Forecasting Global BC and OC Emissions to 2030 and 2050. David G. Streets Argonne National Laboratory, Illinois, USA Workshop on Global Air Pollution Trends to 2030 IIASA, Laxenburg, Austria January 27-28, 2005. Technically, we are most concerned about:
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David G. StreetsArgonne National Laboratory, Illinois, USAWorkshop on Global Air Pollution Trends to 2030IIASA, Laxenburg, AustriaJanuary 27-28, 2005
black carbon (BC), fine aerosol particles generally smaller than 1 micrometer in diameter and mostly elemental carbon,
organic carbon (OC), similar particles in which the carbon is bonded to other atoms.
These particles are small enough to travel in the air for a week or more, forming regional air pollution and ultimately being deposited far from the source.The source of carbonaceous aerosols is unburned carbon emitted during inefficient combustion
Kathmandu: Brick Kilns
China contributes about one-fourth of global BC
Coal-burning cook stoves
in Xi’an, China
A2 and B2 done subsequently
2030 and 2050 done
A1B and B1 used in ICAP
(Courtesy of Loretta Mickley)
EF produces large quantities of black carbonBC = EFPM x F1.0 x FBC x Fcont
EFOC = EFPM x F1.0 x FOC x Fcont
EFPM = bulk particulate emission factor (usually PM10)
F1.0 = fraction of the emissions that are < 1 μm in diameter
FBC, FOC = fraction of the particulate matter that is carbon
Fcont = fraction of the fine PM that penetrates any control device that might be installed (= 1 if no controls)Calculation of BC and OC emission factors (g kg-1 of fuel burned) for a given tech/fuel combination:
(Change with time)
From Bond et al., JGR, 2004
Level: base-year reference point
1 Change in energy use and fuel type, by sector and world region
2 Improvements in particle control technology
3 Shifts in technology from low-level to higher- level technology/fuel combination
4 Improvements in emission performance of a given technology/fuel combinationMajor factors influencing future emissions:
China photo courtesy of Bob Finkelman
Residential coal use has very high BC emissions
Level 1 forecasting
Residential electricity use from nuclear power has zero BC emissions
Electrostatic precipitator, high collection efficiency
Level 2 forecasting
Cyclone, low collection efficiency
At present, we assume that control technology performance does not vary with world region
Photo of street vendor’s stove in Xi’an, courtesy of Beverly Anderson
Coal-fired, high BC
Level 3 forecasting
Gas or electric, low BC
Eight alternative configurations of conventional hard-coal-fired power plants
We assume that regional GDP growth determines the rate of replacement of the worst-performing tech/fuel option, with a “nudge” for the environmental scenarios in some cases
Huge variations in fuel efficiency and BC emission rates, often regulatory driven
Level 4 forecasting
1996 current emission factor (Bond/Streets)
Shape factor depends on lifetime, build rate, etc.
Emission rate (g/kg)
“Net” performance in 2030
Many unpredictable factors influence future biomass burning. The IPCC projects only direct anthropogenic influences related to slash-and-burn agriculture, crop residue burning, loss of grassland, etc., driven by regional food demands. We have added natural fires.
No accounting for fundamental land-use changes, timber industry practices, climate change influence on fire frequency, and other natural influences.
A model has been developed to project the global base-year 1996 inventory of Bond/Streets to future years, driven by IPCC regional forecasts of energy, fuel use, and economic activity.
The rate of technology development and adoption is an important determinant of future emission levels.
The gradual phase-out of inefficient technologies and small-scale solid fuel combustion in the developing world will slowly reduce primary aerosol emissions; more vehicles everywhere will tend to increase emissions
Our results suggest that we are headed for a world with stable or lower primary aerosol emissions in the futureConclusions