Present and future contributions of the household sector to emissions of black carbon in China

1. Present and future contributions of the household sector to emissions of black carbon in China David G. StreetsArgonne National LaboratoryWorkshop on the Mitigation of Air Pollution and Climate Change in ChinaOslo, NorwayOctober 17-19, 2004

2. 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. The source of carbonaceous aerosols is unburned carbon emitted during inefficient combustion of fuel Kathmandu: Brick Kilns

3. Human health! Particles are small enough to be inhaled into the deep lung where they slow clearance mechanisms and provide absorption sites for toxic species Soiling of surfaces of buildings, monuments, homes, etc. Reduced visibility Reduction in crop yields due to lowered insolation Possible surface damage to vegetation Modification of regional and global climates: temperature and precipitation changes, effects on cloud formation Harmful Effects of BC

4. A new bar chart of radiative forcing was constructed by Jim Hansen to replace the IPCC formulation Net forcing = 1.6 +/- 1.1 W/m2

5. Model-simulated summer changes in temperature Model suggests a cooling of 0.5 to 1 deg K over China due to reduction in radiation reaching the surface; in other parts of the world, the surface is warmed due to BC heating From Menon et al., Science, 297, 2250-2253, 2002

6. Model-simulated summertime changes in precipitation The model suggests decreased precipitation in northern China (drought) and increased precipitation in southern China (flooding) due to BC aerosols From Menon et al., Science, 297, 2250-2253, 2002

7. “Our analysis of climate forcings suggests, as a strategy to slow global warming, an alternative scenario focused on reducing non-CO2 GHGs and black carbon (soot) aerosols.… (R)eductions in tropospheric ozone and black carbon would not only improve local health and agricultural productivity but also benefit global climate and air quality.” J. Hansen, M. Sato, R. Ruedy, A. Lacis, and V. Oinas, Global warming in the twenty-first century: an alternative scenario, Proceedings of the National Academy of Sciences, 97, 9875-9880, 2000 Jim Hansen’s “Alternative” Scenario(released August 29, 2000)

8. Global distribution of BC emissions in 1996:it’s mostly China, India, and biomass burning China contributes about one-fourth of global BC

9. Inefficient combustion of coal in small stoves in China produces large quantities of black carbon Coal-burning cook stoves in Xi’an, China

10. Results: Most of the BC in China comes from the domestic/residential sector Emissions in China are about 1 million tons per year of BC and 3.4 million tons per year of OC

11. Distribution of black carbon emissions in East Asia by source type and release height, reveals the regional nature of theproblem (2008 Beijing Olympics?) Second-layer sources (industry) Ground-level sources (residential, transport)

12. ENERGY USE BIOMASS BURNING BC EMISSION FACTORS SOURCE TESTING BC EMISSIONS BC ANALYSIS METHODS MONITORING CAMPAIGNS ATMOSPHERIC MODELING Often, [Global, India, China, …] CALCULATED BC CONCENTRATIONS OBSERVED BC CONCENTRATIONS There are still fundamental problems with our understanding of BC in the atmosphere

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

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

15. Level: 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 combination Major factors influencing future BC emissions:

16. Which fuels are used in which sectors? 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

17. Fuel use is partitioned among sectors and technology types(this example is part of the residential sector)

18. 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 Level 3 forecasting Gas or electric, low BC

19. Net BC emission factors (g/kg) are developed from PM ef’s, C fractions, and sub-micron fractions

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

21. Recent fuel use and BC emission trendsin East Asia (≈ China) BC Emissions Fuel Use

22. Future trends in BC emissions from the household sector

23. Future trends in BC emissions fromresidential coal use

24. Future trends in BC emissions from fuelwood use

25. Future trends in BC emissions from stoves

26. Future trends in BC emissions from residentialuse of crop residues

27. The changing picture of residentialBC emissions in China 2030A2: mainly crop residues 1980: mainly coal 2000: coal, wood, crops mixture

28. We desperately need more source testing inChina to improve emission factors Representativeness of entire population of sources Typical operating practices (air flow) Typical fuels and fuel characteristics Relationship to similar sources in the developed world Daily and seasonal operating cycles

29. U.S. and Europe (and other developed countries) reduce CO2 They are the cause of most of the accumulated CO2 They can afford the more expensive measures of CO2 mitigation They will accrue ancillary energy security benefits They can contribute a long-term solution China and India (and other developing countries) reduce BC They are the cause of most of the emitted BC They can afford the less expensive measures of BC control They will accrue ancillary health benefits They can contribute a near-term solution Embracing BC offers the possibility of a true global compact to address climate change

30. Black carbon in China today is a serious environmental problem, leading to (largely unquantified) inhalation health effects, regional ecological damage, and climate modification. The major causes are the direct combustion of solid fuels in the home, poor combustion efficiency and lack of PM controls in the industrial sector, polluting vehicles, and open biomass burning. In the future, we think that the gradual phase-out of inefficient technologies will slowly reduce primary aerosol emissions; more vehicles, however, will tend to increase emissions. In the household sector, things should improve rapidly in urban areas, but linger in rural areas. BC control could be China’s contribution to a global warming treaty. Conclusions