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How much greenhouse gases in our wastebin ?

september 2003

website of the author : www.manicore.com - contact the author : jean-marc@manicore.com

We europeans throw away a little more domestic waste every day (and this "a little more", after a while, quickly turns into "a lot more" : in France we have increased domestic waste by 33% in 10 years only, which is considerable !) :

Evolution of the domestic waste in a selection of european countries
Country	Domestic waste (thousand tonnes)		Domestic waste per inhabitant (kg)
Country	1980	1990	1980	1990
France	15.570	20.320	290	360
Germany	21.417	21.172	348	333
United Kingdom	15.500	20.000	312	348
Italy	14.040	20.033	252	348
Spain	10.100	18.540	270	322

Data from rapport Miquel du Sénat on the recycling of domestic waste

This domestic waste certainly includes potato scraps, but also a lot of manufactured products :

Breakdown of french domestic waste by nature
Type of waste	% of total	kg/hab/year
Fermentescible (organic waste)	28,8%	125
Paper	16,2%	70
Cardboard	9,1%	39
Plastics	11,1%	48
Glass	13,1%	57
Metals	4,1%	18
Various non combustible	6,8%	30
Misc. combustible	3,2%	14
Textiles	2,6%	11
Sanitary textiles	3,1%	13
Complex (packagings made of several materials)	1,4%	6
Special waste	0,5%	2
TOTAL (1997 or 1998)	100%	434

From : ADEME, Déchets municipaux, les chiffres clefs - février 1998

It is easy to see that organic waste is a little minority of everything we throw away !

Well the production and the processing of all these materials that we will eventually throw away has required energy and led to greenhouse gases emissions . For example, to obtain a steel product from iron ore, it is necessary to perform all the following acts, each of them inducing greenhouse gases emissions :

extract the ore,

transport it,

reduce it with coal (this operation, conducted in a blast furnace, generates the largest part of the emissions),

purify the cast iron (with oxygen for example),

laminate or draw the steel,

transport the steel to the factory where it will be transformed (in cans or car doors),

transform it,

and at last transport the manufactured product to the store.

Emissions - more or less well identified - can be associated to each stage. The main methodological problem arises when a same operation yields several products or services at the same time. For example, if a boat transports at the same time washing machines and bath towels, we must decide of a rule to allocate the emissions of the boat to the various goods transported (depending on their volume ? their weight ?) and it is not always obvious.

This being said, here are some rough figures for the emissions (all greenhouse gases) linked to the production of a tonne of various basic materials :

Matériau	kg carbon equivalent per tonne produced (european value)
Steel from iron ore	850
Steel from steel scraps	300
Aluminium from bauxite	3.000
Aluminium from aluminium scraps	600
Flat glass	400
Bottle glass	120
Basic plastics (polyethylene, polystyrene, PVC, PET)	500 to 1,600
Paper - cardboard	500
Cement	250

Data from Jancovici/ADEME, 2003

Hence, when we buy a kg of packaging steel, made from iron ore, that will end in the bin, we will be responsible, at best, of 300 grammes carbon equivalent of greenhouse gases emissions if this steel is recycled (we therefore can see that recycling does mean zero impact), and, at worst, of 850 grammes grammes carbon equivalent, if this steel came from ore and is not recycled.

But waste can generate other emissions :

fermentescible waste (that is organic waste, paper and cardbord for the most part), when dumped in a yard, lead to emissions of methane while decaying, and methane is a greenhouse gas.

combustible waste (that is plastic, paper, cardboard) lead to CO2 emissions when burnt ; and for plastic, made out of oil, this CO2 is "fossil".

Still it is possible to save "something" through various valorization processes :

it is possible to recycle some materials (most metals, paper, some plastics...), but this recycling nevertheless requires various processes that consume energy and emit greenhouse gases (for paper and cardboard, the overall balance for greenhouse gases is about the same when starting from old paper than when starting from wood !),

it is possible to valorize the combustion heat to produce electricity of urban heating,

it is possible to collect the methane from decaying organic waste to convert it into heat then electricity.

Nevertheless a valorization, just as in the case of steel recycling, never makes throwing away a neutral act : it is by far preferable not to throw, hence to buy products with the least packaging possible.

If we take into account the proportions of the various waste management methods (dumpyard, incineration, with or without valorization), and if we take mean values for the emissions associated to the manufacturing of the materials thrown away, here is the amount of greenhouse gases that we will find in the wastebien of an average French person :

Type of waste	kg/hab/year	*kg carbon equivalent per kg thrown ()**	kg carbon equivalent
Déchets putrescibles	125	0,17	21
Papier - carton	110	0,58	64
Plastiques	48	0,9	43
Verre	57	0,28	16
Métaux	18	0,6	11
Autres	76	0,5	38
TOTAL	434	-	193

(*) this value includes production emissions and end of life emissions (linked to fermentation or incineration).

Hence our wastebin "contains" 200 kg carbon equivalent per person and per year, that is a little 10% of the average emissions for a French person. Significantly decreasing the quantity of waste that we generate - and as a consequence the amount of packaging that we buy - represents an action possibility which, even though not sufficient, is not totally ridiculous in the total.

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