DETROIT – If you've spent any time in Detroit, you've likely noticed the steam pouring out of certain manholes around the city.

To many, the steam is a mystery. Sometimes the steam can be a scenic addition to the Downtown area, but sometimes it can be hazardous to traffic and pedestrians.

To get to the bottom of our steam questions, we went straight to the source: Detroit Thermal.

Detroit Thermal operates a district energy network in the city, including almost 40 miles of underground steam pipes that provide service to many of Detroit's best known buildings, including Cobo Hall, the DMC and the Renaissance Center.

The steam provides cost-effective heating, hot water production, and absorption cooling services, and it supports additional manufacturing processes, according to Detroit Thermal.

The majority of the steam for the network is generated at Detroit Renewable Energy’s waste-to-energy plant, which safely generates renewable energy in the form of electricity and steam by safely processing municipal solid waste.

Why are plumes visible from some Detroit manholes?

Steam is entirely contained underground in the extensive network; however, water vapor is sometimes visible at the street level for two reasons. It most commonly occurs as a result of other water sources, such as groundwater, coming in contact with the steam pipes. This is similar to putting water on a hot pan at home. On rare occasions, plumes can be visible due to failed steam traps or leaks in the network. When maintenance and repairs are required, steam service to the line is temporarily shut off to ensure safety for workers and the public.

Is there any danger to the steam?

No more than household steam. Health and safety are top priorities for Detroit Renewable Energy and we have 24-hour crews monitoring the lines to ensure safe operations. While visible water vapor is often safe, steam can be hot to the touch and we urge caution around any visible plumes. If you see any visible plumes, please contact Detroit Thermal by calling (313) 972-5700 or by texting "renewable" to 55222.

What is being done to address steam issues?

With a new ownership and management team in place driving a new approach, we’re working to improve operations in a number of areas to be a better neighbor. Steam plumes are addressed as a part of that maintenance. We are focused on ensuring that all vapor is diverted and managed in a safe, efficient manner to prevent any interruptions for the city and its residents. Our team is also constantly monitoring the extensive network to perform preventative maintenance and necessary repairs. In addition, we are making major investments to update and modernize the network.

What is the purpose of stacks?

Stacks are necessary to ensure safety in certain areas and are used in cities with district energy networks around the country. They are utilized to direct and disperse water vapor at the street level to ensure public safety and to prevent additional traffic issues.

Is the steam at all a symptom of Detroit’s old infrastructure (high number of water main breaks, etc)?

The district energy network is a unique asset for Detroit that has been a part of our energy infrastructure for more than 100 years. Aging city infrastructure, such as the water system, contributes to issues with plumes, and our team works closely with the City to proactively address any problems. As we work to modernize the City’s infrastructure, the district energy network in Detroit can once again be a model for cities all over the world.