Nam Đỗ Blog

SECTION 4 
You will hear a lecturer discussing techniques for removing carbon dioxide from the 
atmosphere. 
We all know about the role of carbon dioxide in causing global warming. Obviously, 
society needs to reduce the release of carbon dioxide, otherwise known as CO2. This gas 
comes from the burning of fossil fuels, such as coal and oil. and it is virtually impossible 
for society to prevent, or even limit such activity. Our need for energy and power is just 
too great. Instead, a more practical idea is to collect the carbon dioxide from the burning 
process, for example, directly from the chimneys of power stations, and somehow 
prevent this gas from being released into the environment. To do that, you need to store it 
somehow, and that has to be essentially forever. 
It is perhaps for this reason that main believe that, rather than storing the carbon dioxide 
as a gas, it is better to react it with metal oxides, such as magnesium or calcium, which 
results in the formation of a hard carbonate material. The gas is, in effect, turned into a 
stable and unreactive solid, which can simply he dumped anywhere. This process actually 
occurs naturally, although very very slowly, and is one cause of the surface limestone in 
the world. But this slow reaction speed is the problem. Even when enhancing this 
process through high temperature and pressure, or pre-treatment of the mineral, it is still 
far too slow to be economical. 
One other technique which has been suggested is to pump the gas lo the bottom of the 
ocean, where it would react with compounds in the seawater, forming carbonic acid. 
However, this alternative has now been ruled out. The CO2 may be removed from the 
atmosphere, but the high oceanic acidity which would result raises its own set of 
problems, mostly with all the delicate life and the intricate food chains in the seawater, 
some on which we ourselves depend -- and that's something which no one wants to 
experiment with. 

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