Sustainability of silicon feedstock for a low-carbon society

We need to ensure the sustainable management of advanced materials, such as purified silicon, that contribute to a low-carbon society. Because a drastic increase in the demand for photovoltaic (PV) systems is tightening the supply of silicon for PV cells, the sustainability of silicon feedstock needs to be explored. For this purpose, a material flow analysis of silicon in Japan from 1996 to 2006 is presented in this paper. Our analysis finds that rapid growth in demand for polycrystalline silicon (pc-silicon) and single crystalline silicon (sc-silicon) has changed the structure of the purified silicon supply. The strong demand for purified silicon for solar cells is responsible for this change. While off-grade silicon obtained as a by-product of electronic-grade silicon (EG-Si) covered the demand for solar sells before 2000, pc-silicon is currently produced independently for solar cells via an energy-intensive process. Analysis of the resource effective-use index (REI), which indicates how effectively purified silicon is used, shows progress in the effective use of pc- and sc-silicon. REI analysis indicates that the effective use of pc-silicon is reaching a maximum, while the effective use of sc-silicon is advancing, with a corresponding increase in price. To ensure a sustainable supply of silicon feedstock, this paper proposes four solutions: (1) production of solar-grade pc-silicon by a less costly and less energy-consuming method; (2) reduction in the amount of crystalline silicon per watt in solar cells; (3) acceleration of the development and deployment of other solar cell types; and (4) reuse and recycling of solar cells in the future.     

The pathway to a sustainable industrial society – initiative of the Research Institute for Sustainability Science (RISS) at Osaka University

While it is widely known that sustainable development is the only sound and viable pathway for humankind’s future, its attainment remains elusive despite intensive efforts and some successes. The current industrial society approach based on product and process innovation in a variety of fields is not providing the expected results in addressing this important issue. In an attempt to carry out this unavoidable task, Osaka University’s Research Institute for Sustainability Science (RISS) introduces an integral and dynamic innovation system where technology plays a key role in fulfilling societal functions. This innovation system adopts a highly solution-driven approach that makes use of backcasting techniques based on long-term visions and mid-term strategic goals. Since technology management is the key to propelling effective innovation towards sustainability, we propose a technology transition management through the interaction of technology push, demand pull and institutional design, along with eight transition principles. RISS will develop this innovation system based on these three components and through the design of dynamic scenarios and their roadmaps.     

Simulating the effects of urbanization,afforestation and cropland abandonment on a regional carbon balance: a case study for Central Germany

The newly developed model system HILLS is used to simulate recent (1990–2000) and future (up to 2020) changes in land use and carbon sequestration over Central Germany. HILLS is unique as that it integrates the spatially explicit land-use-change model LUC-Hesse with the dynamic ecosystem model Century under a GIS platform. With this new tool, the concurrent effects of urbanization, afforestation and cropland abandonment on regional carbon sequestration are analyzed for an exemplary “Business as Usual” scenario. During the simulation period, afforestation was estimated to sequester 880 Gg C and cropland abandonment 783 Gg C. Urbanization was estimated to release 336 Gg C formerly stored in soil organic matter and thereby offsets about 20% of the C sequestered by cropland abandonment and afforestation. The case study shows that urbanization can partly counteract the benefits of carbon sequestration resulting from other land-use changes and should be investigated in other carbon balances.     

能源消费、经济增长与中国CO2排放量变化

基于我国能源消费和经济增长特点,采用对数平均的Divisa方法对我国1990~2007年的CO2排放进行分解分析。结果表明：经济增长效应是我国CO2排放增加的主要因素,能源强度效应是抑制CO2排放的主要原因,人口效应和结构效应对碳排放的影响不大。分地区的研究表明：东部地区的经济发展和能源强度效应对CO2排放量的影响高于中西部地区,人口效应使东部地区碳排放增加,使中西部地区碳排放降低,能源利用结构变化对东部地区的碳排放有一定的抑制作用,对中西部地区的影响较小。因此,要降低我国的CO2排放,需要针对地区特点制定不同的政策,东部地区需要进一步提升技术水平,进而提高能源利用效率,对中西部地区需要逐步改善以煤为主的能源消费结构,提高清洁能源比重,同时调整产业结构,发展服务业和技术含量高的低能耗制造业。     

Predicting CO2 and SO2 emissions in the Baltic States through reorganization of energy infrastructure

The paper deals with predicting carbon dioxide and sulphur dioxide emissions generated by power production sector in the Baltic States in period up to year 2020. The economies of Lithuania, Latvia and Estonia are rapidly growing therefore forecast of emissions related with this occurrence becomes very important. The Ignalina Nuclear Power Plant (INPP), one of the largest in the world, is situated in the region. Two power production scenarios are modelled to investigate changes in power sector's emissions expected as the consequences of the coming closure of Ignalina NPP. Power market was assumed to be common for all three Baltic countries and was modelled by applying the Balmorel model. The planned closure of Ignalina NPP will bring restructuring of Lithuania power production sector and will change also power transmission between countries. Predictive identified the potential of investments for new modern power generation technologies. At the same time, modelling results show in both scenarios that CO(2) and SO(2) emissions from power production in the Baltic region will increase. The increment of emissions is discussed in the context of meeting requirements of UNFCCC Kyoto protocol and EC Directives. Despite of CO(2) emissions increase the Kyoto protocol's requirements may be expected. At the same time, SO(2) formation in Lithuania power sector may exceed the limits of the EU Council Directive 2001/80/EB therefore the additional measures to control SO(2) emissions have to be investigated.     

A laboratory study on CO2 emission from asphalt binder and its reduction with the use of warm mix asphalt

Oxidation of hydrocarbon in asphalt binder leads to the production of carbon dioxide (CO₂) during the production of hot mix asphalt. The objective of this laboratory study was to investigate the effects of the asphalt additive Sasobit^®, asphalt content and mixing/placement temperature on CO₂ emissions from binder with laboratory measurements. The isolated effects of Sasobit on asphalt absorption into the aggregate were also looked at. Temperature was found to be the only statistically significant factor on emissions. This would suggest that warm mix asphalt technology, which employs the use of Sasobit in asphalt mixtures, is a very effective way of lowering the industry's CO₂ emission impact, both directly and by the use of less energy for heating. This work predicts that greater than 30% reduction of CO₂ emissions is possible with typically used levels of Sasobit.     

CO2 emission driving forces and corresponding mitigation strategies under low-carbon economy mode: evidence from China’s Beijing–Tianjin–Hebei region

On account of the background of China’s “new normal” characterized by slower economic growth, this paper analyses the low-carbon economy status quo in the Beijing–Tianjin–Hebei region and empirically investigates the relationship between carbon dioxide (CO₂) emissions and its various factors for China’s Beijing–Tianjin–Hebei region using panel data econometric technique. We find evidence of existence of Environmental Kuznets Curve. Results also show that economic scale, industrial structure, and urbanization rate are crucial factors to promote CO₂ emissions. However, technological progress, especially the domestic independent research and development, plays a key role in CO₂ emissions abatement. Next, we further analyze the correlation between each subregion and various factors according to Grey Relation Analysis. Thereby, our findings provide important implications for policymakers in air pollution control and CO₂ emissions reduction for this region.     

The Rate of Carbon Dioxide Emission into the Atmosphere from a Southern Karelian Mesooligotrophic Bog

Carbon dioxide exchange in the intact and reclaimed sites of a woodless mesooligotrophic dwarf shrub–cotton grass–sphagnum bog was studied in field experiments. The average values of gross respiration in the ecosystem over the warm period (including respiration of plant cover, CO₂emission from peat, and CO₂flow from the litter) were 3.17 and 6.11 g CO₂/m²per day in the natural and drained sites, respectively.     

Analysis of CO2 emissions peak: China’s objective and strategy

Establishing positive and urgent targets for CO₂ reduction and emission peak, and promoting energy conservation and energy structure adjustment are among the strategies to address global climate change and CO₂ emissions reduction. They are also means to break through the constraints of domestic resources and environment, and internal needs, to achieve sustainable development. Generally speaking, a country's CO₂ emission peak appears after achieving urbanization and industrialization. By then, connotative economic growth will appear, GDP will grow slowly, energy consumption elasticity will decrease, and energy consumption growth will slow down – dependent mainly on new and renewable energies. Fossil fuel consumption will not increase further. When CO₂ emission reaches its peak, the annual reduction rate of CO₂ intensity of GDP is greater than GDP annual growth rate; and the annual reduction rate of CO₂ intensity of energy use is greater than the annual growth rate of energy consumption. Therefore, three important approaches to promotion of CO₂ emission peak can be concluded: maintaining reasonable control of GDP growth, strengthening energy conservation to significantly reduce the GDP energy intensity, and optimizing the energy mix to reduce the CO₂ intensity of energy use. By around 2030, China will basically have completed its rapid development phase of industrialization and urbanization. Connotative economic growth will appear with the acceleration of industrial structure adjustment. The target of GDP energy intensity will still be to maintain an average annual reduction of 3% or higher. The proportion of non-fossil fuels will reach 20–25%, and the aim will be to maintain an average annual growth rate of 6–8%. The total annual energy demand growth of 1.5% will be satisfied by the newly increased supply of non-fossil fuels. The annual decline in CO₂ intensity of GDP will reach 4.5% or higher, which is compatible with an average annual GDP growth rate of approximately 4.5% in order to reach CO₂ emission peak. This corresponds to the level of China's potential economic growth. Achieving CO₂ emission peak will not impose a rigid constraint on economic development, but rather promote economic development and accelerate the transformation of green, low-carbon development. The CO₂ emission peak can be controlled with a cap of 11 billion tons, which means that CO₂ emission will increase by less than 50% compared with 2010. The per capita emission peak will be controlled at a level of less than 8 tons, which is lower than the 9.5 tons in the EU and Japan and much lower than the 20 tons in the US, future economic and social development faces many uncertainties in achieving the CO₂ emission peak discussed above. It depends on current and future strategies and policies, as well as the pace and strength of economic transformation, innovation, and new energy technologies. If the economic transformation pattern fails to meet expectations, the time required to reach CO₂ emission peak would be delayed and the peak level would be higher than expected. Therefore, we need to coordinate thoughts and ideas and deploy these in advance; to highlight the strategic position of low-carbon development and its priorities; to enact mid- to long-term energy development strategies; and to establish and improve a system of laws, regulations, and policies as well as an implementation mechanism for green, low-carbon development. Oriented by positive and urgent CO₂ reduction and peak targets, the government would form a reversed mechanism to promote economic transformation and embark on the path of green, low-carbon development as soon as possible.     

Carbon dioxide exchange in the photosynthetic apparatus of trees in a mature spruce phytocenosis of the northern taiga subzone

Carbon dioxide exchange was studied in the photosynthetic apparatus of Siberian spruce (Picea obovata Ledeb.), Siberian larch (Larix sibirica Ledeb.), and weeping birch (Betula pendula Roth.) in a mature spruce forest. Parameters of CO₂ balance in different weather were characterized quantitatively on the basis of daily measurements of CO₂ exchange in needles and leaves of woody plants. The percent ratios of the components of carbon balance in needles and leaves of woody plants depending on daily photosynthetic fixation of carbon were determined. In summer, trees consumed 210 kg CO₂/ha (57 kg C/ha) in variable weather and 117 kg CO₂/ha (32 kg C/ha) in cloudy weather. Species specificity of CO₂ consumption was revealed, and the effects of environmental factors on the assimilatory activity of trees were determined.     

Ecophysiological Responses of Larix sibiricaLedeb. and Pinus sibiricaDu Tour Undergrowth to Climate Change

The effects of probable climate change—an increase in atmospheric CO₂(by two times), air temperature, precipitation—on CO₂exchange and temperature dependence of net photosynthesis in the larch and Siberian stone pine undergrowth formed in the light larch forests of West Siberia were studied in chambers with an artificial climate. The change of the aforementioned ecological factors caused an increase in the temperature optima of photosynthesis and the range of optimum temperatures (in the case of Siberian stone pine, to a slightly greater degree). Therefore, the ranges of both species may broaden, and the Siberian stone pine can expand to the north, displacing larch tree stands.     

Persistence of radon-222 flux during monsoon at a geothermal zone in Nepal

The Syabru-Bensi hydrothermal zone, Langtang region (Nepal), is characterized by high radon-222 and CO₂ discharge. Seasonal variations of gas fluxes were studied on a reference transect in a newly discovered gas discharge zone. Radon-222 and CO₂ fluxes were measured with the accumulation chamber technique, coupled with the scintillation flask method for radon. In the reference transect, fluxes reach exceptional mean values, as high as 8700 ± 1500 g m⁻² d⁻¹ for CO₂ and 3400 ± 100 × 10⁻³ Bq m⁻² s⁻¹ for radon. Gases fluxes were measured in September 2007 during the monsoon and during the dry winter season, in December 2007 to January 2008 and in December 2008 to January 2009. Contrary to expectations, radon and its carrier gas fluxes were similar during both seasons. The integrated flux along this transect was approximately the same for radon, with a small increase of 11 ± 4% during the wet season, whereas it was reduced by 38 ± 5% during the monsoon for CO₂. In order to account for the persistence of the high gas emissions during monsoon, watering experiments have been performed at selected radon measurement points. After watering, radon flux decreased within 5 min by a factor of 2–7 depending on the point. Subsequently, it returned to its original value, firstly, by an initial partial recovery within 3–4 h, followed by a slow relaxation, lasting around 10 h and possibly superimposed by diurnal variations. Monsoon, in this part of the Himalayas, proceeds generally by brutal rainfall events separated by two- or three-day lapses. Thus, the recovery ability shown in the watering experiments accounts for the observed long-term persistence of gas discharge. This persistence is an important asset for long-term monitoring, for example to study possible temporal variations associated with stress accumulation and release.     

NEWS

Abstract

Co-integration theory has been employed in this paper and Granger causes are found between urbanization rate and GDP, between capital stock and GDP. Scenario analysis of GDP is performed using the GDP model established in the paper. The energy consumptions in Germany, Japan and other developed countries are analyzed and compared with the energy consumption in China. Environmental friendly scenario of energy demand and CO₂ emissions for sustainable China has been formed based on the results of comparison. Under environmental friendly scenario, the primary energy consumption will be 4.31 billion ton coal equivalence (tce) and CO₂ emissions will be 1.854 billion t-c in 2050; energy per capital will be 3.06 tce that is 1.8 times of energy consumed in 2005 in China and 51% of consumed energy per capital in Japan in 2003. In 2050, the energy requirement of unit GDP will be 20% lower than that of Germany in 2003, but will be still 37% higher than that in Japan in 2003. It is certain that to fulfill the environmental friendly Scenario of energy demand and CO₂ emissions is a difficult task and it needs long term efforts of the whole society, not only in production sectors but also in service and household sectors.     

Empirically Analysis of the CO2 Emissions Embodied in Exports of China

Abstract

In this paper, using the input-output model, the author first calculated the CO₂ emissions embodied in exports of China in 2002 and 2007. Then, the author empirically analyzed problems existing in the composition of exported products and analyzed its possible reasons. The research results of this paper are as follows: Since China’s entry into WTO, the CO₂ emissions embodied in exports of China have been increasing rapidly; the value of exported products of high-carbon emissions industries accounts for a relatively higher proportion to China’s total exports value because China’s carbon intensive products have a certain competitive advantage. Additionally, this paper has put forward relevant suggestions based on these results.     

Thermal rehabilitation of Romanian housing: a low cost assessment tool

The numerous buildings that currently require thermal rehabilitation in Romania means that substantial resources and a large number of competent people are required to carry out surveys and energy audits. However, commercial energy balance software is mostly unaffordable for those organisations involved in this process. This paper describes an energy balance programme – ENEFControl – developed to be a rapid, low cost, local tool able to assist in the choice of energy efficient solutions for buildings. To test the software, thermal and energy analyses were carried out on a 1970s built apartment block in Transylvania. Based on these analyses, three constructive scenarios were proposed for thermal rehabilitation. Compared to the performance of the analysed building, the thermal and energy performance of the retrofitted building in all three scenarios significantly improved. Since European Union accession in 2007, rapidly rising energy costs have affected the Romanian population. ENEFControl offers Romanian engineers and architects an opportunity to speed up the rehabilitation programme of buildings without the need for more expensive expertise and tools.     

Soil gas (²²²Rn, CO₂, ⁴He) behaviour over a natural CO₂ accumulation, Montmiral area (Drôme, France): geographical, geological and temporal relationships

The south east basin of France shelters deep CO₂ reservoirs often studied with the aim of better constraining geological CO₂ storage operations. Here we present new soil gas data, completing an existing dataset (CO₂, ²²²Rn, ⁴He), together with mineralogical and physical characterisations of soil columns, in an attempt to better understand the spatial distribution of gas concentrations in the soils and to rule on the sealed character of the CO₂ reservoir at present time.Anomalous gas concentrations were found but did not appear to be clearly related to geological structures that may drain deep gases up to the surface, implying a dominant influence of near surface processes as indicated by carbon isotope ratios. Coarse grained, quartz-rich soils favoured the existence of high CO₂ concentrations. Fine grained clayey soils preferentially favoured the existence of ²²²Rn but not CO₂. Soil formations did not act as barriers preventing gas migrations in soils, either due to water content or due to mineralogical composition. No abundant leakage from the Montmiral reservoir can be highlighted by the measurements, even near the exploitation well. As good correlation between CO₂ and ²²²Rn concentrations still exist, it is suggested that ²²²Rn migration is also CO₂ dependent in non-leaking areas - diffusion dominated systems.     

Contribution of (222)Rn-bearing water to indoor radon and indoor air quality assessment in hot spring hotels of Guangdong, China

This study investigates the contribution of radon (²²²Rn)-bearing water to indoor ²²²Rn in thermal baths. The ²²²Rn concentrations in air were monitored in the bathroom and the bedroom. Particulate matter (PM, both PM₁₀ and PM_2.5) and carbon dioxide (CO₂) were also monitored with portable analyzers. The bathrooms were supplied with hot spring water containing 66-260 kBq m⁻³ of ²²²Rn. The results show that the spray of hot spring water from the bath spouts is the dominant mechanism by which ²²²Rn is released into the air of the bathroom, and then it diffuses into the bedroom. Average ²²²Rn level was 110-410% higher in the bedrooms and 510-1200% higher in the bathrooms compared to the corresponding average levels when there was no use of hot spring water. The indoor ²²²Rn levels were influenced by the ²²²Rn concentrations in the hot spring water and the bathing times. The average ²²²Rn transfer coefficients from water to air were 6.2 × 10⁻⁴-4.1 × 10⁻³. The 24-h average levels of CO₂ and PM₁₀ in the hotel rooms were 89% and 22% higher than the present Indoor Air Quality (IAQ) standard of China. The main particle pollutant in the hotel rooms was PM_2.5. Radon and PM₁₀ levels in some hotel rooms were at much higher concentrations than guideline levels, and thus the potential health risks to tourists and especially to the hotel workers should be of great concern, and measures should be taken to lower inhalation exposure to these air pollutants.     

Carbon accumulation in lowland bog soils of fallow lands in Murmansk oblast

The dynamics of organic carbon accumulation in lowland bog soils of Murmansk oblast were assessed by analyzing soil samples from fields formerly sown with perennial grasses but withdrawn from agricultural use three, six, and eight years ago. Within three years, the organic carbon content in the topsoil (0–20 cm) increased by 0.07%, compared to that in cultivated soil. In six-and eight-year-old fallows, the increase in the soil carbon content averaged 0.2 and 0.46%, respectively. Experimental data were used for verifying calculations of carbon turnover in lowland bog soils of fallows in Murmansk oblast by the RothC model.     

Drastic Reductions in Utilizable Fossil Fuel Reserves: An Environmental Imperative

We are living in a period of exponential growth of world population and energy consumption. Forecasts suggest that the atmospheric CO₂ concentration could reach 750 p.p.m. by 2100. At this level, the coral reefs and the West Antarctic Ice Sheet would be lost and thermohaline circulation in the N. Atlantic could possibly shut down. Crippling the ocean conveyor system would have a major impact on world climate and jeopardize our chances of feeding an enlarged world population. Consumption of the total global hydrocarbon reserves would increase the atmospheric CO₂ concentration to about 2200 p.p.m. We can therefore utilize less than 20% of the global hydrocarbon reserves without an accompanying massive programme for the sequestration of CO₂ if we do not wish to cross the threshold atmospheric CO₂ concentration of 750 p.p.m. and risk a major environmental catastrophe. Attention to the global CO₂ problem will be the major task of the 21st Century.     

Carbon cycle in spruce ecosystems of the northern Taiga subzone

The main components of the carbon balance have been determined in old spruce-bilberry forests of the northern taiga subzone. Annual carbon deposition in live phytomass and necromass has been determined by the weight method. Photosynthetic carbon binding has been calculated using the chlorophyll index, and the daily carbon balance has been estimated on the basis of direct measurements of CO₂ exchange. The results have shown that photosynthetic carbon binding by the phytocenosis amounts to 3.5–4 t/ha per year. Taking into consideration the litter yearly deposition decreased up to 1 t C/ha per year. With more than 70% of carbon accumulated in the organic mass being oxidized within the phytocenosis and returned to the atmosphere in the form of CO₂. Spruce ecosystems serve as a sink for 0.2–0.3 t C/ha per year.