# Presentation: 877768

## Estimating Emissions of Other Greenhouse Gases

- Presentation to the Department of Energy
- Republic of the Philippines
- September 17, 1997
- Arthur Rypinski
- Energy Information Administration
- U.S. Department of Energy
- courtesy of the U.S. Agency for International Development

## Plan of the Presentation

- General Warnings and Cautions
- Global Warming Potentials
- Data Sources and Tools
- Methane Emissions
- Energy Systems
- Agriculture
- Waste Disposal
- Nitrous Oxide
- Halogenated Substances

## General Warnings & Cautions

- Estimation methods for other greenhouse Gases are much less reliable than for carbon dioxide.
- Data to make estimates is often not available or must be inferred.

## Global Warming Potentials

- Greenhouse gases vary in the efficacy with which they warm the planet.  An effective greenhouse gas:
- sits in a part of the spectrum where most light/heat is transmitted through the atmosphere;
- has a long atmospheric lifetime; so that its heating effects persist.
- Is relatively scarce in the atmosphere.

## GWPs--continued

- Policymakers needed to know the “rate of exchange” between various greenhouse gases; so that they can determine the relative desirability of controlling methane vs. carbon dioxide, for example.
- To meet this need, scientists associated with the IPCC developed the concept of global warming potentials.

## GWPs--continued

- A global warming potential is a measure of the warming impact of a particular gas, compared with carbon dioxide.
- A discussion of the development of GWPs can be found in the various IPCC scientific reports:  *Climate Change 1995* and predecessors.

## GWPs

- The current IPCC recommendation for GWPs (100-year integration) is:
- Methane:             31
- Nitrous Oxide:  310
- HFC-134a       1,300
- SF6                23,900

## Data Sources & Tools

- IPCC, *Climate Change 1995:  The Science of Climate Change* (Cambridge University Press, 1996).
- IPCC, *Greenhouse Gas Inventory Reference Manual* (1996 edition)
- US Environmental Protection Agency, *Compilation of Air Pollutant Emission Factors* (AP-42) available on the Internet at www.epa.gov/ttn/chief/
- US EIA, *Emissions of Greenhouse Gases in the United States;* available on the Internet at www.eia.doe.gov/oiaf/1605/frntend.html

## Methane Emissions from Energy Systems

- Fugitive emissions from fossil fuel stationary combustion;
- fugitive emissions from transportation;
- Emissions from coal mining;
- emissions from oil and gas production
- Fugitive emissions from biomass burning

## Methane:  Fossil Fuel Combustion

- Methane is formed in trace amounts from partial combustion of fossil fuels, and escapes through the exhaust.
- Emissions factors from AP-42 and IPCC reference manual:  fuel consumption x emissions factors
- Emissions extremely low; circa 1-10 kg per million Btu; implies Philippine emissions of less than 1,000 metric tons from this source.

## Transportation Methane Emissions

- emissions from vehicles without pollution control devices are higher, but this is still a small source
- emissions factors available from IPCC; for passenger cars 0.8 g CH4/kg of fuel, 0.17 g/kg for diesels, 2.64 g/kg for piston airplanes; 0.087 g/kg for jets
- Philippine emissions probably less than 1,000 metric tons.

## Methane from Coal Mines

- Emissions from shallow coal mines and surface mining very low; typically on the order of 0.2-1.5 kg per ton of coal mined (IPCC)
- Emissions from deeper mines very complex and heterogeneous; best approach is to seek ventilation data from mine operator.
- Philippine emissions probably very low; less than 10 metric tons.

## Methane from Oil Production/Refining

- Crude oil usually has methane dissolved in it; when produced, stored, transported, and refined, dissolved methane gradually escapes.   There are no good methods for estimating oil production emissions.
- Total refining/transport emissions about 16 kg/thousand barrels refined; implies Philippine emissions of about 2,000 metric tons.

## Methane from Biomass Burning

- Biomass burning can produce very large methane emissions per unit of energy; particularly for open fires or residential charcoal/wood combustion.
- Emissions factors from AP-42 and IPCC;
- Based on reported biomass consumption, Philippine emissions might be 3-30,000 metric tons of methane.

## Methane from Agriculture

- Emissions from ruminant animals;
- Emissions from animal waste disposal;
- Emissions from crop stubble burning;
- Emissions from rice cultivation (??)

## Emissions from Ruminant Animals

- Ruminant animals (cows and buffalo) digest their food with the aid of anaerobic bacteria in their stomachs.  The bacteria convert a portion of the feed to methane; which the animal then emits to the atmosphere.
- Emissions determined by the size of the animal and the quality of the feed
- Emissions factors from the IPCC *Reference Manual*; livestock populations from the *Philippine Statistical Yearbook*.
- Philippine emissions probably on the order of 250,000 metric tons (5 million animals x 50 kg/animal).

## Emissions from Animal Waste

- Methane emissions from animal waste occur when large volumes of waste are accumulated in pits or lagoons; and permitted to decompose anaerobically.
- This is typical of disposal practices for feedlots and other intensive husbandry operations.  Waste from grazing animals and small scale operations will usually decompose aerobically.
- Emissions factors are available from the IPCC; however estimators will have to develop information on typical animal waste disposal practices, particularly for swine
- Emissions might be as high as 250,000 metric tons.

## Methane from Crop Burning

- Open burning of agricultural waste (for example, sugar cane) produces low level methane emissions.
- Emissions are estimated by taking area under cultivation by crop; calculating proportion burned; and emissions per hectare depending on the nature of the stubble.

## Emissions from Rice Cultivation

- Rice paddies are flooded with water for a portion of the growing season.  When flooded, organic matter  in the paddy decomposes anaerobically and emits methane.
- Per hectare per day of the growing season emissions factors are available from the IPCC; but how much rice is grown in the Philippines?

## Methane from Waste Disposal

- Methane from landfills is a huge emissions source in the United States; because U.S. landfills are carefully sealed and covered; causing them to decay anaerobically.
- “Tip” waste disposal more typical of the rest of the world permits aerobic decomposition of waste and produces negligible methane emissions.

## Methane from Industrial Processes

- There are several industrial processes that emit methane in small amounts; including manufacture of iron and steel; carbon black; styrene.
- It is unlikely that these industries are present in the Philippines.

## Nitrous Oxide Emissions

- Combustion Processes
- Stationary combustion of fossil fuels
- mobile sources
- biomass
- Industrial Processes
- Use of Nitrogen Fertilizers

## Nitrous Oxide Emissions from Fossil Fuel Stationary Combustion

- Atmospheric nitrogen reacts with oxygen at high temperatures to produce small amounts of nitrous oxide (N2O) when fossil fuel is combusted.
- Determinants of emissions are poorly understood, but amounts are very small.  Emissions factors from IPCC and AP-42
- Philippine emissions probably less than 500 metric tons.

## Nitrous Oxide Emissions from Biomass Burning

- Emissions are caused both by agricultural burning and by biomass burning.
- Emissions factors from the IPCC; crop emissions by type of crop, area under cultivation; and quantity burned.
- Philippine emissions from this source should be very low.

## Nitrous Oxide Emissions from Nitrogenous Fertilizer Use

- Soil bacteria emit nitrous oxide; these bacteria grow and flourish in the prices of elevated levels of soil nitrogen, as induced by the application of nitrogenous fertilizer.
- Study of this phenomenon has failed to reduce uncertainty about the determinants of soil nitrogen emissions.
- A very crude order-of-magnitude estimate can be made by applying an emissions factor to quantity of nitrogen applied in fertilizer. (0.0157 kg N2O/kg N in fertilizer)
- Philippine emissions (407,200 metric tons N x 0.0157) would be about 6,000 metric tons.

## Nitrous Oxide Emissions from Mobile Combustion

- Catalytic converters in U.S. automobiles promote the formation of nitrous oxide in recent models of automobiles;  emissions from uncontrolled vehicles are very low.
- Emissions factors from IPCC;  vehicle fuel consumption from PDOE.
- Philippine emissions probably less than 250 metric tons

## Nitrous Oxide from Industrial Processes

- Several industrial processes emit nitrous oxide; particularly the manufacture of nitric acid and adipic acid (a nylon precursor).
- It is unlikely that these industries exist in the Philippines.

## Halocarbons and Related Chemicals

- Chlorofluorocarbons are being phased out in much of the world.  As CFCs gradually disappear, they are being replaced by an array of new manufactured chemicals; many of which are potent greenhouse gases.
- Chemicals of possible interest for a Philippine emissions inventory include the refrigerant HFC-134a and sulfur hexafluoride (SF6)

## HFC-134a

- This chemical is used as refrigerant in mobile air conditioners and refrigerators; and as a replacement blowing agent.
- If it is used in the Philippines; one can count the number of HFC-134a using equipment manufactured or imported; and assume leak performance; or actually measure imports/production of this chemical.

## Sulfur Hexafluoride

- Sulfur hexafluoride is used by electric utilities as an insulator in transformers and switches.
- consumption can be estimated by asking utilities about their consumption, or possibly by tracking imports.

## Other Irrelevant Sources

- CF4 and C2F6 are emitted from aluminum smelting; and also used in semiconductor fabrication and in magnesium smelting.
- HFC-23 is emitted as a by-product of HCFC-22 manufacture
- There are several other more exotic HFCs that are used in small quantities as refrigerants.