Generators: the backup that burns

Johanna Flood

When the power outage lasts longer than a few seconds, generators step in. Reliable? Yes. Low environmental impact? Not really.

Think of them as small on-site power plants—ready to take over when both the grid and UPS have done their part. Typically, the company producing the gensets purchases the parts from different suppliers making the supply chains complex. 

Sustainability risks (and what to do about them)

Heavy metal (literally) and heavy CO2 footprint

A genset is an electricity-producing unit that includes several sub-systems, such as an engine, fuel system, cooling system, battery charger, and enclosure. They also need tanks with fuel. The gensets needed to back up data centers are typically a large share of a data center’s embodied carbon (if you don’t include the servers).

Gensets are big, heavy, and built mostly from steel and other metals. A single genset with tanks can weigh hundreds of tonnes. This means hundreds of tonnes of embodied carbon and material use.

What to do:

  • Ask for an EPD (Environmental Product Declaration) or LCA to understand the product carbon footprint

  • Ask how the supplier is reducing embodied carbon from the product and their suppliers.

  • Look for if they use low-carbon steel in the tanks, if they know where the materials in the genset come from, and how they work with circularity.

Leaks of fuels and chemicals

Gensets run on diesel or other fuels. Fuel storage always comes with risk. Leaks can contaminate soil and water – and are expensive to fix.

What to do:

Ask your suppliers:

  • Where are the potential leak points?

  • Ask if they have sealed systems meaning that the generator are designed to prevent fluids from leaking out and contaminants from getting in.

  • Ensure secondary containment is included in the design – essentially a bathtub outside of the tank.

  • Ask how your suppliers ensure that coolants and lubricating oil are not leaking during maintenance or use

Emissions when running

Even if data centers don’t use their gensets often, the testing is typically a source of operational GHG emissions for data center companies. Generators emit CO2, NOX, SOX and particulates when in use.

Switching from diesel to HVO (Hydrotreated Vegetable Oil) can significantly reduce lifecycle emissions but not eliminate them. HVO has also recently been questioned because of the use of palm oil from rain forests.

What to do:

  •  Ensure the generator is tested and approved for HVO use

  • Ask for emissions data, not just claims

Noise

Generators are loud. Really loud. This matters more than you think – especially for permits and community relations.

What to do:

  • Check compliance with noise emission limits

  • Ask about acoustic enclosures or mitigation measures

Did I capture the materials impacts and risks of gensets? Did I miss something? Let us know.