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The Fundamentals of Combined Heat and Power(CHP)
Presented to:Association of Energy Engineers
Kansas City ChapterApril 18th, 2008
Presented By:John Cuttica
Midwest CHP Application Center (MAC)University of Illinois at Chicago
www.chpcentermw.org
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Topics to be Covered
CHP Concept Overview
CHP Technology Building Blocks– CHP Resource Guide (Pocket CD)
CHP Example Market Applications– www.chpcentermw.org (RAC Project Profiles)
CHP Economic Analysis– CHP Tool Kit
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Conventional Energy SystemElectricity:– Either purchased from the local utility (regulated market)
or purchased from the utility / competitive electric provider (de-regulated market)
– Power is generated at a central station power plant– Normally generated at approx. 30% energy efficiency (10
units of fuel in, 3 units of electric power (kW) out)– 70% of the fuel’s energy is lost in the form of heat vented
to the atmosphere
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Conventional System
Thermal (heating)– Normally generated on-site with multiple boilers (hot
water or steam loop)– Boiler energy efficiencies between 60% and 80%
Thermal (cooling)– Normally use electric chillers with chilled water loop– May use some absorption chillers in conjunction with
electric chillers to offset peak electric demands
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Conventional SystemCentral Station Electric Power (30% efficiency)
Boilers at the Facility Provide Heat (60% to 80%)
Chillers either using electricity produced at 30% or steam produced at 60% to 80% (Absorption)
__________________________________________
Conventional System Energy Efficiency– Depends on heat/power ratio– Typical system efficiencies range from 40% to 55%
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Distributed Generation
DG is …
• An Electric Generator
• Located At a Substation or Near a Building / Facility
• Generates at least a portion of the Electric Load
DG Technologies …..
• Solar Photovoltaic
• Wind Turbines
• Engine Generator Sets
• Turbine Generator Sets• Combustion Turbines• Micro-Turbines• Steam Turbines
• Fuel Cells
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Combined Heat & Power (CHP)A Form of Distributed Generation
CHP is …
An Integrated System
Located At or Near a Building/Facility
Provides at Least a Portion of the Electrical Load and
Recycles the Thermal Energy for
– Space Heating / Cooling– Process Heating / Cooling– Dehumidification
Picture Courtesy of UIC
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Combined Heat and Power
Natural Gas
Propane
Digester Gas
Landfill Gas
Coal
Steam
Waste Products
Others
35%
50%
15%
100%
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Normal CHP ConfigurationCHP Systems are Normally Installed in Parallel with the Electric Grid (CHP does not replace the grid)
Both the CHP and Grid Supply Electricity to the Customer
Recycled Heat From the Prime Mover Used for:– Space Heating (Steam or Hot Water Loop)– Space Cooling (Absorption Chiller)– Process Heating and/or Cooling– Dehumidification (Desiccant Regeneration)
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What Makes A Good CHP Application?
•• Good Coincidence Between Electric and Thermal Good Coincidence Between Electric and Thermal LoadsLoads
•• Large Cost Differential Between Electricity (Grid) Large Cost Differential Between Electricity (Grid) and CHP Fuel and CHP Fuel ------ ““Spark SpreadSpark Spread””
•• Fair / Favorable Regulatory EnvironmentFair / Favorable Regulatory Environment•• Long Operating HoursLong Operating Hours•• Economic Value of Power Reliability is HighEconomic Value of Power Reliability is High•• Installed Cost Differential Between a Conventional Installed Cost Differential Between a Conventional
and a CHP System (and a CHP System (smaller is bettersmaller is better))
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Candidate Applications for CHPHospitals
Colleges / Universities
High Schools
Residential Confinement
High Rise Hotels
Fitness Centers
Food Processing
Livestock Farms (Digesters)
Waste Water Treatment Facility
Landfill
Ethanol / Biodiesel Plants
Pulp & Paper Mills
Chemicals Manufacturing
Metal Fabrication
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What are the Customer Benefits of CHP?
CHP does not make sense in
all applications, but where it
does make technical and
economic sense, it will provide- Lower Energy Costs
- Reduced Energy Consumption
- Increased Electric Reliability
- Standby Power
- Improved Environmental Quality
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Installed CHP85,184 MW at approx. 3100 sites (Nationally)
Represents approx. 9% of total US generating capacity
Saves an estimated 3 Quads of fuel per year
Eliminates over 400 million tons of CO2 emissions annually
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Kansas / Missouri CHP InstallationsKansas: Total 15 sites ----- 125 MW– US Energy Partners 2001 – 14 MW Ethanol Plant– East Kansas Agri Energy 2005 – 2 MW Ethanol– Prairie Horizon Agri 2006 – 4 MW Ethanol
Missouri: Total 19 sites ---- 227 MW– NE Missouri Grain 2000 – 10 MW Ethanol Plant– Bolling GSA Office 2000 – 100 KW Office Bldg.– Lewistown School District 2003 – 60 KW– POET Biorefining 2007 – 10.7 MW Ethanol
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Market ChallengesUnstable / Uncertain Energy Prices
Lack of Awareness of the Technology Concept, Status, Benefits, and Issues
Electric Utility Resistance
Need for Internal Champions: Technical & Financial
Competing for Capital Development $
Quantifying Non Utility Cost Benefits
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CHP – Technology Building Blocks
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Combined Heat and Power
Natural Gas
Propane
Digester Gas
Landfill Gas
Coal
Steam
Waste Products
Others
35%
50%
15%
100%
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CHP Prime MoversReciprocating EnginesIndustrial Gas TurbinesMicro-turbinesFuel CellsSteam Turbines
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Reciprocating Engine – Energy Distribution
Recycled Heat Good for Hot Water / Low Pressure Steam
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Reciprocating EnginesCaterpillar
Waukesha
Cummins
Wartzila
Jenbacher
Fairbanks-Morse
Waukesha
Caterpillar
Fairbanks-Morse
Jenbacher
Wartzila
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Turbines
Industrial / Aero-derivative Gas Turbines
Micro-turbines
Steam Turbines
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Gas Turbine - UsesAircraftPower Generation– Electric Power Plants– Marine Power Applications– CHP
• Second Most Commonly Used CHP Prime Mover• Generally Used in Larger Systems (>4 MW)• Used When High Quality Waste Heat Required
(High Pressure Steam)• Low NOX Emissions
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How a Gas Turbine Works
1. Intake Air2. Compress Air3. Heat Up the Air
by Burning Fuel4. Re-Expand the
Hot Air
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1
3
4Compressor
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Small PackagesTurbine Here is Roughly 2 feet in Diameter
Output is 7 MW (~10,000 HP)
Solar TurbineSolar Turbine
Power = Torque X Speed
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MicroturbinesAutomotive Turbo-charger Technology
Available in sizes 30 kW to 400 kW
Emissions Better than Recip Engines, not as Good as Gas Turbines -- < 0.49 lbs./MWH
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Microturbine Performance
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Steam TurbinesOne of the oldest prime mover technologiesHigh-pressure steam flows through the turbine blades and turns the turbine shaftSteam turbine shaft is connected to an electric generator for producing electricityPower output is proportional to the steam pressure drop in the turbineNo emissions from turbines
– Emissions are from the boilers used to produce steam
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Hydrogen Rich Fuel
Fuel Reformer
DC PowerPower Section
Air
WATERWATERHEAT ANDHEAT AND
CLEANCLEANEXHAUST
AC Power
Power Conditioner
Natural Gas
Standard Power:Standard Power:480 Volts, 3 phase, 480 Volts, 3 phase,
3 wire, 60Hertz3 wire, 60Hertz
Source: Midwest CHP Application Center
Fuel Cells
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Fuel Cells
Hot Water1750 F33 – 45%Limited Commercial
Proton Exchange Membrane
(PEM)
Steam1,2000 F50 – 60%CommercialMolten Carbonate
(MCFC)
Steam1,8000 F40 – 45%DemonstrationSolid Oxide (SOFC)
Hot Water4800 F38 – 45%CommercialPhosphoric Acid (PAFC)
Heat Utilization
Operating Temperature
EfficiencyAvailabilityFuel Cell Type
Rules-of-Thumb
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Rule of ThumbWhich Prime Mover to Use – T/P Ratio
T/PDivide total thermal (c) by total electric (e)f.
3. Determine T/P Ratio
BtusMultiply by 3,413 Btu/kWh to get Btus purchased e.
kWhSum # of kWh used over last 12 months of billsd.
2. Determine Electric Power Use
BtusMultiply Btus purchased by Boiler Eff. (typical 80%) c.
BtusMultiply a by 100,000 to get thermal Btus purchasedb.
ThermsSum # of therms used over last 12 months of bills a.
1. Determine Thermal Use
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Rule of Thumb T/P Ratio
Consider Steam Turbines3 to 20
Consider Gas Turbines1 to 10
Consider Engines0.5 to 1.5
If T/P =
- If T/P is between 1 and 10 & generator capacity > 1,000kW, choose industrial gas turbine
- If T/P is between 1 and 10 & generator capacity < 1,000kW, choose micro-turbine
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Two Types of Generators
Induction• Requires External Power
Source to Operate (Grid)• When Grid Goes Down,
CHP System Goes Down• Less Complicated & Less
Costly to Interconnect• Preferred by Utilities
Synchronous• Self Excited (Does Not Need
Grid to Operate)• CHP System can Continue to
Operate thru Grid Outages• More Complicated & Costly
to Interconnect (Safety)• Preferred by CHP Customers
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Grid InterconnectionAny CHP Interconnection Must Address:– Safety of customers, line
workers, general public– Integrity of the grid & quality
of service– Protection of equipment– System Control by the utility
Consult with your Electric Utility Early
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System Configuration Rules of Thumb
CHP systems normally interconnected “in parallel”to the grid (electricity supplied by the grid & CHP system simultaneously)
CHP systems normally sized for the thermal load of the facility (excess power sold to the grid, shortage purchased from grid)
Black Start Capability: Should the grid and the CHP go down, the CHP system can be restarted without grid support (needs synchronous generator).
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Absorption Chillers
Absorption Chillers Provide Chilled Water (Cooling)
Refrigeration Cycle Is the Same as Electric Chillers
Major Differences are:– Electric/Mechanical Compressor Replaced with
an Absorber/ Generator– Refrigerants are Different (LiBr and H2O)
CHP Recycled Heat (Water, Steam, Exhaust Gas) Provides “Power” for the Thermal Compressor
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Absorption Chiller Process Schematic
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Desiccant DehumidificationDesiccant DehumidificationActive Desiccant Wheels
Desorption
Desiccant Heater orCHP Reject Heat
Process AirEnteringhumid
Sorption
Reactivation AirEnteringexhausted after passing through wheel
Process AirExitingdrier, warmer
Reactivation AirExitingwetter, cooler
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CHP Equipment, What Have We Covered?
Prime Movers– Recip. Engines, Turbines, Fuel Cells
Generators– Synchronous, Induction, Inverters
Heat Recovery Uses – Space/Process Heat, Absorption Chillers,
Desiccant Dehumidifiers
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CHP Is A Low Technical RiskUtilize Proven Technologies
Employ Standard Design Practices
Incorporate Good Maintenance Practices
CHP Is More a Financial and Regulatory Risk
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CHP – Example Market Applications
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Hospital Application – Reliable Power
Lake Forest Illinois – 214 Beds
4 – 820 kW NG Engines
Frequent Power Interruptions:– 50 to 60 Instantaneous
Outages per Year
CHP Plant: 90% electricity needs, & 30% of the steam load
Installed Cost: $2.7M
Annual Savings: ≈ $640k while reducing power interruptions from 50 to 2
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Hospital Application – Energy Security
Mississippi Baptist Medical Center– 624 bed full service hospital
5th Hour: Lost Grid Power for 52 hours– Elevators on Emergency Power– Restricted Use of MRI– Rest of Operation on CHP
4.0 MW Gas Turbine with HRSG and Absorption Chillers
Value of CHP– Remained open & operational (only
hospital in area to do so)– Provided clothing, food, & housing
August 29th, 2005Hurricane Katrina Hits
Jackson MS.
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Ethanol Plant - PartnershipProvides 60% of Plant Steam Requirements & Full Electric BackupPower Fed to the Local Grid –Plant Purchases Power from the Rural Electric CoopSystem Built on Ethanol Plant, Purchased, Operated, Maintained by the City of MaconCity and Plant Split Cost of Turbine Fuel– Plant gets access to the steam – The City gets credit for the
generation at 50% of normal fuel cost
40 MGY – 10 MW Gas Turbine System
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Biogas Application – Anaerobic Digester
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Interesting FactsBiogas (Anaerobic Gas) Contains:– Methane (CH4) ------ 60 to 70%– Carbon Dioxide (CO2) ------ 30 to 40%– Moisture (considered a saturated fuel)– Traces of: Hydrogen Sulfide, Nitrogen, Hydrogen etc
(Siloxanes present in Landfill and WWTF biogas)– BTU Content ----- ≈ 650 Btu/ft3
1 Dairy Cow Produces ≈ 50 to 80 ft3 per day (5 cows per kW)
1 Hog Produces ≈ 4 to 6 ft3 per day (100 pigs per kW)
1 Beef Cattle Produces ≈ 25 to 40 ft3 per day (10 per kW)
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Products from Anaerobic Digestion
Solid Digestate or Fiber
Biogas
Filtrate
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Biogas Application – Anaerobic Digester Reduces Odor up to 85%
Manages On-Farm Waste to Gov’t Specs
Revenue Streams:– Reduces Electricity Costs– Produces Carbon Credits– Fiber used for Animal Bedding– Liquid Fertilizer (reduces cost of high
phosphor fertilizer)
Recovered Heat Used to Maintain Digester Temperature and On Farm Applications
800 Cow Dairy FarmPearl City, Illinois
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Industrial Application – Steam TurbinePlant Produces 120 psig Steam for Distillation Process – Use Atmospheric Pressure for EvaporatorsStandard Industrial Process –Pressure Reducing Valves (PRV)Install Backpressure Steam Turbine in Parallel with PRV– Pressure drop produces 1.6 MW– ≈ $180,000 per year electric savings
First Ethanol Plant in the U.S. to Incorporate this CHP Concept
Garnett, KansasBackpressure Steam Turbine
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CHP – Economic Analysis
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Technical & Economic Analysis
Implementing CHP System Requires Significant Time, Effort, and Investment
Many Variables to Consider
Every Application Should have an Investment Grade Analysis Performed (Level 4)
Four Levels Of Analysis:
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Four Levels Of Analysis:
Level 1: Preliminary Analysis – Very Rough Rules of Thumb
Level 2: Site Screening– Based on Avg. Annual / Monthly Utility Data– Technical Brief Provided in Handout Material
Level 3: Conceptual Design & Financial Analysis– Should be Based on Hourly Load Data– Computer Models and/or Spread Sheet Analysis Utilized
Level 4: Detailed Design & Engineering Analysis– Full Scale Engineering Study
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Level 3 Computer ModelsSoftware Cost URL Primary Use
BCHP Screening Tool FREE
http://www.ornl.gov/sci/engineering_science_technology/cooling_heating_power/success_analysis_BCHP.htm
Commercial Buildings
Building Energy Analyzer $780 http://www.interenergysoftware.com/BEA/BEAAb
out.htm Commercial Applications (some Industrial)
Cogen Ready Reckoner FREE http://www.eere.energy.gov/de/chp/chp_applicatio
ns/feasibility_analysis.html Industrial Applications
D-Gen Pro $675 http://www.interenergysoftware.com/DGP/DGPAbout.htm
CHP Heating Applications in Commercial Buildings
GT Pro $7,000 www.thermoflow.com Industrial Gas Turbine Applications
Heatmap CHP $4,000 http://www.energy.wsu.edu/ftp-ep/software/heatmap/Heatmap_CHP_5_flyer.pdf
CHP and District Heating and Cooling Applications
Plant Design Expert (PDE) $3,000 www.thermoflow.com Industrial Applications
using Gas Turbines
RECIPRO $1,500 www.thermoflow.com Small Commercial / Industrial
SOAPP-CT .25 $7,500 http://www.soapp.com/soapp/dg/ Industrial Gas Turbine Applications
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Thank YouJohn Cuttica
Midwest CHP Application CenterUniversity of Illinois at Chicago
www.chpcentermw.org
??Questions??
