The wood-fired boilers in District Energy Montpelier’s new central plant are now operating. District Heat Montpelier is a joint project of the City of Montpelier and the State of Vermont to provide local renewable energy to downtown Montpelier.
In the State’s existing central heating plant, located across State Street from the Vermont State House (see photos below), two modern wood-fired boilers are now heating the Capitol Complex with steam. Heat exchangers extract heat from the steam line in an ancillary room in the State’s steam plant to heat the City’s hot water loop, which services City and School buildings as well as private buildings east of the plant in downtown Montpelier.
The newspaper myChamplainValley.com earlier reported that the City of Montpelier had reached an operating agreement with the State and finalized the heating rates for the customers on its hot-water district heating system.
The State’s $15 million Central Heating Plant upgrade includes a architecturally attractive addition to the existing building; two new dual-fuel steam boilers that can burn both woodchips or No. 2 heating oil; a repurposed older boiler that burns No. 2 oil; an automated wood handling and conditioning system; backup water supply storage; and an electrostatic precipitator system that removes and collects particulates from the effluent. Approximately $5 million of additional funding supported enhancements and extensions to the city’s hot water distribution system.
The new steam plant, which retains some of the structure of the much smaller, previous building, will continue to supply steam heating for 19 State buildings as well as provide heat for a similar number of buildings on the City’s hot water heating loop.
The plant features two new, 600 HP, 20 MMBTU, state-of-the-art AFS Energy Systems woodchip-burning boilers, which can also burn No. 2 heating oil as a secondary and emergency fuel source. A third, older 16 MMBTU boiler, made by Johnson Boiler Company, burns only No. 2 heating oil and has been repurposed to have two roles—system startup and backup.
Daniel McLoughlin, the Boiler Room Supervisor, told IDEA that he will start the system by firing up the Johnson. “Oil gives us much more control and makes it easy to warm the system up gradually over 24 hours before starting up on wood chips,” he said. After that, one or both of the new woodchip boilers will be started and run throughout the heating season as required. “As soon as the city gives us load, we’ll start,” he said. The Johnson will then be idled and kept hot in case it is needed as backup. “We’ll end the season on oil,” McLoughlin said, “to ensure we burn up all the chips.”
The City of Montpelier’s hot water district heating loop derives its thermal energy from steam generated in the State plant via a pair of flat-plate heat exchangers located in a dedicated room in the southeast portion of the plant.
A bypass valve enables the steam system to be throttled back if necessary and still maintain heat to the City’s heat exchangers. McLoughlin noted that he requested this change to the design because the original plans did not include such a bypass provision. He also said that constant vigil was maintained during construction to ensure the proper routing of electrical conduit and plumbing. He emphasized: “If you’re hooking a new system into an old system, be sure to include the operators of the old system to review the plans to be sure that what you’re building is compatible with what you have.”
E. Joseph Aja, Jr., Project Manager, [Vermont] Buildings and General Services, told IDEA that, “The plant will consume about 39 tons of wood chips daily during the winter. The City has contracted with the State for an initial capacity of 9.71 MMBTU/H or 24.15% of the total capacity of the heat plant; the contract has a 20-year term, with two five-year extensions.
“The Thermal Energy Purchase and Sale Agreement with the City defines the Heating Season as October 1 through April 30,” said Aja. “This definition pertains to providing energy to the City’s system. The State will operate the plant for the State’s use as needed outside of the Heating Season. Historically, the boilers were started in September and shut down in June.
Earlier this year, the new biomass boilers were providing steam to the State complex during a test phase starting the first week of March and continuing, almost nonstop, until the second week in April. “In the past, the biomass boiler was brought on line after Thanksgiving,” said Aja. “With the additional load from providing energy to the City, one of the biomass boilers should be able to start on October 1. The actual City’s load and outside temperatures will dictate when the biomass boiler(s) are actually started.”
“We’re sort of putting downtown Montpelier on a wood stove,” Montpelier City Manager Bill Fraser told myChamplainValley.com. And that was the vision, to bring buildings in Vermont’s capital city sustainable energy.
“They’re going to be spending less on heat then they were before, because this plant is so efficient,” Fraser said. On Wednesday July 30, Fraser and the City Council set rates for the Montpelier District Heating System.
“You’re paying a base rate to be on the system, and a fluctuating rate depending on how much you use,” Fraser said. The rates Fraser is referring to are a capacity rate of $4.84 per MBTUH and an energy rate of $8.82 per MMBTU, actually a little less than what the state originally projected, for the 2014-2015 heating season, which begins on October 1st.
Organizers are using a British Thermal Unit (Btu) as a measurement of energy. One MMBTU is a million British Thermal Units.
Fraser says buying woodchips from all over New England, including Maine, Vermont, New Hampshire and Canada, is more consistent in price than importing oil.
“Wood does not have the same fluctuation up and down that oil has,” Fraser said. For the business establishments and property owners who signed up for the system, they saw this relative price stability as an opportunity. When they were evaluating if they should join the Montpelier Heating District, they all want to save money for the long run.
“Initially it looks like we’re going to save about eight thousand dollars a year on our heating costs, which for us is enormous,” said Bethany Church Pastor Amy Pitton. Pitton says churches are declining in membership nationwide across denominations, and changing to district heating does more than save money and reduce their carbon footprint. “We’re able to do something that helped the community at large by buying into this so that more people would be a part of it,” Pitton said.
Customers on the City’s hot water loop that are contracted with Montpelier District Heating include: City Hall (which maintains older hot water boilers as backup), the Fire Station, Police Station, Union Elementary School, Federal GSA Building, County Courthouse, Sheriff’s Office, Vermont Mutual, 17, 27, 46 and 52 State Street, 118 Main Street (New England Culinary Institute restaurant), City Center, Bethany Church, Christ Church, FairPoint on School Street, and the Kellogg-Hubbard Library.
The State steam loop includes 19 buildings: 109 (Pavilion Office Building), 110, 111 (Supreme Court Building), 112 (Condo with the People’s United Bank), 115 (State House), 116, 118, 120 (next to the steam plant and on its own dedicated steam line), 122, 126, 128, 132, 133, 134 and 136 State St., 2 & 4 Aiken Ave., and 1 and 6 Baldwin St.