Crankcase Ventilation as an Integral Part of an Emissions Reduction Strategy
The power generation industry is evolving to handle rapidly increasing industrial and consumer energy demand. Expanding data center infrastructure, growing distributed energy consumption, stringent emissions expectations, and increasing operational standards are reshaping how stationary reciprocating engines and gensets are designed and packaged.
For OEMs, packagers, specifying engineers, and operators, emissions reduction strategies are no longer focused solely on exhaust treatment systems. Today’s engine installations are being evaluated more holistically, with increased attention on hydrocarbon emissions, engine protection, facility cleanliness, and overall engine performance and efficiency.
One area receiving increased attention is crankcase blow-by emissions.
Most engine operators and OEMs already understand that crankcase blow-by contributes to oil particulate emissions through vented oil mist aerosols. The challenge has been identifying practical ways to control those emissions without negatively affecting engine performance. High efficiency closed crankcase ventilation systems provide a practical pathway to reduce vented oil mist while enabling the recovery of fugitive methane emissions from natural gas engines.
Operators are evaluating all potential hydrocarbon emission sources from natural gas fueled engines, including crankcase blow-by gases, which can account for up to 20% of total engine emissions. The installation of closed crankcase ventilation systems supports broader emissions reduction strategies by helping reduce vented hydrocarbon emissions while improving engine room and plant cleanliness.
Crankcase ventilation should not be viewed as a standalone emissions solution, but rather as one component of a broader engine emissions management strategy.
Understanding Crankcase Blow-By in Diesel and Natural Gas Engines
All stationary engines generate blow-by during normal operation. Pressurized combustion gases pass beyond the piston rings and enter the crankcase, which must be safely ventilated from the engine.
These blow-by gases may contain:
- Oil mist aerosols
- Unburned hydrocarbons
- Water vapor
- Fine particulate matter
- Combustion gas byproducts (NOx, CO2, CO, etc.)
- Methane slip (natural gas engines)
Without proper ventilation, excessive crankcase pressure will negatively impact seals, gaskets, and overall engine reliability. Crankcase ventilation systems are designed to relieve this pressure while managing the resulting emissions stream.
Historically, many stationary engines operated with an open crankcase that vented untreated blow-by gases directly into the atmosphere. While effective for pressure relief, open systems also release oily aerosols and hydrocarbon-containing gases into the surrounding environment.
Today, as operators place greater emphasis on emissions reduction, equipment cleanliness, and facility standards, crankcase emissions are receiving increased attention.
Why Crankcase Emissions Matter More Today
Several industry trends are driving renewed focus on crankcase ventilation systems.
The first is the rapid expansion of large stationary engine installations supporting power generation and data center infrastructure, many of which operate under strict cleanliness and operational expectations.
The second is the growing emphasis on reducing methane emissions from natural gas engines. Methane is recognized as a highly potent greenhouse gas, and emissions monitoring has become more common across oil and gas, power generation, and renewable natural gas applications.
Operators are increasingly evaluating all hydrocarbon emission sources throughout the engine system, including crankcase blow-by gases.
At the same time, operators are also seeking practical ways to improve:
- Engine room cleanliness
- Facility housekeeping
- Oil residue control
- Maintenance conditions
- Equipment protection
- Overall operational presentation
Closed crankcase ventilation systems simultaneously address all of these concerns.
Diesel Engines Versus Natural Gas Engines
The composition of crankcase emissions differs between diesel and natural gas engines.
For diesel engines, the primary concern is oil aerosol contamination. Open crankcase systems release oily mist that accumulates on surrounding equipment, contributing to maintenance challenges and facility cleanliness issues.
Natural gas engines present an additional challenge because blow-by gases also contain methane slip, which is vented directly to the atmosphere in open systems.
High efficiency crankcase ventilation systems capture oil aerosol emissions from all stationary engines and provide the added benefit of recovering methane slip from natural gas engines, supporting broader emissions reduction objectives.
Open Versus Closed Crankcase Ventilation Systems
Engines with an unfiltered open crankcase vent release blow-by gases directly into the atmosphere, allowing oil aerosols and other pollutants into the surrounding environment.
Alternatively, a closed crankcase configuration returns vented emissions back to the engine intake system. In both cases, a high-efficiency crankcase ventilation system is necessary to protect both the environment and the engine.
Closed Crankcase Spotlight
A properly engineered closed crankcase system, such as the Solberg ACV Series, separates oil aerosols from the blow-by stream before routing cleaner gases back into the engine’s intake.
This approach offers several operational advantages:
- Reduced oily mist emissions
- Improved engine room cleanliness
- Elimination of visible emissions
- Cleaner radiators and ventilation systems
- Reduced oil accumulation on nearby equipment
- Better control of crankcase emissions
- Reduced hydrocarbon venting
For natural gas engines, these systems also support the clean recovery of methane slip after oil aerosol separation. Efficiency is critical to protect turbochargers and intercoolers.
Oil Aerosol Separation
One of the most important functions of a crankcase ventilation system is capturing oil aerosol emissions. Blow-by gases contain suspended oil particles that can contaminate a facility if not properly separated.
High efficiency systems use engineered coalescing media designed to capture fine oil aerosols while maintaining acceptable pressure drop within the crankcase vent system.
Crankcase ventilation systems must balance several key objectives:
- High oil removal efficiency
- Low pressure drop
- Long service life
- Durability under continuous operation
- Proper crankcase vacuum regulation
Crankcase Ventilation Systems and the Data Center Boom
The rise of hyperscale data centers is influencing engine system design across the power generation market.
Many facilities maintain strict standards regarding cleanliness, visible emissions, and operational performance. As a result, engineers are evaluating auxiliary components such as:
- Crankcase emissions reduction systems
- Oil aerosol management solutions
- Enhanced intake air filtration
- Exhaust emissions reduction and silencing
Closed crankcase ventilation systems help create cleaner, more controlled environments in enclosed generator rooms.
This trend is also present in:
- Utility power generation
- Combined heat and power systems
- Renewable natural gas applications
- Landfill gas operations
- Distributed energy systems
- Industrial standby installations
Crankcase Ventilation Systems as Part of a Broader Emissions Strategy
Modern emissions reduction strategies involve multiple technologies working together across the engine system, including:
- Combustion optimization
- Exhaust aftertreatment systems
- Methane slip reduction technologies
- Methane recovery from compressor vents
- Fuel system improvements
- Monitoring and emissions tracking systems
- Crankcase ventilation systems
Crankcase ventilation should be viewed within this larger framework as it plays a key role in managing hydrocarbon emissions and improving overall system cleanliness.
Supporting OEMs, Packagers, and Operators
Crankcase ventilation systems are becoming an increasingly visible component of engine package design.
Operators expect cleaner installations, while engineers are evaluating how auxiliary systems support broader operational and environmental goals.
This is creating demand for systems that offer:
- Effective oil aerosol separation
- Reliable crankcase pressure control
- Durability in industrial environments
- Flexible integration across engine platforms
Changing the Crankcase Ventilation System Narrative
The conversation surrounding crankcase ventilation is evolving. What was once considered primarily a maintenance issue is now viewed through the lens of emissions reduction, sustainability, and modern engine design.
Closed crankcase ventilation systems offer a practical approach to reducing oily emissions while improving handling of hydrocarbon-containing blow-by gases.
As emissions strategies continue to evolve, crankcase ventilation will remain an important part of modern engine package design.