Photovoltaic Silicon Wafer
The enormous number of automobiles and the number of electrical appliances in households and offices are increasing energy consumption. A large part of energy depends on fossil fuels, such as petroleum and coal, which generate CO2 (carbon dioxide) during combustion. The problem of global warming from CO2 emissions makes people to pay attention to the utilization of renewable energy, such as photovoltaic energy.
The photovoltaic energy is acquired by a power generation system that directly converts sunlight into electricity using solar cells.
Fossil fuels, such as petroleum and coal, have the problems of the emission of CO2 and the depletion of the natural resource. On the other hand, photovoltaic energy using the inexhaustible energy of sunlight is one of the promising solutions for environmental and energy resource problems that are becoming more serious every year. The advantages are the complete lack of CO2 emissions, which is believed to cause global warming, and cleanliness and friendliness to the earth.
The photovoltaic energy system is a power generation system where demand is expected to increase most rapidly.
Fig.1 : Trends in total CO2 emissions and CO2 emissions per person in Japan
In 2005, total CO2 emissions were 1,291 million tons, and CO2 emissions per person were 10.1 tons. These values show that total CO2 emissions increased by about 13% and CO2 emissions per person by about 9% in comparison with data from 1990. In order to protect our environment, the reduction of CO2 emissions may be the most urgent task.
Source: National Institute for Environmental Studies
Fig.2 : Total supply of primary energy in FY2007 in Japan
It is said that the CO2 emitted during the combustion of fossil fuels such as petroleum is one of the causes of global warming. Our life is highly dependent on fossil fuels, which occupy about 85% of the total energy supply. Since resources such as petroleum are not limitless, we are concerned about the lack of such resources in the future. It is believed to be necessary to promote the introduction of renewable energy, such as photovoltaic energy, to decrease the degree of dependence on fossil fuels.
Source: Agency for Natural Resources and Energy
Japan's land area is about 380,000 km² and occupies about 0.3% of the world's land area. If we were to pave all of the land area of Japan with solar cells, they would cover about 30% of the total power consumption in the world.
