• How do people produce the greenhouse gases?
• Carbon dioxide (CO₂)
• Methane (CH₄)
• Nitrous oxide (N₂O)
• Halogenated hydrocarbons
• Overview

If we want to turn the tide, we shall have to find out where exactly those greenhouse gases are produced. On the basis of those findings, measures can be elaborated to reduce the impact of greenhouse gases on the global climate.

Below we give a survey of the greenhouse gases produced by specific sectors. Then we compare the impact of the three most important gases.

How do people produce the greenhouse gases?

Carbon dioxide (CO₂) is produced mainly in the burning of fossil fuels such as coal, oil and gas in industry, in electricity generation,  in transport and for heating purposes. In the incineration of waste, a great deal of carbon dioxide is released as well.

Methane (CH₄) is released mainly in cattle farming (digestive processes and manure), in waste treatment (fermentation on landfills), through leaks in the distribution of natural gas and in combustion processes.

Laughing gas or nitrous oxide (N₂O) is released especially in the burning of fossil fuels (mainly in traffic), in a number of processes in the chemical industry and in agriculture.

CFCs and similar substances, and their substitute products (HCFCs and PFC's) are used chiefly as refrigerants, as propellants in aerosols and in the production of foam plastic.

Ozone (O3), finally, as such is not brought into the atmosphere directly by man, but is generated there via a series of chemical reactions involving nitrogen oxides (NOx), carbon monoxide (CO) and volatile organic compounds (VOC). These ozone precursors, as they are called, are produced mainly by the transport and industrial sectors.

Carbon dioxide (CO2) CO2 is the major greenhouse factor in Belgium - and in the world. On a global scale CO2 accounts for more than 50% of the greenhouse effect, while in Belgium this is even more than 80%. It is released mainly in the burning of fossil fuels, such as coal, oil and gas. If we break down by economic sector the amounts produced in Belgium, it becomes clear straight away that the energy generation accounts for a very substantial amount indeed.

Graph 1:  Share in the production of CO2 in 1994

Within that 90.4% of the energy generation, the greatest amount of CO2 is produced by the energy sector itself (more than 80% in the production of electricity and the remainder especially in the petroleum refinery).

Graph 2: Share per sector of CO₂ production in energy generation

Methane (CH4) Worldwide, methane ranges second on the list of greenhouse gases: it accounts for some 20% of the greenhouse effect. In Belgium the agricultural sector is by far the most important producer of methane. In addition, methane is produced in waste treatment and in the distribution of natural gas.

Graph 3: Share in the methane production in 1994

Nitrous oxide (N2O) In general the emission of nitrous oxide is relatively limited, also on a global scale. Still, nitrous oxide has one great disadvantage: it may take up to one hundred and fifty years before it is decomposed. That is why it is classified among the important greenhouse gases. The main sources of nitrous oxide are, on the one hand, agriculture and, on the other hand, the chemical industry, in the production of nitric acid. Apart from that, nitrous oxide is released also in the burning of fossil fuels.

Graph 4: Share in the laughing gas production in 1994*

* * These figures must be treated with the necessary caution. As there are no exact data available, they are estimates. In reality these figures may be up to 50% higher or lower.

Halogenated hydrocarbons 

Several years ago agreements were made internationally to prohibit the use of CFCs. Meanwhile a number of substitutes have become available: HFCs and PFCs, but unfortunately those products also enhance the greenhouse effect.

In Belgium there are few data on the quantities that are used of these new substances. We only have some information about their use in industry: while this was only 20 tonnes of HFC in 1992, it had increased to 750 tonnes in 1996. Their use may be limited, but the rise is substantial.

Overview

Since the three major greenhouse gases - carbon dioxide, methane and nitrous oxide - each have a different impact on the climate, a method has been developed to compare the influence of the different gases. In that way it is possible for policy makers to deduce in what areas measures are needed the most.

In the table we give the figures for Belgium.

It's clear that CO₂ accounts for the bulk of the emissions, and that we shall have to try to curb the production of this gas first and foremost.

Information provided by: http://www.environment.fgov.be