Quantifying CO₂ Emission And Simulation Analysis Of Its Reduction Potentials For Diiernt Type Of Greenhouse Ecosystems In China

With the development of the chemical agriculture, petro-agriculture and agricultural machinery, and the improvement of economic in China, energy consumption caused by agriculture has increased rapidly. The amount of greenhouse gases caused by agricultural production activities is the world’s second most important source of greenhouse gases, which is behind the amount caused by electric production.. How to reduce agricultural greenhouse gas emissions and keep sustainable development have become the priorities of all countries. Researches of agricultural greenhouse gas are mainly about CH4 and Nitrous Oxide. While with the development of agricultural technology, the structure of agriculture is changing from traditional agriculture to facility agriculture. CO2 emissions caused by change of facility structural and resource using have become the main source of agricultural greenhouse gas.Facilities agriculture is an important part of agriculture, and it is one of the high CO2 emissions from agricultural ecosystems. As the main representative of facilities, the optimization of operation scheme and design process for greenhouse agriculture is a prerequisite of quantitative evaluating of controling agricultural facilities life cycle carbon dioxide emissions, and it plays an important role in guiding emission reduction.. In this research, we take three main types of greenhouse in China as objects -solar greenhouse (32°N-48°N, include 20 regions)、plastic greenhouses (10 regions whose latitude is lower than 32°N)、multi-span greenhouse (31 regions all over China) ecosystem. The objective of this study is to quantitatively estimate energy consumption of three types of protected agriculture ecosystems by using life cycle assessment (LCA) and a model-based decision support system for temperature set point optimization for greenhouse heating considering both greenhouse construction and crop production. The key factors that impact the energy consumption were determined. Based on results above, scenario analysis of emission-reduction potential under improved resource utilization of crop production and greenhouse structures were conducted. The main results are as follows:1. The status of CO2 emission in greenhouse production system:CO2 emission per unit yield for greenhouse cucumber production and total of CO2 emission were quantitatively estimated by using LCA based on literature and experimental data. The results show that the range of solar greenhouse CO2 emission per unit crop yield ranges from 1.05 kg(CO2)·kg(cucumber)-1(Hebei) to 1.73 kg(CO2)·kg(cucumber)-1(Xizang). The gap between these area is small; Bamboo material around the sunlight greenhouse CO2 emissions does not exist regularity,183463.2 kg(cO2)·ha-1·cycle-1 (Hubei)～274285.7 kg(Co2)-ha-1·-cycle-1 (Xizang) Most greenhouse CO2 emission is from building, fertilizer and irrigation, which in total account for more than 95% of total emissions. The multi-span greenhouse CO2 emission is lowest founded in southern China that include Hainan (3.59 kg(CO2)·kg(cucumber)-1), Guangxi (5.67 kg(CO2)-kg (cucumber)-1), Guangdong (4.75 kg(CO2)·kg (cucumber)-1), and the highest emission is found in northeast of China that include Liaoning (19.73 kg(CO2)·kg(cucumber)-1), Jilin (20.13 kg(CO2)-kg(cucumber)-1), Heilongjiang (20.33 kg(Co2)·kg(cucumber)-1); Total CO2 emissions from all regions of the multi-reenhouse ecosystem 1089348 kg (cO2)·ha-1·cycle-1 (Guangdong)～7268408 kg(CO2)·ha-1·cycle-1 (Heilongjiang), total emissions with the rise and rise of the geographic latitude. The top three components of CO2 emissions is temperature control, greenhouse construction and fertilizer. carbon dioxide emission caused by temperature control ranges from 53.4%(south China) to 90.4%(northeast) which increased with the increasing of latitude. carbon dioxide emission caused by greenhouse construction ranges from 4.8%(northeast) to 19.8%(south China), which decreased with the rise of latitude.The research of plastic greenhouses of per unit of production in all regions cucumber greenhouses ecosystem CO2 emissions value is small,as 0.88 kg(C02)·kg(cucumber)-1 (Guangdong) to 1.21 kg(CO2)·kg(cucumber)-1(Zhejiang); plastic greenhouse ecosystem range from 54928.5 kg(cO2)·ha-1·cycle-1(Guangdong)～113090.3 kg(cO2)·ha-1·cycle-1(Zhejiang). The top three components of carbon dioxide emissions is fertilizers, construction, irrigation and pesticide.2. Combining the various parts of the carbon dioxide emissions of greenhouse and simulation analysis of its reduction potentials for different type of greenhouse ecosystems, results were listed below:(1) Solar greenhouse:Performed on different structures greenhouse emissions scenario simulation, different levels of solar greenhouse utilization emissions scenario simulation, and both two.①Greenhouses with soil steel structure (compared to a 7% drop in bamboo and wood structure is better for lower CO2 emission in the future, which can make the CO2 emissions dropped to 0.97 kg(CO2)·kg(cucumber)-1(Hebei) to 1.59 kg(cO2)·kg(cucumber)-1(Xizang). ②In the meantime, improvment of the utilization level (compared to current levels fell by 5%～10%) is also helpful, which can make the emissions of carbon dioxide dropped to 0.94 kg(CO2)·kg(cucumber)-1(Hebei) to 1.63 kg(CO2)·kg(cucumber)-1(Xizang). Thus, a maximum reduce of carbon dioxide emission can achieve.③By improving the different resource utilization and improve the greenhouse structure study of CO2 emissions at the same time, the steel structure sunlight greenhouse cucumber emissions observed productivity fell by about 14%, 0.88 kg(CO2)·kg(cucumber)-1(Hebei) to 1.51 kg(CO2)·kg(cucumber)-1(Xizang). Single than to improve the greenhouse structure or improve the utilization rate of resources, can greatly reduce the production of cucumber corresponding CO2 emissions per unit of production value.(2) Multi-span greenhouse:Performed on different energy choice of greenhouse emissions scenario simulation, different levels of greenhouse utilization emissions scenario simulation, and both two.①If the use of such non-fossil energy as wind energy and biomass energy (a fall of 13%～15% compared with the fossil energy, coal) is possible in the future, since using biomass energy can make carbon dioxide emissions dropped to 3.02 kg(CO2)·kg(cucumber)-1(Hainan)～17.43 kg(CO2)·kg(cucumber)-1 (Heilongjiang) and using wind energy can make the CO2 emissions dropped to 2.94 kg(CO2)·kg(cucumber)’(Hainan)～17.01 kg(CO2)·kg(cucumber)-1(Heilongjiang),saving effect is more obvious.③Assumes 1-Greenhouse utilization levels after the improvements, compared with the current emissions only make cucumber CO2 emissions per unit of production decreased by about 50%, saving effect is obvious. Assumes 2-This scenario is guaranteed under the premise of future output unchanged, reducing the amount of nitrogen fertilizer input, water, pesticides, improve resource utilization, the National Greenhouse cucumbers CO2 emissions per unit of production value decreased about 0.9% to 3.55 kg (CO2)·kg (cucumber)-1(Hainan)～20.14 kg (CO2)·kg (cucumber) (Heilongjiang). The simulation scenario, CO2 emissions reduction effect is not obvious, is not considered to improve resource utilization from the conduct.③ Type at the same time to improve resource utilization and air-conditioning energy reduction simulation:through at the same time, improve the utilization rate of resources and change the air-conditioning energy types of the CO2 emissions scenarios of the simulation study of greenhouse, can clearly found that the use of biomass energy of cucumber in greenhouse emissions productivity fell by about 53%, for Hainan area of 1.65 kg(CO2)·kg(cucumber)-1 to Heilongjiang region of 9.26 kg(CO2)·kg(cucumber)-1. Use wind high resource utilization of cucumber in greenhouse emissions productivity fell by about 55%, for Hainan area 1.63 kg(CO2)·kg(cucumber)-1 to Heilongjiang region 9.03 kg(CO2)·kg(cucumber)-1. Single than to change the greenhouse temperature adjustment energy type or improve resource utilization, can greatly reduce the production of cucumber corresponding CO2 emissions per unit of production value.(3) Plastic greenhouse:Plastic greenhouse utilization on different levels of abatement scenarios conducted simulation analysis. After the passage of CO2 emissions per unit of production of cucumber utilization of different levels of plastic greenhouses are calculated can be found to improve the level of utilization, cucumber emissions per unit of production value ten regions fell about 4%, emissions per unit of production of cucumber production rate 0.85 kg(CO2)·kg(cucumber)-1 (Guangdong) to 1.16 kg(CO2)·kg(cucumber)-1 (Zhejiang), can reach a certain emission reduction targets.In summary, the future of our country to the north of 32°N should continue to develop the ecological system in sunlight greenhouse facilities based agriculture, taking improvement of greenhouse structure and increase crop production resource utilization and emission reduction measures, can obtain obvious reduction effect; the future development of facility agriculture in the area south of 32°N should still be the plastic greenhouse ecological system, the way of reducing emissions from crop production can improve resource utilization and ecological system; greenhouse emission reduction potential while the larger, but the reduction is still higher than the other two kinds of simulated greenhouse, so the greenhouse in our country is not suitable for large-scale development.This study accurately estimated the contribution of greenhouse industry CO2 emission reduction to the whole agriculture CO2 emission reduction, studied the potential of reducing CO2 emission of different greenhouse types and methods,further studies on the potential and methods of energy saving will provide indispensable data and decision support for developing energy saving programs of agriculture and optimizing facility layout.