2017年6月英语六级阅读理解练习题：可再生能源

　　Energy is also obtained from wavcs and tides.In some countries such as Japan small scale power generators run by energy from waves of the ocean,have been used as power sources for channcl marking buoys.

　　Biomass

　　Biomass is a renewable energy resource derived from the carbonaceous waste of various human and natural activities.It is derived from numerous sources,including the by-products from the timber industry.agricultural crops,raw material from the forest,major parts of household waste and wood.

　　Biomass does not add carbon dioxide to the atmosphere as it absorbs the same amount of carbon in growing as it releases when consumed as a fuel. Its advantage is that it can be used to generate electricity with the same equipment of power plants that are now burning fossil fuels.Biomass is an important source of energy and the most important fuel worldwide after coal,oil and natural gas.

　　Traditional use of biomass is more than its use in modern application.In the developed world biomass is again becoming important for applications such as combined heat and power generation.In addition,biomass energy is gaining significance as a source of clean heat for domestic heating and community heating applications.In fact in countries like Finland.USA and Sweden the per capita biomass energy used is higher than it is in India.China or in Asia.

　　Geothermal Energy

　　We live between two great sources of energy,the hot rocks beneath the surface of the earth and the sun in the sky.Our ancestors knew che value of geothermal energy;they bathed and cooked in hot springs.Today we have recognized that this resource has potential for much broader application.

　　The core of the earth is very hot and it is possible to make use of this geothermal energy(in Greek it means heat from the earth).These are areas where there are volcanoes.hot springs,and geysers,and methane under the water in the oceans and seas. n some countries,such as in the USA water is pumped from underground hot water deposits and used to heat people's houses.

　　The utilization of geothermal energy for the production of electricity dates back to the early part of thetwentieth century.For 50 years the generation of electricity from geothermal energy was confined to Italy and interest in this technology was slow co spread elsewhere.In 1943 the use of geothermal hot water was pioneered in lceland.

　　Co-generation

　　Co-generation is the concept or producing two forms of energy from one fuel.One of the forms of energy must always be heat and the other may be electricity or mechanical energy.In a conventional power plant,fuel is burnt in a boiler to generate high-pressure steam.This steam is used to drive a turbine.which in turn drives an alternator through a steam turbine to produce electric power.The exhaust steam is generally condensed to water which goes back to the boiler.

　　As the low-pressure steam has a large quantum of heat which is lost in the process of condensing,the efficiency of conventional power plants is only around 35%.In a cogeneration plant,very high efficiency levels,in the range of 75%-90%,can be reached.This is so,because the low-pressure exhaust steam coming out of th turbine is not condensed,but used for heating purposes in factories or houses.

　　Since co-generation can meet both power and heat needs, it has otber advantages as well in the form of significant cost savings for the plant and reduction in emissions of pollutants due to reduced fuel consumption.

　　1.High concentrations of harmful gases are resulted from______________.

　　A) ozone depletion

　　B) global warming

　　C) the consumption of fossil fuels

　　D) serious water and air pollution

　　2.The sun and wind are called renewable energy because they are____________.

　　A) natural

　　B) inexhaustible

　　C) newly-found

　　D) clean

大学英语六级寒假全程班