I-DEV0398: Calculation of BFi,y: Quantity of biomass combusted in the project plant based on indirectly measured data.
|Submitted by||SGS (17 Feb 2011)|
|Project activity||258: Nueva Aldea Biomass Power Plant Phase 1|
|Selected monitoring period||01 Oct 2007 - 30 Sep 2008|
|Title/subject of deviation||Calculation of BFi,y: Quantity of biomass combusted in the project plant based on indirectly measured data.|
NOTE: When inserting the information for this deviation we encountered difficulties with the formatting of the tables/data sets. Please refer to to the attached document (PDF of F-CDM-DEV-ISS form)tabular representation of the above information in PDF format.
The request for deviation is being submitted because the Quantity of biomass combusted in the project is determined based on measured and calculated data and not directly measured data as required by the approved revised monitoring plan page 2 and ACM0006 version 1 page 39: BFi,y: Quantity of biomass type i combusted in the project plant during the year y (mass or volume unit) is to be measured.
The purpose of this deviation is to show that the biomass consumption calculation for this transition period was done correctly, and even more, it was conservative. The biomass combusted in the project arrives from two sources/Annex 1/:
• Inside the complex and
• Outside the complex.
The biomass from outside the complex (sawmill and forestry plantation operations inside the defined area of influence established within the 200 Km radius around the power plant, as per ACM0006 version 1 page 35) is transported by trucks. Each truck has its load weighed (by calibrated weigh bridges) and measured (volume is measured in m³stereo / Annex 3/ at the entrance of the complex before leaving the load at the storage site next to the power plant. Being all this biomass measured (volume and weight).
The biomass residues that come from the production lines located inside the Nueva Aldea Complex, where the project is located, (pulp mill, sawmill and plywood mill) feed the boiler through two points: a conveyor belt from the storage area were most of the biomass is deposited also through belts and in the case of the wood sander dust, it is transported directly from the plywood mill source to the power plant boiler through a pipeline because of safety reasons./Annex 1/
The quantity of biomass residues that come from the different production lines of the complex to the power plant was not directly measured until 31 December 2009 when meters were installed in the two points that feed the boiler.
The Quantity of biomass combusted in the project plant (BFi,y) is calculated using the following equation:
C = S + Vi – I – Vf
C: Biomass Power Plant Consumption
I: Biomass sent to the external plant (Measurement)
Vi: Initial Volume Stock: Monthly topographic measurement of the storage sites
Vf: Final Volume Stock: Monthly topographic measurement of the storage sites
S: Entrance Volume to the storage site: Calculated adding the biomass residues deposited by each production lines according to the following equation:
S = Rpulp mill + R sawmill + Rplywood + Rthird parties
Where S correspond to biomass residues provided by the different production lines of the complex (pulp mill, sawmill and plywood plant) plus the biomass residues, transported by trucks, obtained from other parties like sawmills and forestry operation activities located outside the complex and the by-product of the waste water treatment of the complex, which is a biomass residue consisting of cellulose fiber, sawdust and bark with a high moisture content.
The Quantity of biomass combusted in the project plant (BFi,y) was checked with a monthly stock balance /Annex 2/ according to the following formulas:
Volume inlet – Volume outlet = Volume final-stock
Volume Inlet: Volume entering the storage area (S) plus the initial volume of the stock at the beginning of the measurement period (Vi)
Volume Outlet: The volume sent outsite the complex (I) plus the volume consumed in the power plant (C)
Volume Final-Stock: Volume of the stock on site at the end of the measurement period (Vf).
Volume inlet = S + Vi
Volume outlet = I + C
Volume final –stock = Vf
Each movement of biomass is monitored and recorded in the information database (called SCR).
The quantities of biomass residues that come from pulp mill, sawmill and plywood plant are determined by applying specific factors to the measured volume of logs processed which are the raw material of the sawmill and the pulp mill production lines of the complex and in the case of the plywood mill, the biomass residue is determined quantifiying the production losses and an expansion factor is applied to consider the pilling effect at the storage area. The determination of the biomass residues that come from each production line and the information sources were verified on site and found correct/ Annex 2/. The calculated data is based in operational information collected and recorded by the project participant in the production lines as part of the production efficiency control.
Calculations/Annexes 2.1, 2.2/, data sources and factors/Annex 3/used to determine the quantity of biomass from each source inside the complex were verified against data sources and found correct.
The biomass determination method /Annexes 2.1, 2.2 and 3/ is conservative compared with the energy balance results obtained/Annexes 4.1, 4.2/. The uncertainty of the calculations is considered low because the factors used are factors that come from forestry industry literature, they were verified, deemed appropriate and all are reported in the Annex 3.
The determination of the biomass residues that come from outside the complex were verified against the information sources and found correct/Annexes 2.1, 2.2/.
It is not required to submit a request for approval of changes from the project activity because there is no change from the project activity since it continues to be a project that comprises a renewable energy project activity that involves the installation of a new cogeneration plant that uses a mix of forest plantation and forest industry residues (like sawdust, chips, bark, dust) at a site where no power generation would have occurred. The project was validated against scenario 3 (PDD section A2 and validation report page 10). Under this scenario, the industrial complex (composed of a pulp mill, sawmill and plywood mill), where the project is located, consumes a fraction of the electricity generated by the project, and the rest is supplied to the grid. In the absence of the project activity, a fraction of the total biomass currently used by the project activity would have been used only for heat generation in boilers at the project site and the rest would be dumped in piles to natural decay or burned in an uncontrolled manner according to the page 11 of the validation report and page 41 of the registered PDD. As a result, without any power generation, the industrial facility would have to consume power from the grid and there would be no surplus power available to the grid.
It is not necessary to submit a revision of the monitoring plan because the project participant already installed meters to measure directly the biomass that the power plant consumes in the conveyor belt and in the dust pipeline that goes directly to the boiler boiler. The meters were physically installed on 15 December 2009 and then time was needed to install the monitoring automatic system until 31 December 2009 when the system was fully operational.
The request for deviation seeks the approval from the EB to be applied for the third monitoring period 01 October 2007 - 30 September 2008 and beside Paragraph 214 of CDM Validation and Verification Manual Version 1.2, knowing that the provisions contained in this deviation continued until the monitoring period fourth, the DOE seeks the approval of the extension of deviation including the fourth monitoring period: 01 October 2008 - 31 December 2009 to avoid multiple submissions and delays.
Even though after verifiying the evidence of the proposed deviation, as it is informed in the following section, the deviation was deemed conservative, the project participant analyzed and understood the guidance provided by Meth Panel (Meth panel 37 report/paragraph 34) and given that the deviation period is more than 6 months, the value of the baseline emissions due to natural decay or burning of anthropogenic sources of biomass will be accounted completely for the first six months (from 01 October 2007 - 31 March 2008) of the third monitoring period and then a 25% discount is applied to the rest of the third monitoring period (01 April 2008 – 30 September 2008) and it will be also applied to the entire fourth monitoring period from 01 October 2008 until 31 December 2009 when the meters were installed.
The deviation does not increase the emission reductions verified of the project activity comparing it with the estimated emission reductions of the PDD page 13. The following table is a comparison of the emission reduction estimated and verified:
Emission reduction by monitoring period Verified estimated units Difference months
MP1 : 01 Jan 2005 - 30 Sep 2006 CERs Issued 154,507 147,551 tCO2e 5% 21
MP2: 01 Oct 2006 - 30 Sep 2007 CERs issued 140,995 131,041 tCO2e 7% 12
MP3: 01 Oct 2007 - 30 Sep 2008 CERs requested 165,787 136,385 tCO2e 18% 12
MP4: 01 Oct 2008 - 31 Dec 2009 CERs requested 233,820 158,349 tCO2e 32% 15
The reasons that explain the difference between the estimated and the verified emission reductions /Annex 5/ are not related to the proposed deviation and are the following:
1.- It was verified a higher amount of biomass related to power generation than the amount originally calculated in the PDD. This can be explained due to a change in the calculation methodology of the biomass related to the project activity. In the registered PDD, the Project Proponent used a fixed (and very conservative) biomass performance index to calculate the biomass related to the project activity (for power generation), instead of using equation N° 24 of the ACM0006 (Version 01). This biomass performance index was calculated from the energy/mass balance of the project Nueva Aldea phase 1 power plant, as it is described in pages 41 and 81 of the registered PDD and in pages 8 and A-22 of the corresponding validation report. The use of this biomass performance index corresponded to a conservative approach by the Project Proponent in the calculation of the emission reduction calculation associated to the additional use of biomass for electric power generation, since it implied a constant high efficiency of the power boiler for electric power generation throughout the entire crediting period of the project activity. This approach was, however, changed to the one proposed by the ACM0006 (Version 01) upon an explicit request of the EB by the end of the second verification. As a result, the Project Proponent changed the biomass performance index calculation method to the approach indicated by the baseline methodology, which used equation N° 24 to calculate the additional biomass associated to power generation. Unlike the biomass performance index calculation approach, the use of equation N° 24 of the ACM0006 (Version 01) does account for (future) variations (i.e. decreases) in the power boiler efficiency, which may lead to higher amounts of biomass combusted in the power boielr (i.e. due to a decrease in the boiler efficiency) and therefore, to higher amounts of biomass associated to the project activity (i.e. for which baseline methane emissions are calculated).
2.- As it was stated in the PDD page 70, a measured CH4 emission factor for uncontrolled burning of biomass residues was used which result in a higher value than the one originally used in the PDD: 740.5 (Kg CH4/TJ) instead of 300 (Kg CH4/TJ). The CH4 emission factor of 740.5 (Kg CH4/TJ) was obtained through a study performed on site in Chile by US Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, Montana, USA.
3.- Higher grid emission factors for the years 2007 and 2008 than the ones originally estimated in the PDD. The grid emission factor for 2007 was 640.0 (tCO2/GWh) using nine months and 660.5 (tCO2/GWh) using twelve months, while the estimated grid emission factor for 2007 in the PDD was 511.0 (tCO2/GWh). The grid emission factor for 2008 was 665.0 (tCO2/GWh), while the estimated grid emission factor for 2008 was in the PDD was 528.2 (tCO2/GWh). The actual grid emission factor for 2009 was virtually the same as the one estimated in the PDD. The reason for the higher grid emission factor in 2008 was the replacement of natural gas used for power generation for more carbon-intensive fossil-fuels, such as coal and diesel, because the natural gas supply from Argentina was terminated.
The proposed methodology for determining (through calculations and direct measurements) the quantity of biomass combusted in the project plant (BFi,y) is conservative due to the following reasons:
1.- The monthly cross checks performed between the quantity of biomass combusted in the project plant (BFi,y) and the monthly stock balance showed that the determined amount is not overestimated. /Annex 2/, it shows that the amount of biomass is slightly sub-estimated (-1.2% and -0.2%) (Annex 2.1 and 2.2 sheet biomass consumption).
2.- After the biomass meters were installed, the Project Proponent carried out a comparison during the first 7 months of 2010 between the two methods of determining the biomass data: the measured/calculated method (proposed in this request for deviation) and fully-measured method. The comparison showed that the first method lead to a lower amount of biomass combusted in the power boiler (and related to the project activity) than the fully-measured method. The data can be seen in the following table:
Data of 2010 Calculated and measured Fully-measured
units Jan-July, annualized Jan-July, annualized
Biomass related to heat generation (BDt) 149,611 149,611
Biomass related to power generation (BDt) 210,750 236,927
Total biomass combusted in the project plant (BDt) 360,361 386,538
Note: The deviation is to determine the total biomass combusted in the project plant, the value of the quantity of biomass related to the heat generation is the same because it is calculated according to the second term of the equation 24 of the applicable methodology and the biomass rewlated to power generation is the difference between the other two.
3.- This proposed determination method/Annexes 2 and 3/ which is presented as a deviation is conservative according to the energy balance results obtained /Annex 4.1/ and 4.2/.
For the third monitoring period:
According to the information presented by the Project Participant, the biomass calculation was done in a conservative way. The reported quantity of biomass combusted in the project plant was 2,157,645 m³st (or 281,146 BDt ) and the value obtained from the energy balance was 2,429,580 m³st (or 306,920 BDt) determined using a power boiler efficiency equal to 86.7% (PDD page 10); and 2,339,921 m³st (or 295,593 BDt) was obtained using a power boiler efficiency equal to 90% (nominal power boiler efficiency obtained from the power boiler manual).
The reason to use the power efficiency 86.7% (Refer to the PDD lay out page 10) is due to the inaccurate determination of the BDt factor (the factor used to convert volumetric biomass (m3st) unit to dry mass biomass unit (BDt)/Annex 3/.As it can be seen in the line 21 and 32 of the Annex 4.1, the reason of this BDt factor inaccuracy was that the number of samples taken was not reporresentative enough. It was subsequently verified that the method of sampling for the BDt determination had been improved in the corresponding procedure in order to avoid or minimize this error. The improvement basically consisted in increasing the number of biomass samples, from two to five per month and checking the resulting BDt conversion factor with historic data.
For the fourth Monitoring Period:
The reported quantity of biomass combusted in the project plant during the fourth monitoring period (01 Oct 2008 - 31Dec 2009) was 3,039,876 m3st (or 446,829 BDt), which is consistent with the amount of biomass consumption shown in the 2009 energy balance with an average efficiency of 79.2% /Annex 4.2/.
Considering the three reasons explained above and according to the equation 24 of ACM0006 (Version 01), a lower quantity of biomass combusted in the project plant is conservative since it leads to a lower amount of biomass related to power generation and thus, a lower amount of baseline methane emissions due to avoided uncontrolled biomass burning.
In addition to the information provided above, further information is provided to explain the increase in the amount of biomass related to project activity (for power generation), compared to the one originally estimated in the PDD:
1.- The Nueva Aldea Phase 1 Complex must satisfy process heat demand of internal clients and dispatch an amount of electricity to the grid on an annual-based agreement with the CDEC-SIC dispatch center. In the last years, power generation has become more fossil-fuel intensive in the SIC grid, which has implied that low-cost/must run power plants, such as Nueva Aldea Phase 1 biomass power plant, have been dispatched at high load most of the time.
Sometimes, in order to comply with the dispatch program and generate the required amount of power to the grid, the Nueva Aldea Phase 1 power plant operators have to increase the amount of steam that goes through the turbine to the condenser to the maximum. As a result, the power plant is capable of generating more (condensing) power, which has a lower efficiency per unit of biomass combusted in the boiler than the cogenerated power. This contributes to explain the higher amount of biomass related to power generation and therefore, related to the project activity.
2.- Another possible reason behind the increase of the biomass related to power generation is due to biomass combustion residues accumulation in the power boiler tubes (fowling). These residues decrease the heat exchange capacity of the boiler, which results in a decrease in the power boiler’s efficiency. Some incipient fowling problems were identified in the power boiler during the operational shutdown in July 2008. Due to operational constraints of the Nueva Aldea Complex, the power boiler was finally cleaned during the plant stop of December 2010. This is consistent with the (relatively lower) average monitored efficiency of 79.2% observed in the fourth monitored period.
The following table provides a synthesis of the parameter´s variation from 2007 until 2009, and also provides a comparison between the PDD estimations and the monitored and verified data. As can be seen, the quantity of biomass combusted in the project has not increased considerably as well as the total energy displaced from the grid. The reasons previously discussed explain the difference between the estimated and verified values from 2007 to 2009:
Monitored data 2007 2008 2009 Monit data
(Jan - Dec) (Jan - Dec) (Jan - Dec) (3-yr avg.)
Biomass related to heat generation (BDt) 149,763 155,447 140,197 148,469
Biomass related to power generation (BDt) 128,100 152,660 (*) 214,358 165,039
Total biomass combusted in the project plant (BDt) 277,864 308,106 354,554 313,508
Adjusted methane emission factor for uncontrolled burning of biomass (tCO2/ ton) 262.8 262.6 262.9 262.8
Emission reduction due to biomass
use for power generation (tCO2eq) 33,665 40,091 56,347 43,368
Total electricity displaced from the grid (GWh) 189 205 205 200
Biomass related to project / Net electricity displaced index (BDt/GWh) 676 744 (**) 1,047 826
PDD estimates 2007 2008 2009 PDD data
(Oct - Dec) (Jan - Dec) (Jan - Dec) (3-yr avg.)
Biomass related to heat generation (BDt) 224,537 224,537 224,537 224,537
Biomass related to power generation (BDt) 116,008 116,008 116,008 116,008
Total biomass combusted in the project plant (BDt) 340,545 340,545 340,545 340,545
Adjusted methane emission factor for uncontrolled burning of biomass (tCO2/ton) 89.5 89.5 89.5 89.5
Emission reduction due to biomass use for power generation (tCO2eq) 10,378 10,378 10,378 10,378
Total electricity displaced from the grid (GWh) 193 193 193 193
Biomass related to project / Net electricity displaced index (BDt/GWh) 602 602 602 602
(*) It must be noted that the amount of biomass related to power generation was subestimated due to the unrepresentativeness of the BDt factor sampling done in 2008. This lead to a conservative approach as biomass attributable to project activity is subestimated decreasing baseline emissions due to natural decay or burning of anthropogenic sources of biomass according to the equation 24 of ACM0006 version 1.
(**)The amount of biomass related to power generation was subestimated leading to a lower ratio which is conservative.
m3stereo: it refers to a cubic meter of biomass (e.g. sawdust and bark), a mix that contain air and moisture.
For the year 2010, data was available only from January to July. The numbers shown were annualized to make the comparison more clear.
The main reason of the difference between the biomass determined through the proposed method and through the energy balance corresponds to the insufficient biomass residue sampling for determining the BDt conversion factor (the factor used to convert volumetric biomass (m3st) unit to dry mass biomass unit (BDt) as it can be seen in the row 49 of the Annex 4. A theoretical BDt factor is determined in energy balance spreadsheet (please see row 47)/Annex 4/. It was subsequently verified that the method of sampling for the BDt determination had been improved in the corresponding procedure in order to avoid or minimize this error. The improvement basically consisted in increasing the number of biomass samples, from two to five per month and checking the resulting BDt conversion factor with historic data. This was duly verified on-site by means of checking the new procedure to determine the BDt (TA05- PTE-PO-025 approved on 11/09/2009).
BDt: BDt Bone dried ton (BDT)/Bone dried metric tome (BDMT): it refers to one ton (1,000kg) of biomass with 0% moisture content.
|Annexes||Annex 1 Flow of biomass diagram (6752 bytes)|
|Annex 2.1 Biomass residues calculation third monitoring period (1894 KB)|
|Annex 2.2 Biomass residues calculation fourth monitoring period (1892 KB)|
|Annex 3 Determination method of biomass (43 KB)|
|Annex 4.1 Energy balance third monitoring period (9685 bytes)|
|Annex 4.2 Energy balance fourth monitoring period (37 KB)|
|Annex 5 Data Analysis (31 KB)|
|PDF of F-CDM-DEV-ISS form (112 KB)|
|Link to the documentation made available at validation stage or monitoring report||Link to relevant documentation|
|Signed form||Signed form (544 KB)|
This request for deviation has been accepted.
The Chairs have accepted the proposed request for deviation to the monitoring and reporting process to be applied ONLY FOR THE FIRST 6 MONTHS of the 3rd monitoring period (from 01 Oct 2007 - 31 Mar 2008) and NOT for the rest of the 3rd monitoring period and the entire 4th monitoring period, in line with the guidance provided by Meth Panel in its 37th meeting report, para 34.
|Current status||23 May 2011 - Deviation accepted|
17 Feb 2011 -
17 Mar 2011 - Successfully passed the Completeness Check
31 Mar 2011 - Awaiting DOE input
13 Apr 2011 - Clarifications received
06 May 2011 - Awaiting EB decision
|6 clarification(s) provided on 13 Apr 2011|
|DOE's response to clarification request (85 KB)|
|F-CDM-DEV-ISS Clean (116 KB)|
|F-CDM-DEV-ISS Tracked Changes (164 KB)|
|Annex 4.3 Energy balance fourth monitoring period adjusted efficiency (38 KB)|
|Annex 6 Monthly topographic reports (1037 KB)|
|Annex 7 Biomass residues piles volume determination method. (35 KB)|