District energy project announces grant at biomass conference

By Lisa Gibson | May 03, 2011

An excited Gwen Hallsmith took to the podium May 3 at the fourth annual International Biomass Conference & Expo in St. Louis. Once there, she promptly announced to the audience that her district heating project had just received state funding earlier in the day.

Hallsmith is the director of planning and community development for the city of Montpelier, Vt., which has been planning for about 15 years to replace an old state-owned district heating plant with a new one to burn 100 percent woody biomass. The system provides heat for the capital city’s state government complex, but is antiquated and in need of upgrades. The new system will not only provide cleaner heat to the complex, but will also employ a new network that will include the city government buildings on the other side of the municipality’s small downtown district.

Hallsmith shared the news with her fellow speakers before taking her seat on the stage and preparing for the panel. The project had been awarded $7 million from the state, a matching payment for $7 million in federal money the project had already received. Although the district heating project had been in the works for some time, the money moves it to a new realm of possibility. “Now we’re talking about a real project,” she laughed. The recent news made her presentation on the project timely, relevant and exciting.

Hallsmith was one of four speakers on the panel Small-Scale Savvy: Community and Small-Scale Biomass Heating Projects. Joining her was Bruce Browers, senior consultant for Barr Engineering Co. in Duluth, Minn. Browers discussed a biomass test burn conducted at Wyandotte, Mich., Municipal Services, a community-owned not-for-profit services provider. The test included cofiring biomass with coal in the company’s 25-megawatt circulating fluidized bed boiler.

Important components to start such an experiment include fuel selection, Browers said. That consists of determining air permit compatibility and locally available feedstocks. Equally important to fuel selection, he said, is testing the existing material handling system equipment.

The goals of the test burn were to identify fatal flaws; identify infrastructure upgrade requirements such as delivery, handling and storage; and changes to the boiler operation. Browers made sure to note that environmental performance was not a primary goal.

As can usually be expected with such tests, things didn’t go exactly as planned on the first run, Browers explained. “We had a good plan, but things got in the way,” he said, cautioning that companies doing similar tests will most likely end up making some things up on the fly. “Things are probably going to happen that will cause you some angst. You have to think on your feet and call another play.”

Still, the tests were considered successful, even though the efficiency decreased slightly with biomass blends. Test one consisted of an eight-hour burn of 30 percent wood cubes and a 70 percent coal and tire-derived fuel (TDF) blend, while test two burned 15 percent wood cubes and 85 percent coal/TDF. In general, pollutant emissions were decreased with the biomass feedstocks.

Browers ended with advice to other companies carrying out tests, saying a flexible test plan is crucial. It’s also important to determine the goals and to determine the biomass delivery logistics early. He displayed a short video showing dust billowing from biomass on a conveyor belt and explained dust collection is vital. Looking behind him at the large dust cloud on the projection screen, he said “We didn’t really expect this.”