CWA 45547:2004

SLOVENSKI STANDARD
01-januar-2007
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Manual for Determination of Combined Heat and Power (CHP)
Ta slovenski standard je istoveten z: CWA 45547:2004
ICS:
27.010
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/CENELEC
CWA 45547
WORKSHOP
September 2004
AGREEMENT
ICS 27.100
English version
Manual for Determination of Combined Heat and Power (CHP)
This CEN/CENELEC Workshop Agreement has been drafted and approved by a Workshop of representatives of interested parties, the
constitution of which is indicated in the foreword of this Workshop Agreement.

The formal process followed by the Workshop in the development of this Workshop Agreement has been endorsed by the National
Members of CEN and CENELEC but neither the National Members of CEN or CENELEC nor the CEN Management Centre or the
CENELEC Central Secretariat can be held accountable for the technical content of this CEN/CENELEC Workshop Agreement or possible
conflicts with standards or legislation.

This CEN/CENELEC Workshop Agreement can in no way be held as being an official standard developed by CEN or CENELEC and their
Members.
This CEN/CENELEC Workshop Agreement is publicly available as a reference document from the CEN members national standard bodies
or the CENELEC members national electrotechnical committees.

CEN and CENELEC members are the national standards bodies and national electrotechnical committees, respectively, of Austria,
Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United
Kingdom.
Management Centre: CENELEC Central Secretariat:
rue de Stassart, 36  B-1050 Brussels rue de Stassart, 35  B-1050 Brussels
© 2004 CEN/CENELEC All rights of exploitation in any form and by any means reserved worldwide
for CEN national Members and for CENELEC Members.
Ref. No.:CWA 45547:2004 E
Contents Page
Foreword.4
Symbols and Indices .5
1 Objective and Scope .6
1.1 Relation to Annex II of CHP Directive 2004/8/EC 11 February 2004 .6
2 Reading Instructions (Route Map) .8
2.1 Instructions .8
2.2 Annexes .8
3 Definitions .9
3.1 Energies.9
3.2 Dimensionless Figures of Energies.10
4 Description of CHP and Non-CHP Processes.10
4.1 CHP Plant.11
4.2 CHP Process .11
4.2.1 Electrical/Mechanical Energy-to-Heat Energy Ratio .12
4.2.2 CHP Overall Efficiency .13
4.3 Non-Combined Heat Energy Generation.13
4.4 Non-Combined Electrical/Mechanical Energy Generation .14
4.4.1 Electrical/Mechanical Energy Loss.14
5 Determination Principles .16
6 Determination of Energy In- and Outputs .19
6.1 CHP Plant Boundary.19
6.1.1 CHP Plant Area.21
6.1.2 Consumers Area .21
6.2 Determination of Total Fuel Energy (f) .21
6.2.1 Treatment of Recycled Fuel Energy.22
6.2.2 Classification of Fuels.22
6.2.3 Indirect Determination of Fuel Energy Inputs.23
6.2.4 Imported Energy .24
6.2.5 Steam, Hot Water and Hot Gas.24
6.2.6 Justification for crediting the full heat content (above ambient temperature datum) of the
steam used on site as CHP heat output without deducting all the energy in condensate
returned. .27
6.3 Determination of Total Electrical/Mechanical Energy (p) .29
6.3.1 Determination of Total Electrical Energy (p ) .29
e
6.3.2 Determination of Total Mechanical Energy (p ) .29
m
6.4 Determination of Total Useful Heat (q) .31
6.4.1 Determination of Useful Heat from Steam Delivery .31
6.4.2 Hot Water and Thermal Fluid Systems.32
6.4.3 Direct Use of Exhaust Gases.32
7 Determination of NON-CHP Useful Heat Energy and Referring Fuel Energy.34
7.1 Live Steam Extraction .34
7.2 Auxiliary/Supplementary firing.35
7.3 Complex CHP plants .36
8 Determination of Overall Efficiency (ηηηη) .37
9 Determination of NON-CHP Electrical/Mechanical Energy and the Referring Fuel Energy.38
9.1 Determination of Power Loss Coefficient(s).38
9.1.1 Plants without Power Loss .39
9.1.2 Plants with Power Loss .40
Annex A .41
A.1 Small Scale CHP plants .41
Annex B .42
B.1 Determination of Power Loss Coefficients by Performance Test (Example).42
Annex C .44
C.1 Sample Determinations.44
C.1.1 Molten Carbonate Fuel Cell (MCFC) with Back-up Boiler .44
C.1.2 Gas Turbine with Heat Recovery .47
C.1.3 Steam Backpressure Turbine.49
C.1.4 Gas Turbine with Heat Recovery and Supplementary/Auxiliary Firing .51
C.1.5 Combined Cycle Gas Turbine with Heat Recovery and Supplementary Firing .53
C.1.6 Gas Turbine with Heat Recovery and Bypass Facility .56
C.1.7 Gas Turbine with Heat Recovery, Bypass Facility and Supplementary/Auxiliary Firing.58
C.1.8 Combined Cycle Gas Turbine with Heat Recovery, Bypass Facility and Auxiliary Firing.61
C.1.9 Steam Condensing Extraction Turbine with Live Steam Extraction.64
C.1.10 Steam Condensing Extraction Turbine with Heat Recovery from Flue Gas .67
C.1.11 Combined Cycle with Complex Common Steam Header .69
C.2 CHP Plant Descriptions .73
C.3 CHP Plant Monitoring.75
C.3.1 General Metering Requirements .75
C.4 How to Deal with Uncertainties.77
References .78
Foreword
This CEN/CENELEC Workshop Agreement has been drafted and approved by a Workshop of representatives
of interested parties on 2004-06-16, the constitution of which was supported by CEN and CENELEC following
the public call for participation made in January 2003.
A list of the individuals and organizations which supported the technical consensus represented by the
CEN/CENELEC Workshop Agreement is available to purchasers from the CEN Management Centre. These
organizations were drawn from the following economic sectors: national and international energy (electricity,
gas) and in particular CHP/DHC associations , municipalities owning/operating CHP/DHC systems, utilities
owning/operating CHP/DHC systems, industries owning/operating CHP plants, manufacturers of CHP and/or
DHC plants and equipment, engineering and consulting companies, industrial CHP and/or DHC users (pulp
and paper industry, sugar industry).
The final review/endorsement round for this CWA was started on 2004-05-24 and was successfully closed on
2004-06-16.The final text of this CWA was submitted to CEN for publication on 2004-06-28.
This CEN/CENELEC Workshop Agreement is publicly available as a reference document from the National
Members of CEN and CENELEC.
Comments or suggestions from the users of the CEN/CENELEC Workshop Agreement are welcome and
should be addressed to the CEN Management Centre.

CHP/DHC = Combined heat and power / district heating and cooling
Symbols and Indices
Latin symbols Description unit
f fuel energy MWh
p electrical/mechanical energy MWh
q heat energy MWh
Greek symbols Description units
efficiency MWh/MWh
η
power loss MWh/MWh
β
power-to-heat ratio MWh/MWh
σ
Indices Description
CHP combined heat and power
non-CHP non combined heat and power
q heat energy
p electrical/mechanical capacity, electrical/mechanical energy
m mechanical
e electrical
1 Objective and Scope
CHP can make significant fuel and emissions savings over conventional, separate forms of power generation
and heat-only boilers. The generation of electricity from power stations is generally at efficiencies in the range
30-55%, based on the Net Calorific Value (NCV) or Lower Heating Value (LHV) of the fuel. Further losses
occur in the transmission and distribution of electricity to customers. This means that 45-70% of the energy
content of the fuel is not usefully employed. This unutilised energy content is rejected as heat directly to the
atmosphere or into seas or rivers. The generation of electricity and the recovery of heat in CHP plants typically
achieve overall efficiencies of 70-90% and above, corresponding to efficiencies of heat only boilers. The
higher the overall efficiency and the power to heat ratio, the more effective the CHP process.
Unlike conventional methods of electricity generation, in order to achieve such high overall efficiencies, some
of the heat cogenerated in a CHP Scheme is usefully employed in industrial processes or for heating and hot
water in buildings. The heat used in this way displaces heat that would otherwise have to be supplied by
burning additional fuel in boilers or other direct-fired equipment and so also leads directly to a reduction in
CO -emissions. The development of CHP plays a crucial role in the European energy policy for reducing CO -
2 2
emissions.
The determination of CHP products (heat and power outputs) is important not only for the CHP Directive [1]
but also for the European Emissions Trading Scheme [2], State Aid guidelines for environmental improvement
and the energy taxation Directive [3].
The objective of the CEN/CENELEC Workshop Agreement is to present a set of transparent and accurate
formulae and definitions for determination of CHP (cogeneration) energy products and the referring energy
inputs. The CEN/CENELEC Workshop Agreement shall simply formulate the procedure for quantifying CHP
output and inputs, such as CHP electrical energy, CHP mechanical energy, CHP heat energy and CHP fuel
energy. It does not include quality rankings such as assessments of fuel savings or environmental impact.
Gathering statistics and monitoring developments in the combined heat and power sector is difficult and can
contain a considerable number of uncertainties. Some CHP plants may decouple the generation of heat and
power at certain times or to a certain extent and thus CHP and NON-CHP electricity and heat may be
generated in the same plant.
The lack of reliable information and transparency may be considered in itself as a barrier to the further
development of the technology and negatively affects the image of the CHP sector. To remove the ambiguity
resulting from a lack of standardised procedures across Europe, a set of widely accepted determination rules
is needed. Such rules will create greater certainty that the basic concept of CHP is understood and
determined in the same way.
2) 3)
As a result of this requirement the CEN /CENELEC Workshop on "Manual for Determination of Combined
Heat and Power (CHP)" was initiated. It ran in parallel to the discussions on the Directive on the promotion of
cogeneration based on a useful heat demand in the internal energy market [1].

1.1 Relation to Annex II of CHP Directive 2004/8/EC 11 February 2004
The resulting CEN Workshop Agreement (CWA) is to provide guidance for the implementation of Annex II of
the CHP-Directive and the determination of the power-to-heat ratio (see section 5).

2) European Committee for Standardization (http://www.cenorm.be)
3) European Committee for Electrotechnical Standardization (http://www.cenelec.org)
Whereas the amount of CHP electrical/mechanical energy defined as p in the CWA equals E in the
CHP CHP
CHP Directive.
Whereas total useful heat in the CWA (q) covers heat for a justified demand regardless of the possible CHP
character, in the Directive the concept of useful heat implies useful heat from CHP only.
Whereas the amount of CHP useful heat energy defined as q in the CWA equals H in the CHP Directive.
CHP CHP
Whereas the electrical/mechanical energy-to-heat energy ratio defined as σ in the CWA equals the power-
CHP
to-heat ratio C in the CHP Directive.

2 Reading Instructions (Route Map)
This chapter is a route map through the manual. The manual is prepared/designed to handle all kind of plants
and is therefore to some extent complicated when the plant is simple.
2.1 Instructions
Start to read chapter 3 where all the expressions used in the manual are defined and chapter 4 where the
plant is defined and your plant can be classified. The chapter describes the CHP-plant, the CHP-process and
the non-CHP generation of heat and electrical/mechanical energy. For small and simple plants read Annex A
where useful simplifications are presented. For all other plants try to find the example in Annex C which
corresponds to your plant as close as possible and follow the procedure step by step.
A schematic picture of the principles of the manual is given in chapter 5. The figure 5, 6 and 7 show the
principles from a general overview to detailed equations. To simplify your classification and your determination
of the CHP plant see Annex C.2 for instructions to draw a CHP scheme line diagram.
In chapter 6 the CHP plant boundaries are drawn. The principle is to keep the boundaries around the CHP
process itself. Here all inputs and outputs are determined. Fuel input in 6.2, electrical and mechanical energy
output in 6.3 and useful heat output in 6.4. Measurements are default. In case of lack of such measurement,
indirect methods for determination of energy flows can be used provided they supply the adequate accuracy.
Indirect methods are described in chapter 6.2.3 and 6.4.2.
Chapter 7 gives instructions how to separate non-CHP heat and the corresponding fuel. This is necessary in
plants with live steam extraction and/or auxiliary/supplementary firing.
In chapter 8 determination of CHP overall efficiency is described. How to act when the plant can not run in
complete back pressure mode and how to handle the cooling steam in a extraction steam turbine on minimum
load.
Chapter 9 gives instructions how to separate non-CHP electricity and the corresponding fuel.
2.2 Annexes
Read Annex A to learn about how to simplify the determinations for small and simple plants.
Read Annex B to learn about determination of the power loss coefficients for CHP processes with steam
turbines.
In Annex C.1 determination examples are presented. In C.2 instruction for describing of the CHP plant is given.
Here also the Tag notation used in the manual is presented.
When the principles for determination are clear collecting data is the next step. In Annex C.3 and C.4, CHP
plant monitoring and metering requirements as well as how to treat uncertainties is presented.

3 Definitions
For further explanations see section 4 and subsequent sections.
Combined heat and power (CHP) or "cogeneration" is the simultaneous conversion of primary energy into
mechanical and/or electrical energy and useful heat energy in one (the same) plant. Simultaneously means
that the energy content of a the fuel is used for the generation of both heat and electrical/mechanical power at
the same time within a thermodynamic process (the CHP process) (see Article 3 (a) in [1]).
CHP plants are plants that simultaneously can generate electrical/mechanical power as well as useful heat
power. Thereby all or least at a certain extent of generated useful heat power and electrical/mechanical power
can be CHP useful heat power and cogenerated (CHP) electrical/mechanical power.
Reporting Period is the period of time used for reporting and determination of data for the CHP plant.
Heat rejection facilities are devices for the diversion of heat energy by means of which heat energy is
discharged unused into the environment, e.g.:
 Waste heat condensers
 Compression air coolers not connected to a heat recovery system
 Bypass facilities
 Steam condensers not connected to a heat recovery system
 Radiators
 Cooling air coolers not connected to a heat recovery system
 Lube oil coolers not connected to a heat recovery system
 Charge air coolers not connected to a heat recovery system
 Stacks
 Auxiliary coolers not connected to a heat recovery system
The term "bypass" is used for the direct diversion of the flue gases into the environment, avoiding the waste
heat boiler / flue gas heat exchanger. The consequence is incomplete use of the heat in the flue gas.
3.1 Energies
Total useful heat energy (q) is the heat energy (thermal energy) supplied by a plant in a reporting period. It is
heat energy supplied by a plant that would otherwise demonstrably be supplied from other sources.
Change in total useful heat energy (∆q).
Total electrical/mechanical energy (p) is defined as gross electrical/mechanical energy output of a plant in a
reporting period.
Change in total electrical/mechanical energy (∆p).
Total fuel energy (f) is the total fuel energy based on lower heating value (LHV) needed in a CHP plant to
generate electrical/mechanical energy and useful heat in a reporting period.
CHP useful heat energy (q ) is the heat energy (thermal energy) supplied by a CHP process to a network
CHP
or a production process in a reporting period. It is heat energy that would otherwise be supplied from other
sources (see Article 3 (b) in [1]).
CHP electrical/mechanical energy (p ) is defined as the gross electrical/mechanical energy, which is
CHP
generated in direct relation to the generation of CHP useful heat (see Article 3 (d) in [1]) in a reporting period.
CHP fuel energy (f ) is the fuel energy based on lower heating value (LHV) needed in a CHP process to
CHP
co-generate CHP electrical/mechanical energy and CHP useful heat energy in a reporting period.
Non-combined useful heat energy (q ) is the heat energy (thermal energy) supplied by a CHP plant to
non-CHP
a network or a production process, which is not generated in direct relation to the generation of CHP
electrical/mechanical energy in a reporting period.
Non-combined electrical/mechanical energy (p ) is defined as the gross electrical/mechanical energy,
non-CHP
which is generated in a reporting period at times when no or insufficient heat energy is required. Thus this
electrical/mechanical energy is not generated in direct relation to the generation of useful heat.
Non-combined fuel energy (f = f + f ) is the fuel energy based on lower heating value
non-CHP non-CHP,q non-CHP,p
(LHV) needed in a CHP plant for non-combined generation of useful heat energy and non-combined
electrical/mechanical energy generation in a reporting period.

3.2 Dimensionless Figures of Energies
Total overall efficiency of energies (η = η ) is the ratio of all energy outputs to all
tot CHP+non-CHP,q+non-CHP,p
energy inputs of a plant in a reporting period.
Overall efficiency of energies (η = η ) is the ratio of energy outputs to energy inputs of a plant
CHP+non-CHP,p
excluding non-CHP heat energy and the referring non-CHP fuel energy for generation of non-CHP heat
energy in a reporting period (see Article 3 (g) in [1]).
CHP overall efficiency of energies (η ) is the ratio of CHP energy output to CHP energy inputs of the
CHP
CHP plant in a reporting period.
Electrical/mechanical power-to-heat ratio (σ ) is the ratio between gross electrical/mechanical CHP
CHP
energy (p ) to CHP useful heat energy (q ) in a reporting period (see Article 3 (k) in [1]).
CHP CHP
Electrical/mechanical power loss coefficient (β) is the balance between increasing heat energy recovery
(∆q) and reducing electrical/mechanical energy (∆p) of CHP plants with power loss in a reporting period.
Efficiency of non-combined electrical/mechanical energy generation (η ) is the efficiency of the
non-CHP,p
electrical/mechanical energy generation, which is not generated in direct relation to the generation of useful
heat energy in a reporting period.
Efficiency of non-combined heat energy generation (η ) is the efficiency of the heat energy
non-CHP,q
generation, which is not generated in direct relation to the generation of CHP electrical/mechanical energy in a
reporting period.
4 Description of CHP and Non-CHP Processes
In a combined heat and power (CHP) process high overall efficiencies can be achieved whereby a share of
the energy output is electrical/mechanical power.

4.1 CHP Plant
CHP power plants may generate electrical/mechanical energy as well as useful heat energy at the same time
(simultaneously, see Figure 1 — Transformation of Fuel Energy in a CHP Plant). Thereby not all useful heat
energy and all electrical/mechanical energy has to be generated in CHP mode. Thus:
p = p + p
CHP non-CHP
q = q + q
CHP non-CHP
f = f + f + f
CHP non-CHP,p non-CHP,q
Non-CHP Heat and Non-CHP Electrical/Mechanical Energy
+ CHP Heat and CHP Electrical/Mechanical Energy
100%
Electrical/Mechanical Energy
Useful Heat
Rejected Heat
0%
Figure 1 — Transformation of Fuel Energy in a CHP Plant

4.2 CHP Process
CHP electrical/mechanical energy is defined as the share of electrical/mechanical energy, which is at the
same time generated in direct relation to the generation of useful heat energy, thus being CHP useful heat
energy. Together the CHP electrical/mechanical energy and the CHP useful heat energy is the output from the
CHP process as shown in (Figure 2 — Subdivision of a CHP Plant in Combined and Non-Combined
Processes).
Fuel Energy
CHP Heat and CHP Non-CHP
Electrical/Mechanical Electrical/Mechanical
Non-CHP Heat Energy Energy
100%
Electrical/Mechanical Energy
Useful Heat
Rejected Heat
0%
Steam Steam Steam
FB
NO
ST ST
G G
BP CO
Heat Heat Condenser
Consumer Consumer
Condensate Condensate Condensate

Figure 2 — Subdivision of a CHP Plant in Combined and Non-Combined Processes

4.2.1 Electrical/Mechanical Energy-to-Heat Energy Ratio
σ = p / q Electrical/mechanical energy-to-heat energy ratio in MWh/MWh
CHP CHP CHP
Fuel Energy
4.2.2 CHP Overall Efficiency
The overall efficiency of the CHP process is defined as follows:
η overall efficiency of energies of CHP process in a reporting period in MWh/MWh
CHP
η = (p + q ) / f
CHP CHP CHP CHP
4.3 Non-Combined Heat Energy Generation
Non-Combined useful heat energy generation occurs in processes with generation of useful heat energy
without upstream generation of electrical/mechanical energy (see Figure 3 — Non-Combined Heat Energy
Generation with Additional Boilers), e.g. applying:
 Live steam extraction (steam extraction prior to generation of electrical/mechanical energy)
 Steam boilers without downstream (back-pressure or extraction-condensing) steam turbines
 Waste-heat boilers with auxiliary / supplementary firing without downstream (back-pressure or extraction-
condensing) steam turbines However the waste heat (recovered heat) recovered from the GT exhaust
gases in such boilers is an integral part of the CHP.

The heat efficiency of non-CHP processes is defined as:
η Efficiency of non-combined heat energy generation in MWh/MWh
non-CHP,q
η = q / f
non-CHP,q non-CHP non-CHP,q
Non-Combined Heat
Energy Generation
GT G
FB
Heat
HRB Consumer
Figure 3 — Non-Combined Heat Energy Generation with Additional Boilers
4.4 Non-Combined Electrical/Mechanical Energy Generation
Non-Combined electrical/mechanical energy generation occurs in processes with insufficient or without
generation of useful heat energy or in processes with heat rejection facilities, e.g. applying:
 Fuel cells, gas turbines and internal combustion engines with insufficient or without utilisation of heat thus
becoming rejected heat energy instead of useful heat energy
 In the condensing part of steam cycle power plants and in combined cycle power plants with extraction-
condensing steam turbines
It has to be noted that especially in the latter the non-combined power generation usually cannot be measured
directly. Therefore, in this case the process must be divided into condensing (non-combined) and back
pressure (combined) segments.
The electrical efficiency of non-CHP processes is defined as:
η Efficiency of non-combined electrical/mechanical energy generation in MWh/MWh
non-CHP,p
η = p / f
non-CHP,p non-CHP non-CHP,p
4.4.1 Electrical/Mechanical Energy Loss
The efficiency of non-combined electrical/mechanical power generation is required for the subsequent
calculation of CHP electrical/mechanical power generation and CHP fuel. The calculation method differs
depending on whether for a constant fuel input an increase in useful heat output is accompanied by a
reduction in electrical/mechanical power output. CHP plants where the electrical/mechanical power output
remains unchanged are called Processes without Electrical/Mechanical Energy Loss (such as simple cycle
gas turbine or engine based CHP). CHP plants where the increase in useful heat output is achieved at the
expense of some electrical/mechanical power generation are called Processes with Electrical/Mechanical
Energy Loss (such as, but not exclusively, CHP plants that include steam turbine(s) that exhaust fully or
partially to a condenser). In such cases the electrical/mechanical energy loss arises because the increase in
useful steam output is achieved at the expense of a reduced flow through part of the steam turbine (e.g. the
LP section exhausting to the condenser), resulting in a reduced shaft power output. This reduction is the
Electrical/Mechanical Energy Loss and the relationship between reduced electrical/mechanical energy output
and increased steam energy output is
β = -∆p / ∆q
4.4.1.1 Processes without Electrical/Mechanical Energy Loss
Assuming constant fuel energy input all processes without electricity generation subsequent to heat energy
extraction do not have a electrical/mechanical energy loss. Thus for CHP plants without Electrical/Mechanical
Energy Loss:
β = -∆p / ∆q = 0
This refers mostly to CHP Plants without fully or partially condensing (pass-out) steam turbines like back-
pressure steam turbines, but including back-pressure steam turbines, gas turbines or internal combustion
engines. Moreover at constant load (fuel energy consumption) these plants can not lose electrical/mechanical
energy if useful heat energy is increased (no energy loss). This is typical for back-pressure steam turbines,
fuel cells, gas turbine with heat energy recovery steam generator, Internal combustion engines, etc. (see
section 9.1.1). To increase the useful heat energy output these plants have to increase the fuel energy input
(or reduce heat rejection). Be aware of the fact that steam extraction from heat recovery steam generators in
combined cycles can also cause a electrical/mechanical power loss, even though the steam turbine is a back-
pressure turbine.
4.4.1.2 Processes with Electrical/Mechanical Energy Loss
For CHP plants which include fully or partially condensing (pass-out) steam turbines (i.e. extraction-
condensing steam turbines), electrical/mechanical energy generation will decline as steam extraction
(generation of useful heat energy) increases for a given fuel energy consumption, so there is a balance
between increasing heat energy recovery and reducing electrical/mechanical energy output. Assuming
constant fuel energy input.
The relation between generation of useful heat energy and electrical/mechanical energy/power loss or vice
versa is known as the energy loss coefficient (see Figure 4 — Subdivision of a CHP Plant with
Electrical/Mechanical Energy Loss in Combined and Non-Combined Processes).
The electrical/mechanical power loss coefficient is defined as:
β = -∆p / ∆q electrical/mechanical power loss coefficient in a reporting period in MWh/MWh

CHP Heat and CHP Non-CHP
Electrical/Mechanical Electrical/Mechanical
Non-CHP Heat Energy Energy
100%
0%
Rejected Heat Useful Heat
Electrical/Mechanical Energy Loss Electrical/Mechanical Energy

Figure 4 — Subdivision of a CHP Plant with Electrical/Mechanical Energy Loss in Combined and Non-
Combined Processes
Moreover at constant load (fuel power) these plants do lose electrical/mechanical power if useful heat output
is increased. These are known as plants with “power loss” since the provision of heat power has a negative
effect on the electrical/mechanical power output (for the same fuel input). The electrical/mechanical power
loss is typical for extraction-condensing or extraction-backpressure steam turbines. It is caused by extracting
the working fluid (steam or exhaust gas) from the turbine (expander) for generation of useful heat energy. Be
aware of the fact that steam extraction from heat recovery steam generators in combined cycles can also
cause a electrical/mechanical power loss, even though the steam turbine is a back-pressure turbine.
Fuel Energy
5 Determination Principles
Determine all
energy in- and
outputs in a
reporting period
Determine and
exclude non-CHP
Check overall
efficiency
Determine and exclude non-
CHP electrical/mechanical
energy
Figure 5 — Determination Principles - General
Determine all
energy in- and
Determine in a reporting period
outputs in a
reporting period • total fuel energy
• total electrical/mechanical energy
• total useful heat energy
no yes
Plant with non-CHP useful
heat energy generation?
Determine and
Determine and exclude
exclude non-
• non-CHP useful heat energy
CHP useful
• referring non-CHP fuel energy
heat energy
Overall efficiency exceeds CHP-

Directive Annex II a) value(s)?

no
yes
Check Overall
Efficiency
done
Electrical/mechanical power decreases
at constant fuel load when CHP useful

heat power is increased?
yes
Determine electrical/mechanical
no
power loss coefficient(s)
Determine
and exclude
non-CHP
Apply CHP-Directive Annex II a) value(s) to

electrical/
Determine and exclude
mechanical
• non-CHP electrical/mechanical energy
energy
• referring non-CHP fuel energy

done
Figure 6 — Determination Principles - Detailed
Determination of
Total fuel energy (f) (6.2)
Total electrical/mechanical energy (p) (6.3)
Total useful heat energy (q) (6.4)

no yes
Plant with non-CHP useful heat

energy generation? (7)
Determination of
q = 0 q
non-CHP non-CHP
f = 0 f
non-CHP,q non-CHP,q
Determination of overall efficiency
p + q p + q − q
CHP non−CHP
η = =
f + f f − f
CHP non−CHP,p non−CHP,q
Overall efficiency exceeds CHP-

yes
Directive Annex II a) value(s)? (8)

no
q = q - q
CHP non-CHP
p = p
CHP
f = f - f
CHP non-CHP,q
Electrical/mechanical power decreases

at constant fuel load when CHP useful
Determination of
heat power is increased?
yes
ββ
ββ
CHP
no
η = CHP-Directive Annex II a) value(s)
CHP
p + β ⋅ q p
CHP CHP
η =
η =
non−CHP,p
non−CHP,p
f − f f − f
non−CHP,q non−CHP,q
η − β ⋅ η
η
non−CHP,p CHP CHP
non−CHP,p
σ =
CHP σ =
chp
η − η
CHP non−CHP,p
η − η
CHP non−CHP,p
p = q ⋅ σ
CHP CHP CHP
p = q ⋅ σ
CHP CHP CHP
f = (p + q )/η
CHP CHP CHP CHP
f = (p + q )/η
CHP CHP CHP CHP
Figure 7 — Determination Principles – Equations and References
6 Determination of Energy In- and Outputs
All CHP plants must determine all energy input and outputs: f, q, p.
A CHP plant supplies energy products to a Consumer Area (see Figure 8 — CHP ). The Consumer Area does
not belong to the CHP Plant but consumes the energy products that are produced by the CHP Plant The two
areas are not necessarily distinct geographical plot areas within the site but, rather, areas that may be
conveniently represented as shown below. The consumer area is either the industrial process or for district
heating the community or the public electric grid, which in all three cases consumes the energy outputs from
the CHP plant.
Heat
OUT
Fuel
CHP SCHEME ENERGY
IN
CHP Plant
USED
Electricity
OUT
Boundary
UTILITIES AREA PROCESS AREA
CONSUMER AREA
Figure 8 — CHP Site
6.1 CHP Plant Boundary
Auxiliary heat or electricity production equipment such as heat only boilers and electricity only power units that
do not contribute to combined generation of heat and power must not be included in the CHP plant boundary.
Therefore auxiliary (top-up) boilers, standby (back-up) boilers, process waste heat boilers and standby
generators have to be excluded (see Figure 9 — Choosing the Right Scheme Boundaries in Case of
Auxiliary/Standby Boilers). In case of chilling processes, these also should be placed outside the CHP
boundary limit. The meters should be placed on the these boundaries.
The auxiliary or parasitic consumption of heat energy and mechanical energy of a CHP plant do not belong to
its energy outputs.
However, some sites will have secondary steam turbines driving pumps or compressors delivering mechanical
energy and also provide heat to the consumer area. In these cases the steam turbines and its energy outputs
do not belong to the auxiliary consumption of the CHP plant but to the energy outputs. Possible determination
methods for the heat and electrical/mechanical energy output are those outlined for prime movers (see section
6.3.2). The secondary steam turbines must be included in the CHP Plant boundaries (see Figure 10 —
Choosing the Right Scheme Boundaries in Case of Secondary Steam Turbines). The electrical/mechanical
energy outputs have to be included as energy outputs from the CHP Plant. The heat energy required to
produce these additional electrical/mechanical energy outputs must be deducted from the useful heat energy
output.
Where steam turbine-driven pumps or generators are driven with steam from the CHP plant, the energy flow
from the CHP plant should be included in the CHP energy flow if they supply the energy to the consumer area
and do not belong to the auxiliary energy consumption. For example, the steam heat power used by the
steam-driven pumps or generators should be deducted from the CHP plant heat power outputs to the process
and, similarly, the mechanical/electrical power output from the steam-driven pumps (see section 6.3.2) or
generators should then be added to the CHP plant power outputs if they do not contribute to the auxiliary
power consumption of the CHP plant but supplied to the consumer area.

WRONG RIGHT
Boundary Boundary
GT GG
GT G
FB
FB
(M)
HRB
HRB
Additional Heat Meter
Figure 9 — Choosing the Right Scheme Boundaries in Case of Auxiliary/Standby Boilers

WRONG RIGHT
Boundary
Boundary
Secondary
Secondary
Steam Turbine
Steam Turbine
FB
FB
ST G
ST G
ST ST
G G
Figure 10 — Choosing the Right Scheme Boundaries in Case of Secondary Steam Turbines

4)
Where prime movers are connected in series by heat distribution systems, in combined cycle mode (where
the heat from one prime mover is converted to steam to supply a steam turbine) the prime movers cannot be
considered separately, even if the steam turbine is located on a different site (Figure 11 — CHP Plant
Boundary).
CHP Plant Boundary
CHP Scheme Boundary
PRIME MOVER PRIME MOVER
(GT) (ST)
Fuel Heat Heat Heat
IN OUT IN OUT
Figure 11 — CHP Plant Boundary

6.1.1 CHP Plant Area
The CHP Plant contains the main CHP Prime Mover(s) and associated heat recovery equipment.
The CHP Plant includes all prime movers, such as steam turbine-driven pumps or generators that are
delivering heat and/or electrical/mechanical energy to the consumer area. These must be shown within the
main CHP boundary with the appropriate connections to the consumer area.

6.1.2 Consumers Area
The consumers area consumes the CHP energy outputs. This can be the district heating network and the
public electric grid when the electricity is sold on the market or industrial processes that consume heat energy
and/or electrical/mechanical energy at an industrial site.

6.2 Determination of Total Fuel Energy (f)
All fuel energy inputs shall be based on net calorific value (lower heating value) and should be determined in
MWh. The total fuel energy input in a reporting period is the sum of all fuel energy inputs:

4) A machine or mechanism that converts energy.
Electricity
OUT
Electricity
OUT
n
f = f in MWh.
∑
i
i=1
NOTE Indirect methods shall only be used if direct methods cannot be applied. Measurements are prescribed
in all cases where this can technically been done.

6.2.1 Treatment of Recycled Fuel Energy
If a share of the energy content of the fuel energy input to the cogeneration process is recovered in chemicals
and recycled this share must be deducted from fuel energy input.
EXAMPLE A CHP plant
produces
300 MWh of electricity/mechanical energy
400 MWh of useful heat
Consumes
1,000 MWh of fuel energy
Recovers
50 MWh of chemi
...