Best Practice Action Detail

Best Practice Action 23.4

GreenStep City Best Practices: Environmental Management
Local Air Quality No. 23

Prevent generation of local air contaminants so as to improve community health.

Best Practice Action 4

Minimize pollution from fuel generators including portable generators, emergency generators, backup generators, and engines.

NOTE: BPA 23.4 was added in August 2026. Any actions relating to generators reported prior to this change will remain under BPA 23.3

Portable Generators: 

Backup Generators & Stationary Engines:

  • Emergency and backup generators typically have long operating lives, so older units with minimal or no emission controls are still in use. Large generators typically run on diesel fuel, which releases more pollution when it is burned than gasoline or natural gas. Emergency and backup generators are commonly found at hospitals, nursing homes, grocery stores, critical public facilities (water treatment, wastewater treatment, emergency operations centers, etc.), and data centers. 
  • Data centers often rely on backup generators to keep up operations during power outages. Learn more about data centers (Pew Research, 2025), how they operate and recommendations for local regulation of data centers including model ordinances (Urban Land Institute, 2024), and the role local governments can take in data center development (National League of Cities, 2025). See also, GreenStep’s 2026 webinar and resources on local considerations.  
  • This comprehensive guide from EPA covers power resiliency for water and wastewater utilities, including the selection and operation of backup generators. The guide highlights the importance of energy efficiency for power resiliency as it reduces the amount of backup power needed in case of a power outage. 
  • Improve efficiency of your generators through right-sizing, routine maintenance, and fuel management as described by these Emergency generators and stationary engines recommended practices (MPCA) and Generator Fuel Management Guide: Best Practices for Efficiency & Safety (Mid-America Engine, 2025)
  • Learn more about best practices for backup and standby generators (Pacific Northwest National Labs, 2021) that can improve performance and safety, and reduce emissions.
  • EPA’s Controlling Air Pollution from Stationary Engines webpage details federal regulations for stationary engines such as generators. 
  • One way to increase power resiliency and limit the need for backup generators during power outages is to incorporate renewable energy sources. This recorded webinar outlines strategies beyond backup generators (US Department of Energy, 2020) for providing power during outages. The REopt calculator from National Labs of the Rockies can help determine if the energy supply can meet the critical load.
  • Fuel cells are a potential alternative to generators as a backup power source. This in-depth report (National Renewable Energy Lab, 2014) provides a detailed analysis of a 2013 pilot program that compared the costs and performance of fuel cells to traditional generators.

Food Trucks and Construction Generators: 

1 star

  • Conduct an education campaign with businesses and residents that have emergency or backup generators about how to minimize pollution and find alternatives, or
  • Document how public events are set up to minimize the use of portable generators or are laid out to prevent attendee exposure to portable generator exhaust and noise 
2 star

  • Work with food trucks, construction trades, and others to decrease noise and pollutants from portable generators, or
  • Support event and construction site efforts to replace portable generators with temporary electrical supplies, or
  • Document agreements made between public/private entities to share generators or pool microgrid technologies to reduce the number of fuel generators 
3 star

  • Change licensing to require public events and food trucks to use generators that meet specific emissions standards, or
  • Adopt an ordinance that requires reduced pollution from emergency and backup generators by requiring electric, natural gas, ultra-low sulfur diesel, or other fuels that release less pollution, or
  • For government-owned generators, document that they are properly-sized for your needs, are routinely maintained, and use smart fuel management