European neocloud Nebius has reported a 32x spike in carbon emissions over the last year as a result of the rapid expansion of its data center footprint.

In its 2025 sustainability report, the company disclosed 65,001 tons of CO2e in combined Scope 1 and Scope 2 emissions on a market-based basis for the year. This is up from 2,036 tons reported for 2024. The increase is largely driven by the expansion of its operational base to seven active sites. It said that 99 percent of its market-based Scope 1 and 2 emissions in 2025 came from data center operations.

Nebius did not disclose its Scope 3 emissions, which cover indirect emissions from hardware manufacturing, construction, and the supply chain. It claimed that reporting boundaries, data systems, and processes needed to collect reliable supplier and activity data "are still being developed," and that available data "would not support a representative inventory" for 2025.

Nebius reported a weighted average power usage effectiveness (PUE) of 1.25 across its portfolio in 2025, compared against a global industry average of 1.54, according to the Uptime Institute.

On water, Nebius reported a water usage effectiveness of 0.018 liters per kWh at its Finland-1 data center, which it attributed to closed-loop liquid cooling and air-based free cooling that avoid water intake.

Nebius has yet to publish quantified targets for emissions reduction and resource use. It stated that targets are still being developed alongside its data infrastructure and governance processes.

The report paid particular attention to Nebius’ deal with fuel cell firm Bloom Energy. Signed in May, the companies agreed to deploy 328MW of behind-the-meter solid oxide fuel cell capacity at a US site, in a deal worth up to $2.6 billion in service fees over ten years.

According to previous reporting, the fuel cells were expected to replace gas turbines previously planned for deployment at the site. The report frames the fuel cells as "non-combustion generation" with "lower local pollutants, lower water use." While this is the case, the fuel cells are most likely to be powered via natural gas, which will still lead to significant emissions.

Nebius has a data center presence across the US, the Middle East, and Europe. In the US, the firm is set to lease data centers in New Jersey (Vineland, DataOne) and Missouri (Kansas City, Patmos). The firm is also developing its own data centers in Independence, Missouri, and Birmingham, Alabama.

Earlier this month, it was reported that Nebius was seeking to develop a 1.2GW campus in Butler Township, Pennsylvania