde031fb2c13baf4.png", "app_video_url": null, "dday_video_url": null, "company_photos": [], "primary_partner": { "name": "Garry Tan", "url": "https://www.ycombinator.com/people/garry-tan" }, "founders": [ { "user_id": 67382, "full_name": "David Kirtley", "title": "Founder/CEO", "founder_bio": "", "is_active": true, "linkedin_url": "https://www.linkedin.com/in/david-kirtley-490b8230/", "x_url": "https://twitter.com/dekirtley", "avatar_thumb_url": "https://bookface-images.s3.us-west-2.amazonaws.com/avatars/8c9187f74176ca43139b443259bb0109dfb49407.jpg" }, { "user_id": 3056, "full_name": "Chris Pihl", "title": "Founder/CTO", "founder_bio": null, "is_active": true, "linkedin_url": "https://www.linkedin.com/in/chris-pihl-4a84b1a/", "x_url": null, "avatar_thumb_url": "https://bookface-images.s3.us-west-2.amazonaws.com/avatars/992f1901f2931a53242ae96e2364a9275135655f.jpg" } ], "jobs": [], "news": [ { "title": "Helion, the Sam Altman-backed fusion startup, raises $465M to build a power plant for Microsoft | TechCrunch", "url": "https://techcrunch.com/2026/06/04/helion-the-sam-altman-backed-fusion-startup-raises-465m-to-build-a-power-plant-for-microsoft/?utm_source=dlvr.it&utm_medium=twitter", "date": "Jun 04, 2026" }, { "title": "Helion raises $425M to help build a fusion reactor for Microsoft | TechCrunch", "url": "https://techcrunch.com/2025/01/28/helion-raises-425m-to-help-build-a-fusion-reactor-for-microsoft/", "date": "Jan 28, 2025" }, { "title": "This startup says its first fusion plant is five years away", "url": "https://www.technologyreview.com/2023/05/10/1072812/this-startup-says-its-first-fusion-plant-is-five-years-away-experts-doubt-it/", "date": "May 10, 2023" }, { "title": "Helion secures $2.2B to commercialize fusion energy – TechCrunch", "url": "https://techcrunch.com/2021/11/05/helion-series-e/", "date": "Nov 05, 2021" } ], "launches": [] }, { "id": 30224, "name": "Maritime Fusion", "slug": "maritime-fusion", "former_names": [], "small_logo_thumb_url": "https://bookface-images.s3.amazonaws.com/small_logos/2af0192d25e843e5333e635fa35115413fbca155.png", "website": "https://maritimefusion.com", "all_locations": "San Francisco, CA, USA", "long_description": "Maritime Fusion is building fusion reactors for ships and off grid energy markets. En route on this endeavor we’re commercializing High Temperature Superconducting (HTS) cable technology for power distribution while advancing the physics basis of our HTS tokamak to decarbonize global shipping. \r\n\r\nBreakeven fusion is coming soon, but the first-of-a-kind (FOAK) reactors will be costly, high maintenance, and have low capacity factors, leading to 5–10x higher electricity cost on the grid. Maritime Fusion is pursuing the most widely accepted approach to fusion, the tokamak, but specifically designed for the marine environment where the challenges that arise between breakeven and a commercially viable energy source are alleviated. The market we're targeting requires 15x less power, lower up-time, and costs the same as alternative fuels but without any emissions. Since fusion does not use highly radioactive fuels or materials – unlike fission – we sidestep the vast majority of regulatory challenges and safety risks associated with nuclear energy. Our team brings over a decade of industry and research experience in plasma physics, nuclear engineering, and electrical engineering with backgrounds at SpaceX, Tesla, Columbia University, and University of Pennsylvania.", "one_liner": "Fusion reactors for ships", "team_size": 6, "industry": "Industrials", "subindustry": "Industrials -> Energy", "launched_at": 1739572830, "tags": [ "Fusion Energy", "Hard Tech", "Energy" ], "tags_highlighted": [], "top_company": false, "isHiring": true, "nonprofit": false, "batch": "Winter 2025", "status": "Active", "industries": [ "Industrials", "Energy" ], "regions": [ "United States of America", "America / Canada" ], "stage": "Early", "app_video_public": false, "demo_day_video_public": false, "app_answers": null, "question_answers": null, "url": "https://www.ycombinator.com/companies/maritime-fusion", "api": "https://devasheeshg.github.io/yc-api/batches/winter-2025/maritime-fusion.json", "year_founded": 2024, "city": "San Francisco", "country": "US", "linkedin_url": "https://www.linkedin.com/company/maritime-fusion", "x_url": "https://x.com/maritimefusion", "fb_url": null, "cb_url": null, "github_url": null, "logo_url": "https://bookface-images.s3.amazonaws.com/small_logos/2af0192d25e843e5333e635fa35115413fbca155.png", "app_video_url": null, "dday_video_url": null, "company_photos": [], "primary_partner": { "name": "Aaron Epstein", "url": "https://www.ycombinator.com/people/aaron-epstein" }, "founders": [ { "user_id": 2336806, "full_name": "Justin Cohen", "title": "Founder/CEO", "founder_bio": "Nuclear engineer and plasma physicist working on fusion reactors for defense and commercial shipping applications. Previously Tesla, SpaceX, Columbia University, Princeton Plasma Physics Laboratory, NC State.", "is_active": true, "linkedin_url": "https://www.linkedin.com/in/justin-cohen707", "x_url": "", "avatar_thumb_url": "https://bookface-images.s3.us-west-2.amazonaws.com/avatars/c63b262e560db673d53a59a25f5d906a3b7acaef.jpg" }, { "user_id": 2364454, "full_name": "Jason Kaufmann", "title": "Founder/CTO", "founder_bio": "I'm a hardware engineer with a passion for building cool electronics and systems. With a background in physics and computer engineering from Penn, I've worked on everything from AI hardware at Tesla to power systems for rockets at SpaceX. Currently focused on making a fusion reactor for ships.", "is_active": true, "linkedin_url": "https://www.linkedin.com/in/jasonskaufmann/", "x_url": "", "avatar_thumb_url": "https://bookface-images.s3.us-west-2.amazonaws.com/avatars/de5bd445a30e5ded336464f26afb4873ba9b1435.jpg" } ], "jobs": [ { "id": 75503, "title": " Member of Technical Staff - R&D Engineering", "url": "https://www.ycombinator.com/companies/maritime-fusion/jobs/jF7a5Wc-member-of-technical-staff-r-d-engineering", "location": "San Francisco, CA, US", "type": "Full-time", "role": "Engineering", "role_type": "Hardware", "salary_range": "$120K - $200K", "equity_range": "0.10% - 1.00%", "experience": "Any (new grads ok)", "visa": "Will sponsor", "skills": [] }, { "id": 75505, "title": "Member of Technical Staff - Plasma Physics", "url": "https://www.ycombinator.com/companies/maritime-fusion/jobs/sX8ipt6-member-of-technical-staff-plasma-physics", "location": "San Francisco, CA, US", "type": "Full-time", "role": "Science", "role_type": "Laboratory", "salary_range": "$120K - $200K", "equity_range": "0.10% - 1.00%", "experience": "Any (new grads ok)", "visa": "Will sponsor", "skills": [] }, { "id": 85661, "title": "R&D Technician", "url": "https://www.ycombinator.com/companies/maritime-fusion/jobs/vbJGLSZ-r-d-technician", "location": "San Francisco, CA, US", "type": "Full-time", "role": "Engineering", "role_type": "Hardware", "salary_range": "$100K - $160K", "equity_range": "0.10% - 0.25%", "experience": "Any (new grads ok)", "visa": "US citizen/visa only", "skills": [] }, { "id": 85662, "title": "Business Development & Strategic Partnerships Lead", "url": "https://www.ycombinator.com/companies/maritime-fusion/jobs/fpZ2pbI-business-development-strategic-partnerships-lead", "location": "San Francisco, CA, US", "type": "Full-time", "role": "Operations", "role_type": null, "salary_range": "$120K - $200K", "equity_range": "0.10% - 0.50%", "experience": "Any (new grads ok)", "visa": "US citizen/visa only", "skills": [] } ], "news": [ { "title": "This startup wants to build a fusion reactor — on a boat | TechCrunch", "url": "https://techcrunch.com/2025/11/24/this-startup-wants-to-build-a-fusion-reactor-on-a-boat/", "date": "Nov 24, 2025" } ], "launches": [ { "id": 87909, "title": "Maritime Fusion - Fusion reactors for ships", "tagline": "The application where first generation fusion reactors can thrive", "body": "[We are building the first fusion reactors for marine applications](https://www.youtube.com/watch?v=5ThTnDoKzLU)\n\n**The Problem**\\\nBreakeven fusion is on the horizon, but first-of-a-kind (FOAK) reactors will be expensive, high-maintenance, and have low capacity factors, leading to 5–10x higher electricity cost on the grid. Additionally, these reactors face significant physics challenges for steady-state operation, such as managing first wall heat flux and mitigating nuclear activation of structural components that require novel materials to solve.\n\n**The Solution**\\\nWe are leveraging the most proven approach to fusion energy, the HTS tokamak, but designed specifically for maritime applications. This reactor bridges the gap between achieving breakeven fusion and commercial viability. Our target market, commercial shipping vessels, require 15x less power and lower uptime compared to traditional grid reactors all while matching the cost of alternative bunker fuels—without any emissions. Operating at reduced power densities also alleviates many of the materials hurdles, paving the way for a more robust and reliable technology in the near term. We’re also leveraging the same reactor to meet the Department of Defense’s need for mobile power plants via Ship-to-Shore power.\n\n![uploaded image](/media/?type=post&id=87909&key=user_uploads/2336806/28482a6e-e905-4e36-9aad-41bd64336dff)\n\n**Who We Are**\\\nOur team brings over a decade of industry and research experience in plasma physics, nuclear engineering, and electrical engineering with backgrounds at SpaceX, Tesla, Columbia University, and University of Pennsylvania. We first met at SpaceX while conducting radiation tests for Starship electronics, and later worked together at Tesla on Cybertruck and Optimus.\n\n![uploaded image](/media/?type=post&id=87909&key=user_uploads/2336806/3b3e4061-2aff-4cb0-a183-5755dc8fae50)\n\n**How the YC Community Can Help**\\\nWe’re in process of making inroads to the Department of Defense, Navy, DARPA, and Department of Energy, as well as connections to the commercial shipping industry, if you know anyone we should speak with please reach out!\\\n[maritimefusion.com](http://maritimefusion.com)\\\n[founders@maritimefusion.com](mailto:founders@maritimefusion.com)", "url": "https://www.ycombinator.com/launches/Mrt-maritime-fusion-fusion-reactors-for-ships", "votes": 28, "created_at": "2025-02-21T20:38:05.707Z" } ] }, { "id": 31021, "name": "Zephyr Fusion", "slug": "zephyr-fusion", "former_names": [], "small_logo_thumb_url": "https://bookface-images.s3.amazonaws.com/small_logos/c896e2a98ef03115005ed5ae8acd4500d7eea752.png", "website": "https://www.zephyrfusion.com", "all_locations": "San Diego, CA, USA", "long_description": "Zephyr Fusion is building the first in-orbit fusion power source: a megawatt-class reactor enabling large-scale industry in space, at a fraction of the cost of equivalent solar.\r\n\r\nFounded by former physicists from Lawrence Livermore and Oak Ridge National Laboratories, Zephyr leverages decades of fusion research to deliver a compact magnetic confinement system designed to take advantage of the space environment.", "one_liner": "Powering tomorrow's industrial revolution in space", "team_size": 2, "industry": "Industrials", "subindustry": "Industrials -> Energy", "launched_at": 1762532179, "tags": [ "Fusion Energy", "Hard Tech", "Satellites", "Aerospace" ], "tags_highlighted": [], "top_company": false, "isHiring": false, "nonprofit": false, "batch": "Fall 2025", "status": "Active", "industries": [ "Industrials", "Energy" ], "regions": [ "United States of America", "America / Canada" ], "stage": "Early", "app_video_public": false, "demo_day_video_public": false, "app_answers": null, "question_answers": null, "url": "https://www.ycombinator.com/companies/zephyr-fusion", "api": "https://devasheeshg.github.io/yc-api/batches/fall-2025/zephyr-fusion.json", "year_founded": 2025, "city": "San Diego", "country": "US", "linkedin_url": "https://www.linkedin.com/company/zephyr-fusion", "x_url": "https://x.com/Zephyr_Fusion", "fb_url": null, "cb_url": null, "github_url": null, "logo_url": "https://bookface-images.s3.amazonaws.com/small_logos/c896e2a98ef03115005ed5ae8acd4500d7eea752.png", "app_video_url": null, "dday_video_url": null, "company_photos": [], "primary_partner": { "name": "Garry Tan", "url": "https://www.ycombinator.com/people/garry-tan" }, "founders": [ { "user_id": 2842889, "full_name": "Edward Hinson", "title": "Founder", "founder_bio": "Cofounder of Zephyr Fusion, an in-orbit fusion power company. 20+ years in mathematical modeling and experimental plasma physics. Former scientist at Oak Ridge National Lab and UW-Madison. PhD in Nuclear Engineering and Engineering Physics.", "is_active": true, "linkedin_url": "https://www.linkedin.com/in/edward-hinson-078b15143/", "x_url": "", "avatar_thumb_url": "https://bookface-images.s3.us-west-2.amazonaws.com/avatars/7d140c01f06bf0f6bd2775b56bbb6dd17665d759.jpg" }, { "user_id": 2938721, "full_name": "Galen Burke", "title": "Founder", "founder_bio": "Co-founder of Zephyr fusion, an in-orbit fusion power company. 15+ years in cutting edge diagnostics and plasma physics. Former scientist at Lawrence Livermore National Laboratory and the University of Wisconsin-Madison. PhD in Nuclear Engineering and Engineering Physics.", "is_active": true, "linkedin_url": "https://www.linkedin.com/in/galen-burke-78923317/", "x_url": "", "avatar_thumb_url": "https://bookface-images.s3.us-west-2.amazonaws.com/avatars/98c843bf90dac8ffc44e771edb2b7073905edb05.jpg" } ], "jobs": [], "news": [], "launches": [ { "id": 95415, "title": "Zephyr Fusion: In-orbit fusion power", "tagline": "Powering tomorrow's industrial revolution in space", "body": "**TL;DR: Most satellites are limited to kilowatt-scale solar power, constraining high-power applications in orbit. The unlimited vacuum in space allows a dipole magnetic confinement device to form the large plasma confinement regions fusion requires without bulky reactor hardware. With HTS magnets and declining launch costs, compact megawatt-class fusion in orbit is now within reach, unlocking an industrial space economy.**\n\n![uploaded image](/media/?type=post&id=95415&key=user_uploads/2938721/f0f7e94a-1ebe-4b6d-8d0e-b4fa8aad7051)\n\n**Who We Are**\n\nHi everyone! We’re Dr. Galen Burke and Dr. Edward Hinson, founders of Zephyr Fusion. After years working on some of the hardest problems in fusion energy at Oak Ridge and Lawrence Livermore National Labs, we realized something fundamental: fusion actually gets easier in space.\n\nWe’ve been friends and collaborators since 2010 in grad school at the University of Wisconsin-Madison, where we operated a spherical tokamak. We subsequently continued research at premier fusion research facilities, like the W7-X stellarator in Greifswald and the premier US tokamak, the DIII-D National Fusion Facility in San Diego, as employees of US DOE National Labs. Between us, we’ve accumulated 35+ years of experimental fusion research experience, publishing in _Physical Review Letters_, _Nuclear Fusion_, and _Physics of Plasmas_, and others.\n\n**Launching Zephyr Fusion**\n\n“Fusion in space” sounds ambitious - and it is - but it is grounded in well-established physics and enabled by new economics. Zephyr Fusion exists because the physics and economics now align: high-temperature superconductors and drastically reduced launch costs make it possible to build compact, megawatt-class orbital fusion power. We’re here to bring real power to the space economy.\n\nOur goal is simple: Provide megawatt-class power in orbit.\n\nThe space economy is fundamentally power-limited. Most satellites operate on the power equivalent of a toaster or two. While the Sun provides about 1 kW/m², scaling solar beyond \\~10 kW rapidly becomes mass- and cost-prohibitive. For example, the ISS’s new 120 kW roll-out arrays cost roughly $100M, or about $1B/MW installed. Advancing beyond this power limit would catalyze a new economy: large-scale industrial activity, data centers, high-power electrical propulsion, large human habitats, and more.\n\n**Why Space Makes Fusion Easier**\n\nThe performance of magnetic fusion devices scales with the size of the plasma, specifically the magnetized vacuum volume they occupy. Magnetized vacuum is in fact the most essential resource for fusion plasmas. The performance improvement is quantified with “energy confinement time,” τₑ, roughly how long energy stays in the plasma. For tokamaks, global experiments have shown roughly:\n\nτₑ \\~ R²\n\nwhere R is the device radius. Fusion gets easier when the plasma is big.\n\nOn Earth, increasing plasma size forces the entire reactor to scale up with it, driving cost - which is why ITER - the world’s largest tokamak - has a \\~6m plasma radius and a \\~$65B price tag ([DOE 2018](https://www.govinfo.gov/content/pkg/CHRG-115shrg19104909/pdf/CHRG-115shrg19104909.pdf)). It is a research project, but ball-parking ITER as a 100MWe reactor, the expense amounts to $0.65B/MW - notably still less than what is being paid now for large-scale space solar, but a long way from commercial viability in the competitive commodity market back on Earth. The physics imperative for larger plasmas leads to devices that are larger still.\n\nBut in space, the link between hardware size and plasma size can be broken.\n\nA dipole magnetic field (which may be familiar from planetary magnetospheres), allows the plasma to form a large, self-organized region enclosing a single coil, extending into the external vacuum. In space, the outer boundary is not a physical wall but free vacuum. This “inside-out” configuration removes the dominant energy loss channel in terrestrial devices and allows for very large effective magnetized vacuum volumes with minimized hardware footprint. Furthermore, scalings obtained from the physics of magnetospheric dipoles appear to hold in dipole reactors as well ([LDX Nature Physics 2010](https://www.nature.com/articles/nphys1510)), implying that fusion power in a dipole reactor grows extremely strongly with radius.\n\nIn other words:\n\nA meter-scale dipole coil in orbit, that can be built today, can produce a magnetized volume exceeding that of ITER, at a tiny fraction of the mass and cost, and ITER-scale confinement may be accessible with hardware that fits on a SpaceX Falcon 9 launch vehicle.\n\n![uploaded image](/media/?type=post&id=95415&key=user_uploads/2938721/b30c091c-ecb7-4b4d-9998-f738a5d5352c)\n\nDipole fusion reactors in space have been proposed before, notably by [Edward Teller](https://www.tandfonline.com/doi/abs/10.13182/FST92-A30057), but have only become practical now because:\n\n• Launch costs have dropped by \\~10x in the last decade.\n\n• Mass-produced, HTS tapes provide - 10x more field per kg in the last decade\n\nThe _two price shocks multiply_: cost of field-per-kilogram and cost of kilograms-to-orbit are both independently collapsing. In orbit this results in an ongoing “price shock squared” in just the resource we need for fusion: magnetized vacuum.\n\n**Why This Matters**\n\nPower is the final barrier to a real space economy:\n\n• Large computing and data centers in orbit\n\n• Industrial manufacturing and materials processing in microgravity\n\n• High-power electric propulsion stages\n\n• Defense platforms\n\n• Human habitats and long-duration exploration\n\nAll of these require MW-class power.\n\nHumanity's ability to harness concentrated energy has been the driving force behind Earth's industrial revolutions.\n\nWhen hydrocarbons arrived, heavy industry followed.\n\nWhen cheap, compact fusion arrives in orbit, the same thing will happen - off-planet.\n\nAnd the early movers shape the infrastructure layer.\n\nWe founded Zephyr Fusion because we believe the space economy is transitioning from exploration to industry, and industry requires power at scale.\n\nLet’s build it.\n\n**Ask**\n\n**Feedback -** We’d love to discuss the physics and roadmap - reach out anytime.\n\n**Introductions -** If you know satellite, defense, or other teams that have an interest in MW-class power, we’d appreciate intros. Let us know at [founders@zephyrfusion.com](mailto:founders@zephyrfusion.com).\n\nThanks!\n\n\\- The Zephyr Fusion Team\n\n![uploaded image](/media/?type=post&id=95415&key=user_uploads/2938721/ce082155-315b-44b0-af6a-017346eb99db)\n\n", "url": "https://www.ycombinator.com/launches/Oox-zephyr-fusion-in-orbit-fusion-power", "votes": 59, "created_at": "2025-11-12T06:56:27.373Z" } ] } ]