industry and environment - DTIE

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Figure 2
SANGEA summary chart
example, indirect emissions could
include those from the production of
purchased electricity, contract manufacturing,
contracted drilling operations
and product transport by third parties.
The Guidelines provide a rationale for
accounting and reporting indirect emissions
from energy consumption. An
example for the petroleum industry
illustrated in the Guidelines is accounting
for power plants located within a
refinery that export electricity and/or
steam to other companies.
Another unique situation for the
petroleum industry is contract operations
where a petroleum company provides
fuel to a contract operator. This
occurs in drilling operations, as well as
in transportation of crude oil or products.
The Guidelines suggest that companies
consider accounting for significant
contract operations as sources of indirect
emissions. Based on the accounting approach
described in the Guidelines, provision of fuel to a
contract operator should not influence whether
the emissions are included as operated or equity
share. Since the emissions come from a contracted
operation, they are indirect emissions.
Once the inventory accounting approach has
been set, and decisions have been made as to what
types of reports will be developed and what the
data will be used for, the next step is to understand
the specific sources included in each facility
and what methodology is appropriate to
estimate the emissions. The Guidelines provide
an overview of the types of methodologies that
are appropriate for exploration and production
facilities and petroleum and petrochemical refining/manufacturing
facilities. These approaches
are described for the two types of facilities for various
ranges of accuracy, using a tiered approach.
Tier A represents the highest level of accuracy.
Tier B includes somewhat less rigorous methods,
and is therefore likely to be more straightforward
and less costly to implement. However, the
uncertainty associated with these methods is
greater. Finally, for an assessment of
emissions where uncertainties of 30-
60% are acceptable, Tier C methods
may be employed. Each of the Tiers in
the Guidelines is linked to appropriate
calculational methodologies in the
API Compendium.
Specific information about the
types of approaches available for estimating
emissions is found in the
Compendium. For a given facility, and
a given range of uncertainty, the specific
method used for each source will
de pend on the information available
about that source. For example, the
Compendium recommends that the
preferred method for estimating emissions
from combustion sources is to
determine the mass of carbon per mass
of fuel and the mass of fuel used. However,
the Guidelines and the Compendium
recognize that this type of information is
not available for all devices in all facilities. Where
the preferred information is not available, the
Compendium provides alternative methodologies
that utilize existing information to develop a reasonable
estimate of emissions. For example, in
many cases a facility may measure the volume of
fuel used and periodically analyze the specific
gravity and/or heating value of the fuel. As an
alternative to mass based estimates, this information
can be used to estimate carbon dioxide emissions
from fuel combustion.
Developing an inventory:
methodologies
As described above, the Guidelines provide information
on accounting for and reporting to corporate
level of greenhouse gas emissions at the facility.
A companion publication, the API Compendium of
Greenhouse Gas Emissions Estimation Methodologies
for the Oil and Gas Industry, documents a number
of currently recognized calculation techniques and
emission factors available for developing GHG
emissions inventories for oil and gas industry operations.
The Compendium was developed to
Figure 3
SANGEA normalized emissions summary
accomplish the following:
1. assemble an expanse of relevant
emission factors for estimating GHG
emissions from oil and gas industry
activities, based on currently available
public documents;
2. outline detailed procedures for conversions
between different measurement
unit systems, with particular
emphasis on implementation of oil
and gas industry standards;
3. provide descriptions of the multitude
of oil and gas industry operations
– from exploration and production
through refining to the marketing of
products, as well as the transportation
of crude oil, natural gas and petroleum
products – and the associated emissions
sources that should be considered;
4. develop emission inventory examples
– based on selected facilities from the various
industry segments – to demonstrate the broad
applicability of the methodologies.
The Compendium is neither a standard nor a
recommended practice for the development of
GHG inventories. Rather, it represents a compilation
of recognized methodologies for estimating
GHG emissions specific to oil and gas industry
operations.
Source classification
The Compendium groups oil and gas industry
GHG emission sources into three categories:
combustion devices, process emissions and fugitive
emissions.
1. Combustion devices include both stationary
sources, such as engines, burners, heaters and
flares, and fleet-type transportation devices, such
as trucks and ships, where these sources are essential
to operations (i.e. transportation of material or
personnel);
2. Point sources include vents from oil and gas
industry units, such as hydrogen plants and glycol
dehydrators, that emit CO 2 and/or CH 4 . They
also include other stationary devices such as storage
tanks, loading racks and similar equipment;
3. Non-point sources include fugitive
emissions (equipment leaks), emissions
from wastewater treatment facilities,
and a variety of other emissions
generated by waste handling;
4. Non-routine activities, associated
with maintenance or emergency operations,
also may generate GHG emissions;
5. Indirect emissions are defined as
GHG emissions associated with oil
and gas company operations, but
physically occurring from sites or operations
owned or operated by another
organization.
The Compendium includes calculation
and estimating techniques for
determining CO 2 , CH 4 and N 2 O
emissions from all of these sources.
74 ◆ UNEP Industry and Environment April – September 2004