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Cogeneration
•Cogeneration Definition
•Thermodynamics background
•Cogeneration Parameters
•National Legislation
•Cogeneration Systems & Technologies
•Cogeneration in Portugal
•Cogeneration Facilities (examples)
• Industrial Sector
• Building Sector
Equipamentos Térmicos
Cogeneration Definition
What is cogeneration
Cogeneration: simultaneous production of power and heat,
with a view to the practical application of both products
Equipamentos Térmicos
Cogeneration Definition
What is cogeneration
• Integrated system
• Located at or near a building/facility
• A way of local energy production
• Uses heat that is lost otherwise (cooling, heating,
dehumidification and process heat)
• Way to use energy more efficient
• Different areas of application
• Different technologies
Equipamentos Térmicos
Cogeneration Synonyms
• Cogeneration
• Combined Heat and Power (CHP)
• Cooling, Heating and Power (CHP)
• Trigeneration (Trigen)
• Integrated Energy Systems (IES)
• Building Cooling, Heating, and Power (BCHP)
Equipamentos Térmicos
• Improves energy efficiency
• Conserves natural resources (fossil fuels)
• Lower emissions (including CO2)
• Lower energy costs
• If heat fits demand, cheapest way of electricity production
• Improves security of supply
• Reduces transmission and distribution losses
• Enhances competition
Benefits of Cogeneration
Equipamentos Térmicos
Thermodynamics and Cogeneration
Thermodynamics:
To produce work from heat is necessary a thermal cycle and part
of the energy (heat) obtained from the hot reservoir is release to
the could reservoir.
Carnot Cycle Efficiency
TB - Cold reservoir temperature
TA - Hot reservoir temperature
Cogeneration:
Is necessary produce heat at an appropriate temperature (Qu
useful Heat).
Equipamentos Térmicos
Combined Gas Turbine Cycle
The combine Gas turbine cycle can be used as a cogeneration
system.
Even when useful heat are not produced, there are a recover of
heat of the gas turbine in the recover boiler. The generated steam
is used tor produce electricity by a Rankine Cycle.
The efficiency of the combined cycle is the sum of the efficiency of
both Cycles
Equipamentos Térmicos
Cogeneration Parameters I
• Electrical/Mechanical Efficiency / Rendimento Mecânico/Electico
•Global Efficiency / Rendimento global ou Factor de utilização de
Energia
•Heat/Power ratio / Razão Calor/Electricidade
Equipamentos Térmicos
Cogeneration Parameters II
• FESR-Fuel Energy Saving ratio / PEP – Poupança de Energia
Primária
• EEE-Equivalente electrical efficiency / REE - Rendimento Elétrico
Equivalente
specific consumption (inverse)
Equipamentos Térmicos
Equivalent Electrical Efficiency
Rendimento Eléctrico equivalente
• DL 538/99 – EEE = 55 % (from 1999)
-EEE = 45 % (1995-1999)
• DL 313/01 from 2001 defines the EEE was a function of the Fuel used in the
Combined heat and Power Plant
•55 % Natural Gás, LPG-liquefied petroleum gas, liquid fuel (not fuel oil)
•50 % Fuel oil, heavy fuel oil
•45 % Biomass or residual fuels with support
•Reference boiler efficiency
•90 % - Fossil Fuel
•70 % - Renewable Fuel
• CR - Energy from Renewable Fuel
•The FESR depends on the Country Electric Systems
Equipamentos Térmicos
Fuel input
Separate
generation
Fuel input
Cogeneration
92
Electricity
35
Heat
50 53
100
Power plant
h = 38%
Boiler
h = 95%
Electricity
h = 35%
Heat
h = 50%
Total
145
Total
100
Energy conservation = (145-100)/145 = 31%
Conventional Generation Versus
Cogeneration
Equipamentos Térmicos
Fuel input
Separate
generation
Fuel input
Cogeneration
81
Electricity
35
Heat
50 53
100
Power plant
h = 43%
Boiler
h = 95%
Electricity
h = 35%
Heat
h = 50%
Total
134
Total
100
Energy conservation = (134-100)/134 = 25%
Conventional Generation Versus
Cogeneration
Equipamentos Térmicos
Fuel input
Separate
generation
Fuel input
Cogeneration
64
Electricity
35
Heat
50 53
100
Power plant
h = 55%
Boiler
h = 95%
Electricity
h = 35%
Heat
h = 50%
Total
117
Total
100
Energy conservation = (117-100)/117 = 15%
Conventional Generation Versus
Cogeneration
Equipamentos Térmicos
Influence of increase the heat production
with a low efficiency equipment
The demand
of heat
increase
The demand of
Heat/Electricity
change over the
year but the
legislation is based
on the annual
value
Equipamentos Térmicos
FESR
Influence of the electric and thermal efficiency on FESR for
different values of Heat/Electricity ratio
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FESR/Global Efficiency Specific
technologies
Heat/Electricity ratio
typical values:
TG Gas Turbine: 0,5-1,5
TV Stream Turbines: 1-4
(back pressure)
Source: Pita, 1995
Equipamentos Térmicos
Thermodynamic Cycles Classification
• Depending on the temperatures at the thermal energy is used
-Bottom Cycles (Heat → Power/Work)
-Top Cycles (Power/Work→Heat)
• Depending on the Technologies
•Gas Cycles – Gas turbines, Diesel/SI Engines with recovery boiler to produce
steam or with the use of flue gases direct on a process (greenhouses, drying
processes)
•Steam Cycles (Rankine cycles) – Water/steam is the work fluid. The hot
water/steam could be used directly on a process or as a energy transport fluid.
•Back Pressure Turbines/ Turbinas de Contrapressão (process that need
steam at an elevate temperature or at high pressure)
•Extraction Condensing Turbines/ Turbinas de Extracção/Condensação to
maximize the Electric generation
•Gas turbine combined cycle – Gas turbine cycle with a recover boiler to
generate steam used in a Rankine Cycle
•Others: Heat Pumps, Fuel Cells
Equipamentos Térmicos
Technologies Main Properties
•The efficiency of a Rakine cycle can reach 40 % and the gas turbine combined
cycle 55 %
•For all cases the global efficiency is near 80 % in CHP
•CHP whit heat pumps have normally a Global Efficiency greater than 100 %
Technology Power (MW) Electric
Efficiency
Extraction/Condensing Steam Turbine 30-300 0.25-0.3
Back Pressure Stream Turbines 1-200 0.2-0.25
Gas Turbines Cycles (0.15) 1-150 0.18-0.35
Internal Combustion Engines 0.05 – 25 0.35-0.4
Fuel Cells 0.005 – 0.2 0.37-0.4
Equipamentos Térmicos
Turbine Cycles used on Electric Power
Generation
Cycle
Source: Horlock, 1987
W Q The electric efficiency increase
Gas Turbine
Steam Turbine
Combined Gas Turbine
The cycle with the lower
electric efficiency allows the
use of heat at a higher
temperatures
In the steam turbine and
combined gas turbine cycle
to maximize the electric
efficiency the heat should be
reject at the lower possible
temperature
Equipamentos Térmicos
Source: Horlock, 1987
In the steam turbines plant an
increase in the useful Heat Qu
decrease the electric efficiency
Its normal have several levels
of temperature to use the Qu
In the steam turbine and
combined gas turbine cycle
the thermal energy is used to
generate steam in the recover
boiler, In the stream turbine
cycle the steam is expand in a
turbine to produce electricity
Cycle
Sigel Turbine Cycles for Combined Heat
and Power Plats
Equipamentos Térmicos
Cogeneration Parameters for Single
Turbines Cycles
Source: Horlock, 1987 (reference values considered ηT=0.9 and ηE=0.4)
Cycle E Qu ηg FESR QU/E
Extraction/Condensing Steam Turbine 0.38 0.10 0.48 0.057 0.26
Back Pressure Stream Turbines 0.25 0.60 0.85 0.235 2.4
Gas Turbines Cycles with recuperator 0.30 0.55 0.85 0.265 1.83
Combined gas turbines (Gas/back pressure Steam Turbines)
0.40 0.42 0.82 0.318 1.05
In the gas turbine cycle the injection of steam (generated in the recover
boiler) in the turbine increase the electric capacity and the electric efficiency
(STIG).
Equipamentos Térmicos
* taken from Cogeneration Guide, Cogen Europe
Typical Cogeneration Performance
Parameters
Equipamentos Térmicos
DL 23/2010 de 25 de Março de 2012
•Adaptation of the European directive 2004/8/CE
• Defines benefits/premium to the cogenerations sector based on:
1) Reduction of the primary energy consumption and CO2 emissions
2) Promote the high efficiency cogeneration plants and renewable
cogeneration based on renewable sources of energy
3) Promote the integration of Cogeneration in the electricity market
•Define two exploration regimes
•General regime (all capacity): The market define the energy price
(temporary-benefit/premium for Plant with Electric capacity < 100 MW)
•Special regime (Electric capacity < 100 MW):
•The market define the Heat price
•The tariff of the electricity have benefit/premium based on the efficiency
Equipamentos Térmicos
Portaria 140/2012 de 14 de Maio de 2012
•Review of the Cogeneration Electric Tariff
• Reference tariff for the Natural Gas, LPG or liquid Fuel (except Fueloil)
Cogeneration Plants:
• 89.89 €/MWh for Electric capacity < 10 MW
• 80.44 €/MWh for Electric capacity between 10 MW and 20 MW
• 70.33 €/MWh for Electric capacity between 20 MW and 50 MW
• 63.95 €/MWh for Electric capacity between 50 MW and 100 MW
•Reference tariff for the Cogeneration from renewable sources:
• 81.17 €/MWh for Electric capacity < 2 MW
• 65.92 €/MWh for Electric capacity between 2 MW and 100 MW
•Reference tariff for the Fueloil Cogeneration Plants:
• 89.12 €/MWh for Electric capacity < 10 MW
• 79.96 €/MWh for Electric capacity between 10 MW and 100 MW
•Hora ponta/hours with high electricity demand + 10%
•Vazio e supervazio/ hours with low electricity demand -13 %
Equipamentos Térmicos
Prémios de eficiência / Efficiency
premium
a) PEm Efficiency premium value in month m
b) PC Reference costs for the valorization of Primary Energy saving 28.71 €/MWh
c) PEP Primary energy savings (certified)
d) EEPlm Net electric energy generated by the cogeneration plant in month m
(total electric energy generated – electric energy consumed by the Cogeneration Plant)
e) K Primary energy saved differentiates factor
(0.5 to high efficient cogeneration plant and 0.3 efficient plant)
f) EP/EE Ratio between the Primary Energy consumed by the Cogeneration Plant
and the Electric energy generated (typical values)
Equipamentos Térmicos
Ratio EP/EE
i) Natural gas Internal combustion engines: 2.86
ii) Gas Turbines (Natural Gas) eclectic capacity < 20 MWe: 3.70
iii) Gas Turbines (Natural Gas) eclectic capacity > 20 MWe: 3.12
iv) Fueloil Internal combustion engines: 2.60
v) Steam turbines: 5
vi) Combined gas turbines: 2.5
vii) Renewable cogenerations plats: 5
Equipamentos Térmicos
Portaria 140/2012 de 14 de Maio de 2012
Transition Regime:
•Plants with electric capacity > 20 MW
•The transition to the new remuneration regime occurs at the beginning of
the month following the EEGO audit (EEGO - entity that certifies the
primary energy savings)
•For all other cases the transition occurs in the following quarter
•During the extension period, the reference tariff for no renewable
installations is depreciated annually by one percent, for installation with a
capacity of 20 MW or less
Equipamentos Térmicos
Portaria 140/2012 de 14 de Maio de 2012
Cogeneration Classification:
•According to capacity
-< 1 MW Small Cogeneration
-< 50 kW Micro Cogeneration (Biomass Plant Electric capacity < 3.68 kWe
have a subsidized regime DL 363/2007)
•introduces efficiency levels :
-high efficient cogeneration plant:
-Efficiency: Other cases
Equipamentos Térmicos
Electric Energy Certification
•The electricity produced in cogeneration plant with high efficiency is certified
based on a series of data (fuel, amount of heat used, PEP, CO2 emissions)
•EEGO – Is the entity responsible for certificates the Cogenerations electrical
energy (and control the CO2 emissions)
•DGEG – Is the entity that identify the high efficiency Cogenerations Plants.
•For the installations type a) and c) the annual global efficiency as to be > 80 %
•For the installations type b), d), e), f), and g) as to be > 75 %
•When the annual global efficiency are lower, the C implicit value is used to
calculate the:
ECHP = HCHP/C
Equipamentos Térmicos
Cogenerations Installations Types
a) Combined gas turbine cycle with heat recover 0.95
b) Back pressure steam turbines 0.45
c) Extraction/condensing steam turbine 0.45
d) Gas turbine wit heat recovery 0.55
e) Internal combustion Engines 0.75
f) Microturbines
g) Stirling Engines
h) FuelCells
i) Steam Engines
j) Rankine Organic Cycles
l) Other technologies
Technologies for small plants
Implicit ratio
C = E/H
Equipamentos Térmicos
Economics
Costs:
• Capital
• Operation and maintenance
• Fuel
Benefits:
• Heat
• Electricity less purchase
sell to grid
Economic value of cogeneration
• Depends very much on tariff system
• Heat: avoided cost of separate heat production
• Electricity: less purchase (kWh); sale of surplus electricity and peak
shaving (kWe)
• Carbon credits
Cogeneration Economics Analysis
Equipamentos Térmicos
Economic Analysis
PT-Payback Time \ Tempo de retorno do investimento
NPV - Net Present Value \ VAL – Valor Atual líquido
IRR - Internal Rate of Return \ TIR – Taxa interna de Rentabilidade
•The Payback time in a first approach is determine by:
PT = Initial Investment / Annual Cash flow
Cash flow= (Revenues - Expenses)
•NPV/VAL:
CFi – Cash Flow in year i
Ii – Investment value in year i
ai – Discount Rate (the rate of return that could be earned on an investment in
the financial markets with similar risk.); the opportunity cost of capital
i – time period
•TIR/IRR- The discount rate that makes the net present value of all cash flows from a
particular project equal to zero. Generally speaking, the higher a project's internal rate of
return, the more desirable it is to undertake the project.
Equipamentos Térmicos
Economic Analysis
IRR - Example
Year (i) Cash flow (i)
0 -123400
1 36200
2 54800
3 48100
In this case r = 5.96%
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Economical Parameters
•The Fuel price/cost
•The Electricity price/cost
•The useful heat price/cost
•The cost of the useful heat depends of the temperature level at the
heat is used.
•Price-weighted Global Efficiency / Factor de utilização de energia
ponderado pelo preço
*Heat pump produce heat by a compressor cycle (using electricity) PE = 0.1
Fuel Heat €/kWh(ηT = 90 %)
Propane/Butane Gas LGP 0.09
Natural Gas 0.05
Diesel for heat 0.05
*Heat pump (Cop = 4) 0.03
Heat approximate costs (Investment costs not included)
Equipamentos Térmicos
Reference Efficiency Values
Source: Manual de Procedimentos da EEGO Entidade Emissora de Garantias de Oringem
Available: www.dgeg.pt (areas sectoriais-energia electrica-produção em regime especial
Equipamentos Térmicos
Reference Efficiency Values
Source: Manual de Procedimentos da EEGO Entidade Emissora de Garantias de Oringem
Available: www.dgeg.pt (areas sectoriais-energia electrica-produção em regime especial
Equipamentos Térmicos
Reference Efficiency Values
Source: Manual de Procedimentos da EEGO Entidade Emissora de Garantias de Oringem
Available: www.dgeg.pt (areas sectoriais-energia electrica-produção em regime especial
Equipamentos Térmicos
Reference Efficiency Values
Source: Manual de Procedimentos da EEGO Entidade Emissora de Garantias de Oringem
Available: www.dgeg.pt (areas sectoriais-energia electrica-produção em regime especial
Equipamentos Térmicos
Example
Source: Cogen Portugal
Otto Natural gas Engine Gas engine
Nominal Electrical Power 1100 kW
Fuel Natural Gas
Electrical Grid Connection Tension 0.380 kV
Annual Average Temperature 19 ºC
Construction year 2006
Annual operating hours 8 000 h
Fuel consumption (LHV based) 25 150 MWh
Useful Heat 10 560 MWh
Electrical Energy Generated 8 800 MWh
Electrical Energy Consumptions 176 MWh
Global Efficiency
FESR-Fuel Energy Saving Ratio
Reference Electrical efficiency corrected by the average temperature
Fraction of Electric Energy Exported to the National Electric System
Correction factors
Equipamentos Térmicos
CO2 Emission- EEGO Proceedings
Manual • CO2 emissions from CHP
• Avoid CO2 emissions
The CO2 emissions factor are defined by the IPCC, intergovernmental Panel on Climate
Change, publish in Despacho 17313/2008 (June 26).
Source: Manual de Procedimentos da EEGO Entidade Emissora de Garantias de Oringem
Equipamentos Térmicos
Cogeneration in Portugal
The installation of Cogeneration Plants in Portugal occurred in three phases:
-1st Large industries
-2nd The possibility of sold electricity to the National Electric System
-3rd The introduction of Natural Gas in Portugal (Otto, GT and CC)
Cogeneration Install Capacity in Portugal
Natural gas
Engines
Natural gas
Turbines
Heavy
Fueloil
Engines
Back
pressure
Turbines
Propane
Engines Biogas
Engines Micro
Turbines
New CHP Plants:
Combined gas turbine
cycles in Sines and
Matosinhos Petroleum
Refinery
Source: Cogen Portugal
Equipamentos Térmicos
Sector by Technologies
Cogeneration Install Capacity by Technologies
The back pressure Steam turbine are installed
mainly in the Pulp paper and chemical Industries
Natural gas
Engines
Natural gas
Turbines Heavy Fueloil
Engines
Back pressure
Turbines
Propane
Engines
Biogas
Engines
Micro
Turbines
Pulp Paper Industry Chemical and
Petroleum Industry
Food Industry
Others Industry Textile Industry
Total capacity at the end of 2005 1200 MW
Actually the Combined Gas Turbines and the Gas
turbines are present in some of this sectors
Equipamentos Térmicos
Sector by Fuel
Fueoil Cogeneration Install Capacity by Sector
Other include the building Sector
Fueloil Engines have environmental
limitations
Some Fueloil Engines can be converted
to Natural Gas
Natural Gas Cogeneration Install Capacity by Sector
Total Natural Gas Capacity at the end 2005 322 MW
Wood Food
Textile Others
Chemical
Glass an Ceramics
Pulp paper
Tertiary
Wood
Food
Textile
Others
Chemical
Glass an Ceramics
Pulp paper
Tertiary
Equipamentos Térmicos
Pulp Paper Industry Cogeneration Plant
Two steam boiler produce steam for one
circuit
The steam circuit have different pressures
levels
The biomass boiler burn wood residues
rejected by the pulp paper process
The recover boiler burn black liquor
Equipamentos Térmicos
Internal Combustion Engines
Source: Horlock, 1987
Capacity MW
Input Energy Fraction
Electricity 7.5 40 %
Heat 6.7 35 %
Capacity MW
Economizer 1.0
Recover Boiler 3.0
Jacket 2.7
Equipamentos Térmicos
Commercial Center Colombo
Cogeneration Plant
ηg = 86 %
EEE = 37 %
Electric Capacity 37 MW
Shops 11.2 MW
Hyper Market 4 MW
Commons Spaces 21.7 MW
Cooling Capacity 14.8 MW
3 Compressor Chillers
2 Absorptions Chillers
Diesel /Fueliol Engines
Convertibles to
Natural gas
Equipamentos Térmicos
Combined Gas Turbine Plants
GALP - Oil Refining Plants - combined gas cycle
Electric Capacity [MW]
Exported Eclectic
Energy (MW)
Steam Production (t/h; bar)
EEE/REE (%)
Matosinhos 80 60-80 200; 67 65
Sines 2 X 80 100-140 415; 82
Fuel: Natural Gas and Refinery Gas
Equipamentos Térmicos
• Industrial cogeneration wood and agro-industries, food processing, pharmaceutical, pulp
and paper, oil refinery, textile industry, steel industry, cement
industry, glass industry, ceramic industry
• Residential/commercial/institutional cogeneration hospitals, schools and universities, hotels, houses and apartments,
stores and supermarkets, office buildings
Typical Cogeneration Applications
Equipamentos Térmicos
Trigeneration Plant Climaespaço
absorption chiller
Gas turbine
Heat exchanger inside
the buildings
Equipamentos Térmicos
Main Steps to Realize The Cogeneration
Project
1) Obtain the representative annual diagram of useful/economical Heat/Cooling based on
demand.
1) Based on the dally diagram for different month of the year
2) Careful with the temperature/condition necessary to use the heat
2) Research /define the technology appropriate to the Energy demand
1) Electrical capacity
2) Economical Useful Heat capacity
3) Turn down ratio
4) Availability Factor
5) Type of Fuel and efficiency of the equipments
6) Energy needed to operate (peripherals equipments)
7) Energy Storage Systems
8) Startup time
9) Live time of the equipments
3) Define the business model and the Operation Conditions
1) Useful heat price – Based on Market values
2) Electricity Energy Price – Based on Market values
3) Investment
4) Maintenance/Operational Cost – Based on Technical information
5) Other cost (environmental tariffs, eventual financial penalties when the cogeneration plant have
to stop, other cost associate to the project, taxis,)
Equipamentos Térmicos
Main Steps to Realize The Cogeneration
Project
4) Verify The Legislation/Regulation
Check if the defined operating conditions are according to the legislation / regulation
5) Economical Analisys
Sensitivity analysis of the main project variables
The Final Report:
A descriptions of the heat useful demand and the conditions of the heat client
A descriptions of the CHP and the technology
(technical/economical justification of the option)
Economic analysis of the project
(with a justification of the values used)
Technique analysis that proves the cogeneration benefits:
Reduction of the primary energy consumption
Increasing the efficiency
Reduction of the green gas emissions
Equipamentos Térmicos
Useful Documentation
Available Online
• Decreto Lei n.º 23/2010 de 25 de Março
• Lei n.º 19/2010 de 23 Agosto
• Portaria n.º 140/2012 de 14 de Maio
• Portarian.º 325-A/2012 de 16 de Outubro
• Despacho 17313/2008 de 26 de Junho
• Manual de Procedimentos da Entidade Emossora da Garantias de Origem
www.dgeg.pt (areas sectoriais-energia electrica-produção em regime especial
• Cogen Portugal- Cogeração
http://www.cogenportugal.com/ficheirosupload/Brochura%20Cogera%C3%A7%C3%A3o.pdf
• Estudo do Potencial de Cogeração de Elevada Eficiência em Portugal
(Direcção Geral de Energia e Geologia)