As a reference unit for climate plans, a tonne of carbon dioxide remains an abstract notion for most of us.
Carbon dioxide is an invisible, odourless and colourless gas. This does not prevent it, like the air, from having a mass: 1,964 g/litre or 1.964 kg/m3. These equivalents will help you understand the scales we’re talking about when discussing one tonne of CO2:
Just to give you an indication...
The average CO2 emission of a person living in Belgium is 8 tonnes per year.
To limit global warming to 2°C, the average level of CO2 emission per capita on our planet must not exceed 2,1 tonnes by 2050. We still have a long way to go!
Quite simply, from combustion: when you burn petrol, gas, wood, etc. All combustible fuels (except hydrogen), whether renewable or fossil, contain carbon.
Inside the flame, the carbon reacts with the oxygen in the air to produce heat and carbon dioxide. Chemists express this in a small formula: C + O2 = CO2 + heat
And in terms of the weight of the various components, this represents:
1 kg of carbon + 2.67 kg of oxygen give 3.67 kg of carbon dioxide and heat
To know that, you have to find out how the energy you use, is generated. In Belgium, for instance, many people would like to abandon nuclear energy. Still, neither CCGT-power plants (or worse: lignite plants, as is the case in Germany) will help to reduce our CO2 emission level.
The following table shows the amount of CO2 produced per kWh for specific types of electricity generators:
|Production method||g CO2/kWh|
|gas-fired power plant||490|
|coal-fired power plant||820|
In Belgium, 1 kWh of electricity currently 'costs' 220 g of carbon dioxide. In 1998, it was 290 g. Our country has reduced its carbon footprint by developing renewable energy sources and improving the efficiency of gas-fired power plants (gas-steam turbines).
Each fuel contains a greater or lesser amount of carbon. Consequently, they emit various amounts of carbon dioxide to produce the same energy:
|Fuel||kg CO2/ kWh generated|
This means that, if someone uses 20,000 kWh of natural gas per year to heat their house, they produce 4,120 kg of carbon dioxide. Unless you opt for a more sustainable alternative, which can be used for exactly the same applications as natural gas: green gas.
Going strictly by the amount of CO2 emitted per litre of fuel, LPG comes out as the big winner:
|Fuel||kg CO2 / litre|
Other data must also be taken into account:
In short, the differences are more subtle than they seem!
Considering only the transport, you can calculate the amount of carbon dioxide emitted according to the means of transport you choose.
|Means of transport||kg CO2 /passenger per 100 km|
|Alone by car||10,4|
Source: European Environment Agency
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