Cooling, Heating, and Power (CHP) Revolution at UIC
UIC is growing rapidly and already has underway a 10-year south campus project including housing for more than 750 students, three major academic buildings, more than 850 units of market-rate residential housing, new retail establishments, and parking facilities. On the west side of campus, a $100-million College of Medicine research building and other new high-tech research facilities will be constructed by 2003.
To manage the energy needs of this thriving institution, the UIC fiscal plant team is continuing on a course originally begun in the early 1990s, when the university first started to generate some electricity for the east campus.
When complete and linked together, the east and west campus CHP plants will generate enough power to supply electricity to its entire 8-million-sq-ft (2.4-million-m2) campus, as well as provide steam for two neighboring hospitals, various state of Illinois buildings, and a few private entities.
"The east and west campus CHP plants are about one mile (1.6 km) apart and are designed to operate as if they are a single plant," said Ken Buric, director of utility operations for the university. "We've installed a 69,000-V electrical line between the two campuses that will link the two CHP plants. A control system will determine which prime mover, or combination thereof, will operate based on the electrical and heating load."
East Campus CHP PlantUIC began generating power at its east campus CHP plant in 1993. Two Cooper-Bessemer 20-cylinder LSVB engines drive Ideal Electric generators, each rated at 6.3 MW. The initial 12.6 megawatts elecrical (MWe) capacity of the plant served the base electrical load of the east campus.
Seven years later, two Wartsila 18V28SG engines driving ABB generators rated 3.8 MWe each were added to pick up the east campus' seasonal load, which is primarily the electrically driven centrifugal chillers in the university's central chilled water plant. This addition brought the east campus CHP plant's total capacity to about 20 MWe.
The Wartsila 28SG lean-burn engine is characterized by its high electrical efficiency, dependable operation, and low maintenance cost. The engines will be managed and monitored with a state-of-the-art control and supervision system, that will enable a reliable and flexible operation with a minimum number of personnel.
The east campus plant operates with the existing engines supplying the campus with electricity and thermal energy for heating and cooling. The plant is equipped with supplementary-fired hot water generators to efficiently meet the energy needs of the university.
Power at the east campus is generated at 12 kV and distributed to the buildings as 12 kV via a university-owned distribution system. Each building has switchgear, transforming 12 kV down to 480 V for building use.
"All engines at the east campus facility are equipped with high-temperature hot water heat recovery systems," said Buric. "The east campus uses 400 degrees F (205 degrees C) water and distributes it throughout the campus for heating and absorption air conditioning.
"The two Wartsila engines at the east campus have gas-fired afterburners for emissions control, and supplemental firing of the heat recovery boilers. This was necessary because the EPA considered the east and west CHP plants as a single source of emissions." On the Wartsila engines, heat is first routed through a gas-fired afterburner and then through heat recovery boilers. Engine exhaust from the Cooper-Bessemer engines is routed through heat recovery boilers with recovered heat tied into the campus' central high-temperature hot water heating distribution system.
The UIC east campus has two electrical loads. "Our nighttime load gets down to about 10 or 11 MWe. At 8 a.m., students wake up, coffee pots get turned on, people start using power, and the load goes up to about 12 or 13 MWe. It will hold there until around 4:30 or 5 p.m. when people go home. Our typical baseload, which is our wintertime load, is 12 or 13 MWe."
"In the summertime, it's a little different because the campus has a central chilled water plant. We've got 6,000 tons (21.0 megawatts thermal (MWth)) of electrically driven centrifugal chillers in our central plant, and it's supplemented by 1,350 tons (4.83 MWth) of absorption air conditioning out in the buildings. We distributed absorption chillers out in the buildings as a heat load specifically for the CHP plant and added a Trane 1,000-ton (3.5 MWth) absorber to our existing chilled water plant."
The university's electrical load goes from a normal daily load of 12 or 13 MW up to a peak load of about 18 MW in the summer. Its peak load comes on around May 1 and turns off around October 15.
East Campus Energy/Financial AnalysisThe following assumptions were made when calculating the east campus CHP plant economics:
- Operates 24 hours/day, 7 days/week.
- Majority of the time the plant generates sufficient electricity to meet east campus demands.
- When site demand exceeds generation, power is purchased from the utility. When generation exceeds demand, excess is sold back to the utility.
- The 7.6 MWe addition provided by the Wartsila engine-generators began operation in July 2000. Therefore, the analysis assumed six months of plant operation at 12.6 MWe and six months at 20.2 MWe.
- Since the 1,000-refrigeration tons (RT) absorption chiller was not commissioned until May 2001, it was not included in the analysis.
- The baseline plant that the east campus CHP plant was compared to purchases all of its electricity from the utility and provides heating and cooling through the heating boilers and electrical chillers.
- The same thermal loads are used for the baseline plant and the CHP. The load is supplied by the high-temperature hot water generator in the baseline plant instead of part of the load provided by recovered engine heat.
East Campus Financial ResultsThe original east campus CHP plant (12.6 MWe) began operating in 1993 with the following economic results:
- Total cost: $15 million.
- Original goal: Payback in 10 years.
- Actual performance: Payback in 7.5 years.
- Operating savings: Approximately $2 million/yr.
The east campus CHP plant upgrade began operation in mid-2000 (additional 7.6 MWe systems and heat recovery) and the following economic data has been collected:
- Total cost: $10.7 million.
- Original goal: Designed for a payback of 10 years.
- Actual performance: First full year of operation will be 2001.
- Operating savings: $1.9 million in 2000 (With only six months of operation with the additional 7.6 MW and no 1,000-RT absorption chiller operation).
It is important to note that the $1.9 million in annual savings was calculated at a time when natural gas prices were at record highs.
For the east campus CHP plant, the annual costs are based on the actual monthly expenditures paid by the university. For the baseline plant, estimates have been made for the annual cost of electricity and natural gas.
Based on total costs, CHP provides an estimated savings of $1,931,518 that correlates to an 18.62% savings for the year 2000. However, these savings are lower than experienced in previous years because natural gas costs for several months during 2000 were uncharacteristically high. A sensitivity analysis was performed assuming the same information for both the CHP and baseline plant, but assuming various average natural gas prices fixed for the year. The estimated savings based on various gas prices are provided below.
Additional ConsiderationsTaking into consideration replacement of electricity and recovered thermal energy, the east campus CHP plant provides an overall source energy reduction of 14.15% (236,856 MMBtu/yr). The CHP also represents an estimated 28.5% (29,545 tons/yr) reduction in CO2, a 52.8% (126 tons/yr) reduction in NOx, and an 89.1% (551 tons/yr) reduction in SO2.
The Cooper-Bessemer units have been running for over 50,000 hours without a major overhaul. While they are operated almost exclusively on natural gas, the ability to operate on #2 diesel fuel provides additional flexibility.
The university recently installed catalytic oxidizers on the Cooper-Bessemer engine-generators and afterburners on the Wartsila engine-generators to receive emission credits, which were applied to the installation of the engine-generators at the west campus facility. Emission testing has not yet been performed on the retrofitted engines.
West Campus CHP Plant"A steam plant already was in existence on the west campus," said Buric, which had a capacity of 750,000 lb/hr of 150-psi (10.35 bar) steam. "We removed four of the existing seven boilers and used those emissions credits to help us get our new plant permitted."
When completed, the west campus CHP plant will have a load capacity of 37.2 MWe, with the ability to increase its load capacity to 50 or 55 MWe, depending on what future prime movers are installed. The plant will have a maximum heat output of approximately 360,000 lb/hr (45.4 kg/s) or 150-psi (10.35 bar) steam, plus an additional 360,000 lb/hr (45.4 kg/s) from existing boilers.
The west campus plant includes three solar Taurus 70 combustion turbines driving Ideal Electric generators each rated at 7 MWe. Three supplemental turbine exhaust duct firing systems and three ERI heat recovery steam generators (HRSGs) will produce 120,000 lb/hr (15.1 kg/s) of steam.
Three 5.4 MWe Wartsila 18V34SG lean-burning, reciprocating engines will drive ABB generators currently with no heat recovery. The engines are equipped with catalytic oxidizers for pollution control.
The site permits for the facility were readily obtained. As part of the agreement for the site permit, the university retired four of the old boiler units on the west campus and retrofitted catalytic oxidizers on the two Cooper-Bessemer units and installed afterburners on the Wartsila engine-generators on the east campus.
The new, 37.2-MW west campus CHP plant is expected to commence operation in late 2001. Calculated economics for this facility are:
- Total cost: $38 million.
- Original goal: Designed for a payback of 7 years.
- Actual performance: First full year of operation will be 2002.
- Operating savings: Estimated annual savings of $7 million.
Poised for the Future"Our plant is designed to serve our needs at the university with some capacity for redundancy. Both projects were totally financed by the university with no federal, state, or utility subsidies. We believe that the future of CHP systems that service multiple facilities like universities and district energy systems will be very bright as the electric utilities continue to restructure," Buric concluded.
These two CHP plants are not the only energy-efficiency-related activities at UIC. The Energy Resources Center (ERC) is a College of Engineering (UIC) interdisciplinary public service, research, and special projects organization dedicated to improving energy efficiency and the environment. It was established in 1973 by the board of trustees as an approved Illinois Board of Higher Education center with the mandate to conduct studies in the fields of energy and environment and to provide industry, utilities, government agencies, and the public with assistance, information, and advice on new technologies, public policy, and professional development training.
The ERC is not a traditional university academic unit. The center was created as a "fast response" team of experts capable of quickly extending technical expertise, advice, and professional assistance to organizations in need of the center's resources. To carry out these objectives, the ERC is staffed by a group of hands-on professional engineers, economists, architects, computer science specialists, educators, and public policy analysts. In brief, the center's staff represents "technical specialists" accustomed to working collaboratively with our clients at their respective institutions.
CHP for Buildings Program at DOEElectricity has been supplied by regulated monopolies for nearly a century with vertically integrated utilities selling electricity they generated, over wires they own, to captive customers. The entire framework of regulation of this industry, both at the federal and the state levels, has operated on this basis. One rationale for this structure in the past was the belief that a regulated monopoly could sell power more cheaply and efficiently than a multiplicity of competitors. Technological advancements have largely relegated this rationale to the dustbin of history.
Distributed energy resource technologies provide site-specific benefits to end-use customers and electric utilities, such as high power quality, improved reliability, and low-cost power delivery.
Advancement in on-site power technologies and growth of thermally activated equipment has led to packaged and modular CHP systems being developed specifically for institutional and commercial buildings.
About 53% of the end-use loads in commercial buildings are potential users of recoverable thermal energy while about 42% of the end-use requires some form of electric energy.
CHP is the most efficient use of fossil fuels because it captures and utilizes heat that is generated during the power production process and utilizes it in the form of building heating, cooling, and/or humidity control.
Over two hundred technical and policy experts representing manufacturers, utilities, building operators, research and development organizations, industry associations, ESCOs, engineers, universities, and national laboratory personnel worked together to define their vision for on-site/near-site power generation; energy recovery; energy management; and utilization for commercial, institutional, multifamily, and community-based buildings.
2001 Brings DOE Partnership to UICIt is difficult for advanced technology trying to enter the building industry. This is particularly true when examining complex systems requiring engineering expertise. The modern consulting engineer is not paid to take risks and, to some extent, today's engineering depends more on quickly and cheaply copying the past than engineering the future.
The Department of Energy (DOE), partnering with industry, believes an essential element to integrating new energy-efficient technologies, like CHP, requires education of the engineering community, the building trades, real estate developers, and building owners.
In partnership with UIC's ERC, DOE's Office of Distributed Energy Resources has formed the first of several Regional Application Centers at its Chicago campus. The Application Center's mission is to:
- Assess their respective regions for opportunities for CHP.
- Manage a "SWAT Team" of technical experts that can be dispatched on a cost-shared basis to develop strategic CHP projects.
- Provide critical interface with state agencies, Public Utilities Commissions, legislatures, EPA, ASHRAE, etc. to move the CHP benefit agenda forward.
- Maintain installation database for all installation within the region.
- Develop pertinent educational material including regional-based case studies, presentation material, and workshops.
EDITOR'S NOTE: Some of the graphics that accompany this article can not be translated to this website. If you wish to view the graphic, please refer to the print version of this issue.
EQUIPMENTWest Campus CHP Equipment
- Three natural gas Wartsila engine-generators rated at 5.4 MWe each.
- Three natural gas Solar Taurus turbine-generators each rated at 7.0 MWe. These turbines require gas pressure to be increased to 300 psi from the nominal 150 psi delivered to the site.
- Three dual-fuel (natural gas/#6 fuel oil) boilers.
- Three exhaust gas heat recovery systems with duct burners on each of the solar turbines that are capable of providing a total capacity of 90,000 lb/hr (11.3 kg/s) to 360,000 lb/hr (45.4 kg/s) of steam.
East Campus CHP Equipment
- Two Cooper-Bessemer dual-fuel reciprocating engine-generators each rated at 6.3 MWe.
- Two Wartsila 18V-28SG natural-gas reciprocating engine-generators each rated at 3.8 MWe.
- Four exhaust gas heat recovery systems providing a total recovered energy of 30 MMBtuh (8.8 MWth).
- Two jacket water heat recovery systems for a total recovered energy of 8 MMBtuh (2.4 MWth).
- Several remote building absorption chillers, activated by the hot water loop, for a total of 1,350 tons (4.83 MWth).
- One Trane two-stage absorption chiller rated at 1,000 RT (3.5 MWth).
- Three high temperature hot water generators (natural gas/#6 fuel oil): two rated at 75 MMBtuh (22 MWth) and one rated at 50 MMBtuh (15 MWth).
- Three York International electric centrifugal chillers each rated at 2,000 RT (7.0 MWth).