As the proliferation of AI data centers accelerates across the nation, their rising energy demands and the associated greenhouse gas emissions have become a focal point of environmental concerns. These facilities, equipped with constantly operating servers and energy-intensive cooling systems, can consume power ranging from several megawatts for smaller centers to over 100 megawatts for larger, hyperscale data centers. For context, a typical large natural gas power plant in the U.S. produces under 1,000 megawatts.
When fueled by fossil sources, these data centers can significantly contribute to climate-warming emissions unless mitigated by technologies like carbon capture and storage (CCS).
In a noteworthy move, Google has initiated a corporate power purchase agreement to facilitate the development of a natural gas power plant in Illinois, which will incorporate carbon capture and storage technology.
But how exactly does carbon capture and storage operate in such scenarios?
As an engineer with expertise in carbon storage, I’ve authored a book covering various carbon storage methodologies. Here’s a brief overview.
Understanding Carbon Capture and Storage (CCS)
The combustion of fossil fuels for electricity releases carbon dioxide (CO2), a potent greenhouse gas that persists in the atmosphere for centuries. This accumulation acts as a thermal blanket, trapping heat near the Earth’s surface and triggering climate changes such as intense heat waves, rising sea levels, and severe storms.
CCS technology captures CO2 from power plants, industrial operations, or directly from the air, and transports it to locations where it can be injected underground for safe, long-term storage.
Congressional Budget Office, U.S. Federal Government
CO2 can be transported as a supercritical fluid, maintaining properties of both liquid and gas, or dissolved in a liquid. Once injected deep underground, the CO2 can become trapped geologically, dissolve in brine, or mineralize into rock.
The overarching aim of CCS is to ensure the long-term sequestration of CO2 from the atmosphere.
Exploring Underground Carbon Storage Options
Various methods exist for storing CO2 underground.
Depleted oil and gas reservoirs offer ample storage space, with the advantage of pre-existing geological mapping and their historical retention of hydrocarbons for millennia.
Injecting CO2 into active oil or gas reservoirs can facilitate further extraction of these resources, leaving most CO2 behind. This technique, known as enhanced oil recovery, is the most prevalent CCS method in the U.S., although it has drawn criticism from environmental advocates.
Volcanic basalt and carbonate formations are promising for secure, long-term storage due to their mineral composition, which facilitates CO2 mineralization. Iceland has pioneered this approach using its volcanic basalt foundation. Additionally, researchers are investigating sub-seafloor storage potential.
In the United States, deep saline aquifers are projected to be highly viable for industrial CO2 storage, a strategy Google intends to employ. These aquifers, composed of porous sediments like sandstone and limestone, are unsuitable for drinking water but ideal for CO2 storage.
These aquifers boast substantial storage capacities, from approximately 1,000 to 20,000 gigatons. For comparison, U.S. fossil fuel emissions amounted to 4.9 gigatons in 2024.
As of late 2025, 21 U.S. facilities were utilizing CCS, spanning industries like natural gas and biofuels. Of these, five employed deep saline aquifers, with the remainder focusing on enhanced oil recovery. An additional eight CCS projects were under construction.
Google’s Saline Aquifer Storage Initiative
Google’s groundbreaking 400-megawatt natural gas plant, developed with Broadwing Energy, aims to capture 90% of its CO2 emissions, storing them in a nearby deep saline aquifer within the Mount Simon formation.
The Mount Simon formation, a vast saline aquifer, extends beneath much of Illinois and parts of adjacent states. Its porous sandstone layer, exceeding 800 meters in depth, is ideal for CO2 injection, while the overlying Eau Claire shale serves as a caprock to contain the gas.
The Mount Simon’s storage capacity is estimated between 27 and 109 gigatons.
Google’s project will leverage an existing injection site from the first large-scale CCS demonstration in the region. Archer Daniels Midland has been injecting CO2 here since 2012.
While CCS faces challenges, including a pipeline rupture incident in Mississippi and a leak in Illinois, improvements in monitoring and technology continue to advance the field.
The Role of CCS in a Sustainable Future
With data centers growing rapidly, there’s an urgent need to expand power capacity. OpenAI suggests the U.S. add 100 gigawatts of capacity annually, doubling current expansion rates.
Experts, including those at the International Energy Agency, assert that carbon capture and storage is crucial to mitigating climate change as energy demands escalate.
