Optimization of a Cogeneration Systemin the Automotive Industry

Steve SpentzasEnergy Resources Center

University of Illinois at ChicagoMidwest CHP Application Center

Overview• Cogeneration in the Automotive Industry• What is Cogeneration?

– Why Co-generate?– Power Generation Equipment– Heat Recovery

• Case Study– Optimization of a Cogeneration System

• Conclusion

Cogeneration in the Automotive Industry

• The Automotive Industry:– Engine Manufacturers– Part Manufacturers– Assembly Plants

• Ideal for Cogeneration:– High Utility Costs– Coincident Thermal and Electrical Loads– Many Recycled Energy Applications

What is Cogeneration?

• Cogeneration (Cogen) is– An Integrated System– Located at or Near a Building/Facility– Providing a Portion of the Electrical Load and– Utilizes the Thermal Energy for

• Process or Space Heat• Process or Space Cooling• Direct Applications

What is Cogeneration?

Why Co-generate?

• Reduce Energy Costs• Improve Electric Reliability• Improve Power Quality• Improve Economics for Enhancing Indoor

Air Quality• Improve Environmental Quality• Ability to Recycle Waste Heat Streams

Power Generation Equipment

• Reciprocating Engines

• Combustion Turbines

Power Generation Equipment

• Microturbines • Steam Turbines

Power Generation Equipment

Prime Movers Steam Turbine MicroturbinesCapacity Range (kW) --- 100-400

Efficiency (%) 15-40 25-30Installed Cost ($/kW) $300-$700 $2,000-$1,000

Low Grade Heat Recovery --- Hot Water (180oF-212oF)High Grade Heat Recovery --- Low Pressure Steam (15 psig)

O&M Costs ($/kWh) $0.0015-$0.0035 $0.015-$0.001

Prime Movers Reciprocating Engines Combustion TurbinesCapacity Range (kW) 100-2,000 1,000-10,000

Efficiency (%) 24-38 24-28Installed Cost ($/kW) $1,800-$1,000 $1,500-$800

Low Grade Heat Recovery Hot Water (180oF-212oF) Hot Water (over 180oF)High Grade Heat Recovery Low Pressure Steam (15 psig) Low Pressure Steam (150 psig)

O&M Costs ($/kWh) $0.015-$0.012 $0.008-$0.005

Heat Recovery• Heat Recovery Steam Generator (HRSG)

Heat Recovery• Absorption Chillers

Heat Recovery• Direct Use of Exhaust Gasses

Case Study• Engine manufacturer in the Midwest US:

– 8,000,000 square feet• The facility spends: $4,500,000/yr in utilities

– Electrical Costs: $2,000,000/yr– Natural Gas Costs: $3,500,000/yr

• Cogeneration system was installed over a decade ago

• Cogeneration system had a paid its self-back in 7.5 years

The Cogeneration System• 9.2 MW Cogeneration

System• 12 Caterpillar

reciprocating engines• 6 HRSGs (1,200 lbs/hr ea;

7,200 lbs/hr total)– Supplies base summer

load– Boilers fire during winter

• 1.6 MW Backup Diesel Generator

Understanding Electrical Demand

7,000

7,500

8,000

8,500

9,000

9,500

Janua

ryFeb

ruary

March

April

May June

July

August

Septem

ber

Octobe

rNov

embe

rDece

mber

Dem

and

(kW

)

Maximum Electrical Demand as Seen from the Utility

Thermal Equipment

• 3 Oversized Boilers (30 psig steam)– 5,000 lbs/hr-18,000

lbs/hr seasonal steam load

– 2/3 of load for space heating

– Domestic hot water– Very little process

steam usage

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000

20,000

June

July

August

Septem

ber

Octobe

rNov

embe

rDece

mber

Janua

ryFeb

ruary

March

April

MaySt

eam

Flo

w (l

bs/h

r)

Base Load Heating Load

Thermal Equipment

Thermal Equipment

• Decentralized chilled water supply– 500 Tons Total, 1,300

gpm (44oF-54oF)– Engineering Testing

Department (200 tons)– VAV System (300

tons)

Steps to Optimize Plant

• Improved Utility Pricing– Natural Gas:

• Annual Contracting• Monthly Variable Commodity Rate

– Electrical:• Operate Under General Service Energy Pricing• Operate With Day-Ahead Energy Pricing• Operate With Real-Time Energy Pricing

Steps to Optimize Plant

• Improve Electrical Capacity – Reduce plant energy demand– Add generating capacity– Install power factor correction

Steps to Optimize Plant

• Increase Heat Recovery – Convert Distributed Generation units to

Cogeneration units (additional HRSGs)– Install absorption chilling– Reduce winter steam load to meet max

thermal output of cogeneration plant

Conclusions

• Cogeneration at this plant:– Reduces Energy Costs– Improves Electric Reliability– Provides Flexibility for Expansion– Reduced Overall Environmental Emissions– Facilitates Use of Excess Energy Streams– Gives the Facility More Control Over Utility

Costs

Conclusions• How to optimize a cogeneration system:

– Increasing heat recovery increases cost savings

– Installing absorption chilling increases heat recovery and increases cost savings

– Load shedding increases capacity and to avoids the need for additional generators:

• Increased power factor• Reduced electric load from an absorption chiller

Midwest CHP Application Center• Formed by U.S. DOE in 2001• Goal is to provide Education,

Technical Information, and Application Assistance on the concepts and technologies of CHP

• Services (12) twelve state Midwest region (IL, IN, IA, KS, MI, MN, MO, NE, ND, OH, SD, WI)

• Formed close relationships with state energy offices, engineering firms, utilities, and other key CHP stakeholders

Contact Information• Steve Spentzas:

sspent1@uic.edu• Phone: (312) 996-4490• www.chpcenterMW.org

Energy Resources Center• Located at University of Illinois at

Chicago (UIC)• Provide Cost Efficient, Innovative

and comprehensive energy solutions to Our Clients

• Create Effective Working Partnerships With Academia, Industry, Public Institutions, Local and Federal Agencies, Energy Consortiums and Foundations

• Maintain a Strong Commitment to and Actively Implement Innovative Public Outreach and Education

Contact Information• William Worek (Director):

wworek@uic.edu• Phone: (312) 996-4490• www.erc.uic.edu