Land degradation and desertification have become severe environmental problems in arid areas due to excessive use of water resources. It is urgent to reduce agricultural water use for ecological rehabilitation, which ...Land degradation and desertification have become severe environmental problems in arid areas due to excessive use of water resources. It is urgent to reduce agricultural water use for ecological rehabilitation, which may result in a decrease in agricultural production and farmer's welfare. This paper focused on the impacts of some main measures including extensions of watersaving irrigation, expanding solar green house and increasing off-farm employment, which are generally recognized to be important to alleviate water shortage and poverty. A bioconomic model is applied taking Minqin Oasis in Gansu Province as a case study site. Simulation results showed that the effect of expanding solar greenhouse was more positive than other ones so it drew more attention. On the view of the different effects between each irrigation zone, mixed policy patterns suitable for them are suggested. In Baqu, expanding solar greenhouse should be the most important, auxiliary with encouraging pipe irrigation. Inversely, with regard to Quanshan, the major attention should be paid to subsidy for pipe irrigation and it would be better to supply the off-farm employment opportunities to the households in Huqu, where the expanding of solar greenhouse should also be summoned. Finally, it should be noted that farmer's income would only resume to 90% of the current level in the short run by putting more effort into local policies. Thus, the ecological compensation is needed to ensure farmer's welfare.展开更多
Many kinds of factors that influence rural housing construction in Northern China are analyzed systematically and the connections between them are weighed from ecology and sustainable angles, so that an optimized gree...Many kinds of factors that influence rural housing construction in Northern China are analyzed systematically and the connections between them are weighed from ecology and sustainable angles, so that an optimized green house can be built. At the same time, the energy efficient envelope structure and the method of choosing insulation material in the cost of unit thermal resistance are proposed. Integrated quality evaluation by computer shows that thermal comfort in the house would be improved remarkably for the value of PPD drops from 35%-40% to 15%, the rate of saving energy is 51.73%, much higher than the third goal of saving energy in China, and the comprehensive ecological benefit achieves good effect so as to promote the sustainable development of rural housing and community in cold areas of Northern China.展开更多
To create a comfortable microclimate environment,the design methods of green layout and green structure of four common forms of urban green space(park green space,road green space,waterfront open green space,and green...To create a comfortable microclimate environment,the design methods of green layout and green structure of four common forms of urban green space(park green space,road green space,waterfront open green space,and green space between houses)were discussed,and the modes"concentric three rings"and"three-layer sandwich cake",as well as the matching principles of three-dimensional green elements of trees and shrubs with lawn and hard matrix elements,were proposed.展开更多
We studied seedling survival and growth ofAquilaria malaccensis in three different environmental conditions (homegardens, green house and in different canopy conditions) of northeast India. Results show that mean se...We studied seedling survival and growth ofAquilaria malaccensis in three different environmental conditions (homegardens, green house and in different canopy conditions) of northeast India. Results show that mean seasonal survival was highest in green house (95.53%±2.33), followed by homegardens (89.3%±1.89) and different canopy conditions (77.62%±6.73); the highest values were found during February to April for both the homegardens (96%±1.68) and green house (98% ± 0.88) and lowest during November to January (78%±2.99) in homegardens and May to July (90%:t:4.53) in green house. In case of transplanted seedlings in different canopy conditions, mean seasonal survival was highest during May to July (98%±1.92) and lowest during August to October (66%±12.81). However, mean seasonal growth of collar diameter was highest in different canopy conditions (23.99%±1.76) compared to green house (21.52%±2.70) and homegardens (12.44%±1.33) and it was highest during rainy season (May to July) and lowest during dry winter (November to January) in all the three experi- mental sites. These variations may be due to the different microclimatic conditions as well as nutrient status of the soil in all the three experimen- tal sites. Although, seedling quality plays a great role in their survival and growth, based on the result of green house experiment, it can be concluded that maintenance of seedlings in green house conditions during their early growth period may improve both the survival and growth for large scale plantation of the species. Thus, the species can be reintroduced in its natural forest range to compensate the loss of natural population of this precious species in northeast India.展开更多
The resultant climate change on sustainable food supply has greatly affected agricultural production by the level of great volumes of gasses emitted into the atmosphere by human activities. The human factors that emit...The resultant climate change on sustainable food supply has greatly affected agricultural production by the level of great volumes of gasses emitted into the atmosphere by human activities. The human factors that emit large amount of green house gases include industrialization, burning of fossil fuel and gas flaring. Increase in air temperature and consequent increase in the rates of evaporation also affect the level of food supply. Data for this study were collected from primary and secondary sources. Primary source were collected through field investigation and structured questionnaire. A total of 450 questionnaires were administered. Results revealed that varieties of crops ranging from tree crops to cereals were cultivated within the study area. The effect of climate change on food supply has resulted into change in crop yields, change in rainfall pattern, soil loss and has greatly affected planting period and harvesting. The study therefore recommended awareness campaigns on the causes and consequences of global climate change on food production, environmental education and afforestation campaign programmes on sustainable food supply and environmental safety must be intensified.展开更多
Climate change impacts on Earth’s atmosphere have caused drastic changes in the environment of most regions of the world. The Middle East region ranks among the worst affected of these regions. This has taken forms o...Climate change impacts on Earth’s atmosphere have caused drastic changes in the environment of most regions of the world. The Middle East region ranks among the worst affected of these regions. This has taken forms of increasing atmospheric temperatures, intensive heat waves, decreased and erratic precipitation and general decline in water resources;all leading to frequent and longer droughts, desertification and giving rise to intensive and recurrent (SDS). The present conditions have led to increasing emissions of (GHG) in the earth atmosphere. All future projections especially those using (IPCC) models and emission scenarios indicate that the Middle East will undergo appreciable decrease in winter precipitation with increasing temperature until the end of this century both of which are inductive to increased dryness and desertification. Iraq as one of the countries of this region and due to its geographical location, its dependence mostly on surface water resources originating from neighboring countries, long years of neglect and bad land management put it in the most precarious and unstable position among the other countries of the region. Modelling studies have shown that Iraq is suffering now from excessive dryness and droughts, increasing loss of vegetation cover areas, increasing encroachment of sand dunes on agricultural lands, in addition to severe and frequent (SDS). These negative repercussions and their mitigations require solutions not on the local level alone but collective cooperation and work from all the countries of the region.展开更多
Presently the world faces what most likely will be the greatest challenge humanity has ever faced.Climate change is a phenomenon,or rather a set of phenomena,that directly influences the daily lives of human populatio...Presently the world faces what most likely will be the greatest challenge humanity has ever faced.Climate change is a phenomenon,or rather a set of phenomena,that directly influences the daily lives of human populations all over the planet.However,this influence normally negative also affects ecosystems,with emphasis on agroforestry systems,of which human populations are directly dependent on food and in a large number of primary raw materials.It is with this premise as a starting point that this work makes an analysis on the current state of climate change in Portugal,since,being a country of Mediterranean climate influence,it should be one of the territories where changes will be felt with more intensity and severity.In this work,the current position on energy production in Portugal regarding Green House Gases(GHGs)emissions and the evolution prospects for the near future,namely in the perspective of the impacts caused on forest resources,are discussed.展开更多
The effects of chemical agent(Sodium Azide)on Onion growing in organic and inorganic fertile soil was to be examined during this study.The analysis work was carried out within the green house of the research lab...The effects of chemical agent(Sodium Azide)on Onion growing in organic and inorganic fertile soil was to be examined during this study.The analysis work was carried out within the green house of the research laboratory technology of the Oke Ogun Science Laboratory Technology,Saki,Oyo State.Onion seeds were soaked inside different beakers containing the mixture of Sodium Azide and water mixed with 10 ml of Phosphate solution for 4 hours.Also,the control was soaked with normal water and 10 ml of Phosphate buffer solution.The treated seeds of onions was planted in plastic containers containing 4.2 g of weighed humus soil within the green house at the Department of research lab Technology of The Oke Ogun polytechnic school,Saki Oyo State.The samples parameter were taken daily for six consecutive months.The result obtained was additionally subjected to statistical analysis by using DMRT techniques.The results showed that the stem length was ranged from 11.39±0.62 and 9.98±0.52 with sample of onion without sodium Azide and inorganic had the highest stem length values and samples of onion with Sodium Azide and inorganic had very cheap stem length.However,the leave length ranged from 29.63±0.12 and 22.45±0.10 with the Onion samples with inorganic and Organic fertilizers which had the highest leave length and sample of onion without Sodium Azide was very low leave length.The results of this study showed that each one the parameters studied within the plant were low with Sodium Azide treatment.The decrease in plant growth,plant heights,root lengths,and Phaonerogam survival,fruit yield per plant and height at maturity with agent concentration.It is hereof suggested that Sodium Azide(NaN3)was expected to produce mutation in onion that area unit extremely liable to harmful pathogens and making them cheap to be useful for farmers.展开更多
Green house gases reduction is critical in current climate emergency and was declared as major target by United Nations.This manuscript proposes the progressive adaptive recursive multi threshold control strategy for ...Green house gases reduction is critical in current climate emergency and was declared as major target by United Nations.This manuscript proposes the progressive adaptive recursive multi threshold control strategy for hybrid energy storage system that combines thermal storage reservoirs,heat pumps,storage heaters,photovoltaic array and a battery.The newest control strategy is tested in numerical experiment against primal dual simplex optimisation method as benchmark and previous iterations of RED WoLF threshold approaches.The proposed algorithm allows improvement in reduction of CO_(2) emissions by 9%comparatively to RED WoLF double threshold approach and by 26%comparatively to RED WoLF single threshold approach.Besides,the proposed technique is at least 100 times faster than linear optimisation,making the algorithm applicable to edge systems.The proposed method is later tested in numerical experiment on two measured datasets from Luxembourg school and office,equipped with batteries and ground source heat pumps.The system allows the reduction of CO_(2) emission and improvement of self-consumption,size reduction of the photovoltaic array installed at the facilities by at least by half as well as substituting battery storage by thermal storage,reducing the initial investment to the system.Intriguingly,despite 3.6 times difference in efficiency between heat pumps and storage heaters,the system equipped with latter have potential to achieve similar performance in carbon reduction,suggesting that energy storage have more prominent carbon reduction effect,than the power consumption,making cheaper systems with storage heaters a possible alternative to heat pumps.展开更多
Daqing is situated in one of the severely cold resions of China. The livin8 environment in this region is extremely poor because of the harsh climate and the backward economy. The external wall is an important compone...Daqing is situated in one of the severely cold resions of China. The livin8 environment in this region is extremely poor because of the harsh climate and the backward economy. The external wall is an important component of the external envelope of buildings, and it greatly contributes to the indoor thermal environment. By taking the external wall as the research object, this study summarizes the characteristics of the external wall structure and analyzes the common materials used in existing rural residences. Specifically, we combine life cycle theory and ecological footprint (EF) theory and introduce the green external wall structure, as well as its application in practice, in accordance with the local ecosystem. Results show that anecotosical residence offers a better environment and greater economic benefits than a traditional residence. The annual energy consumption, C02 consumption, and EF of the ecological residence in this study are lower than those of the traditional residence by 69.61%, 17.5 t, and 99.47%, respectively.展开更多
If substantial amounts of CO_(2),which according to actual scenarios may in the future be captured from industrial processes and power generation,shall be utilized effectively,scalable energy efficient technologies wi...If substantial amounts of CO_(2),which according to actual scenarios may in the future be captured from industrial processes and power generation,shall be utilized effectively,scalable energy efficient technologies will be required.Thus,a survey was performed to assess a large variety of applications utilizing CO_(2) chemically(e.g.,production of synthesis-gas,methanol synthesis),biologically(e.g.,CO_(2) as fertilizer in green houses,production of algae),or physically(enhancement of fossil fuel recovery,use as refrigerant).For each of the processes,material and energy balances were set up.Starting with pure CO_(2) at standard conditions,expenditure for transport and further process specific treatment were included.Based on these calculations,the avoidance of greenhouse gas emissions by applying the discussed technologies was evaluated.Based on the currently available technologies,applications for enhanced fossil fuel recovery turn out to be most attractive regarding the potential of utilizing large quantities of CO_(2)(total capacity>1000 Gt CO_(2))and producing significant amounts of marketable products on one hand and having good energy and material balances on the other hand(t_(CO_(2)-emitted)/t_(CO_(2)-utilized)<0.2-0.4).Nevertheless,large scale chemical fixation of CO_(2)providing valuable products like fuels is worth considering,if carbon-free energy sources are used to provide the process energy and H2 being essential as a reactant in a lot of chemical processes(e.g.,production of DME:t_(CO_(2)-emitted)/t_(CO_(2)-utilized)>0.34).Biological processes such as CO_(2) fixation using microalgae look attractive as long as energy and CO_(2) balance are considered.However,the development of effective photobioreactors for growing algae with low requirements for footprint area is a challenge.展开更多
Although Beijing has carried out municipal solid waste (MSW) source separation since 1996, it has largely been ineffective. In 2012, a "Green House" program was established as a new attempt for central sorting. In...Although Beijing has carried out municipal solid waste (MSW) source separation since 1996, it has largely been ineffective. In 2012, a "Green House" program was established as a new attempt for central sorting. In this study, the authors used material flow analysis (MFA) and cost benefit analysis (CBA) methods to investigate Green House's environment and economic feasibility. Results showed that the program did have significant environmental benefits on waste reduction, which reduced the amount of waste by 34%. If the Green House program is implemented in a residential community with wet waste ratio of 66%, the proportion of waste reduction can reach 37%. However, the Green House is now running with a monthly loss of 1982 CNY. This is mainly because most of its benefits come from waste reduction (i.e., 5878 CNY per month), which does not turn a monetary benefit, but is instead distributed to the whole of society as positive environmental externalities. Lack of government involvement, small program scale, and technical/managerial deficiency are three main barriers of the Green House. We, thus, make three recommendations: involve government authority and financial support, expand the program scale to separate 91.4 tons of waste every month, and use more professional equipment/technologies. If the Green House program can successfully adopt these suggestions, 33.8 tons of waste can be reduced monthly, and it would be able to flip the loss into a profit worth 35034 CNY.展开更多
基金the Grant for Outstanding Hundred Scholars of Chinese Academy of Sciences.
文摘Land degradation and desertification have become severe environmental problems in arid areas due to excessive use of water resources. It is urgent to reduce agricultural water use for ecological rehabilitation, which may result in a decrease in agricultural production and farmer's welfare. This paper focused on the impacts of some main measures including extensions of watersaving irrigation, expanding solar green house and increasing off-farm employment, which are generally recognized to be important to alleviate water shortage and poverty. A bioconomic model is applied taking Minqin Oasis in Gansu Province as a case study site. Simulation results showed that the effect of expanding solar greenhouse was more positive than other ones so it drew more attention. On the view of the different effects between each irrigation zone, mixed policy patterns suitable for them are suggested. In Baqu, expanding solar greenhouse should be the most important, auxiliary with encouraging pipe irrigation. Inversely, with regard to Quanshan, the major attention should be paid to subsidy for pipe irrigation and it would be better to supply the off-farm employment opportunities to the households in Huqu, where the expanding of solar greenhouse should also be summoned. Finally, it should be noted that farmer's income would only resume to 90% of the current level in the short run by putting more effort into local policies. Thus, the ecological compensation is needed to ensure farmer's welfare.
文摘Many kinds of factors that influence rural housing construction in Northern China are analyzed systematically and the connections between them are weighed from ecology and sustainable angles, so that an optimized green house can be built. At the same time, the energy efficient envelope structure and the method of choosing insulation material in the cost of unit thermal resistance are proposed. Integrated quality evaluation by computer shows that thermal comfort in the house would be improved remarkably for the value of PPD drops from 35%-40% to 15%, the rate of saving energy is 51.73%, much higher than the third goal of saving energy in China, and the comprehensive ecological benefit achieves good effect so as to promote the sustainable development of rural housing and community in cold areas of Northern China.
基金Supported by the Special Project for Cultural Research in Xing Culture Project of Henan(2022XWH132)。
文摘To create a comfortable microclimate environment,the design methods of green layout and green structure of four common forms of urban green space(park green space,road green space,waterfront open green space,and green space between houses)were discussed,and the modes"concentric three rings"and"three-layer sandwich cake",as well as the matching principles of three-dimensional green elements of trees and shrubs with lawn and hard matrix elements,were proposed.
基金supported by DBT,Govt. of India through the project "Mapping and quantitative assessment of geographic distribution and population status of plant resources of Eastern Himalayan Region"
文摘We studied seedling survival and growth ofAquilaria malaccensis in three different environmental conditions (homegardens, green house and in different canopy conditions) of northeast India. Results show that mean seasonal survival was highest in green house (95.53%±2.33), followed by homegardens (89.3%±1.89) and different canopy conditions (77.62%±6.73); the highest values were found during February to April for both the homegardens (96%±1.68) and green house (98% ± 0.88) and lowest during November to January (78%±2.99) in homegardens and May to July (90%:t:4.53) in green house. In case of transplanted seedlings in different canopy conditions, mean seasonal survival was highest during May to July (98%±1.92) and lowest during August to October (66%±12.81). However, mean seasonal growth of collar diameter was highest in different canopy conditions (23.99%±1.76) compared to green house (21.52%±2.70) and homegardens (12.44%±1.33) and it was highest during rainy season (May to July) and lowest during dry winter (November to January) in all the three experi- mental sites. These variations may be due to the different microclimatic conditions as well as nutrient status of the soil in all the three experimen- tal sites. Although, seedling quality plays a great role in their survival and growth, based on the result of green house experiment, it can be concluded that maintenance of seedlings in green house conditions during their early growth period may improve both the survival and growth for large scale plantation of the species. Thus, the species can be reintroduced in its natural forest range to compensate the loss of natural population of this precious species in northeast India.
文摘The resultant climate change on sustainable food supply has greatly affected agricultural production by the level of great volumes of gasses emitted into the atmosphere by human activities. The human factors that emit large amount of green house gases include industrialization, burning of fossil fuel and gas flaring. Increase in air temperature and consequent increase in the rates of evaporation also affect the level of food supply. Data for this study were collected from primary and secondary sources. Primary source were collected through field investigation and structured questionnaire. A total of 450 questionnaires were administered. Results revealed that varieties of crops ranging from tree crops to cereals were cultivated within the study area. The effect of climate change on food supply has resulted into change in crop yields, change in rainfall pattern, soil loss and has greatly affected planting period and harvesting. The study therefore recommended awareness campaigns on the causes and consequences of global climate change on food production, environmental education and afforestation campaign programmes on sustainable food supply and environmental safety must be intensified.
文摘Climate change impacts on Earth’s atmosphere have caused drastic changes in the environment of most regions of the world. The Middle East region ranks among the worst affected of these regions. This has taken forms of increasing atmospheric temperatures, intensive heat waves, decreased and erratic precipitation and general decline in water resources;all leading to frequent and longer droughts, desertification and giving rise to intensive and recurrent (SDS). The present conditions have led to increasing emissions of (GHG) in the earth atmosphere. All future projections especially those using (IPCC) models and emission scenarios indicate that the Middle East will undergo appreciable decrease in winter precipitation with increasing temperature until the end of this century both of which are inductive to increased dryness and desertification. Iraq as one of the countries of this region and due to its geographical location, its dependence mostly on surface water resources originating from neighboring countries, long years of neglect and bad land management put it in the most precarious and unstable position among the other countries of the region. Modelling studies have shown that Iraq is suffering now from excessive dryness and droughts, increasing loss of vegetation cover areas, increasing encroachment of sand dunes on agricultural lands, in addition to severe and frequent (SDS). These negative repercussions and their mitigations require solutions not on the local level alone but collective cooperation and work from all the countries of the region.
文摘Presently the world faces what most likely will be the greatest challenge humanity has ever faced.Climate change is a phenomenon,or rather a set of phenomena,that directly influences the daily lives of human populations all over the planet.However,this influence normally negative also affects ecosystems,with emphasis on agroforestry systems,of which human populations are directly dependent on food and in a large number of primary raw materials.It is with this premise as a starting point that this work makes an analysis on the current state of climate change in Portugal,since,being a country of Mediterranean climate influence,it should be one of the territories where changes will be felt with more intensity and severity.In this work,the current position on energy production in Portugal regarding Green House Gases(GHGs)emissions and the evolution prospects for the near future,namely in the perspective of the impacts caused on forest resources,are discussed.
文摘The effects of chemical agent(Sodium Azide)on Onion growing in organic and inorganic fertile soil was to be examined during this study.The analysis work was carried out within the green house of the research laboratory technology of the Oke Ogun Science Laboratory Technology,Saki,Oyo State.Onion seeds were soaked inside different beakers containing the mixture of Sodium Azide and water mixed with 10 ml of Phosphate solution for 4 hours.Also,the control was soaked with normal water and 10 ml of Phosphate buffer solution.The treated seeds of onions was planted in plastic containers containing 4.2 g of weighed humus soil within the green house at the Department of research lab Technology of The Oke Ogun polytechnic school,Saki Oyo State.The samples parameter were taken daily for six consecutive months.The result obtained was additionally subjected to statistical analysis by using DMRT techniques.The results showed that the stem length was ranged from 11.39±0.62 and 9.98±0.52 with sample of onion without sodium Azide and inorganic had the highest stem length values and samples of onion with Sodium Azide and inorganic had very cheap stem length.However,the leave length ranged from 29.63±0.12 and 22.45±0.10 with the Onion samples with inorganic and Organic fertilizers which had the highest leave length and sample of onion without Sodium Azide was very low leave length.The results of this study showed that each one the parameters studied within the plant were low with Sodium Azide treatment.The decrease in plant growth,plant heights,root lengths,and Phaonerogam survival,fruit yield per plant and height at maturity with agent concentration.It is hereof suggested that Sodium Azide(NaN3)was expected to produce mutation in onion that area unit extremely liable to harmful pathogens and making them cheap to be useful for farmers.
文摘Green house gases reduction is critical in current climate emergency and was declared as major target by United Nations.This manuscript proposes the progressive adaptive recursive multi threshold control strategy for hybrid energy storage system that combines thermal storage reservoirs,heat pumps,storage heaters,photovoltaic array and a battery.The newest control strategy is tested in numerical experiment against primal dual simplex optimisation method as benchmark and previous iterations of RED WoLF threshold approaches.The proposed algorithm allows improvement in reduction of CO_(2) emissions by 9%comparatively to RED WoLF double threshold approach and by 26%comparatively to RED WoLF single threshold approach.Besides,the proposed technique is at least 100 times faster than linear optimisation,making the algorithm applicable to edge systems.The proposed method is later tested in numerical experiment on two measured datasets from Luxembourg school and office,equipped with batteries and ground source heat pumps.The system allows the reduction of CO_(2) emission and improvement of self-consumption,size reduction of the photovoltaic array installed at the facilities by at least by half as well as substituting battery storage by thermal storage,reducing the initial investment to the system.Intriguingly,despite 3.6 times difference in efficiency between heat pumps and storage heaters,the system equipped with latter have potential to achieve similar performance in carbon reduction,suggesting that energy storage have more prominent carbon reduction effect,than the power consumption,making cheaper systems with storage heaters a possible alternative to heat pumps.
文摘Daqing is situated in one of the severely cold resions of China. The livin8 environment in this region is extremely poor because of the harsh climate and the backward economy. The external wall is an important component of the external envelope of buildings, and it greatly contributes to the indoor thermal environment. By taking the external wall as the research object, this study summarizes the characteristics of the external wall structure and analyzes the common materials used in existing rural residences. Specifically, we combine life cycle theory and ecological footprint (EF) theory and introduce the green external wall structure, as well as its application in practice, in accordance with the local ecosystem. Results show that anecotosical residence offers a better environment and greater economic benefits than a traditional residence. The annual energy consumption, C02 consumption, and EF of the ecological residence in this study are lower than those of the traditional residence by 69.61%, 17.5 t, and 99.47%, respectively.
文摘If substantial amounts of CO_(2),which according to actual scenarios may in the future be captured from industrial processes and power generation,shall be utilized effectively,scalable energy efficient technologies will be required.Thus,a survey was performed to assess a large variety of applications utilizing CO_(2) chemically(e.g.,production of synthesis-gas,methanol synthesis),biologically(e.g.,CO_(2) as fertilizer in green houses,production of algae),or physically(enhancement of fossil fuel recovery,use as refrigerant).For each of the processes,material and energy balances were set up.Starting with pure CO_(2) at standard conditions,expenditure for transport and further process specific treatment were included.Based on these calculations,the avoidance of greenhouse gas emissions by applying the discussed technologies was evaluated.Based on the currently available technologies,applications for enhanced fossil fuel recovery turn out to be most attractive regarding the potential of utilizing large quantities of CO_(2)(total capacity>1000 Gt CO_(2))and producing significant amounts of marketable products on one hand and having good energy and material balances on the other hand(t_(CO_(2)-emitted)/t_(CO_(2)-utilized)<0.2-0.4).Nevertheless,large scale chemical fixation of CO_(2)providing valuable products like fuels is worth considering,if carbon-free energy sources are used to provide the process energy and H2 being essential as a reactant in a lot of chemical processes(e.g.,production of DME:t_(CO_(2)-emitted)/t_(CO_(2)-utilized)>0.34).Biological processes such as CO_(2) fixation using microalgae look attractive as long as energy and CO_(2) balance are considered.However,the development of effective photobioreactors for growing algae with low requirements for footprint area is a challenge.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 41201104), the Fundamental Research Funds for the Central Universities (No. 2652014013), and the Volvo Group in a research project of the Research Center for Green Economy and Sustainable Development, Tsinghua University (No. 20153000181). The authors would like to acknowledge Xiaoshan Huang for his invaluable assistance with this study.
文摘Although Beijing has carried out municipal solid waste (MSW) source separation since 1996, it has largely been ineffective. In 2012, a "Green House" program was established as a new attempt for central sorting. In this study, the authors used material flow analysis (MFA) and cost benefit analysis (CBA) methods to investigate Green House's environment and economic feasibility. Results showed that the program did have significant environmental benefits on waste reduction, which reduced the amount of waste by 34%. If the Green House program is implemented in a residential community with wet waste ratio of 66%, the proportion of waste reduction can reach 37%. However, the Green House is now running with a monthly loss of 1982 CNY. This is mainly because most of its benefits come from waste reduction (i.e., 5878 CNY per month), which does not turn a monetary benefit, but is instead distributed to the whole of society as positive environmental externalities. Lack of government involvement, small program scale, and technical/managerial deficiency are three main barriers of the Green House. We, thus, make three recommendations: involve government authority and financial support, expand the program scale to separate 91.4 tons of waste every month, and use more professional equipment/technologies. If the Green House program can successfully adopt these suggestions, 33.8 tons of waste can be reduced monthly, and it would be able to flip the loss into a profit worth 35034 CNY.