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Direct combustion of solid biomass fuel is one of the most common energy sources in developing countries. Evaluation of technology for household biomass pellet fuel combustion is critical, since promoting poorly designed devices may have risks due to exposure to high levels of emissions. This study evaluated the effects of various testing conditions on a top-lit forced-up-draft semi-gasifier cooking stove. An orthogonal test was designed with different fuel masses, chamber heights, air supply rates, and ending points. The investigation showed that using forced secondary air and more fuel tended to improve both thermal and gas emissions performance. The ending points did not have significant effects on thermal efficiency or the carbon dioxide emission factor, but did affect particulate matter emission. A relatively lower chamber height demonstrated better performance on thermal metrics. However, a taller flame had better performance on particulate matter emission factors. The results of the indicators reported by different bases, such as fuel mass-based or useful energy-based were also quite different. The study showed that different testing conditions had significant effects on combustion performances. Testing sequences and emission factors should be reviewed and defined clearly when forming testing methods and standards for biomass pellet fuel combustion. [ABSTRACT FROM AUTHOR]

Abstract: In order to further study the realization of carbon intensity target, find the key influencing factors of CO2 emissions, and explore the path of developing low-carbon economy, this paper empirically studied the influences of urbanization level, economic level, industry proportion, tertiary industry proportion, energy intensity and R&D output on CO2 emissions in Beijing using improved STIRPAT (stochastic impacts by regression on population, affluence and technology) model. The model is examined using partial least square regression. Results show that urbanization level, economic level and industry proportion positively influence the CO2 emissions, while tertiary industry proportion, energy intensity and R&D output negatively do. Urbanization level is the main driving factor of CO2 emissions, and tertiary industry proportion is the main inhibiting factor. In addition, along with the growth of per capita GDP, the increase of CO2 emissions does not follow the Environmental Kuznets Curve model. Based on these empirical findings and the specific circumstances of Beijing, we provide some policy recommendations on how to reduce carbon intensity. Beijing should pay more attention to tertiary industry and residential energy consumption for carbon emission reduction. It is necessary to establish a comprehensive evaluation index of social development. Investing more capital on carbon emission reduction science and technology, and promoting R&D output is also an efficient way to reduce CO2 emissions. [Copyright &y& Elsevier]

Indoor air pollution is ranked the 5th in the Global Burden of Disease index of the World Health Organization (WHO). Almost half of the world's population depends on biomass fuels to meet their basic energy requirements for cooking, lighting and space heating. When fuel is badly combusted in poorly designed stoves, the fuel-stove combination results in high level of noxious emissions entering the home, accumulating to dangerous levels. In this study, a Chinese unvented top lit updraft (TLUD) biomass stove was operated with three different biomass pellets formed from corn stover, cotton stalk and peanut shells. The performance tests were conducted according to the latest standard from the Chinese Ministry of Agriculture. The calorific value, moisture level, volatile matter and elemental composition are reported for each. The thermal efficiencies of the stove were 15.3%, 10.1% and 14.4%, respectively. The cooking powers were 2.68 kW, 1.61 kW and 1.57 kW. The exhaust was collected using a hood and tunnel. The CO, NO and NOX were drawn after passing 1.5 m along the tunnel and the Particulate Matter (PM) was sampled after 1.6 m. The Emission Factors (EF) for CO, NO, NOX and PM10 are reported on both a mass per unit energy delivered to the pot (g/MJNET) and a mass per mass of fuel basis (g/kg). The range for CO was 4.56-7.61 g/MJNET (11.25-21.25 g/kg); NO was 0.75-1.23 g/MJNET (2.09-3.04 g/kg); NOx was 1.13-1.90 g/MJNET (3.14-4.86 g/kg); PM10 was 0.59-0.85 g/MJNET (1.67-2.09 g/kg). The range in these values was more significantly influenced by the fuel moisture content and the percentage of volatile matter than by variations in the elemental composition. [ABSTRACT FROM AUTHOR]