• Energy Research
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With concerns of energy shortages, China, like the United States, European Union, and other countries, is promoting the development of biofuels. However, China also faces high future demand for food and feed, and so its bioenergy program must try to strike a balance between food and fuel. The goals of this paper are to provide an overview of China's current bioethanol program, identify the potential for using marginal lands for feedstock production, and measure the likely impacts of China's bioethanol development on the nation's future food self-sufficiency. Our results indicate that the potential to use marginal land for bioethanol feedstock production is limited. Applying a modeling approach based on highly disaggregated data by region, our analysis shows that the target of 10 million t of bioethanol by 2020 seems to be a prudent target, causing no major disturbances in China's food security. But the expansion of bioethanol may increase environmental pressures due to the higher levels of fertilizer use. This study shows also that if China were able to cultivate 45% of its required bioethanol feedstock on new marginal land, it would further limit negative effects of the bioethanol program on the domestic and international economy, but at the expense of having to apply another 750 thousand t of fertilizer.

In 2010, China was responsible for 45% of global steel production, while consuming 15.8EJ of final energy and emitting 1344Mt CO2eq, 8.4Mt of PM (particulate matter) emissions, and 5.3Mt of SO2 emissions. In this paper we analyse the co-benefits of implementing energy efficiency measures that jointly reduce greenhouse gas emissions and air pollutants, in comparison to applying only air pollution control (end-of-pipe technology). For this purpose we construct ECSC (energy conservation supply curves) that contain potentials and costs of energy efficiency measures and implement these in the GAINS (greenhouse gas and air pollution interactions and synergies) model. Findings show that the technical energy saving potential for the Chinese iron and steel industry for 2030 is around 5.7EJ. This is equivalent to 28% of reference energy use in 2030. The emissions mitigation of GHGs (greenhouse gases) and air pollutants in BAEEM_S3 scenario would be reduce 27% CO2eq, 3% of PM, and 22% of SO2, compared to the BL scenario in 2030. Investments and cost savings were calculated for different scenarios, showing that energy efficiency investments will result in significant reductions in air pollution control costs. Hence, Energy efficiency measures should be integrated in air quality policy in China.

This research aimed to study the quality of the fuel briquettes made from sewage sludge mixed with water hyacinth and sewage sludge mixed with sedge. Sewage sludge were mixed with water hyacinth and sedge at the ratios of 1:1, 1:2, 1:3, 2:1 and 3:1 then compressed these mixtures with hydraulic pressure to obtain fuel briquettes and finalized them by analyzing fuel briquettes properties including moisture content, calorific value and compressive strength, then comparing them to the properties of the wood charcoal standard . The result showed that the ratio of wastewater sludge and sedge at 1:3 provided the highest calorific value ( 3,362.9 cal/g ) but still lower than the standard ( 5,000 cal/g) and the ratio of wastewater sludge and water hyacinth at 1:3 gave the highest compressive strength value ( 4,545 N ) . And the moisture content of them was between 4.78% and 7.86%.

Abstract The optimal fuel gas production conditions for gasification of sacha inchi shell waste were studied with a drop tube reactor. This waste was derived from production of sacha inchi seed oil. Ultimate, proximate and heating value of raw material were analyzed by CHNS/O analyzer, thermogravimetric analysis (TGA) and bomb calorimeter, respectively. Waste particle size was 0.50 - 0.85 mm and the reactor temperature was varied from 700 to 900°C with the equivalent ratio of 0.20 - 0.50. To reduce undesired liquid product, the Ni/dolomite was used as primary catalyst. Solid residue was analyzed for elemental composition while liquid and gas products were analyzed by gas chromatography-mass spectrometry and portable gas analyzer, respectively. It was found that at optimal operating conditions (ER 0.20, 900°C), conversions of carbon to CO, CO2 and CH4 were approximately 30.63%, 14.50% and 6.27%, respectively. Similarly, the conversion of hydrogen to H2 and CH4 were approximately 26.94% and 15.40%, respectively, with the lower heating value at 2.27 MJ/m3 and cold gas efficiency of gasification process is nearly 40% whereas liquid and solid product were 4.55 % and 34.50%. Apparently, higher temperature had a positive effect on greater gas yield and lower liquid production. Furthermore, catalyst addition reduced liquid proportion and increased potential of CO and H2 production especially for Ni loading of 5% on calcined dolomite. The result showed that conversions of carbon to CO increased to 37.95% and conversion of hydrogen to H2 increased to 34.50%. In addition, liquid and solid production decreased to 2.87% and 14.10%, respectively. The feasibility of incorporating the catalytic process on this particular thermal waste conversion method was discussed.

Abstract Biogas upgrading to biomethane is a necessary process for biohydrogen production from renewable source. In this work, absorption processes using water and diethanolamine (DEA) as absorbent were modeled in Aspen Plus software. The purpose was to find the optimal operating condition for sustainable production of biomethane using multi-criteria perspective considering technical, environmental and economic aspects. The absorption system was modified by including one additional absorber unit for improving biogas upgrading efficiency. The performance of the biogas upgrading system was evaluated and compared in terms of methane recovery, methane content in biomethane, and energy consumption. Effects of operating conditions such as operating pressure in absorber, concentration, and total flow rate of absorbents were investigated. The results revealed that the performance of the modified absorption system was superior to the conventional system. The methane content in biomethane, methane recovery, and energy consumption increased with the increase of operating pressure in the absorbers. Increasing concentration and total flow rate of absorbents increased the methane content in biomethane and the energy consumption but decreased the methane recovery. The optimal operating condition could achieve 96%v/v of methane content in biomethane with methane recovery of higher than 95%v/v in the modified water absorption system. The optimum operating pressures of absorber Units 1 and 2, and total absorbent flow rates were at 13 and 5 bar and 16,000 kmol/h, respectively.

Slow progress in expanding clean cooking access is hindering progress on health, gender, equity, climate and air quality goals globally. Despite a rising population share with clean cooking access, the number of cooking poor remains stagnant. In this study we explored clean cooking access until 2050 under three reference scenarios, a COVID-19 recovery scenario and ambitious climate mitigation policy scenarios. Our analysis shows that universal access may not be achieved even in 2050. A protracted recession after the pandemic could leave an additional 470 million people unable to afford clean cooking services in 2030 relative to a reference scenario, with populations in sub-Saharan Africa and Asia the worst affected. Ambitious climate mitigation needs to be twinned with robust energy access policies to prevent an additional 200 million people being unable to transition to clean cooking in 2030. Our findings underline the need for immediate acceleration in efforts to make clean cooking accessible and affordable to all.

Abstract Thailand has depended heavily on imported fossil fuels since the 1990s, which hindered the nation's economic development because it created uncertainty in the nation's fuel supply. An energy conservation policy was implemented in 1995 to require industries to reduce their energy intensity (EI) and consumption immediately. This study investigates the effectiveness of the policy between 1995 and 2010 using the hybrid input–output approach. Surprisingly, EI improvement was observed in only a few sectors, such as transportation, non-metallic, paper, and textile. An embodied energy decomposition analysis revealed that while households were the largest energy consumer in 1995, energy consumption in exports exceeded that of households in 2000, 2005 and 2010. In addition, structural decomposition analysis revealed the final demand effect was the strongest factor in determining the efficacy of energy conservation, whereas the energy efficiency effect was not an effective factor as expected for decreasing energy consumption. Policy barriers and conflicting economic plans were factors that affected the outcome of these energy policies.

Abstract In this paper, we show how nature oriented forestry measures in a typical temperate forest type in combination with bioenergy systems could lead to continuous and permanent removal of CO2 from the atmosphere. We employ a forest growth model suited for modeling uneven-aged mixed temperate stands and analyze the interaction with biomass energy systems that allow for CO2 removal and long-term sequestration in geological formations. On global scales this technological option to convert the global energy system from a CO2 emitter to a CO2 remover has been overlooked by both the science and policy communities. Removal of the major Greenhouse Gas (GHG) CO2 from the atmosphere is possible using biomass energy to produce both carbon neutral energy carriers (e.g., electricity and hydrogen) and, at the same time, offer a permanent CO2 sink by capturing carbon at the conversion facility and permanently storing it in geological formations. This technological option resolves the issues of permanence and saturation of biological sinks while at the same time this option respects the multiple benefits of sustaining diverse, healthy, and resilient forests. Our results indicate that a typical temperate forest in combination with capturing and long-term storage can permanently remove and on a continuous basis about 2.5 t C yr −1 ha −1 on a sustainable basis respecting the ecological integrity of the ecosystem.

Abstract Heat load profiles of new residential developments in rural, sub-urban, and urban context were generated by means of a generic model and dynamic simulations. The combined effect of district building density, building energy efficiency standard, and hot water preparation system on the heat load is discussed in detail. Hundred residential districts representing medium sized developments were defined by varying the distribution of building types. Therefore, a simplified building typology of 13 fictitious buildings was developed. The presented methodology allows to quickly estimate the total heat demand of new residential developments based on the plot ratio and buildings’ energy efficiency standard only. The investigations reveal that the building density as well as the hot water preparation system have a significant impact on the yearly district heating return temperatures. Instantaneous domestic hot water preparation results in up to 14 K lower annual average district heating return temperatures. However, the building density also has a significant influence on the return temperature, resulting in important differences between urban and rural districts.