COVER STORY |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| Powering the future from remains of the past Facing a boiler capacity shortage, the University of Minnesota rehabilitated a retired, antiquated steam plant into a model of modern efficiency and sustainability. Chris Farr, PE, Project Manager, Jacobs Engineering Group Inc. Courtesy University of Minnesota. he University of Minnesota Twin Cities encompasses Until 2017, all steam provided to the Minneapolis campus – divided by the approximately 24 million gross sq ft throughout 250 Mississippi River into east and west bank buildings across two campuses – in Minneapolis and areas – was generated at the Southeast Steam Plant (SE Plant). The plant had been TSt. Paul – approximately 3 miles apart. This flagship of acquired by the university in 1977 and the University of Minnesota system comprises 19 colleges and received major upgrades in 2000. The upgrades included a solid-fuel circulat- schools, with sister campuses in Crookston, Duluth, Morris and ing fluidized bed boiler and two dual-fuel (natural gas/No. 2 fuel oil) package boilers. Rochester. Two older coal-fired boilers were also re- tained to provide backup steam capacity. Energy Management, a division of Facilities Management within Prior to the acquisition of the SE Plant, University Services, oversees the production and distribution of steam for the Minneapolis campus was heating, cooling and electricity services to approximately 70,000 produced at a facility known as the Old Main Heating Plant. Originally constructed students and staff across the Twin Cities campuses. These include in 1912 and expanded/renovated many times over its life, this plant is located on • centralized steam production and distribution systems the East Bank of the Mississippi River at delivering high-pressure (200-psig) steam; the base of a former rock quarry excava- tion. It is highly visible to the public from • multiple district chilled-water plants providing 41,000 tons of the Interstate 35 river crossing and from total cooling capacity; parts of downtown Minneapolis. This building served as the primary source of five 13.8 kV switch stations (four in Minneapolis and one in St. campus steam energy for 88 years prior to • completion of the SE Plant upgrades. Paul) receiving power from multiple Xcel Energy substations Following the SE Plant upgrade, how- and distributing it to the campuses via an underground ever, the Old Main facility was largely neglected and fell into a state of disrepair. distribution network; and The exhaust stacks were demolished, the civil utility infrastructure supporting domestic water, sanitary site was overgrown with vegetation, the • roof was leaking, and the utility services sewer and storm water drainage that connects to city and to and from the building were failing. Ex- cept for the stacks, essentially all of the regional systems. plant equipment was electrically discon- nected and abandoned in place, including 12 District Energy / First Quarter 2018 © 2018 International District Energy Association. ALL RIGHTS RESERVED. COVER STORY |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||| Powering the future from remains of the past Facing a boiler capacity shortage, the University of Minnesota rehabilitated a retired, antiquated steam plant into a model of modern efficiency and sustainability. Chris Farr, PE, Project Manager, Jacobs Engineering Group Inc. six large coal-fired steam boilers and one AN EFFICIENT SOLUTION Once the decision was made in 2011 gas-/oil-fired boiler. A substantial abate- Subsequent to the completion of the to rehabilitate the Old Main Heating Plant ment effort was needed to remove asbes- master plan, the university evaluated po- site, Energy Management, in collabora- tos, lead, mercury and other hazardous tential solutions to address the shortage tion with the university’s department of materials that were known to exist. in firm boiler capacity, using reliability, Capital Planning and Project Manage- sustainability and cost-effectiveness as its ment, took the analysis a step further. guiding principles. The analysis resulted They performed a preliminary evaluation WITHOUT ACTION, THE ABILITY TO PROVIDE in three options: adding another boiler at of various combinations of equipment RELIABLE STEAM ENERGY TO UNIVERSITY FA- the SE Plant, rehabilitating the Old Main systems including package natural gas CILITIES WOULD BE AT SUBSTANTIAL RISK. Heating Plant or building a new steam boilers and combined heat and power plant in the northeast area of campus. equipment. After careful consideration, rehabili- The CHP option considered in the In 2009, a utility master plan was per- tation of the Old Main Heating Plant was preliminary evaluation contemplated the formed by the university to evaluate all identified as the best choice among these installation of two 7 MW dual-fuel com- utility systems on campus with respect to options for several reasons. First, generat- bustion turbine generators (CTGs). Since the institution’s 20-year growth plans. Due ing steam from a second location mitigat- the university maintains an interruptible to both the heating demand load growth ed the risks associated with having a single gas contract with CenterPoint Energy, the projections and the age of the two older source of steam for the Minneapolis cam- equipment selected had to be capable of coal-fired boilers in the SE Plant, a short- pus, which had been identified as one of operating on an alternate fuel during age of firm boiler capacity was forecast to the campus’s top two risks by property in- natural gas curtailments for the heat gen- become a significant operating obstacle by surers. Second, reusing the existing facility erated to be considered as contributing 2014. Without action, the ability to provide was perceived to be more economical than toward the campus’s firm boiler capac- reliable steam energy to university facili- building a new steam plant in the north- ity. Using heat recovery steam genera- ties, including a hospital and multiple re- east (another option that would diversify tors (HRSGs) with duct burners, the two search centers, would be at substantial risk. steam production locations) and install- combustion turbine generators would be Prompted by this assessment, and ing new distribution system components capable of producing up to 250,000 lb/hr following further study, the university required to deliver that energy to campus. of total steam, achieving the firm capacity responded to this anticipated shortage And finally, the Old Main Heating Plant needed to meet the projected load growth. by reinvesting in and reconfiguring its was considered large enough to house ad- The analysis concluded that the cor- historic Old Main plant. The facility was ditional utility systems, including power responding reduction of total purchased transformed into a new 22.8 MW com- generation equipment and the next district utility costs (natural gas and electricity) bined heat and power system that sup- chilling plant, without requiring the con- over the life of the equipment would out- plies steam and electricity to the Min- struction of additional facilities. In other weigh the higher capital investment and neapolis campus – reducing utility grid words, the building rehabilitation invest- operations and maintenance costs of CHP purchases and greenhouse gas emis- ment at Old Main would represent a down equipment, making it the wisest long- sions in the process. payment on future utility projects. term strategic decision for the university. © 2018 International District Energy Association. ALL RIGHTS RESERVED. District Energy / First Quarter 2018 13 Courtesy Collaborative Design Group. Photo Mike Jordan. Above: The University of Minnesota’s Old Main Heating Plant prior to rehabilitation. Following the Southeast Steam Plant upgrade in 2000, this facility was largely neglected and fell into a state of disrepair. Left: The rehabilitated Old Main plant, now the Combined Heat and Power Plant, began operating in 2017. Its combustion turbine generator air intake structure and heat recovery steam generator exhaust stack stand against the backdrop of the Minneapolis Courtesy Jacobs Engineering Inc. Photo Dana Wheelock, ©Wheelock Photography. skyline. Courtesy Jacobs Engineering Inc. Photo Dana Wheelock, Wheelock Photography. In addition to lifecycle cost savings, the the same total heating capacity (250,000 tion was estimated to reduce the cost of analysis predicted that the higher process lb/hr); but this configuration was expect- utilities, operation and maintenance by efficiency would substantially reduce the ed to reduce the total cost of utilities, an additional $98 million over the same university’s carbon footprint. operation and maintenance by $69 mil- 20-year period! lion in the first 20 years of operation. OPTIMIZATION OF CHP However, the original recommen- The University of Minnesota teamed dation did not represent the optimal THE SINGLE TURBINE SOLUTION WAS with Jacobs Engineering Group Inc. in CHP solution. As a general rule, a plant ESTIMATED TO REDUCE THE COST OF December 2011 to provide detailed en- designed around a single, larger turbine UTILITIES, OPERATION AND MAINTENANCE gineering design, construction