A recent report by the American Bureau of Shipping (ABS) and Herbert Engineering presents a new concept to meet the growing energy needs of AI data centers – floating, nuclear-powered facilities located in coastal waters and river estuaries.
The report “Pathways to a Low Carbon Future: Floating Nuclear Power Data Center” details design considerations for a floating data center that would use large river estuaries or coastal waters as a heat sink for both servers and small modular reactors (SMR) onboard a purpose-built barge. These floating platforms would use surrounding water bodies to naturally cool both the servers and the reactors.
The design assumes a sheltered, pier-moored setup for easy access to personnel, backup power, and fast fiberoptic connections, eliminating the need for anchoring systems. Offshore deployment is considered impractical due to limited connectivity options, high costs of underwater cabling and challenges in personnel access and power backup, which would require resident staff and larger living quarters.
However, no environmental or security impact assessments were conducted. Nevertheless, once a site is selected, detailed studies will be needed to ensure safe heat dissipation and adequate facility security.
According to ABS, the proposed solution aims to tackle two major challenges, the increasing energy demand of AI technologies and the growing pressure on current power grids.
The intersection of new nuclear technologies and rapidly growing AI capabilities represents a generational opportunity to power humanity’s future. As demand for data centers increases, moving them offshore and powering them with on board nuclear energy could mitigate certain risks and reduce the strain on local grids.
…said Christopher J. Wiernicki, Chairman and CEO, ABS.
Waste heat and environmental impact
The data center design is based on the fundamental assumption that the heat generated by reactors and servers can be discharged in the water/air surrounding the barge. This is effectively equal to the large majority of the rated thermal power of the BWXT Advanced Nuclear Reactors (BANR), i.e. 4 x 50 megawatt thermal (MWt) = 200 MWt or approximately 700 MBtu/hour (although a smaller portion of this heat will be dissipated through air ventilation or if air cooling system for the servers is selected).
This requires the floating data center to be in a location with adequate water/air current flow. The minimum natural current flow under the keel needed to dissipate the above mentioned heat depends on the amount of water used to cool servers and steam in the power plant condensers. In turn, this depends on the maximum allowed temperature change between inlet and outlet seawater (often referred to as Delta-T). This is generally around 10° C for open waters, but it can be lowered to as little as 2° C in inland and coastal waters.
The lower the Delta-T, the larger the amount of water needed to dissipate the produced heat, and therefore the larger the minimum current flow under the keel. In summary, the integration of a nuclear power plant into a floating data center introduces significant heat dissipation challenges that must be taken into account during the early stages of project planning. As mentioned, a 200 MWt nuclear data center producing 70 MWe power can generate up to 200 MW of residual thermal heat (nuclear waste heat plus server cooling) that must be safely and efficiently released into the surrounding environment.
Without careful planning, this heat discharge could significantly impact the local air and water temperatures (>5° C Delta-T increase in some cases), posing risks to equipment performance, marine ecosystems and regulatory compliance. By carefully evaluating the site location, heat sink size/capacity, discharge angle and water/air flow dynamics, one can minimize environmental risks while ensuring stable operating conditions.
