to food waste (due to the presence of wood), combined with the lower water content in garden waste, results in
a higher heating value of garden waste than the average heating value for food and garden waste. Thus,
incineration is favoured compared to composting and the conclusions should not be interpreted with reference to
all organic waste.
Study no 3
This study compares two types of home composting and centralised composting to disposal in a landfill. The
results for the two types of home composting are identical except for climate change, where the most important
parameter is the form of degradation assumed. The study takes into account two ‘extreme’ artificial cases in
order to provide a range of values according to the degree of aerobic conditions operating. This range varies from
a value based on an assumption of total aerobic conditions (case 3[FW2]) and a value for assumed total
anaerobic conditions (case 3[FW3]). For the remaining impact categories, study no 3 uses average values for
home composting. According to the results, composting is preferable for climate change except for the anaerobic
version. Home composting is the best regarding primary energy demand and all types of compost are better than
landfill regarding water consumption. Generally, home composting is the best option, followed by centralised
composting even in the rest of the impact categories. In this study also, no energy recovery is assumed to take
place in the landfill.
Study no 4
This study compares the traditional disposal options (incineration, landfill and composting) to two types of
anaerobic digestion. Anaerobic digestion is the best option regarding resource depletion and climate change, but
behind incineration when examining primary energy demand. The better efficiencies achieved in a modern
incineration plant are primarily responsible for this outcome. Composting, on the other hand, is the worst option
for resource consumption and primary energy, while landfill takes its place for climate change. When the rest of
indicators are examined the classification of options becomes more complicated.
Study No 5
This US study produces results only for climate change and energy demand, while comparing composting to
incineration and landfill. Carbon binding is taken into account when examining the composting option. Energy
recovery is assumed for both incineration and landfill. Incineration is the best option for both categories, although
composting presents equivalent results for climate change. Landfill is the worst option for climate change and the
second regarding energy use.
Study no 6
Only climate change is included in this study as an environmental indicator. All well established options are
analysed in this study: landfill with energy recovery, incineration with energy recovery, composting and anaerobic
digestion. Anaerobic digestion appears to be preferable, but it is closely followed by composting. On the other
hand, landfill is the worst option and the one (together with incineration) that has a net positive contribution to
global warming. It should also be mentioned that carbon binding is taken into account in this study.
Study no 7
This Danish study compares incineration to anaerobic digestion in a strictly Danish context. Among the basic
indicators, only climate change is included, in spite of this being a full LCA. Incineration prevails in terms of global
warming, but it should be noted that incineration is favoured by the assumptions chosen. Indeed, the state-of-
the-art dedicated combustion plant examined produces energy on a quite high efficiency and the substituted
electricity is assumed to be produced in a coal-fired power plant (the same assumption is applied for the energy
recovered through anaerobic digestion).