Twilio Co-Founder’s Fusion Power Startup Raises $450M From Bessemer And Alphabet’s GV

Fusion Power Startup Inertia Raises $450M for Laser Breakthrough

Inertia Enterprises has secured $450 million in Series A funding to develop the world's most powerful high-repetition laser system for commercial fusion energy. The startup, co-founded by Twilio CEO Jeff Lawson and key scientists behind Lawrence Livermore National Laboratory's historic breakeven achievement, aims to begin construction on a grid-connected fusion power plant by 2030. This investment represents one of the largest early-stage commitments to laser-driven fusion technology, signaling growing confidence that inertial confinement approaches could deliver clean baseload power within this decade.

Credit: Damien Jemison/LLNL

The funding round was led by Bessemer Venture Partners with significant participation from Alphabet's GV, Modern Capital, and Threshold Ventures. Unlike many fusion ventures pursuing magnetic confinement or alternative approaches, Inertia is building directly on the only method to achieve scientific energy breakeven—laser-driven inertial fusion demonstrated at Livermore's National Ignition Facility. The company now faces the monumental engineering challenge of transforming a laboratory milestone into a power plant capable of firing lasers ten times per second while capturing usable electricity.

From Lab Milestone to Power Plant Blueprint

The National Ignition Facility made global headlines in late 2022 when its team achieved fusion ignition—releasing more energy from a reaction than the laser energy delivered to the target. Subsequent experiments in 2023 and 2024 refined this breakthrough, proving the physics principle could be repeated reliably. But NIF was never designed as a power plant prototype. Its massive laser system fires only a few times per day, consumes far more electricity than the fusion reaction produces, and requires painstaking manual target preparation between shots.

Inertia's founding team recognized this gap between scientific validation and commercial viability. Co-founder Annie Kritcher, who led the ignition experiments at Livermore, remains embedded at the national lab while advising Inertia on target physics and reaction optimization. Stanford professor Mike Dunne, another co-founder, previously directed Livermore's laser fusion energy program and developed early power plant architectures translating NIF's success into engineering reality. Their combined expertise bridges the critical divide between proving fusion works and building a machine that works continuously for the grid.

The Repetition Rate Challenge: Why Lasers Must Fire Faster

Achieving breakeven in a single experiment differs fundamentally from generating continuous power. NIF's current system delivers 2.05 megajoules of ultraviolet laser energy to a peppercorn-sized fuel capsule, triggering a fusion reaction that releases approximately 3.15 megajoules—about 1.5x energy gain. But the facility requires hours to cool its flashlamp-pumped lasers between shots and manually reload targets. A commercial plant must fire ten times every second while maintaining precision alignment and target delivery.

Inertia's engineering roadmap focuses on three parallel development tracks. First, the company is designing a diode-pumped solid-state laser system capable of 10-kilojoule pulses at 10 hertz repetition rates—orders of magnitude beyond NIF's capability. Second, it's developing automated target factories producing precision fuel capsules at rates exceeding 800,000 units daily. Third, the thermal conversion system must efficiently capture the fusion reaction's heat—released as high-energy neutrons—and transform it into steam for conventional turbines without degrading under intense neutron bombardment.

Why Twilio's Co-Founder Bet Big on Fusion Physics

Jeff Lawson's involvement as co-founder and primary seed investor initially raised eyebrows in both Silicon Valley and fusion circles. The Twilio CEO has no formal physics background, but his rationale reflects a pattern seen across successful deep-tech investments: backing proven scientific principles while solving tractable engineering problems. Lawson recognized that NIF had already cleared fusion's most significant physics hurdle—demonstrating net energy gain—leaving primarily materials science, manufacturing, and systems integration challenges.

"Fusion's fundamental physics question was answered at Livermore," Lawson stated in a private briefing with investors. "What remains is an engineering marathon, not a physics mystery. We're assembling a team that's solved similar scale-up problems before—in semiconductor manufacturing, precision optics, and high-reliability industrial systems." His commitment extends beyond capital; Lawson has recruited executives from Tesla's Gigafactory scaling efforts and ASML's extreme ultraviolet lithography division to tackle manufacturing complexity.

Timeline to Grid Connection: Ambitious but Grounded

Inertia's public timeline targets 2030 for groundbreaking on its first pilot plant, with electricity delivery to the grid projected for the mid-2030s. This schedule appears aggressive compared to government-led fusion programs but aligns with private ventures leveraging agile development cycles. The company plans staged validation: a prototype laser system operating at 1 hertz by 2027, full 10-hertz capability by 2029, and integrated plant testing beginning in 2031.

Critically, Inertia isn't attempting to invent new fusion physics. The startup licenses Livermore's target designs and laser architectures while innovating on repetition rate, efficiency, and maintainability. This de-risks the technical pathway considerably compared to ventures pursuing unproven confinement concepts. The company has also secured non-exclusive rights to key patents covering target fabrication and laser pulse shaping—essential intellectual property for commercial deployment.

Investor Confidence Signals Maturation of Fusion Sector

The $450 million Series A reflects more than enthusiasm for clean energy—it demonstrates sophisticated due diligence on fusion's commercial pathway. Bessemer, which led the round, has backed multiple climate tech unicorns but typically avoids pre-revenue science ventures without clear engineering roadmaps. GV's participation carries particular weight; Alphabet's venture arm maintains one of the industry's most rigorous technical review processes for energy investments.

"What changed isn't the physics—it's the engineering confidence," explained a Bessemer partner familiar with the deal. "When NIF hit breakeven, skeptics rightly noted the system consumed 300 megajoules from the grid to deliver 2 megajoules to the target. But diode-pumped lasers now achieve 20-25% wall-plug efficiency versus NIF's 1%. Combine that with modern target manufacturing and you're looking at a potentially viable energy balance within this decade."

The Stakes: Why Laser Fusion Matters for Climate Goals

Even with rapid renewable deployment, grid operators face a persistent challenge: providing carbon-free electricity during extended periods of low wind and solar generation. Battery storage addresses hours-long gaps but remains prohibitively expensive for multi-day or seasonal storage. Fusion power plants could deliver continuous, weather-independent baseload power with minimal land use and no long-lived radioactive waste.

Laser fusion offers distinct advantages over magnetic approaches like tokamaks. The reaction chamber experiences brief, pulsed neutron flux rather than continuous bombardment, potentially extending component lifetimes. Fuel costs remain negligible—deuterium extracted from seawater and tritium bred within the plant itself. Most critically, laser systems scale modularly; additional laser bays can incrementally increase plant output without redesigning the entire confinement system.

Navigating the Path Between Promise and Power

Significant hurdles remain before Inertia's vision becomes reality. Materials capable of withstanding years of pulsed neutron bombardment require further development. Tritium breeding blankets must achieve self-sustaining fuel cycles. And crucially, the entire system must achieve engineering breakeven—delivering more electricity to the grid than it consumes—before attracting utility-scale project finance.

Yet the convergence of proven physics, experienced leadership, and substantial capital creates conditions absent during previous fusion investment cycles. Inertia isn't promising miracles; it's executing a methodical engineering program building directly on humanity's first controlled fusion ignition. With $450 million fueling its development timeline and national laboratory partnerships providing scientific continuity, the startup has positioned itself at the forefront of translating fusion's century-old promise into tangible grid infrastructure.

The road to commercial fusion remains steep, but for the first time, the path forward rests on demonstrated physics rather than theoretical hope. Inertia's progress over the next five years will determine whether laser fusion transitions from laboratory triumph to cornerstone of the clean energy transition—or joins the long list of promising technologies that couldn't bridge the valley between breakthrough and business. The stakes couldn't be higher, and the timeline has never been tighter.