Executive Summary
- Brian Ambo Petersen, Sales Manager at LiqTech, explores how diesel generators are attracting scrutiny because of their emissions and how backup power shouldn’t come at the expense of the air quality for communities surrounding data centres.
- Operators are under pressure to show their facilities aren’t burdening the environment with toxic emissions, and consider how equipment is tested, maintained and operated whilst limiting emissions.
- Alternative backup technologies are developing, but diesel continues to offer rapid response, high power density and extended operation where fuel supplies are available
Standby diesel generation remains essential to data centres and other critical infrastructure, but its emissions are attracting greater scrutiny. Reducing particulate emissions without compromising resilience depends on matching DPF components to the engine, operating profile and wider exhaust system.
The rapid expansion of data centres has brought renewed attention to an indispensable element of critical infrastructure: standby diesel generation. However sophisticated a facility’s digital systems or power management may be, it must continue operating when the grid cannot meet its needs. Backup generators therefore remain central to data centres, hospitals, telecommunications networks and industrial plants.
At the same time, the environmental impact of that capacity is receiving closer attention. Operators face concern about local air quality, tighter permitting expectations and pressure to show that expanded facilities will not create an unacceptable emissions burden. The challenge is no longer simply to install enough generation to cover the electrical load. Operators must also consider how that equipment will be tested, maintained and operated while limiting particulate emissions.
The intermittent nature of standby power does not remove the issue. Generators need regular testing, while a prolonged grid outage may require several units to run continuously. At a large data centre campus, combined emissions from testing or emergency operation can therefore become an important planning consideration.
Standby duty creates a different filtration challenge
Diesel particulate filters are a proven means of reducing particulate emissions, but successful application requires more than adding a filter to an exhaust line. The duty cycle influences filtration performance, soot accumulation and regeneration, while standby generators operate very differently from engines running continuously at predictable loads.
A generator may remain inactive for long periods and then operate briefly during scheduled testing, sometimes at only a proportion of its rated output. Under emergency conditions, the same unit may be expected to start immediately and run at a much higher load for several hours or days. These changes affect exhaust temperature, gas flow and soot accumulation.
Temperature is particularly important because captured soot must be removed through regeneration. Where the exhaust remains sufficiently hot, passive regeneration can oxidise accumulated particulate matter during normal operation. Standby engines may not consistently achieve those conditions during short or lightly loaded tests. If the filter, coating and regeneration approach are not matched to the duty cycle, soot can accumulate and increase exhaust back pressure.
A diesel particulate filter, or DPF, captures soot and other particulate matter from the engine exhaust before it is released into the atmosphere. However, a DPF configuration proven on a continuously operated engine cannot automatically be transferred to a standby application. The specification must reflect the engine model, loading pattern, exhaust temperature profile, fuel quality and allowable back pressure, while testing frequency and the likely duration of emergency operation will also influence regeneration and maintenance requirements.
Any emissions-control technology fitted to critical backup power must support dependable operation and remain practical to maintain. A solution that introduces excessive back pressure or difficult servicing creates a new risk in an application built around resilience.
Matching the filter to operating conditions
The filter substrate must capture very small particles while allowing exhaust gases to pass through, and retain its performance through repeated heating, cooling and regeneration cycles. Material selection therefore affects efficiency, thermal behaviour and durability.
Silicon carbide is well suited to demanding diesel applications because it combines high filtration efficiency with mechanical strength and strong thermal conductivity. LiqTech’s silicon carbide filters can provide filtration efficiency above 99 per cent, reaching up to 99.96 per cent in suitable configurations. High thermal conductivity helps distribute heat evenly during regeneration, reducing concentrated hot spots.
That performance does not remove the need for careful engineering. Silicon carbide expands as temperatures rise, so the substrate must be appropriately segmented, supported and sleeved. Cordierite can remain suitable in less thermally demanding applications where temperatures are predictable and regeneration is well controlled. The choice should reflect the conditions the filter will encounter and the consequences of thermal or mechanical stress.
Physical configuration also needs to suit the installation. Generator exhaust systems vary according to engine size, enclosure design and available space. Filters may therefore be required in round, square or segmented formats, with dimensions selected around exhaust flow and pressure-drop requirements. Retrofit projects can be especially constrained because components must fit without extensive modification.
LiqTech supplies silicon carbide DPF filters and modular sleeved elements in a range of forms and dimensions for integration by exhaust and emissions-control system providers. This allows the configuration to suit the available space and operating requirements while the system designer or integrator retains responsibility for the complete exhaust arrangement.
The coating must support the duty cycle
Substrate selection is only part of the specification process. The catalytic coating influences how the DPF performs at different exhaust temperatures and under different fuel and operating conditions. This is particularly important for standby engines, where short run times and low-load testing can make passive regeneration difficult to sustain.
A diesel oxidation catalyst can oxidise carbon monoxide and hydrocarbons while supporting passive soot regeneration. Other coating options may be more suitable for engines operating at lower temperatures, experiencing challenging duty cycles or facing specific nitrogen dioxide requirements. The correct choice depends on how the generator will be used rather than simply on its rated output.
Fuel quality must also be considered because sulphur and other contaminants can affect catalyst activity and service life. Sites relying on fuel held for emergency use over extended periods may encounter greater variability than an engine supplied continuously from a controlled source. Coating recommendations therefore need to reflect realistic fuel and operating conditions.
Poorly matched components can have consequences beyond emissions performance. Inadequate regeneration can lead to rising back pressure and more frequent cleaning, while an unsuitable catalyst formulation may fail to deliver the expected result at the temperatures produced by the engine. In a critical-power application, these problems can increase maintenance demands and reduce confidence that the generator will be ready when required.
LiqTech supports system providers and operators with application-specific recommendations covering the filter substrate, coating options and sleeved configuration. This recognises that emissions performance results from the interaction between components and operating conditions rather than from any single specification value.
Integration and certification build confidence
Early consideration of particulate control makes it easier to integrate the DPF without creating avoidable compromises. Filter dimensions, coating selection, sleeving and maintenance access can be considered alongside exhaust routing, enclosure design and generator servicing requirements. Addressing these questions during system design is more effective than attempting to resolve emissions concerns after the installation has been finalised.
Independent certification can provide additional confidence in the underlying filtration technology. VERT certification is widely recognised as an exacting verification standard for diesel particulate filters and can support technical assessments and discussions with permitting authorities. It gives system providers and operators a stronger evidence base than relying solely on an unverified product claim.
Certification does not remove the need for application engineering. A certified filter must still be used on a suitable engine, integrated into an appropriate housing and operated within the conditions for which it was selected. Regeneration, monitoring and maintenance remain important because installed performance depends on more than substrate filtration efficiency.
The strongest approach combines independently verified DPF technology with a clear understanding of the engine and duty cycle, supporting permitting objectives without compromising readiness.
Cleaner operation is part of infrastructure resilience
Diesel generators are likely to remain an important part of critical infrastructure for some time. Alternative backup technologies are developing, but diesel continues to offer rapid response, high power density and extended operation where fuel supplies are available. For many data centres and essential facilities, those characteristics remain difficult to replace at scale.
Continued reliance on diesel brings a responsibility to manage emissions effectively. As critical facilities expand and more standby capacity is concentrated at individual sites, particulate control will increasingly form part of planning, permitting and community discussions.
The appropriate response is not to weaken backup-power requirements, but to apply the same engineering discipline to emissions control that operators apply to electrical resilience. The DPF substrate, catalytic coating and sleeved element must be selected around the engine’s real operating profile and integrated into a wider system capable of managing back pressure, regeneration and maintenance.
Addressing these questions early allows particulate reduction to become part of the backup-power strategy rather than a problem tackled late in project development. With application-specific components and effective system integration, critical infrastructure can maintain dependable standby generation while reducing its impact on local air quality.
