Flarei TFGhk NCVk EFk k

Where:

FGi k = amount of gas k flared during production of petrochemical i, tonnes

NCVk = net calorific value of flared gas k, TJ/tonne

(Note: In Table 1.2 in Chapter 1 of Volume 2, net calorific values are expressed in TJ/kg)

EFk = CO2 emission factor of flared gas k, tonnes CO2/TJ

(Note: In Table 1.4 in Chapter 1 of Volume 2, CO2 emission factors are expressed in kg/TJ)

Table 3.10

Specific carbon content of petrochemical feedstocks and products

Substance

Carbon (tonne carbon per tonne feedstock or product)

Acetonitrile

0.5852

Acrylonitrile

0.6664

Butadiene

0.888

Carbon black

0.970

Carbon Black Feedstock

0.900

Ethane

0.856

Ethylene

0.856

Ethylene dichloride

0.245

Ethylene glycol

0.387

Ethylene oxide

0.545

Hydrogen Cyanide

0.4444

Methanol

0.375

Methane

0.749

Propane

0.817

Propylene

0.8563

Vinyl Chloride Monomer

0.384

Note: Carbon content values for natural gas and naphtha vary by country and region. Net calorific values (NCV) for natural gas, naphtha, and other primary fuels that may be used as petrochemical feedstocks are included in Table 1.2 in Chapter 1 of Volume 2: Energy. Feedstock carbon contents are included in Table 1.3 in Chapter 1 of Volume 2: Energy.

METHANE

The decision tree for choice of method for CH4 emissions is shown in Figure 3.9. The Tier 1 and Tier 3 methods for CH4 are described in this section. There is no Tier 2 method applicable to CH4 emissions.

Tier 1 product-based emission factor method

CH4 emissions from petrochemical processes may be fugitive emissions and/or process vent emissions. Fugitive emissions are emitted from flanges, valves, and other process equipment. Emissions from process vent sources include incomplete combustion of waste gas in flare and energy recovery systems. CH4 emissions using the Tier 1 method may be calculated using Equation 3.23 for fugitive CH4 emissions and Equation 3.24 for process vent emissions and Equation 3.25 for total CH4 emissions. If annual primary product production data are not available but feedstock consumption data are available for the petrochemical process, Equation 3.16 would be utilised to estimate the annual production of primary products, and the annual primary product production estimated using Equation 3.16 would then be applied in Equations 3.23 and 3.24 to estimate the emissions.

Equation 3.23 Tier 1 CH4 fugitive emission calculation

Equation 3.24 Tier 1 CH4 process vent emission calculation

Equation 3.25 Tier 1 CH4 total emissions calculation

ECH 4Total ,i = ECH 4 Fugitive,i + ECH 4ProcessVent,i

Where:

ECH4 Totai,i = total emissions of CH4 from production of petrochemical i, kg ECH4 Fugitive,i = fugitive emissions of CH4 from production of petrochemical i, kg ECH4 Process Vent,i = process vent emissions of CH4 from production of petrochemical i, kg PPi = annual production of petrochemical i, tonnes

EFfi = CH4 fugitive emission factor for petrochemical i, kg CH4/tonne product EFpi = CH4 process vent emission factor for petrochemical i, kg CH4/tonne product

Tier 2 total feedstock carbon balance method

The total feedstock carbon mass balance method is not applicable to estimation of CH4 emissions. The total carbon mass balance method estimates the total carbon emissions from the process but does not directly provide an estimate of the amount of the total carbon emissions that is emitted as CO2, CH4, CO, or NMVOC.

Tier 3 direct estimate of plant-specific emissions

The Tier 3 method is based on continuous or periodic plant-specific measurements. The emissions from the petrochemical production process include CH4 emitted from fuel or process by-products combusted to provide heat or thermal energy to the production process, CH4 emitted from process vents, and CH4 emitted from flared waste gases. If methane is vented directly to the atmosphere this will dominate the emissions. CH4 emissions from process vents may also be combusted in a flare or energy recovery device. Measurement of atmospheric concentration of VOCs directly above the plants or in the plume is the preferred activity data for estimating fugitive CH4 emissions; however, such data may not be available. The atmospheric measurements are generally expensive and will most often not be continuous measurements but rather a discrete and periodic measurement program to obtain data to be used as basis for the development of plant specific emission factors. The results of such measurement programs would then be related to other plant process parameters to enable estimation of emissions between measurement periods.

Direct measurement of VOC and CH4 concentrations in plant exhaust gas streams and direct measurement of fugitive VOC and CH4 emissions from plant valves, fittings, and related equipment using a comprehensive leak detection programme can also be used to obtain plant-specific activity data for developing Tier 3 estimates of CH4 emissions. However the plant-specific leak detection programme should provide fugitive CH4 emissions data for all of the relevant CH4-emitting plant equipment. Similarly, the plant-specific measurement data for stacks and vents would need to cover the major portion of stack and vent CH4 emissions sources at the plant in order to provide a basis for a Tier 3 emission calculation.

Emissions of CH4 from process stacks and vents may be estimated by direct measurement of the CH4 concentration of the exhaust gas or estimated as a component of the total VOC concentration measured in the exhaust gas. Fugitive emissions of CH4 from plant equipment (e.g., valves, fittings) may be estimated through application of plant-specific leak detection data and plant equipment inventories, provided that the plant-specific leak detection program and equipment inventory are comprehensive, such that the program provides fugitive CH4 emissions data for all of the relevant CH4-emitting plant equipment. Similarly, the plant-specific measurement data for stacks and vents would need to cover the major portion of stack and vent CH4 emissions sources at the plant in order to provide a basis for a Tier 3 emission calculation.

Measurement of fugitive emissions may also be based on the CH4 concentration in the atmosphere immediately above the plant or in a plume downwind. Such atmospheric measurement data would generally measure emissions from the entire plant, and does not separate between the different sources. In addition to CH4 concentration the area of the plume and the wind speed must be measured. The emissions are given by Equation 3.26.

Equation 3.26

Tier 3 CH4 emission calculation based on atmospheric measurement data

CH4 Emissions = [ [ total VOCs • CH4 fraction - CH4background level)• WS • pA[

Where:

CH4 Emissions = total plant CH4 emissions, ^g/s

C total voCs = VOC concentration at the plant, ^g/m3

CH4 fraction = fraction of total VOC concentration that is CH4, fraction

CH4 background level = ambient CH4 concentration at background location, ^g/m3

Note: jt means the quantity should be summed over time.

Note that the Tier 3 methodology does not direct inventory compilers to conduct atmospheric measurements or other specific types of direct measurements to estimate site-specific CH4 emissions. It is anticipated that plant-specific leak detection data and plant-specific stack and vent emission data will be more readily available than atmospheric measurement data. However, if atmospheric measurement data are available the data may be used to develop Tier 3 estimates of CH4 emissions, or to verify other estimates. Atmospheric measurement data may provide a more accurate estimate of process CH4 emissions than leak detection data and stack and vent emission data. A plant would use either i) Equation 3.26 or ii) Equations 3.27, 3.28, and 3.29 to estimate CH4 emissions. Process vent emissions are assumed to be monitored either discretely or continuously. The method of calculation will vary depending upon the type of data, and therefore no separate equation is provided for process vent emissions calculation.

Overall emissions of CH4 from the petrochemical production process based on plant-specific leak detection data and plant-specific stack and vent emissions data are calculated using Equation 3.27

Equation 3.27 Tier 3 CH4 emissions calculation equation

ECH 4i — ECombustion,i + EProcessVent ,i + EFlare,i

Where:

ECH4i = total emissions of CH4 from production of petrochemical i, kg

E i^mtaitroiy = emissions of CH4 from fuel or process by-products combusted to provide heat or thermal energy to the production process for petrochemical i, kg

E Process Vent,i = emissions of CH4 from process vents during production of petrochemical i, kg

E Flare,i = emissions of CH4 from flared waste gases during production of petrochemical i, kg

E combustion and E flare are given by Equations 3.28 and 3.29 where plant specific or national net calorific value data should be used.

Equation 3.28 Fuel combustion Tier 3 CH4 emissions calculation

Where:

FAik = amount of fuel k consumed for production of petrochemical i, tonnes

NCVk = net calorific value of fuel k, TJ/tonne

(Note: In Table 1.2 in Chapter 1 of Volume 2, net calorific values are expressed in TJ/kg)

EFk = CH4 emission factor of fuel k, kg/TJ

Equation 3.29 Flare gas Tier 3 CH4 emissions calculation

Where:

FGlk = amount of gas k flared during production of petrochemical i, tonnes

NCVk = net calorific value of flared gas k, TJ/tonne

(Note: In Table 1.2 in Chapter 1 of Volume2, net calorific values are expressed in TJ/kg)

EFk = CH4 emission factor of flared gas k, kg/TJ

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Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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