Target Field will join a handful of other downtown Minneapolis buildings that are getting their heat from one of the cityâÄôs first large-scale, renewable energy ventures, completed earlier this year. A 1,600-foot steam line has been carrying steam produced by burning municipal waste at the Hennepin Energy Recovery Center to the NRG Energy Center âÄôs downtown district heating system since February. The steam line is a pipe that runs from HERC, down North Seventh Street, to a vault that leads to the downtown district heating system. The $3.4 million project was sponsored by Hennepin County and the NRG Energy Center. It represents a very small portion of the total district heating system. Currently, NRG uses steam powered by natural gas and oil to power steam in the six miles of piping that make up the system, Tom Davison, general manager for NRG Energy, said. Another four miles provides chilled water in warm months. But since burning refuse to create steam is cleaner and less expensive than gas, the ultimate goal is to expand the method, Jake Smith, senior environmentalist for Hennepin County Environmental Services , said. âÄúItâÄôs green steam,âÄù he said. âÄúEven though itâÄôs a small amount, itâÄôs a direction to head in to provide reliable energy and green energy.âÄù But given HERCâÄôs limited capacity to create steam from burned municipal waste, Davison said he believes the project wonâÄôt expand in the near future. Burning municipal waste is a sustainable heating method because it eliminates solid waste, reduces the impact of pollution and conserves natural resources, said Shaina Brown, energy engineer for the Minnesota Technical Assistance Program , which advises businesses on how to efficiently use energy. âÄúThe more the better at this point,âÄù she said. Burning municipal waste is not a new thing for HERC âÄî itâÄôs burned about 6.5 million tons since it opened in 1990. However, this is the first time itâÄôs using that steam to create heat. The majority of the steam produced from burning waste powers a turbine that creates electricity to be sold to Xcel Energy. HERCâÄôs electricity powers about 25,000 homes per year. In total, HERC burns 365,000 tons of solid waste per year, about 35 percent of all waste generated by Hennepin County residents and businesses. Any opportunity to reduce dependence on fossil fuels is beneficial, said Lowell Rasmussen, vice chancellor of finance and facilities at the University of Minnesota-Morris . âÄúThereâÄôs a finite amount of carbon in this world,âÄù he said. The Morris campus has been experimenting with a novel system of using biomass to make steam to power up to 80 percent of the campus. But the potential for harmful emissions from burning waste on such a large scale is a concern, environmentalist Smith said. HERC takes a number of precautions to ensure the safety of their emissions. It relies on alternate locations for residents to dispose of household hazardous waste, solvents and toxic chemicals so that such materials donâÄôt reach the power plant. HERC also encourages recycling of paper, glass, plastic, batteries and appliances. When the waste reaches their plant, HERC employees sort through it and remove anything that canâÄôt be burned. After the waste is burned inside the plant, a number of solvents are introduced to the resulting gas to neutralize potentially harmful acid gases such as sulfur dioxide, hydrogen chloride and mercury. A filter is used to capture particulates, metals and dioxins. The downtown district heating system includes 100 buildings and 130 square blocks of Minneapolis. Many urban cities use similar joint systems because itâÄôs less expensive and easier to regulate, compared with holding each building responsible for its own energy regulation, Smith said.