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A good example
of a CHP power plant can be uploaded from Helsinki Energy's Internet home page:
http://www.helsinginenergia.fi/en/tuotanto/chp.html. In the same pages, we can also find good
examples of district heating: http://www.helsinginenergia.fi/en/heat/heating.html
and of district cooling: http://www.helsinginenergia.fi/en/heat/cooling.html.
Their impact on
the urban air quality crucially depends on their location, pollution control systems and on the
meteorological features of the site.
SO2: Russian natural gas originates
in western Siberia. All natural gas which we use here in Finland is from Russia. In Finland gas makes up about 11.5% of all energy consumption
(2003). Fuel use comprises about 50 % of Helsinki Energy’s consumption (It was
51,8 % in 2003).
The composition of NG depends on where it is produced. Western Siberia natural gas composition is: methane CH4
(98%); ethane C2H6 (<1%); nitrogen N2
(<1%) and carbon dioxide CO2 (0,1%).
NOX: Modern power plants using low-NOX combustion techniques
have reduced the formation of NOX.
Also catalytic reduction of NOX is becoming more common.
PM: Main sources of PM concentration in urban air are natural emissions,
traffic (diesel and petrol vehicle exhaust emissions and road surfaces) and
construction works that create dust emissions.
Heavy Metals: Modern emission control techniques have substantially reduced heavy
metals emissions including those in the vapour phase such as those from
mercury.
Conclusion: Positive aspects have also to be taken into account. It has to be mentioned that power plants,
especially when also producing heat (CHP plants), have greatly reduced urban
pollution formerly due to decentralized heating systems. |