GHG emission reductions through optimization of boiler operation in Indonesia
Explanatory note1.

Mechanism of emission reductions

Many industrial facilities own multiple boilers to provide heat. Furthermore, it is common for
an industrial facility to own and operate boilers of various load-efficiency characteristics orfuel types. However, such boilers are not always operated in an optimal manner. During
periods of intermediate demand, multiple boilers and generators may continue to be operated
outside their optimal load when it is more efficient to shut down one and operate anotherboiler at full capacity. Less efficient boilers may be continued to operate while the more
efficient ones are shut down due to factors such as historical practice.

Utility Facility Operation Optimization Technology attempts to optimize the operation ofboilers through application of software algorithm using linear programming method.
Specifically, the program instructs the operator of boilers to select the optimal configurationof boilers to meet the utility demand of the industrial facility. The objective function for thepurpose of the methodology is to meet the heat demand with the least amount of CO 2emissions, though other types of objective can be chosen such as minimal cost or least
amount of energy consumed. Factors such as type of fuel, output capacity and load-efficiency
characteristics are taken into account.

Utility Facility Operation Optimization Technology can be implemented in a wide range ofindustrial facilities, with varying circumstances. This methodology includes measures toaddress irregular situations which may occur in the industrial facilities which the project isundertaken.

2.

Establishment and calculation of reference emissions2.1. Basic structure of the calculation of reference emissions
The methodology calculates reference emissions by multiplying the steam generation after
implementation of the project by historical specific emission factor of steam, obtained
through linear regression analysis of historical one-year data (taken hourly) before
implementation of the project. The one-year history is deemed appropriate since it is long

enough to cover possible variation of operation and ensures enough data points to yield areliable regression equation.

Reference emissions calculated as above is compared with the project emissions, calculatedon the basis of actual fuel consumption after the implementation of the project.

2.2. Ensuring conservativeness
The methodology ensures conservativeness by assuming that emission reductions of fuel andelectricity consumed by auxiliary equipments (e.g. fans and pumps) which is expected tooccur as a result of reduction in fuel consumption from the project is not included.
Furthermore, it is assumed in case of equipment substitution that the new boiler, upon
introduction, will substitute existing boilers with a higher emission factor (boilers that areless efficient or uses a higher emitting fuel) up to the point where the new boiler is operating
at full load. In reality, new boilers do not always replace higher emitting facilities providing
the same type of utility, and they may operate at less than 100% load. Therefore, theassumption is conservative.

2.3. Measures to be taken when the regression does not meet the required level of themethodology
Upon determination of historical specific emission factor, there could be situations where one
or few of the boilers yield poor correlation between steam generation and CO 2 emissions due
to various reasons such as equipment malfunction, which affects the overall regression. To
address this, a procedure is included in the methodology where, if the overall regression
coefficient R 2 is less than 0.49, then the performance of individual boiler with low regression
are recalibrated and examined, and their relationship between steam generation and CO 2emissions is measured in a one-month campaign.

The result of this campaign is fed into the original one-year data to yield an adjusted one-year
database, upon which historical emission factor is re-calculated. For example, if therelationship between steam generation and hourly total CO 2 emissions by the boiler inquestion during the one-month campaign (ST j,ch and HE j,ch , respectively) is established to be
HE j,ch , = a j * ST j,ch +b j , then CO 2 emissions of that boiler for hour h of the one-year historicalperiod is calculated from its steam generation on that hour as HE j,xh , = a j ×ST j,xh +b j , insteadof calculating from its fuel consumption on that hour as HE j,ch , = FC j,ch ×NCV i ×EF i , where

NCV i and EF i are net calorific value and CO 2 emission factor of the fuel used in the boiler. If
the overall regression R 2 becomes higher than 0.49, then the methodology is applicable since
it can be assumed that the original monitoring of fuel consumption was flawed but wascorrected.

2.4. Indicative example of “Provisions for recalculation of reference emissions when
new boilers are introduced”
It is plausible for many industrial facilities which operate many boilers that they areoccasionally replaced, overhauled or added. If this happens, then the assumption that thehistorical relationship between steam generation and CO 2 emissions will continue becomes
untenable. A provision to address this situation is introduced in the methodology. An
indicative example is shown below.

Assume an industrial facility with boilers A, B, C, D and E, with descending order of specific
CO 2 emission factor with the specification and performance for the hour as shown below.
When a new boiler F is added (or replaces existing boilers) after the implementation of theproject, new boiler F is deemed to replace boilers A and B whose specific CO 2 emission
factor is higher than boiler F, since the combined steam generation of the boilers A and B isbelow what boiler F can generate. New boiler F only partially replaces boiler C and does not
replace boiler D even though their specific CO 2 emission factor is higher than boiler F, since
the combined steam generation by boilers A to C exceeds that of what boiler F an generate atfull capacity. The resulting HE adj,j,xh is calculated as shown in Table 1. By this algorithm,
hourly CO 2 emissions are adjusted downwards by approximately 10% from 26.1t-CO 2 to
23.5t-CO 2 .

Table 1: Illustrative example of adjustment procedure when a new boiler is introduced.
BoilerCapacityTph
A (existing)

10

Design andactualefficiency

Load factor

%%
70%

Fuel

Emissionfactor offuel (EF i )Historical CO 2
Design CO 2 Steamemissions fromemission
generation
the boiler (HE j,xh ) factor ofboiler (EF j )t-CO 2 /TJ
t-CO 2 /hr
t-CO 2 /TJ
t-steam/hr

50% Diesel

74.1

1.42

105.9

Adjustment to Adjusted
HE j,xh
HE j,xh(HE adj,j,xh )5.00 adjust

t-CO 20.83

B (existing)

20

85%

80% Diesel

74.1

3.73

87.2

16.00 adjust

2.67

C (existing)

30

75%

100% Gas

56.1

6.00

74.8

30.00 partially adjust

5.04

D (existing)

40

85%

100% Gas

56.1

7.06

66.0

40.00 no adjust

7.06

E (existing)

50

95%

100% Gas

56.1

7.90

59.1

50.00 no adjust

7.90

Total (whereappropriate)
F (new)

150

141.0023.50

50

26.1190%100% Gas

56.1

62.33

*For the purpose of simplicity, boilers are assumed to operate at their respective design efficiencies.