Inertia Enterprises has raised $450 million to build one of the world’s most powerful lasers, which it hopes will serve as the foundation for a grid-scale power plant that the fusion startup wants to start building in 2030. Inertia Enterprises builds on technology developed at Lawrence Livermore National Laboratory’s National Ignition Facility (NIF). NIF is the site of the only controlled fusion reactions in the world which reached the scientific breakevenwhere the reaction releases more energy than was required to start.

The Series A was led by Bessemer Venture Partners with participation from GV, Modern Capital, Threshold Ventures, and others. Inertia’s co-founders include Jeff Lawson, who founded Twilio and serves as its CEO; Annie Kritcher, who led successful NIF experiments; and Mike Dunne, a Stanford professor who helped Lawrence Livermore develop a power plant design based on NIF. Kritcher remains in his position at Lawrence Livermore.

NIF’s breakeven experiments are an important milestone on the road to widespread fusion power. However, there needs to be a lot of progress before a fusion power plant can deliver electricity to the grid. For Inertia, that means building a laser that can deliver 10 kilojoules 10 times per second.

The reactor initially relied on a form of fusion known as inertial confinement. In Inertia’s flavor of inertial confinement, lasers bombard a target with fuel, forcing the fuel until the atoms inside fuse and release energy. The technique is based on NIF designs, where laser light is converted into X-rays inside the target. X-rays are what heat and compress the fuel pellet.

Each of Inertia’s power plants will require 1,000 of its lasers bombarding 4.5 mm targets costing less than $1 each to be mass produced. In contrast, the NIF system uses 192 lasers to fire meticulously crafted targets that take many hours to make. Inertia is betting that by using the same basic principles as NIF and applying a more commercial mindset, it can reduce costs.

Inertia’s new round is the latest in a string of funding announcements from fusion startups in recent months. With this round and others, fusion startups have attracted more than $10 billion in investment. And at least a dozen companies have raised over $100 million.

Last week, the Avalanche said it had raised $29 million to advance its desktop-sized fusion reactor. Earlier this year, Type One Energy told TechCrunch that it had attracted $87 million in investment ahead of the $250 million Series B it has so far raised. Last summer, Commonwealth Fusion Systems raised $863 million from multiple investorsincluding Google, Nvidia, and Breakthrough Energy Ventures.

Two fusion companies recently announced that they are going public through reverse mergers. General Fusion said in January that it could merged with the company that acquired Spring Valley III in a deal that values ​​the combined company at $1 billion. General Fusion used to be struggling to raise money from private investors. Earlier last month, TAE Technologies announced that it merged with Donald Trump’s social media companyTrump Media & Technology Group; the combined company will be worth $6 billion, according to the all-stock transaction.