Lime: The Overlooked Decarbonization Lever in Data Center Construction
Lime is embedded in nearly every major material a data center is built from. Here's why that matters, and what to do about it.
We are living through the largest infrastructure build in modern history. The five major hyperscalers (Amazon, Microsoft, Google, Meta, and Oracle) are projected to spend $1.15 trillion on capital expenditure between 2025 and 2027, more than double the $477 billion spent across the prior three years (Goldman Sachs, 2025). Every major hyperscaler now individually exceeds $100 billion in annual capital spending. With AI infrastructure increasingly framed as a matter of national security on both sides of the Atlantic — and in China — this is not a spending cycle that is expected to slow.
The sustainability conversation has focused, understandably, on electricity. Renewable energy procurement, power purchase agreements, 24/7 carbon-free energy commitments… these have been the primary tools. But the AI buildout is outrunning clean power supply. Natural gas currently provides over 40% of US data center electricity, coal around 15%, with renewables at around 24% (IEA, 2025). The gap between stated commitments and actual grid reality is widening: Google's total emissions are up 51% since 2019, and Microsoft's have risen 23.4% from their 2020 baseline, despite both being among the world's largest corporate clean energy buyers. The build rate is simply outrunning grid decarbonization.
But there is a second, less-discussed problem compounding this: embodied carbon. The CO₂ locked into construction materials before a single server is switched on, before a renewable energy certificate is purchased, and before any offset can be applied.
Meta's 2025 Sustainability Report discloses that 63% of its total carbon footprint comes from capital goods, construction materials first among them (Meta Sustainability, 2025). Microsoft's Scope 3 emissions now comprise 97% of its total footprint and have risen 26% over five years (Microsoft Sustainability, 2025). Lifecycle assessments show that in a fully renewable energy scenario, embodied carbon can account for 50–80% of a data center's total lifecycle emissions (Opna, 2025)."
And at the heart of this embodied carbon challenge is a material almost nobody in the data center industry is talking about: lime.
Lime is everywhere in a data center. You just can't see it.
Lime — calcium oxide (CaO) in quicklime form, or calcium hydroxide Ca(OH)₂ as hydrated lime — isn't procured directly by data center developers. It sits several tiers deep in the supply chains of nearly every major construction material category. The carbon has already been emitted by the time lime reaches a site. That invisibility is exactly why it has been underestimated as a decarbonization lever.
Lime is, at its core, one of the most chemically reactive and versatile alkaline materials on earth. It neutralizes acids, binds impurities, stabilizes structures, and drives chemical reactions across an enormous range of industrial processes — which is why it shows up in everything from steelmaking to water treatment to battery production. That versatility isn't incidental: in most of these applications, lime works because of specific chemistry that other materials simply can't replicate at industrial scale. It isn't a commodity that can be swapped out for something greener. The problem is that producing it has always come with a large carbon cost baked into the chemistry itself.
Before construction begins: the ground itself
Data center campuses frequently sit on clay-rich soils that can't support a foundation as-is. The standard fix is soil stabilization: quicklime mixed directly into the soil, chemically modifying its structure to improve load-bearing capacity and cut moisture content, avoiding the need for large-scale excavation. Without it, large-scale site preparation on reactive soils isn’t viable. It's the first intervention that happens on site, before anything else is built.
Hydrated lime is also added to the asphalt roads and masonry mortar used across a data center campus to improve durability, moisture resistance, and bond strength in both applications.
The building structure: concrete and steel
Concrete is built on Portland cement clinker, which is produced by calcining (heating) limestone at high temperatures — the same chemistry that makes lime. This process happens inside cement producers' own kilns: they don't buy lime as an input, but the carbon embedded in concrete ultimately traces back to limestone calcination.
Structural steel follows a parallel path. Both blast furnace and electric arc furnace steelmaking require lime as a flux (around 40–80 kg per tonne of steel) to remove silica, phosphorus, and sulfur impurities from molten metal. A large hyperscale campus uses tens of thousands of tonnes of structural steel, and there is no industrial substitute for lime in this process at scale.
Inside the structure: metals and lithium
Aluminum, which is used throughout cooling systems, server chassis, and cable management, is refined from bauxite via the Bayer process. Lime is a continuous and essential input in this process, used to regenerate the caustic solution needed to dissolve aluminum from ore and remove silicate and organic impurities from the circuit. Without it, the refinery chemistry breaks down.
Copper, which runs through hundreds of kilometers of cabling in a hyperscale facility, requires lime during ore concentration to control the chemistry in the flotation tanks that separate metal from rock.
And then there's lithium. The UPS battery systems that keep data centers running through power interruptions rely on lithium-ion batteries. Lime is used to remove magnesium impurities during lithium purification, and to convert lithium carbonate into battery-grade lithium hydroxide, the form used in high-performance lithium-ion cells (IEA Global Critical Minerals Outlook, 2025). As AI workloads push data centers toward larger battery backup systems, this pathway grows with them.
During operation: water and backup systems
Once a facility is live, lime keeps showing up. Cooling towers are the largest water users at air-cooled hyperscale sites, consuming up to 26 million liters per year per facility. This system requires regular lime dosing to control pH and prevent scale buildup in pipes and heat exchangers, a requirement for equipment integrity and permit compliance.
Wastewater from maintenance and chemical treatment is typically acidic and must be neutralized before it can be discharged, and lime is the standard reagent for this. In water-stressed regions like Texas, Arizona, and Nevada, operators are increasingly investing in water recycling systems that also rely on lime as a core treatment step.
Where backup diesel or gas generators operate regularly, or where air quality permits require continuous emissions control, sites use lime-based scrubbers to remove sulfur dioxide and acid gases from generator exhaust before it is released.
How much lime is in a single data center?
Individually, each of these uses may be easy to overlook. Collectively, they add up to something hard to ignore. A single representative 200 MW hyperscale campus requires an estimated 25,000–100,000 tonnes of lime across construction materials and site works, a range that reflects variation in site geology, structural design, and project scale.
Compare that against the build-out pipeline. Synergy Research Group counted 1,297 operational hyperscale data centers globally in late 2025, with 770 more in the development pipeline. Across the scale of new facilities currently in development, the cumulative net-new lime demand runs into the tens of millions of tonnes. The embedded CO₂ at conventional production intensity: over 50 million tonnes on the base case alone. That carbon is already emitted by the time of construction. It cannot be reduced after the fact through operational efficiency, renewable energy, or offsets.
Why is conventional lime so hard to decarbonize?
Lime's carbon problem is different from most industrial inputs. The majority of its emissions come from chemistry, not energy.
The core reaction — heating limestone (CaCO₃) until it releases CO₂ to become lime (CaO) — releases 0.8 tonnes of CO₂ per tonne of lime as a basic matter of chemistry. This process CO₂ accounts for 60–70% of total lime production emissions, and cannot be reduced by switching to renewables, using green hydrogen, or improving energy efficiency. Even a lime producer running entirely on clean energy would still emit 0.8 tonnes of CO₂ per tonne of lime from calcination alone, unless the CO₂ is captured.
The IEA has classified lime production as one of the hardest-to-abate industrial sectors globally (IEA, Net Zero by 2050). Conventional approaches, like better fuels or more efficient kilns, can cut emissions by 30–40% at most. Full decarbonization requires a different kiln design: one that captures CO₂ at the point of production. Conventional kilns can't do this cost-effectively, because their exhaust gas is too dilute.
What is Origen's solution?
Origen is developing zero-emission lime using a proprietary oxy-fuel kiln that produces a near-pure CO₂ exhaust stream, making carbon capture both practical and cost-effective. A lifecycle assessment conducted by Hatch as part of the recently completed pre-FEED study found the process reduces emissions intensity by approximately 90% compared to conventional lime production - and confirmed that zero-emission lime can be produced at no green premium over conventional supply, even at first commercial scale.
Because the kiln produces a near-pure CO₂ stream, that CO₂ can be permanently stored underground rather than released to the atmosphere — meaning the full emissions of lime production, both from calcination and combustion, are eliminated at the source.
Data centers are a vivid illustration of a broader truth: trace the full value chain of almost any complex industrial product or built system, and lime is embedded in nearly every material, process, and supply chain. In any single application it can look incidental. Across the whole system it adds up to something very substantial. If decarbonization is going to keep pace with the scale of industrial development, it must address levers like lime — the materials that are everywhere, but invisible. That's what Origen is building toward: a proven kiln, ready to deploy, offering a genuinely zero-emission source of supply for data centers and every other sector where the same math applies