Co-generation is the concept of producing two forms of energy from one fuel. One of the forms of energy must always be heat and the other may he 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 the 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 other 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 wanning
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
3. Biomass, though a renewable energy, mainly causes_____.
A) indoor pollution B) outdoor pollution
C) industrial pollution D) agricultural pollution
4. In the 1970s, some countries began to be concerned about solar energy because of_____.
A) economic recession B) sharp rise in oil prices
C) reduced oil production D) increased research funds
5. In the hills of the Himalayas, "chakki" are used for_____.
A) purifying water B) keeping animals
C) producing power D) exchanging goods
6. What is recommended to be used by the remote rural areas with little access to conventional energy sources?
A) Small hydropower plants. B) Solar energy heaters.
C) Wind power mills. D) Hot spring thermal energy.
7. It is mentioned that, between the surface and the depth of the ocean, there are great differences in____.
A) dissolved substance B) natural resource variety
C) marine life species D) water temperature
8. After coal, oil and natural gases, the fourth most important fuel is____.
9. Iceland was the first country that____.
10. In the conventional power plants, a large quantum of heat is lost in theprocess of condensing____.