Solar in the City

March 22, 2011

Posted by: Michael Noble on Mar 21, 2011 with Fresh Energy

I am always delighted to blog about my home town, St. Paul. On Friday morning (March 18), Mayor Chris Coleman and U.S. Representative Betty McCollum cut the ribbon on a 1 megawatt solar power plant on the roof of the RiverCentre. Yeah, a 1 megawatt solar plant is a very big deal, nearly doubling the total solar energy installed in Minnesota, more or less. With a room full of business and civic leaders, reporters and politicians, the sun came out and the system kicked in, almost on cue for the press event.

This new addition to downtown's success story is a solar hot water system, not a photovoltaic electric system. At half the size of a football field, it's the largest solar thermal system in the Upper Midwest. After the sun meets all the needs for domestic hot water at the convention center, then it supplies space heat. When there's no more need for hot water or space heat, a valve opens and water flows into the grid of hot water pipes under the streets of St. Paul. (Maybe my building two blocks away is getting some solar hot water right now in the bathroom!

Powered by renewable biomass energy, and now solar too, most of downtown St. Paul is heated by a network of hot water pipes that weaves through the city and into the basements of 80 percent of the commercial buildings. The Minnesota State Capitol is heated with renewable energy too! Ken Smith, President of District Energy St. Paul tells me that this is the first solar thermal project in North America that is connected to a district energy system. Although it is capable of running on natural gas or coal, St. Paul's heating system mostly runs on wood chips from around the metro area, largely from crews that keep the urban forest trimmed. Having a market for the tree trimmings is a good way to keep boulevard trees healthy and beautiful. Huge!

Using funds from the American Recovery and Reinvestment Act, this project went up in record time. Talk about shovel ready: when a competition was announced for innovative solar projects, the partnership of the City of St. Paul, St. Paul District Energy, the State of Minnesota Office of Energy Security, and the River Centre convention hall jumped. Because of its location, its size and its innovative aspects, it was a sure winner. A U.S. Department of Energy Solar America Cities team that includes Fresh Energy and is led by Anne Hunt, a former Fresh Energy board chair, helped conceive the project and pull together the players. Within months, pipefitters, electricians, and construction crews went to work!
If a heavy snow blankets the solar panels, they don't have to wait for it to melt, or send workers up to clear the snow. The city system can feed a little hot water back into the solar panels until they warm up enough for the snow to sluff off.

District Energy St. Paul has always been an innovator, ever since founders Mayor George Latimer and Don Taylor and Bill Mahlum hired the Swedish district energy guru Hans Nyman to be its first president in 1981. After a couple of decades of pioneer work, the second CEO, another Swede, Anders Rydaker continued innovation while maintaining stable energy prices at the 80 percent of St. Paul office buildings who rely on district energy. In his tenure as president that ended last year, Anders added summer cooling to the services, weaned the system off its reliance on coal, and began generating electricity to sell to Xcel Energy on a long-term contract.