Data centers operate under tight uptime requirements, often aiming for no more than a few minutes of downtime per year. To meet these demands, every aspect of infrastructure needs to be engineered for resilience, including backup power. While diesel generators have long been the default choice for emergency power systems, natural gas generators and microgrids are becoming a serious alternative.
Choosing between natural gas and diesel isn’t just a matter of cost or convenience. It requires evaluating performance under real-world conditions, regulatory expectations, fuel logistics, environmental impact, and long-term operational strategy. Below is a side-by-side breakdown of the two options as they relate specifically to data center environments.
Fuel Storage and Supply Chain
Diesel
Diesel fuel must be stored on-site in large tanks, which poses a few challenges. First, there’s a finite amount of fuel available, typically enough for 24 to 72 hours of runtime unless deliveries can be made. Second, diesel has a limited shelf life and may degrade without proper treatment, requiring regular testing and maintenance. In extended outages or disaster scenarios, resupplying fuel can become difficult.
Natural Gas
Natural gas is delivered continuously through underground pipelines, which are far less vulnerable to weather and logistics issues. This means no need for onsite storage and no concerns about refueling during long-duration outages. However, reliability depends on the strength and redundancy of the local gas utility infrastructure. In some regions, dual-fuel systems or compressed gas storage can mitigate this risk.
Emissions and Environmental Impact
Diesel
Diesel generators emit high levels of nitrogen oxides (NOx), particulate matter, and greenhouse gases. Because of this, they are heavily regulated in many states and municipalities. Facilities may be limited in how many hours they can operate diesel systems per year unless they install costly emissions controls.
Natural Gas
Natural gas burns cleaner than diesel, producing lower levels of NOx, carbon monoxide, and CO₂ per unit of energy. Many natural gas systems qualify as low-emission or ultra-low-emission solutions, making them easier to permit and operate for extended durations. This makes them a better fit for organizations with sustainability goals or ESG reporting requirements.
Maintenance and Lifecycle Costs
Diesel
Diesel generators require regular testing, fuel quality checks, and more frequent maintenance. Wet-stacking, fuel polishing, and tank inspections add to the cost of ownership. While initial installation costs may be lower, the long-term upkeep can become expensive, especially in environments where they are called on more than a few times per year.
Natural Gas
Natural gas generators, particularly microturbines, have fewer moving parts and longer maintenance intervals. They don’t suffer from fuel degradation issues and often include predictive maintenance features when paired with modern control systems. Over time, the total cost of ownership is often lower, especially when used as part of a hybrid or grid-supporting strategy.
Permitting and Regulatory Pressure
Diesel
In areas with strict environmental laws, diesel generators can be difficult to permit. Standby use is typically allowed, but limitations are placed on runtime and testing hours. Some regions also require emissions mitigation equipment, adding to both installation and ongoing compliance costs.
Natural Gas
Because of their cleaner emissions profile, natural gas systems face fewer regulatory hurdles. They’re often allowed to operate longer, and in some cases can be used not just for backup, but for peak shaving or participation in grid programs. This added flexibility can improve the ROI of the power system as a whole.
Use Case Flexibility
Diesel
Diesel generators are primarily used for backup only. Running them for extended periods is costly and usually not permitted. They are best suited for applications where uptime is critical, but usage is minimal.
Natural Gas
Natural gas systems can be used for both backup and daily operations. In microgrid configurations, they can provide baseload power, support critical loads, and enable grid independence. This flexibility makes them ideal for facilities looking to offset utility rates, support sustainability goals, or add on-site generation capabilities.
Which Is Better Depends on the Application
For data centers that require high-speed backup and already have infrastructure in place for diesel, maintaining those systems might make sense in the short term. But for operators planning long-term strategies that include sustainability, cost control, and fuel resilience, natural gas microgrids are increasingly difficult to ignore.