M-DEV0450: Deviation from the "Tool to calculate the emission factor for an electricity system" to allow the use of alternative weights based on the intermittent and non-dispatchable nature of power a project applying AMS-I.D.

AMS-I.D. ver. 7: Renewable electricity generation for a grid

On October 22nd, 2010 the Request for Revision SSC_486 was submitted to the Small Scale Working
Group (SSC WG)1. The request aimed at proposing new weights for build and operating margins while
calculating the combined margin for small hydropower plants during their second crediting period,
owing to their intermittent and non-dispatchable nature.
In January, 2011, the SSC WG provided forwarded the issue to the attention of the Meth Panel, since
based on the information previously submitted the panel could not draw a conclusion2. Also it was
informed that the matter should be addressed as a revision of the "Tool to calculate the emission factor
for an electricity system". Yet, the SSC WG requested that the following additional information should
be provided:
- A definition of run-of-the-river hydro plant (dispatchable/intermittent vs. non-dispatchable / non-
intermittent) would be required;
- Further elaboration about the impact on the grid by run-of-the-river hydro vs. wind/solar project
activities, justifying that the same OM/BM weights could be applied for all these cases.
From the additional information sent to the SSC WG, the following excerpts are worth recalling.
Concerning the definition of run-of-river hydro power plants, the explanation provided by International
Energy Agency (IEA, 2004)3 is as follows:
"Run-of-river plants produce electricity according to the flow of water in the river it has been built in.
Water is shored at low head hydroelectric plants and channeled through turbines using the natural
force of the river flow. Seasonal variations determine the water level in the river and thus the strength
of the water flow and its implicit available energy."
Besides, as pointed out by IEA (2008) in another report entitled "Empowering Variable Renewable
Options for Flexible Electricity Systems", small hydropower plants can also be listed as an intermittent
source of electricity. In its report, the agency equals small hydropower plants to other sources such as
wind and solar, as highlighted in the two excerpts presented below:
"A number of renewable electricity technologies, such as wind, wave, tidal, solar, and run-of-river
hydro share a characteristic that distinguishes them from conventional power plants: their output varies
according to the availability of the resource. (...)
"Variable types. Var-RE power plants rely on resources that fluctuate on the timescale of seconds to
days, and do not include some form of integrated storage. Such technologies include wind power, wave
and tidal power, run-of-river hydropower, and solar photovoltaics (PV). Output from such plants
fluctuates upwards and downwards according to the resource: the wind, cloud cover, rain, waves, tide,
etc. Such technologies are often referred to as intermittent (...)"
In connection with the second request for additional information made by the SSC WG, it is worth to
recall information provided regarding Brazilian typical grid resources. The studies conducted by the
Energy Research Company (from Portuguese Empresa de Pesquisa Energética - EPE) foresee an
increase in the electricity demand in Brazil in the order of 3,300 MW4
per year. EPE is the responsible
for envisaging the future scenarios of the Brazilian energy market in order to subsidize the Brazilian
Energy Ministry. According to Brazilian Electricity Regulatory Agency5, as of August 2011, Brazil
possesses 2.467 power plants in operation summing up 118,402MW of installed capacity. From this
total, 67.5% of the electricity generation comes from large hydropower plants with an average installed
capacity over 400MW per plant6. Therefore, for the specific case of Pesqueiro SHPP (12.4 MW of
installed capacity), the project's capacity value is lower than that of a typical grid resource which may
influence the build margin.
Taking into account the additional information, briefly summarized here, the Meth Panel (MP), at its
50th meeting, decided not to revise the methodological tool7. However, in their final answer, the MP
suggested that the revision of weights could be made individually for each CDM Project Activity,
considering its particularities. The PPs would like to clarify that to the best of their understanding
different OM/BM weights are generically applicable to solar/wind power plants, due to their intermittent
and non-dispatchable nature without any further elaboration. To the best of the PPs understanding, as
discussed above, run-of-river hydro power plants have by definition the same nature. Actually as in the
case of the Pesqueiro SHHP the intermittent and non-dispatchable nature is at least as evident as a few
registered CDM wind power plants (examples below were supplied during the requests for clarification
and review).
In light with the examples and recommendations provided by the Meth Panel, a request for deviation
which is going to be applied to the renewal of the crediting period of "Pesqueiro Energia Small
Hydroelectric Project" is submitted to attention of the Meth Panel, addressing the point of view
presented by the panel as further discussed below.
The answer provided by the MP argues that depending on the availability of the resource (i.e., river flow
in the case of run-of-river hydropower plants), the plant could be able to "save" the resource and use it
for electricity generation during the peak hours. Besides, differently from small hydropower plants and
biomass power plants, wind power plants cannot choose when to generate electricity since they can only
be operational in the exact moment when the resource is available.
However, two aspects shall also be considered. Run-of-river hydropower plants have very limited
"water saving" capabilities. Additionally, the river flow greatly varies throughout the year. In this sense,
the example given by the MP for small hydropower plants could only be observed, if possible at all, if
the river flow is considered constant throughout the years.
In hydropower projects variations in the river flow is widely observed between the years. Consequently
it makes difficult to predict the possible electricity generation by the plant, consequently saving water in
the reservoir. With the purpose of exemplifying this variation, values of the Natural Affluent Energy
(from the Portuguese Energia Natural Afluente - ENA), published by ONS were used8.
The ENA represents the amount of water flowing into the reservoir that is available to electricity
generation. The ENA is expressed in a percentage over the Long Term Average (from the Portuguese
Média de Longo Termo - MLT) registered and is directly connected to the amount of rain feeding the
river flow9.
The chart below is the ENA of the south region of Brazil, where the project is located. Data from 2000
to 2010 was used. An important aspect to highlight from the below figure is that within a year, the
availability of water varies significantly. As it can be observed, there is not a clear pattern that makes
feasible for the project owner to predict electricity generation.

Additionally, diverse from what is stated by the MP, not always small hydropower plants can
continuously generate electricity. It must also be considered that in some exceptional years, there also
may be some periods in which the river flow is not sufficient to run the plant. See historical yearly and
monthly variation in the river flow compared to the long term, 1930 to 2005 averages, in the two
following figures, stressing the intermittent character of the hydropower potential
10.

Moreover, some wind power plants may also generate electricity continuously throughout the year. This
can be seen by the observing the electricity generation of three registered CDM wind power plants
project activities as presented in the figure below.

In fact, the project generation profile is very similar to the profile of three other wind power plants. As it
can be seen from the figure below, Pesqueiro Small Hydro Power Plant generates electricity throughout
the year significantly varying its electricity output within a year.

Small Hydropower Plant Pesqueiro possesses a small reservoir which allows the plant to store water for
approximately five hours. Taking this information into account the MP inferred that the plant could shift
its generation to the peak hours. However, it shall be noted that this assumption (generating electricity
only during the peak hours) would only be reasonable it the river flow is considered to be constant and
stable throughout the day, week and year, which is not.
Moreover, comparing the actual generation data from the plant and the load of the system for the most
recent years, it can be seen that the generation by the plant matches the load profile of the system (~37%
of electricity generation during low consumption periods; ~53% of electricity generation during average
consumption period; ~10% of electricity generation during peak load periods). This evidences that the
reservoir is not used to save water to favor electricity generation in the peak hours. On the contrary,
whenever the resource (i.e. water) is available, the plant is operational and generates electricity.
The figure below presents data from 2006. According to CCEE the Load Threshold means the
classification of the hours of the month according to the load profile defined by ONS, which may be:
Light (low consumption period), Average (average consumption period) and Heavy (peak load period).
Information from 2007, 2008 and 2009 is also available and results in the same profile.

As per the argumentation presented above, it is evident that the Pesqueiro SHPP Project Activity has an
intermittent and non-dispatchable nature fully comparable to wind power plants in the same region
(Brazil) and the adoption of the corresponding weighting values (wOM = 0.75 and wBM = 0.25) not only
reasonable but natural.

During the 50th Meth Panel meeting the recommendation was provided:
... the Methodologies Panel recommends not to revise the "Tool to calculate the emission factor for an
electricity system", as no general conclusion can be drawn which applies to all run-of-river hydro power
plants. However, hydro power plants may have different impacts on the share of the BM and OM
depending on the specific circumstances, and a change to the ratio of OM/BM weights may be proposed
for individual project activities through a deviation request.
Therefore, considering this request for deviation is project specific, it is understood that no revision of
the tool is required.

The proposed deviation request is submitted in the context of the revalidation of Pesqueiro Energia Small
Hydroelectricity Project. Emission Reductions by this CDM Project Activity are generated due to
electricity generation by a Small Hydro Power Plant which is dispatched into Brazilian Interconnected
Grid.
Baseline emissions are determined multiplying electricity generated by the plant by the emission factor
of the grid. Electricity to be generated during the second crediting period of the proposed CDM Project
Activity is estimated considering the plant load factor as established by the Brazilian Electricity
Regulatory Agency (form the Portuguese Agéncia Nacional de Energia Elétrica - ANEEL) - ANEEL
Ordinance #325, dated August 13th, 2001.
Trough this ordinance, ANEEL established that the plant is authorized to generated 80,942.4MW/year on
average. This figure is used to estimate the future emission reductions by the plant during the second
crediting period.
For the purpose of estimate, the build margin and operating margin emission factors for the year 2009,
which were published by the Brazilian DNA, are going to be used to describe the impact of the proposed
deviation on the estimates of emission reductions for the proposed project activity. The numbers
published by the Brazilian DNA for that year are:
Build Margin (BM2009) emission factor: 0.0794 tCO2/MWh
Operating Margin (OM2009) emission factor: 0.2476 tCO2/MWh
The weighting for calculation of the combined margin during the second crediting period, as established
by the latest version of the "Tool to calculate the emission factor for an electricity system" for projects
other than wind and solar is wOM = 0.25 and wBM = 0.75. Considering these weights, the combined
margin emission factor to be used while estimating the emission reductions by the proposed project
activity is 0.1214 tCO2/MWh. Consequently, the emission reductions by the project during its second
crediting period are 9,830 tCO2/year.
If the proposed deviation request is deemed appropriate, the weights for estimating the combined margin
would be wOM = 0.75 and wBM = 0.25. Using these weights, the result is that the combined margin
emission factor is 0.2055 tCO2/MWh, which results in an average emission reduction equal to 16,635
tCO2/MWh.