Fossil fuels (化石燃料).ppt

Energy and environment WHAT Types of energy; energy crisis WHY Current status of energy consumption (能源消费的现状) HOW Solutions to energy shortage and pollution (能源短缺和污染问题的对策) Fossil fuels (化石燃料) Solid: coal, world deposits 10 times greater than oil and gas resources combined 可燃成分: carbon and hydrogen Fossil fuels (化石燃料) Liquid: petroleum, most used fossil fuel in developed countries Fossil fuels (化石燃料) Gas: natural gas, world’s 3rd largest commercial fuel; produce less CO2 compared to coal and oil Main component: methane (甲烷) Environmental Effects Water pollution Releases CO2 when burned Air pollution when burned Artificially low price encourages waste and discourages search for alternatives Need to find substitute within 50 years Disadvantages Low land use Easily transported within and between countries High net energy yield Low cost (with huge subsidies) Ample supply for 42–93 years Advantages Efficient distribu- tion system 石油的优缺点 Advantages Low land use Easily transported by pipeline Moderate environ- mental impact Lower CO2 emissions than other fossil fuels Less air pollution than other fossil fuels Low cost (with huge subsidies) High net energy yield Ample supplies (125 years) Disadvantages Sometimes burned off and wasted at wells because of low price Methane (a greenhouse gas) can leak from pipelines Releases CO2 when burned Nonrenewable resource Difficult to transfer from one country to another Needs pipelines 天然气的优缺点 可燃冰 (flammable ice) CH4·H2O(水合天然气), new energy in 21st century Formation: similar to oil and natural gas, but low temperature and high pressure are necessary. 1 m3 = 164 m3 natural gas total energy = 2-3 times of the sum of coal, oil and natural gas. Precautions Difficulty with extraction of flammable ice. May speed up global warming if CH4 is released into the atmosphere. Mining (开采) Processing (加工) Using (使用) Air, water, soil pollution; solid waste; noise, etc. Air, wat