Future emissions of carbonaceous aerosols David G. Streets Argonne National Laboratory ICAP Workshop Research Triangle Park, NC October , 2004

The source of carbonaceous aerosols is unburned carbon emitted during inefficient combustion of fuel Technically, we are most concerned about: black carbon (BC), fine aerosol particles generally smaller than 1 micrometer in diameter and mostly elemental carbon, and 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. Kathmandu: Brick Kilns

“Give me a future, any future…” (Range of IPCC forecasts of temperature change) (Courtesy of Loretta Mickley) A1B and B1 used in ICAP A2 and B2 done subsequently 2030 and 2050 done

IPCC forecasts the future emissions of many greenhouse gases, but no particles (CO sometimes used as proxy for BC/OC) (Courtesy of Loretta Mickley) A1B is a world of slowly increasing CO emissions B1 is a world of slowly declining CO emissions

IPCC energy forecasts have been disaggregated to world regions by the IMAGE team (RIVM, The Netherlands)

Calculation of BC and OC emission factors (g kg -1 of fuel burned) for a given tech/fuel combination: EF BC = EF PM x F 1.0 x F BC x F cont EF OC = EF PM x F 1.0 x F OC x F cont where: EF PM = bulk particulate emission factor (usually PM 10 ) F 1.0 = fraction of the emissions that are < 1 μm in diameter F BC, F OC = fraction of the particulate matter that is carbon F cont = fraction of the fine PM that penetrates any control device that might be installed (= 1 if no controls) (Change with time)

Approach to forecasting BC and OC emissions from the 1996 base-year reference point From Bond et al., JGR, 2004

Major factors influencing future emissions: Level: 1Change in energy use and fuel type, by sector and world region 2Improvements in particle control technology 3Shifts in technology from low-level to higher- level technology/fuel combination 4Improvements in emission performance of a given technology/fuel combination

Which fuels are used in which sectors in which parts of the world? China photo courtesy of Bob Finkelman Residential coal use has very high BC emissions Residential electricity use from nuclear power has zero BC emissions Level 1 forecasting

Fuel use is partitioned among technology types as in the base- year inventory (this example is part of the residential sector)

How fast will particle control technology improve (better designs, capture of smaller particles)? Level 2 forecasting Electrostatic precipitator, high collection efficiency Cyclone, low collection efficiency

Particle penetration fractions (F cont ) are included for each type of control device (this example is the power sector) At present, we assume that control technology performance does not vary with world region

A stove is a stove is a… (tech/fuel shifts for a particular energy service) Photo of street vendor’s stove in Xi’an, courtesy of Beverly Anderson Coal-fired, high BC Gas or electric, low BC Level 3 forecasting

Technology splits reflect scenario, regional, and technology differences, and change with time 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

Insight, tuk-tuk, or Hummer? (technology performance within a tech/fuel class) Huge variations in fuel efficiency and BC emission rates, often regulatory driven Level 4 forecasting

Emission factors for a given tech/fuel combination are determined using an S-shaped technology penetration curve Emission rate (g/kg) Time (years) 1996 current emission factor (Bond/Streets) “Ultimate” performance Shape factor depends on lifetime, build rate, etc. “Net” performance in 2030

How to forecast future biomass burning?? The view is greatly obscured 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.

Components of BC emission changes between 1996 and 2030A1B: technology development overcomes energy growth! Net 2030A1B (Gg) 1996 Bond/Streets Energy growth Technology improvement

Results for all scenarios: a general decline in all cases BC/anthroBC bioburn OC/anthro OC/bioburn

BC emissions in 2050 from anthropogenic activities under the A1B Scenario

BC emissions from open biomass burning in 2050 under the A1B Scenario

Conclusions l 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. l The rate of technology development and adoption is an important determinant of future emission levels. l The gradual phase-out of inefficient technologies in the developing world will slowly reduce primary aerosol emissions; more vehicles everywhere will tend to increase emissions l Our preliminary results suggest we are headed for a world with stable or lower primary aerosol emissions in the future