Energy Consumption and Exhaust Emissions
One fifth of Finland’s energy use
Transportation accounts for about a fifth of all the energy used in Finland, and about 40 % of the energy produced using oil. Transport’s share of total energy consumption has been gradually rising in recent years.
Individual vehicles’ emissions have declined since the 1970s. Even though the rapid increase in traffic has slowed the overall decline in vehicle emissions, many harmful emissions have been reduced significantly. But traffic still accounts for large proportions of the total emissions of many harmful pollutants in Finland, including more than half of carbon monoxide emissions, and about half of all emissions of hydrocarbons and nitrogen oxides. The most serious problem is still carbon dioxide emissions, however. Unlike other emissions, no successful ways have been found to reduce CO2 emissions.
Across the EU, traffic accounts for 21 % of all greenhouse gas emissions (excluding international air traffic and shipping). Some 93% of these emissions are generated by road traffic. Emissions from international air traffic have risen rapidly – increasing by 86 % over the period 1990-2004.
Emissions from fuel combustion
The exhaust gases from an ideal petrol-driven or diesel motor would consist only of carbon dioxide and water vapour. But in practice motors also release partially combusted or uncombusted fuel components, as well as harmful combustion by-products such as nitrogen oxides.
Carbon monoxide and carbon dioxide
Fuels containing hydrocarbons initially release carbon monoxide (CO) when combusted, but most of this CO then reacts with oxygen to produce carbon dioxide (CO2). Exhaust gases may still contain considerable amounts of CO, however. Incomplete combustion also produces aldehydes, ketones and various acids.
Hydrocarbons
Some fuel components may pass through motors without being combusted, resulting in emissions of various hydrocarbons (HC).
Nitrogen oxides
The most common by-products of combustion in motors are nitrogen oxides (NO, NO2, N2O), known collectively as NOX emissions.
Sulphur dioxide
Exhaust gases from petrol-driven motors previously contained significant quantities of harmful lead compounds and other pollutants such as sulphur dioxide (SO2). Leaded petrol may no longer be sold in Finland. The sulphur content of fuels sold in Finland has been reduced considerably, so vehicle exhausts today contain much less sulphur dioxide than previously.
Particles
Most of the emissions in vehicle exhausts are gaseous, but diesel motors may also emit considerable quantities of solid particles, formed when fuel droplets are not completely combusted, but instead leave behind tiny particles of soot, which may be partially coated with condensed hydrocarbons. Other impurities in diesel fuels include sulphur compounds. Sulphur dioxide emitted on combustion may combine to form sulphates that can become attached to particles in exhaust gases.
