Wednesday, June 6, 2007

Solar Energy Prospects

The scientific development and utilization practice on solar energy in the 20th century laid a sound foundation for large-scale utilization of solar energy in the 21st century. Recently, it is estimated by some famous analysis and research institutes, multinational companies, solar expertise and governments that solar energy is to occupy 50% of worldwide energy structure including wind energy and biomass energy around the middle of the 21st century (2050). Until that time, solar energy is to be the foundation energy for the worldwide sustainable development. Regarding this estimate, viewpoints are varying; some supports and some are suspicious. In order to scientifically treat this problem, we can analyze from three aspects including the worldwide fossil fuels production and consumption, environment protection and technology advance so as that to reach considerably objective results.

The worldwide consumption of fossil fuels is expanding remarkably while the storage of resources is limited. Right now, the worldwide storage of fossil fuels is about 130 billion tons, while the annual worldwide consumption is about 3.5 billion of petroleum and Asia is consumed incrementally. If this tendency remains unchanged, in the coming 25 years, the average annual consumption is accounting for 5 billion tons, which can exhaust all of the storage. Even if there are new oil fields to be found in this period, experts estimate that the world storage of petroleum will not exceed 200 billion tons, which will be used up within 30 to 50 years.

What can replace the petroleum in the future? After the petroleum crisis happened in the 1970s, focus has been concentrated on the gasification and liquefaction of coal. But 30 years passing, nothing remarkable results have been achieved. Complex technologies and huge investment limits the extensive utilization of gasified coal and liquefied coal.

Social-economic development should be supported by energy. But it is completely impractical to compensate the insufficient supply of petroleum by increasing the consumption of coal, which is an approach for energy development paid by the environment. According to estimates, direct burning of 1 tons coal may produce 3 to 11 tons of powder, 60kg of SO2, 3 to 9 kg of NaO2 and large quantity of CO2. In China, directly discharging fuel dust in 1995 was accounted for 17.44 million tons, and SO2 for 23.7 million tons, among which discharging of coal occupied 70% and 85%. At present, carbon discharged from coal can be amounted for 1 billion tons annually. The excessive exploitation and utilization of coal has been the main reason to pose the deterioration of worldwide environment. According to the World Environment and Development Conference hold by the UN in 1992, the consumption of coal should not be increased and should be limited and decreased gradually.

Moreover, analysis on PV power system can review the market penetration of solar energy in the next century.

If we calculated in accordance with the constant price in the 1970s, the price for solar cells has been declined for 10 times in recent 30 years. Experts estimate that PV power generation is competitive than conventional power generation after 2030 along with the mass production and technology advance. In 2050, the price of solar cells is to be 10 times lower than the present level, that is 4.5 Yuan per watt, and the electricity price is 0.2 Yuan per kWh. After the development for 50 years, PV power can produce 50% of the worldwide electricity.

The above-mentioned analysis shows that the worldwide energy structure will be variable in fundamentality in the 21st century. The petroleum, which is leading in the energy structure, will be gradually decreased until used up. The coal will be limited to use. But in view of the requirement in developing countries, the utilization of coal is likely to be rising up before 2030 and will be gradually decreased after that. Since the nuclear safety and treatment of nuclear waste technologies cannot be tackled and no any breakthrough comes out, the utilization of nuclear power will be gradually closed to operation in the industrial country in the coming 50 years and new nuclear plant will be built in developing countries. The total amount will not be rising but declining on the contrary. The solar energy and other renewable energy will replace the petroleum and coal to be the majority of worldwide energy.

Estimates on the percentage of which each primary energy occupies in the worldwide energy structure in 2050, show that petroleum occupy 0, natural gas 13%, coal 20%, nuclear energy 10%, hydropower 5%, solar energy including wind energy and biomass energy occupies 50% and others 2%.

The 21st century must be a century of widespread use of solar energy, which is to be the foregone conclusion on social development and cannot be transferred by any people's volition.

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