It's Wednesday. The Fourth of July fireworks are done, but the most consequential spark of the long weekend went off quietly in the Idaho desert, where a reactor designed to feed AI data centers reached criticality.
In today's edition:
⚛️ Big Story: A data-center microreactor hits criticality on the Fourth
⚡ Quick Hits: Space compute, Kiwi hydro, a coal plant's second life, and the $329 number
💰 Capital Stack: Anthropic's $19B lease and Europe's biggest-ever fusion check
🏛️ Policy Watch: New Jersey, Maryland, and the new fight over your bill
📊 Chart of the Day: How much of the world's data-center power runs on US soil
The Big Story
Aalo Atomics microreactor reaches criticality in Idaho
Aalo Atomics said its Aalo-X Critical Test Reactor achieved criticality in the early hours of July 4 at Idaho National Laboratory, hitting the deadline set under the Department of Energy's Reactor Pilot Program. Criticality, the point at which a reactor sustains its own chain reaction, is the clearest technical proof yet that the company's data-center power model can leave the drawing board. Aalo broke ground on the test unit last September, roughly ten months ago, and became the fourth pilot-program company to reach the milestone, after Antares, Valar, and Deployable Energy.
"Reaching criticality is our most significant milestone to date, as it paves the way for the deployment of the Aalo Pod to power commercial data centers once it receives authorization from the Nuclear Regulatory Commission. The Aalo-X Critical Test Reactor has the same full-scale core components as our commercial reactors."
The Aalo-X carries the same full-scale core components as the planned commercial reactor, so the test doubles as a validation run for the production design.
The flagship Aalo Pod is a 50 MW unit built from five 10 MWe reactors driving a single turbine; it is sodium- and air-cooled and needs no external water source, easing siting near data centers.
Aalo plans to build a co-located data center next to the reactor to demonstrate proof of concept, and recently tied up with Microsoft and Nvidia on an automated co-piloting system for reactor safety.
The DOE pilot launched last year with 11 advanced-reactor firms; commercial deployment still hinges on NRC authorization.
Source: Data Center Dynamics
Quick Hits
Small bites from across the grid.
Orbital filed with regulators for a 100,000-satellite constellation to build up to 10 GW of orbital compute, pitching passive radiative cooling in space as a way to skip data-center cooling entirely. Data Center Dynamics
Meridian Energy won a three-year fast-track consent to tap up to 545 GWh of contingent hydro storage at New Zealand's Lake Pūkaki, a large lever for firming a hydro-heavy grid. Energy-Storage News
Arizona Public Service said it will convert two retired units at its shuttered Cholla coal plant to natural gas, citing surging demand and multi-year lead times on new generation. RTO Insider
PJM capacity prices have jumped 1,038% to $329.17/MW-day, and Reuters found one Ohio brickmaker whose monthly capacity charge climbed from about $1,600 to $12,000 as data-center demand reprices the market. Reuters
Researchers published a method to retrofit residential air-source heat pumps to run on DC, estimating 12.5% to 16.7% electricity savings by cutting conversion losses in solar-and-storage homes. pv magazine USA
The Capital Stack
Anthropic signs a $19B, 20-year lease for a TeraWulf AI campus
Anthropic agreed to a 20-year lease worth roughly $19 billion in contracted revenue for a purpose-built AI campus at TeraWulf's Justified Data site in Hawesville, Kentucky, a former aluminum smelter. The site will support about 401 MW of critical IT load, with initial capacity targeted for the second half of 2027 and full capacity by early 2028. Alongside the lease, TeraWulf sold a majority interest in its Abernathy joint venture to Fluidstack, sharpening its pivot from bitcoin mining to AI infrastructure landlord.
Source: TeraWulf
Also in the capital stack:
Proxima Fusion raised €411 million ($469M) at a €2.4 billion valuation in the largest private fusion round ever recorded in Europe, led by XTX Ventures and East X Ventures with strategic checks from Google, its first investment in a European fusion company, and RWE; the money funds Alpha, the startup's net-energy stellarator demonstrator near Munich. EU-Startups
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Policy Watch
New Jersey lawmakers sent a data-center tariff bill to the governor covering new and existing sites of 50 MW or more, aiming to keep AI-driven grid costs off other ratepayers' bills. Utility Dive
Maryland agencies asked FERC to end RTO-membership financial incentives now that a new state law makes PJM membership mandatory, a move that would trim transmission-owner returns and, they argue, ratepayer costs. RTO Insider
A new crop of energy groups is swapping climate messaging for market-economics arguments and taking the affordability fight to state legislatures, a shift that could reshape how DER and rate cases get sold. Latitude Media
Chart of the Day
America runs the world's data-center load.
In 2025, nearly 40% of all electricity used by data centers worldwide came from facilities on US soil, which drew about 313 terawatt-hours, more than Australia, Italy, Spain, or the UK each generated to power their entire economies. It is the first year the Energy Institute's Statistical Review of World Energy has broken out data-center demand, a marker of how central grid-power questions have become to AI.
Source: Canary Media, Energy Institute Statistical Review of World Energy
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