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Combined Heat & Power (CHP) Success Stories

ALL SYSTEMS COGENERATION, INC.

Background

All Systems Cogeneration, Inc. is a developer and operator of small-scale cogeneration systems. Their combined heat and power plants help meet the electrical and thermal needs of the host facility while reducing energy costs. The company has installed thirteen internal combustion engines at eleven different retirement centers throughout the state of New York.

Project Description

The CHP systems consist of a 60 kW internal combustion engine (manufactured by Coast Intelligen, Inc.) with heat recovery from the engine block, engine oil, and exhaust manifold. The engines burn natural gas and use 3-way catalysts to lower NOx emissions. The electricity generated by the engines directly feeds into the main distribution panel of the facilities, and the recovered thermal energy serves individual buildings. Thermal output is used for space heating, production of domestic hot water, heating for swimming pools and Jacuzzis, and for air conditioning through a steam absorption chiller.

All Systems Cogeneration, Inc. Cogeneration Plant Operating Data for 1999*

Project Design Capacity (MWe) 0.78
Power to Heat Ratio 0.5
Total Net Efficiency (HHV) 76%
% Fuel Savings [1] 11% (140 metric tons of carbon)
Effective Electric Efficiency (HHV) [2] 65%
% NOx Decrease [3] 79% (12 tons)

*Data based on 8,500 annual hours of operation

[1] Savings based on 50% efficient electric and 83% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.83). Assumes thermal output provided at 83% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Success Strategy

All Systems focuses on retirement centers because they are ideal locations for CHP. They have nearly constant thermal and electric demands and sizing the projects to be thermally base loaded maximized economics. All Systems incorporates 14,000 gallons of thermal storage in at each facility to take full advantage of heat recovery. By opting not to sell electricity back to the grid, All Systems avoids interconnection issues.

Benefits

The projects implemented by All Systems Cogeneration demonstrate the use of combined heat and power at institutional facilities. Besides saving money for clients by limiting power purchases from the grid, the cogeneration facilities also provide a positive emissions benefit. Compared to separate heat and power, the company&##8217;s eleven cogeneration systems annually save a combined total 10 million standard cubic feet of gas, equivalent to 570 tons of CO2. The carbon reduction is comparable to the planting 160 acres of forest or displacing the annual greenhouse gas emissions from 50 households. The combined NOx reductions are equal to the annual emissions from 600 vehicles.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of these CHP facilities with a CHP Certificate of Recognition. More information on #settings.esLogo# CHP awards.

All Systems Cogeneration, Inc. (PDF, 70K) PDF

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THE COLLEGE OF NEW JERSEY

Background

The College of New Jersey (TCNJ) is located in Ewing, NJ, and is part of New Jersey&##8217;s state system of higher education. The campus occupies 340 acres and has a central steam, chilled water, and cogeneration plant to service 3.2 million square feet of building space, including housing facilities for students. There are currently 6,700 students enrolled at the college.

Project Description

In late 1999, the four-year-old 3.2 MW Solar Centaur T-4700 water-injected gas turbine was scheduled for an overhaul. However, recognizing the need for a larger turbine to accommodate increased campus energy demand, TCNJ decided to replace, rather than refurbish, the existing turbine. The new turbine increased the plant&##8217;s power output by 2 MW, improved efficiency to 77%, and improved the environmental performance of the plant. The new Solar Taurus 60 gas turbine was installed in December 1999 with minimal modifications to the existing heat recovery steam generator (HRSG)/duct burner and other plant equipment. The gas turbine and duct burner use natural gas as the primary fuel. Distillate fuel oil with a sulfur content of 0.1% (by weight) is used when natural gas is not available.

TCNJ Cogeneration Plant Operating Data for 2000*

Project Design Capacity (MWe) 5.2
Power to Heat Ratio 0.5
Total Net Efficiency (HHV) 77%
% Fuel Savings [1] 13% (900 metric tons of carbon)
Effective Electric Efficiency (HHV) [2] 71%
% NOx Decrease [3] 72% (55 tons)

*Data based on 8,342.75 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Success Strategy

The air permit obtained by TCNJ for the larger turbine required the plant to meet more stringent emission limits of 25 part per million (ppmdv) for NOx and 50 ppmdv for carbon monoxide. However, at the time the project was being evaluated in July 1999, Solar Turbines did not manufacture a Centaur gas turbine capable of achieving the required emissions limit. Therefore, the College decided to install a 5.2 MW Solar Taurus 60 gas turbine with SoLoNox technology that met the necessary emissions requirements.

Benefits

By switching from a 3.2 MW output to a 5.2 MW output, the project increased the amount of on-site generation from 68% to 90% of total campus electricity needs. In addition, by installing a new gas turbine instead of overhauling the existing Centaur turbine, the amount of available waste heat increased by 30%. This in turn reduced the duct burner firing duty by 36%. Even though the power output of the plant rose by 56%, by replacing a 42-ppm turbine with a 25-ppm turbine there was a reduction in potential NOx emissions of 2.6 tons/yr. The replacement of the water injection system with a dry low NOx combustor yielded the extra benefit of decreasing water consumption. The annual NOx reduction from this facility is equivalent to the annual emissions from 2,800 vehicles.

The project provides significant financial benefits to the college. In spite of higher gas prices, total cost savings in the year 2000 were $3.2 million. TCNJ expected to save more than $3.6 million in 2001.

The project also offers significant climate benefits. The effective electric efficiency of the facility is 71%. This is 17% better than the best electric-only fossil-fired generation. Compared to separate heat and power, the project annually conserves 66 million standard cubic feet of natural gas and emits 3,800 fewer tons of CO2. This is equivalent to planting 1,000 acres of trees or offsetting the annual greenhouse gas emissions from 340 households.

In March 2001, the United States Environmental Protection Agency and Department of Energy presented an ENERGY STAR CHP Award to The College of New Jersey for &##8220;demonstrating leadership in its campus energy supply.&##8221; More information on #settings.esLogo# CHP awards.

The College of New Jersey (PDF, 70K) PDF

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THE DOW CHEMICAL COMPANY

Background

The Dow Chemical Company develops and manufacturers a portfolio of chemical, plastic, and agricultural products and services in 170 countries around the world. With annual sales more than $18 billion, Dow conducts operations through 14 global businesses employing 40,000 people. The company has 123 manufacturing sites in 32 countries and supplies more than 3,500 products.

Dow initiated an ambitious &##8220;Power Conversion Project&##8221; in the mid 1980&##8217;s because of the higher efficiencies and environmental benefits that could be achieved through cogeneration. The Freeport Texas Operations (one of the world&##8217;s largest chemical complexes) is Dow&##8217;s largest manufacturing operation in terms of pounds of product manufactured. The energy intensive research and production processes of the site made cogeneration an ideal choice. The Freeport complex manufactures plastics, epoxies, and hydrocarbons among many other products.

Project Description

The Dow Chemical Company maintains four cogeneration plants to meet the expanding power and steam demands at the Freeport Texas Operations complex. These plants (primarily fired by natural gas) include twelve combustion turbines with heat recovery steam generators ranging in size from 65 MW to 100 MW. This system is supplemented by three 500,000-lbs/hr boilers with back pressure steam turbines.

Dow&##8217; s Freeport Texas Operations Cogeneration Plant Operating Data for 1999*

Project Design Capacity (MWe) 1,600
Power to Heat Ratio 0.8
Total Net Efficiency (HHV) 74%
% Fuel Savings [1] 14% (230,000 metric tons carbon)
Effective Electric Efficiency (HHV) [2] 67%
% NOx Decrease [3] 57% (12,000 tons)

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Success Strategy

Dow has a corporate goal to improve energy efficiency by 20% from 1994 to 2005. This is in addition to the 20% improvement accomplished from 1990 to 1994. With this type of high-level support for energy efficiency, funds and personnel are available for cost-effective projects to reduce energy intensity. Dow&##8217;s cogeneration project in Freeport, Texas is a financial success, providing significant power and steam costs savings. The complex uses approximately 87% of the electricity generated and sells the remainder to the grid.

Benefits

The project also produces considerable emissions benefits by reducing emissions of NOx, SOx, and CO2. The annual NOx reduction from the facility is equivalent to the annual emissions from 610,000 vehicles. The project benefits the climate since it uses 14% less fuel than separate heat and power, conserving 16 billion standard cubic feet of natural gas a year, and annually releases 930,000 fewer tons of CO2. This is the equivalent of planting 250,000 acres of forest or displacing the annual greenhouse gas emissions from 84,000 households.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an #settings.esLogo# CHP Award. More information on #settings.esLogo# CHP awards.

The Dow Chemical Company (PDF, 230K) PDF

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LOUISIANA STATE UNIVERSITY & SEMPRA ENERGY SERVICES

Background

Louisiana State University (LSU) is located in Baton Rouge, Louisiana and has a population of 24,000 faculty, staff, and students, and a 650-acre main campus with 160 buildings. Sempra Energy Services, the project developer, offers commercial and institutional business energy outsourcing services.

The original central power plant at LSU serviced a limited number of buildings and the university had to maintain eight small additional facilities to supply the energy needs of the remaining buildings on campus. Over time, the combination of the central power plant and smaller satellite plants decreased in efficiency and overall reliability because of constant modifications to the system and the addition of new buildings to the system. LSU realized it needed a more modern and reliable central power plant. In November 1989, LSU negotiated an energy performance contract with Sempra to construct a cogeneration system to meet increased chilled water and steam demand on campus. The new cogeneration system was linked to the older central power plant to supplement existing chilled water and steam service.

Project Description

LSU initially envisioned chilled water generation from a turbine-driven chiller that could respond to variable campus cooling loads, coupled with waste-heat recovery from the turbine for campus-wide steam distribution. The existing contracted rate structure with the local utility precluded electric generation, but since electricity was not generated by the project this was not relevant. Sempra Energy Services&##8217; modeled their &##8220;part-load&##8221; cogeneration plant on this concept. The system consists of a 5,000 HP gas turbine direct driving a 6,300-ton chiller and producing 115,000 lb/hr of steam using a waste heat boiler and supplemental firing.

LSU Cogeneration Plant Operating Data for 1999*

Project Design Capacity (MWe) 3.8 (mechanical)
Power to Heat Ratio 0.5
Total Net Efficiency (HHV) 77%
% Fuel Savings [1] 14% (560 metric tons of carbon)
Effective Electricity Efficiency (HHV) [2] 71%
% NOx Decrease [3] 24% (10 tons)

*Data based on 8,322 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

To ensure a paid-from-savings status, the scale of the project had to be expanded by upgrading from the originally intended 4,200-ton chiller to a 6,300-ton chiller. In order to accommodate the increased chiller capacity, several satellite plants were tied into the new system so that it now serves 100 of the approximately 160 buildings on campus. The end result is 4.5 miles of underground piping, 8,000 tons of cooling capacity, and 2.25 miles of fiber-optic cable to control the delivery of steam and chilled water.

Success Strategy

Limited state funding and strict procurement regulations had prevented LSU from implementing new systems and undertaking capital renewal projects. These difficulties were overcome in 1987 when Louisiana authorized state agencies to enter into energy performance contracts. LSU&##8217;s performance contract proved to be the solution to the university&##8217;s cash flow and capacity problems. Sempra provided the financing ($18 million) to meet the university&##8217;s expansion needs with no additional out-of-pocket cost to the institution. The performance contract allowed project savings to pay for the investment.

Benefits

The project saves the university about $4.7 million in energy costs each year. The plant performed so well and consistently met targeted savings that the university exercised its right to opt for an early buy-out in 1994. At the time, the plant had increased in value by $10 million on a net present value basis.

The project also has significant climate benefits as it annually saves 39 million standard cubic feet of natural gas (emitting 2,200 less tons of CO2) compared to conventional separate heat and power generation. This is the equivalent of planting 610 acres of forest or offsetting the annual greenhouse gas emissions from 200 households. The annual avoided NOx emissions are equivalent to the annual emissions from 530 vehicles.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an ENERGY STAR&##174; CHP Award. More information on #settings.esLogo# CHP awards.

Louisiana State University & Sempra Energy Services (PDF, 70K) PDF

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MALDEN MILLS

Background

Malden Mills, a family-owned textile mill based in Lawrence, Massachusetts, has annual sales of $400 million and is the exclusive producer of Polartec&##174; and Polarfleece&##174; synthetic fabrics, and various other upholstery fabrics. Henry Feuerstein, grandfather of current CEO and owner Aaron Feuerstein, founded Malden Mills in 1906. When a fire destroyed three out of ten buildings on its complex in December 1995, Aaron Feuerstein decided to rebuild the mill rather than relocate or dissolve the business. He later won numerous accolades for his decision to continue paying employees for three months while the mill was being rebuilt.

Project Description

The CHP project was implemented in two phases. The first phase of the project involved the installation of two Solar Centaur turbines with heat recovery steam generators. Each unit is rated at 4.2 MW and 23,800 lbs/hr of steam. The second phase of the project in 1999 involved retrofitting both turbines with ceramic combustor liners to reduce NOx emissions to 15 parts per million (ppm).

Malden Mills Cogeneration Plant Operating Data for 1999*

Project Design Capacity (MWe) 8.4
Power to Heat Ratio 0.6
Total Net Efficiency (HHV) 71%
% Fuel Savings [1] 8% (740 metric tons carbon)
Effective Electric Efficiency (HHV) [2] 60%
% NOx Decrease [3] 84% (83 tons)

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Success Strategy

When Malden Mills first submitted a plan for a cogeneration facility in 1992, the Massachusetts Department of Environmental Protection rejected it on grounds that without additional controls the plant would not meet the state&##8217;s NOx emission standards. After the fire, the company intended to rebuild the facility and incorporate a CHP system. In order to comply with environmental regulations Malden Mills collaborated with The Department of Energy&##8217;s Advanced Turbine System (ATS) program. The company proposed an ultra-low-NOx CHP system built through the ATS program in 1997, for which the state granted a technology demonstration permit.

To comply with the air permit and achieve additional emissions reductions Malden Mills installed continuous fiber ceramic composite combustion liners on the two Solar Centaur turbines in 1999. This technology provided a substantial environmental benefit and decreased the facility&##8217;s NOx emissions by 40 percent, from 25 ppm to 15 ppm.

Benefits

Besides saving Malden Mills $1 million annually, the project reduces pollutant emissions. The annual NOx reduction from the facility is equivalent to the annual emissions from 4,300 vehicles. The project benefits the climate since it uses 8% less fuel, annually saving 52 million standard cubic feet of natural gas, and releasing 3,000 fewer tons of CO2 each year than separate heat and power. This is the equivalent of planting 810 acres of forest or displacing the annual greenhouse gas emissions from 270 households.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with a Certificate of Recognition. More information on #settings.esLogo# CHP awards.

Malden Mills (PDF, 68K) PDF

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RUTGERS UNIVERSITY

Background

Rutgers University of New Jersey is located on three regional campuses: New Brunswick/Piscataway, Camden, and Newark. Total student enrollment is 48,000 (13,500 of them graduate students); the university employs 2,600 faculty.

A central plant has provided district heating at Rutgers University in Piscataway, NJ since 1950. The University completed the Busch Cogeneration Plant in December 1995 to economically meet the needs of an expanding campus. The system provides electricity, hot water, steam for campus laboratories and dining hall-serving lines, and district cooling using absorption chillers.

Project Description

The old central heating plant consisted of one 50 MMBtu/hr and two 100 MMBtu/hr high temperature water heaters primarily fueled by natural gas. The system also contained two 250 kW backup diesel generators to provide emergency power to the heating plant. To meet increasing heating demand Rutgers chose to cogenerate because of the efficiency and cost savings. They added three Solar Taurus 60 gas turbines with three heat recovery high temperature water heaters (HR-HTWH), which together produce up to 14 MW of electric power and 75 MMBtu/hr of heat. When needed, duct burners produce an additional 75 MMBtu/hr of thermal energy increasing the total thermal output of the turbines to 150 MMBtu/hr. The resulting facility is an integrated plant with a heating capacity of 400 MMBtu/hr. The heat generated maintains 250,000 gallons of water in the closed-loop high temperature hot water system at a nominal temperature of 370&##176;F. The entire HTHW system is maintained at 150 psig (above the saturation pressure) to prevent boiling in the system. The water is then piped to campus buildings using four zone pumps.

Rutgers University Cogeneration Plant Operating Data for 1999*

Project Design Capacity (MWe) 14
Power to Heat Ratio 0.5
Total Net Efficiency (HHV) 73%
% Fuel Savings [1] 9% (1,900 metric tons of carbon)
Effective Electricity Efficiency (HHV) [2] 62%
% NOx Decrease [3] 66% (150 tons)

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Success Strategy

Rutgers provided seed money for a feasibility study, with university bonds funding project development and construction. During the feasibility study, the University spent considerable time in mapping current and future trends in campus electricity and thermal energy consumption and comparing them to fuel and power prices. This process identified cogeneration as the most economic match for meeting their energy demands.

After repayment of capital and interest, savings that the plant generates accrue to a special account, the Energy Conservation Savings Fund, which supports energy efficiency projects. The new demand-side management program saves another $1 million a year.

Benefits

The Busch Cogeneration Plant has an overall efficiency of 73 percent, and meets approximately 90 percent of the Busch and Livingston campuses&##8217; winter electric demands (two of the four campuses located at the University&##8217;s New Brunswick site), and about half the demand in summer. This translates into savings of $1.5 to $2 million in annual utility costs. The University expects to recover its investment in the plant within a payback period of five years.

In addition to the monetary gains, the plant offers significant pollution prevention benefits. It uses 9 percent less fuel than separate heat and power, conserving 130 million standard cubic feet of natural gas and 470 barrels of oil a year, which equates to 7,600 tons of CO2 annually. This is the equivalent of planting 2,100 acres of forest or offsetting the annual greenhouse gas emissions from 680 households. The NOx reductions are equivalent to the annual emissions from 7,700 vehicles.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with a CHP Certificate of Recognition. More information on #settings.esLogo# CHP awards.

Rutgers University (PDF, 68K) PDF

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TRIGEN ENERGY CORPORATION, GRAYS FERRY COGENERATION PROJECT

Background

Trigen Energy Corporation provides heating, cooling, and electricity to more than 1,500 customer facilities nationwide, including municipalities, industrial complexes, hotels, sports arenas, convention centers, and residential complexes. Trigen &##8212; Philadelphia, the largest operating company of Trigen, constructed a new central power plant in 1996 to produce steam for the Trigen Philadelphia District Heating System. The plant, known as Grays Ferry Cogeneration Project (GFCP), was a joint venture between Trigen, PECO&##8217;s Exelon Corp., and NRG Generating.

When Trigen bought the district energy system in 1993, large oil-fired boilers produced the steam. Trigen constructed the new 170 MWe combined cycle plant on the existing Schuylkill Station Plant site. Several of the prior existing boilers serve as reserve and peaking capacity. Trigen provides 375 customers (70% of Philadelphia&##8217;s downtown buildings and institutional facilities) with steam for heating, cooling, domestic hot water production, and cooking through 33 miles of underground steam pipe.

Project Description

The Grays Ferry Cogeneration Project prime mover is a dual-fueled, 118 MWe combustion turbine. The turbine can use either natural gas or ##2 oil, depending on price and availability. Exhaust gas from the combustion turbine produces high-pressure steam, which produces as much as an extra 52 MWe using a condensing/extracting steam turbine. The plant also consists of a stand-alone 700,000 pound per hour auxiliary boiler. In total, the plant has an electric capacity of 170 MWe and a steam output of 1.5 million pounds per hour.

The project integrates several technologies including direct-mechanical drives, direct heating, and absorption chillers among others to bring the overall plant efficiency to 74 percent. In addition, Grays Facility uses a dry low NOx turbine in combination with selective catalytic reduction (SCR) to control NOx emissions.

Trigen &##8212; Gray&##8217;s Ferry Cogeneration Project Operating Data for 1998*

Project Design Capacity (MWe) 170
Power to Heat Ratio 0.6
Total Net Efficiency (HHV) 74%
% Fuel Savings [1] 13% (27,000 metric tons of carbon)
Effective Electric Efficiency (HHV) [2] 66%
% NOx Decrease [3] 77% (1,800 tons)

*Data based on 8,760 annual hours of operation Success Strategy

[1] Savings based on 49% efficient electric and 81% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.81). Assumes thermal output provided at 81% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Trigen formed a partnership with Adwin Cogeneration, a subsidiary of the local utility PECO Energy, as soon as it acquired the district heating system in 1993. Consequently, the Grays Ferry project had a relatively smooth start without lengthy dispute over stranded costs. Adwin supervised the development of the central steam system to handle electric power generation while NRG Generating managed construction of the project. Under the partnership agreement, Trigen-Philadelphia will oversee system operation for the length of its 25-year electric-steam contract, while PECO Energy will purchase up to 150 MW of the plant&##8217;s electricity under a 20-year contract. Currently, the Grays Ferry plant sells 97 percent of electricity generated to the grid.

Benefits

The Grays Ferry project was a particularly attractive investment opportunity for Trigen-Philadelphia, because Philadelphia has one of the largest district energy systems in the United States. For Trigen&##8217;s customers, the district energy system provides economic energy, saves building owners the cost of constructing and operating boilers and chillers, eliminates fuel storage requirements, and increases available leasing space.

While Grays Ferry Cogeneration Project expanded Trigen-Philadelphia&##8217;s energy capacity, it had the added benefit of lowering Philadelphia&##8217;s regional emissions. The annual NOx reduction from the facility is equivalent to the annual emissions from 94,000 cars. The project also uses 13% less fuel than separate heat and power, conserving 1.6 billion standard cubic feet of natural gas and 61,000 barrels of oil a year, and has climate benefits as it annually releases 110,000 fewer tons of CO2. This is the equivalent of planting 30,000 acres of forest or displacing the annual greenhouse gas emissions from 10,000 households.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an ENERGY STAR&##174; CHP Award. More information on #settings.esLogo# CHP awards.

Trigen Energy Corporation, Grays Ferry Cogeneration Project (PDF, 231K) PDF

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TRIGEN ENERGY CORPORATION, OKLAHOMA CITY, OKLAHOMA

Background

Trigen is a developer, owner, and operator of industrial, commercial, institutional, and district energy systems in North America. Trigen acquired the central heating and cooling plant that supplied the energy needs of downtown Oklahoma City in 1989. Soon after the purchase was completed, Trigen began to make enhancements to the facility in order to improve its efficiency and reduce emissions. Today, the Trigen-Oklahoma City plant has 16 employees and supplies the energy and thermal needs of 12 customers in downtown Oklahoma City, with a total of 19 buildings. The plant manages two miles of high-pressure steam piping and two miles of chilled water piping to service its customers.

Project Description

Trigen focused on integrating a mix of technologies to achieve the greatest efficiency gains at the Oklahoma City plant. In 1992, the company chose their patented trigeneration technology for the new system. Trigeneration is the simultaneous production of chilled water, steam, and electricity from a single fuel source. Trigen added a 1.2 MWe gas turbine with a heat recovery steam generator to drive both a 1.2 MWe electric generator and an ammonia screw compressor for the production of chilled water. A steam turbine drives three chillers with capacities ranging from 3,200 hp to 5,500 hp and various pumps and a fan with a total capacity of 2,300 hp. An electric motor drives the fifth chiller in the loop. Together these improvements increased overall plant efficiency, added 2,000 tons of cooling capacity, 6,000 pounds per hour of steam production, and 500 kW of electricity production. Peak capacity for the facility is 99,000 pounds per hour of steam and 11,000 tons of chilled water.

Trigen-Oklahoma City Plant Operating Data for 1998*

Project Design Capacity (MWe) 9
Power to Heat Ratio 0.2
Total Net Efficiency (HHV) 82%
% Fuel Savings [1] 12% (720 metric tons of carbon)

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

Success Strategy

In undertaking the upgrade of the old central heating and cooling plant, Trigen choose to integrate existing technologies to produce steam, chilled water, and electricity. This strategy reduced costs for the company without compromising the ability to meet customer needs or achieve gains in overall plant efficiency.

Benefits

Trigen&##8217;s cogeneration project at the central facility in downtown Oklahoma City significantly decreases production costs. The cogeneration facility is a popular choice with many institutional and commercial buildings in the downtown area. Trigen-Oklahoma City serves the County of Oklahoma, the General Services Administration, and the United States Internal Revenue Service among other prominent customers.

In addition to financial gains, the project has also realized significant climate benefits. Trigen-Oklahoma City uses 12% less fuel than separate heat and power, conserving 51 million standard cubic feet of natural gas a year, which equates to annually reducing 2,900 tons of CO2. This is the equivalent of planting 790 acres of forest or offsetting the annual greenhouse gas emissions from 260 households.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an ENERGY STAR&##174; CHP Award. More information on #settings.esLogo# CHP awards.

Trigen Energy Corporation, Oklahoma City, Oklahoma (PDF, 230K) PDF

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TRIGEN-PEOPLES DISTRICT ENERGY COMPANY, McCORMICK PLACE

Background

Trigen is a developer, owner, and operator of industrial, commercial, institutional, and district energy systems in North America. In 1992, the Chicago Metropolitan Pier and Exposition Authority (MPEA) was planning a 2.2 million square-foot expansion to its 2.8 million square-foot McCormick Place Exhibition and Convention Center and sought to outsource the operation of its existing energy plant and its future energy needs. Trigen partnered with Peoples Energy Corporation to provide the McCormick Place facility with heating, cooling, and power for the duration of the 29-year contract.

In 1997, the contract was expanded to include servicing the new 32-story, 800-room Hyatt Regency Hotel with heating, air conditioning, and domestic hot water. In 2000, the contract was again expanded to provide heating and cooling to the new 250,000 square foot conference center and corporate office complex.

Project Description

Trigen achieved higher efficiencies over the older heating and cooling system by adding three trigeneration machines and a Thermal Energy Storage (TES) system to the original system design. Each trigeneration machine is a combination of a natural gas fueled turbine, a motor/generator, a heat recovery steam generator, and an ammonia screw compressor. This design allows for the simultaneous production of electricity, chilled water, and steam from a single steam source. The TES system is an 8.5 million-gallon chilled water tank (the largest in North America) measuring 127 feet in diameter. Chilled water (Trigen&##8217;s antifreeze additive increases the effective chilling storage capacity by 50%) is produced during the night for use during daytime peak cooling loads. This results in fewer chillers being online during the day with those in operation functioning at higher efficiency. Trigen also added steam absorption chillers to use excess steam generated during summer months thereby enabling chilled water production without the use of CFC refrigerants.

Trigen Energy Corporation &##8212; Chicago, IL*

Project Design Capacity (MWe) 3
Power to Heat Ratio 0.12
Total Net Efficiency (HHV) 84%
% Fuel Savings [1] 11% (1,600 metric tons of carbon)
% NOx Decrease [2] 67% (63 tons)

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.1 lb NOx/MMBtu.

Success Strategy

Trigen partnered with Peoples Energy Corporation to own and operate the energy plant by agreeing to a long-term energy supply contract with MPEA. This allowed MPEA to avoid the $27 million capital outlay required to upgrade the heating and cooling facilities. Additionally, the system design takes advantage of daily and seasonal changes in gas and electric prices, further reducing operating expenditures.

Benefits

The cogeneration facility meets the heating and cooling needs of the McCormick Place Convention Center located in Chicago&##8217;s Park District. This not only saves MPEA $1 million annually, but also allows them to focus on their core business of serving more than 4 million visitors each year.

The efficiency improvements have provided a substantial environmental benefit as well - saving 110 million standard cubic feet of natural gas a year and annual emissions of carbon dioxide are 6,400 tons lower than separate heat and power. This is equivalent to planting 1,700 acres of forest or displacing the annual greenhouse gas emissions from 570 households. The avoided annual NOx emission is equivalent to the annual emissions from 3,200 vehicles.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an ENERGY STAR&##174; CHP Award. More information on #settings.esLogo# CHP awards.

Trigen-Peoples District Energy Company, McCormick Place (PDf, 230K) PDF

TRIGEN ENERGY CORPORATION, TRENTON, NEW JERSEY

Background

The city of Trenton, New Jersey used a grant from the United States Department of Energy to conduct a cogeneration project feasibility study. Officials found that the city could save money by building a cogeneration plant. In order to limit their costs, the city contracted with Trigen Energy Corporation (a developer, owner, and operator of industrial, commercial, institutional, and district energy systems in North America) to build and operate a new cogeneration facility. Trigen developed the district energy system in 1983 to provide for the thermal and electricity needs of 40 buildings in downtown Trenton. When the system came online, it displaced 50 separate boilers and 30 separate chillers. Since then, four new office buildings covering 200,000 to 500,000 square feet have signed up with the facility.

Project Description

Trigen &##8212; Trenton consists of two natural-gas fueled internal combustion engines with capacities of 6 MWe each. The system is primarily gas fired but can also use diesel fuel. Waste heat from the engines produces high temperature hot water. An underground distribution network channels thermal output from the plant to service the city&##8217;s heating load and the local utility purchases the electricity.

In 1985, Trigen began expanding the facility to accommodate district cooling by using waste heat from electricity generation during summer. When the cooling system initially came online in 1988, it began by serving three state buildings. In 2001, service expanded to 31 buildings. A mix of hot water/steam absorption and electric chillers (a combined capacity of 7,500 tons) produce chilled water. A 2.6 million gallon Thermal Energy Storage (TES) chilled water system was installed in 1989 to match the city&##8217;s cooling load and meet peak demand. The tank, which stores chilled water at night for use during the day, reduces the number of electric chillers that must operate and improves the efficiency of the cooling system. In addition, desiccant dehumidification systems in customer buildings allow more precise control of interior conditions.

Trigen &##8212; Trenton Plant Operating Data for 1999*

Project Design Capacity (MWe) 12
Power to Heat Ratio 0.6
Total Net Efficiency (HHV) 75%
% Fuel Savings [1] 13% (2,900 metric tons of carbon)
Effective Electric Efficiency (HHV) [2] 68%

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

Success Strategy

To avoid paying all the construction and maintenance costs by itself, Trigen partnered with another private company. The private company keeps the returns from electricity sales while Trigen retained profits from district heating and cooling services. The agreement allowed Trigen to move forward by reducing its initial capital investment.

Benefits

The Trenton cogeneration plant encourages commercial development in downtown Trenton by providing low-cost heating and cooling. The plant has been well-received by institutional and commercial customers, and has seen a growing client roster since development was completed in 1989. According to Alan Mallach, the Director of the Department of Housing and Development for the city of Trenton, &##8220;The city has realized some energy efficiencies and cost savings, and customers are satisfied with the service.&##8221;

The efficiency improvements have provided a substantial environmental benefit as well &##8212; conserving 190 million standard cubic feet of natural gas and 2,500 barrels of oil and reducing emissions of carbon dioxide by 12,000 tons annually compared to separate heat and power. This is equivalent to planting 3,200 acres of forest or displacing the annual greenhouse gas emissions from 1,000 households.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an #settings.esLogo#&##174; CHP Award. More information on #settings.esLogo# CHP awards.

Trigen Energy Corporation, Trenton, New Jersey (PDF, 230K) ;PDF

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TRIGEN ENERGY CORPORATION, TULSA, OKLAHOMA

Background

Trigen is a developer, owner, and operator of industrial, commercial, institutional, and district energy systems in North America. In 1989, Trigen purchased Tulsa&##8217;s 19-year-old district heating and cooling facility from a local utility. The facility now provides steam for heating, cooling, and domestic hot water services for 32 commercial buildings (approximately one million square feet) in downtown Tulsa under a 20-year contract with the city. A 5-mile underground distribution network feeds steam and chilled water to buildings.

Project Description

When Trigen purchased the facility, it consisted of a large steam turbine driving three centrifugal R-12 chillers with a total capacity of 16,700 tons. This system was coupled with three boilers, each with a capacity of 100,000 lbs/hr at 600 psig. Upon a closer study of the load profile, Trigen decided to replace part of the existing system with 200-ton screw chillers driven by a 1,200 kW gas turbine with an induction motor generator designed to match the chillers&##8217; specific electrical requirements. The base load system meets approximately 50 percent of the annual cooling load of the plant. Trigen supplemented this system by adding two smaller R-134 electric chillers with capacities of 1,000 and 2,000 tons respectively. To further improve boiler efficiency, Trigen channeled exhaust gas from the turbine to the boiler to be used as pre-heated inlet air.

The steam distribution network was upgraded by adding a backpressure steam turbine to replace an existing pressure reducing valve. Lowering the steam pressure from 600 psig to 150 psig through a backpressure turbine generates an additional 500 kW of electricity. Trigen-Tulsa currently sells 75 percent of electricity generated to the grid.

Trigen &##8212; Tulsa Plant Operating Data for 1999*

Project Design Capacity (MWe) 17
Power to Heat Ratio 0.4
Total Net Efficiency (HHV) 77%
% Fuel Savings [1] 11% (1,400 metric tons of carbon)
Effective Electricity Efficiency (HHV) [2] 70%

*Data based on 8,760 annual hours of operation

[1] Savings based on 50% efficient electric and 80% efficient thermal generation with natural gas as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.8). Assumes thermal output provided at 80% efficiency.

Success Strategy

Trigen conducted a thorough study of the load profile at the district heating and cooling facility in order to determine technology additions to the system. This allowed the company to take advantage of most of the existing equipment in the facility, reducing capital investments. Efficiency improvements throughout the new system ensured further capacity gains for Trigen-Tulsa.

Signing a Real Time Pricing (RTP) agreement with the local electric utility further reduced costs. This allows the plant to switch from electric chillers, used during low RTP prices (off-peak period), to steam chillers during high RTP prices (summer peak period). An added benefit to the plant of this fuel-switching capacity was the increase in overall reliability.

Benefits

Technology improvements also increased flexibility, allowed the plant to better match the load profile during periods of low demand, and reduced fuel use by 11 percent compared to separate heat and power. Aside from the economic advantages, technology and efficiency improvements at the plant substantially reduced emissions of CO2. Compared to separate heat and power generation, the system annually saves 99 million standard cubic feet of natural gas and emits 5,600 fewer tons of CO2. This is the equivalent of planting 1,500 acres of forest or offsetting the annual greenhouse gas emissions from 510 households.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with an #settings.esLogo#&##174; CHP Award. More information on #settings.esLogo# CHP awards.

Trigen Energy Corporation, Tulsa, Oklahoma (PDF, 230K)

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THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL

Background

Energy services at the University of North Carolina at Chapel Hill (UNC-CH) are provided by an on-site, university-owned and operated combined heat and power plant. The University has been generating electricity since 1895 and cogenerating since 1939. The steam generated from the plant is distributed through 45 miles of underground piping and provides space heating and cooling, sterilization, domestic hot water, humidification, cooking, and cleaning across the 13 million square foot campus and UNC hospitals. An additional ten miles of piping distributes chilled water.

Project Description

In 1992, the University replaced its previous cogeneration system in order to meet increasing heating needs and to reduce total energy costs. Circulating fluidized bed (CFB) combustion technology was chosen as an environmentally friendly and economical approach to meet campus energy demand. The new plant consists of two atmospheric circulating fluidized bed boilers (producing up to 500,000 pounds of steam per hour), a single steam driven turbo-generator rated at 28 MW (generates 1/3 of campus electric requirements), and a back-up gas and oil fired boiler. The two CFB boilers use bituminous coal as the primary fuel, with natural gas and fuel oil as auxiliary fuels. The back-up boiler is reserved for emergencies and peaking. Steam is generated at a high pressure (1,300 psig) to drive the turbo-generator, and then is extracted through dual variable pressure extraction points for end use on campus. Lower pressure steam resulting from this process is used for space/water heating and driving 11,110 tons of steam absorption chillers for space cooling, while slightly higher pressure steam is used for process loads such as sterilizing medical equipment. The annual plant reliability rating has ranged between 99.61 to 99.99 percent

UNC-CH Cogeneration Plant Operating Data for 1996*

Project Design Capacity (MWe) 28
Power to Heat Ratio 0.3
Total Net Efficiency (HHV) 72%
% Fuel Savings [1] 9% (9,000 metric tons of carbon)
Effective Electric Efficiency (HHV) [2] 66%
% NOx Decrease [3] 24% (180 tons)

*Data based on 8,760 annual hours of plant operation

[1] Savings based on 37% efficient electric and 83% efficient thermal generation with coal as the primary fuel.

[2] Effective Electric Efficiency = (CHP power output)/(Total energy input to CHP system &##8212; total heat recovered/0.83). Assumes thermal output provided at 83% efficiency.

[3] Compared to electric emissions of 3.6 lb NOx/MWh (1998 national average) and boiler emissions of 0.4 lb NOx/MMBtu.

Success Strategy

From conception, the University had to endeavor to gain public approval for the facility. There were two main stages to this process: gaining legislative approval and securing a special land use permit. The University hired a former member of the North Carolina legislature to assist in the legislative process and attained state legislature approval to sell bonds to finance the cogeneration project.

They gained public approval for the use of the land by attending and testifying at public hearings. Since the facility is located in a residential area, the University spent significant resources on noise abatement and designing an aesthetically pleasing plant. Aesthetic measures include tinted blue glass exteriors on the boiler and turbine buildings, active coal storage silos, totally enclosed coal and ash handling systems, extensive landscaping, and reuse of the old stately power plant building for maintenance shops, warehousing, and administration. The noise reduction strategy includes inlet and outlet silencers on fans, noise dampening enclosures, and mufflers on vents. In normal operation, the noise level at the property line is 55 dBa.

The University prepurchased major equipment (CFB boilers, the baghouse, the turbine generator, and the condenser) and this allowed for the designer of record to detail the design of the actual equipment into the project prior to the project design package being released for bidding. The balance of the plant was designed and built on a lump-sum contract. The prepurchased equipment was then assigned to the general contractor.

Benefits

The UNC-CH Cogeneration Facility uses 9% less fuel than separate heat and power generation, saving 16,000 tons of coal annually. The new circulating fluidized combustion technology ensures that combustion occurs at temperatures between 800-900&##176;C, resulting in lower NOx formation, compared to the pulverized coal combustion technology used in the older plant. UNC-CH&##8217;s previous cogeneration plant did not have any emissions controls other than a baghouse for filtering particulates. The newer plant is equipped with a built-in calcium carbonate bin for decreasing SOx emissions, as well as a baghouse. These features enable the University to operate at emissions levels of 0.33 lb/MMBtu of NOx and 0.118 lb/MMBtu of SO2, and reduce emissions over those of the old plant.

The NOx reduction from the facility is equivalent to the annual emissions from 9,200 vehicles. The project also has significant climatological benefits since it emits 36,000 fewer tons of CO2 than separate heat and power. This is equivalent to planting 10,000 acres of forest or offsetting the annual greenhouse gas emissions from 3,200 households.

In 1997, the University switched from a Purchased Power (PP) contract to an Hourly Pricing (HP) structure with their local utility, Duke Power Company. Under this arrangement, Duke Power notifies them of the marginal hourly cost of electricity for the next day. This rate structure gives UNC-CH greater economic flexibility as they use this information to decide whether to make or buy electricity by the hour for the next day. According to the energy services staff at UNC-CH, the cogeneration plant along with the HP rate structure is a huge financial win for the University. While the cost of power under the old PP agreement was approximately 4.3 cents per kilowatt-hour, the University is able to cogenerate power at a marginal cost of less than a penny per Kilowatt-hour. The HP agreement provides a net savings of $750,000 during the summer months of June, July, and August, and total annual avoided costs amount to $1.8 million.

In March 2000, the United States Environmental Protection Agency and the Department of Energy recognized the pollution prevention benefits of this CHP facility with a CHP Certificate of Recognition. For more information on #settings.esLogo#&##174; CHP awards, please click here.

The University of North Carolina at Chapel Hill (PDF, 72K) PDF

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