Helion Energy closed a $425 million Series F round in January 2025, resulting in a post-money valuation of approximately $5.4 billion. The round included participation from existing investors such as Sam Altman, a long-time supporter of the company.

In November 2021, the company raised a $500 million Series E, which was among the largest private fusion investments at that time. Prior to that, Helion secured $40 million in a Series D round in September 2020, which valued the company at $1.25 billion.

Notable investors across these funding rounds include SoftBank Vision Fund 2, Lightspeed Venture Partners, Mithril Capital, Capricorn Investment Group, Dustin Moskovitz through Good Ventures, and strategic investor Nucor. Cumulatively, Helion has raised over $1 billion in funding.

Helion develops container-sized fusion generators that generate electricity directly from nuclear reactions without relying on steam turbines or cooling towers. The system operates by firing two plasma formations, known as Field-Reversed Configurations, from opposite ends of a 19-meter vacuum tube.

Capacitor banks power and accelerate these plasmas toward a central collision point within the machine. Upon collision, external coils compress the plasma to temperatures exceeding 100 million degrees, initiating deuterium fusion reactions.

The resulting hot, expanding plasma exerts pressure against the magnetic coils that initially compressed it. This interaction creates a changing magnetic field, which induces an electric current that flows back into the capacitor banks and out to the grid. The process is analogous to regenerative braking in electric vehicles but operates at significantly higher power levels.

The system employs a closed fuel cycle, beginning with deuterium extracted from water and subsequently utilizing helium-3 produced during the initial reactions as a higher-yield fuel. This design eliminates reliance on helium-3 sourced from lunar mining.

For customers such as Microsoft and Nucor, Helion's units function as 50-500 MW baseload power substations. These units integrate directly with existing transmission infrastructure and operate under state radiological materials licensing, similar to hospital particle accelerators, without requiring specialized nuclear operator training.

Helion develops fusion power plants and sells electricity through long-term power purchase agreements with large industrial customers and hyperscale technology companies. The business model focuses on direct electricity sales rather than equipment manufacturing or licensing.

The company targets B2B customers with substantial, consistent power requirements who prioritize carbon-free baseload generation. Microsoft represents the hyperscale computing segment, while Nucor addresses the energy-intensive manufacturing sector, including steel, aluminum, and chemicals.

Revenue is generated through fixed-price or indexed power sales under 15-25 year contracts. These agreements provide predictable cash flows once plants are operational, resembling renewable energy project finance models but with higher capacity factors compared to wind or solar.

Helion's direct-to-electricity approach removes the need for steam turbines and associated balance-of-plant costs, potentially reducing capital expenditure per megawatt relative to traditional nuclear or fossil fuel plants. The pulsed fusion design also allows for rapid ramping to accommodate demand fluctuations.

The company retains ownership and operation of its fusion plants rather than selling equipment to utilities. This vertically integrated model captures the full value of electricity generation but requires significant upfront capital investment for each facility.

Commonwealth Fusion Systems focuses on high-temperature superconducting tokamaks, with $3 billion in total funding, including a $900 million Series E in August 2025. The company operates its own magnet manufacturing facility and targets SPARC demonstration by 2027, followed by commercial ARC plants in the early 2030s.

CFS has signed a power purchase agreement with Google for 200 MW, directly competing for hyperscale customers. While the company leverages established tokamak physics and collaborations with national laboratories, its steam-cycle approach requires more complex balance-of-plant infrastructure compared to Helion's direct electricity generation method.

Tokamak Energy is developing spherical tokamaks with high-temperature superconductors, aiming for 200 MW pilot plants by the early 2030s. This design could enable smaller reactor vessels but shares the steam turbine complexity seen in CFS's approach.

TAE Technologies is advancing field-reversed configuration reactors, which share similarities with Helion's design but differ in fuel cycles and magnetic field geometries. The company has secured significant funding and constructed multiple prototype machines, though its timeline for achieving commercial power generation remains undefined.

General Fusion is working on magnetized target fusion, using pistons to compress plasma as a pathway to pulsed fusion power. The company collaborates with the UK Atomic Energy Authority and benefits from government support, offering an alternative to Helion's approach.

Zap Energy is developing sheared-flow Z-pinch technology, which eliminates the need for external magnetic coils and could lower capital costs. Initially targeting smaller-scale applications, this approach may eventually scale to compete with Helion's industrial customer base.

Marvel Fusion, First Light Fusion, and Focused Energy are pursuing laser- or projectile-driven inertial confinement fusion. These methods face technical challenges related to target manufacturing and repetition rates but represent alternative routes to commercial fusion power.

The inertial fusion sector has seen progress through recent net energy gain demonstrations at national laboratories. However, transitioning from laboratory experiments to commercial power plants will require addressing engineering issues such as target injection, debris management, and high-frequency operation.

Helion's transition from 50 MW Microsoft units to 500 MW Nucor plants outlines a pathway to utility-scale fusion power. Industrial customers, including steel manufacturers, aluminum smelters, and chemical plants, require hundreds of megawatts of baseload power and face mounting regulatory and market pressures to decarbonize operations.

The global industrial electricity market accounts for trillions of dollars in annual spending. Heavy industries frequently locate near low-cost power sources, presenting opportunities for co-located fusion plants that can supply both electricity and high-temperature process heat.

Modular fusion plants could facilitate distributed industrial power generation, lowering transmission costs and enhancing grid resilience. This model is particularly advantageous for energy-intensive manufacturing sectors that depend on uninterrupted 24/7 baseload power.

Electricity demand from data centers is expected to double to 945 TWh by 2030, largely driven by artificial intelligence workloads. Hyperscale operators such as Microsoft, Google, Amazon, and Meta face growing requirements to achieve carbon neutrality while ensuring reliable power for expanding facilities.

Helion's containerized fusion units could integrate with data center infrastructure, potentially delivering DC power output that avoids transformer losses. Co-location with data centers reduces transmission costs and provides dedicated power sources for critical computing operations.

The rapid growth of AI workloads underscores the need for clean baseload power that solar and wind cannot fully supply. Fusion power combines carbon-free generation with 24/7 availability, meeting the operational demands of hyperscale operators' most energy-intensive workloads.

Direct-electric fusion, combined with high-temperature electrolysis, enables industrial-scale green hydrogen production. The integration of carbon-free electricity and process heat could support ammonia synthesis, synthetic fuel production, and other chemical processes requiring both power and thermal energy.

Government incentives for clean hydrogen and synthetic fuels create additional revenue streams beyond electricity sales. Fusion plants could operate in dual modes, supplying grid electricity during peak demand and producing hydrogen during off-peak periods.

The maritime shipping and aviation industries require carbon-neutral fuels that cannot be directly electrified. Fusion-powered synthetic fuel production could address these hard-to-decarbonize sectors while generating higher-value revenue streams compared to commodity electricity sales.

Technical execution: Helion must achieve sustained net energy gain and reliable electricity generation from its pulsed fusion approach, which has not yet been validated at commercial scale. Meeting the 2028 timeline for the Microsoft plant depends on the successful operation of the Polaris prototype and the ability to scale to commercial-grade systems without significant technical delays.

Capital intensity: Developing each fusion plant requires upfront investments in the hundreds of millions of dollars before revenue generation begins, posing financing risks if construction costs exceed estimates or schedules are delayed. The company needs to secure project financing for multiple plants while continuing to fund R&D and operational expenses at the corporate level.

Regulatory uncertainty: Although fusion benefits from a more streamlined licensing process compared to fission reactors, the regulatory framework for commercial fusion plants remains largely untested. Permitting delays or unforeseen safety requirements could significantly increase development costs and postpone revenue generation.