Life Cycle Research On Carbon Emissions Of Polycrystalline Silicon-Photovoltaic System

Based on the clear concept of carbon emissions and carbon-link of polycrystalline-silicon photovoltaic system in the life cycle, this paper starting from the example, analysis three companies on the polycrystalline-silicon PV industrial chain. The study shows carbon emissions of1MW polycrystalline-silicon PV modules. Then according to’Access Condition of Polycrystallinc-Silicon Industry’,1MW and the current mainstream production size and production technology polycrystalline-silicon PV system carbon emission in the life cycle is calculated. Comparing the1kW Polycrystalline-Silicon photovoltaic system carbon emission per generation with thermal power, carbon payback period and the relevant factors is concluded. The conclusions show:(1) Polycrystalline-Silicon PV systems industry chain include the production of metal silicon,polycrystalline-silicon,polycrystalline-silicon ingot,polycrystalline-silicon film,solar cells,PV module,PV system balance components.Carbon-links of polycrystalline-silicon PV system are energy consumption, resource consumption, plant construction, equipment generation, transportation, waste disposal.(2) Based on the example, carbon emission of280MW PV syestem is752,859.4tons. Carbon emission due to energy consumption is538912tons, which are71.58%of the total.Carbon emission due to resource consumption is173316tons, which are23.02%. Carbon emission due to plant construction is36833tons which are4.89%. Carbon emission due to equipment produces is3623.5tons, which are0.49%. Carbon emission due to waste dispoal is174.9tons, which account for only0.02%.Under this scale,carbon emission of1MW PV system is2688.78tons.280MW PV system carbon emission due to energy consumption is538,912tons.The rate of carbon emission due to energy consumption of high-purity polysilicon production processes is91%which plays a decisive role. The rate of carbon emissions due to energy consumption of polycrystalline ingot and slice is3.1%. The rate of carbon emission due to energy consumption of polycrystalline silicon solar cells and PV modules is5.9%.(3) According to’Access Condition of Polycrystalline-Silicon Industry’,take the current mainstream production technology and production scale of polycrystalline-silicon industry for example, carbon emission of370MW vertical product is1130202.47tons. Carbon emission due to energy consumption is416135tons, which are36.82%of the total.Carbon emission due to resource consumption is439567tons, which are38.01%. Carbon emission due to plant construction is277984tons which are24.60%. Carbon emission due to equipment produces is6258.6tons, which are0.55%. Carbon emission due to waste dispoal is230.87tons, which account for only0.02%.Under this scale,carbon emission of1MW PV system is3054.6tons.(4) Comparing with power generation, the annual generation capacity of1kW grid-connected photovoltaic system which settles in the south of Changzhou and for the best angle is2288kWh,and emission reduction capacity is:1418.56-3054.6/N. The results show that solar energy resources has significant influence on carbon emission payback period. Lhasa is1.7years, Changzhou is2.1years, Chengdu is4.7years. Angle installation also has a part in carbon emission payback period.