This is an article from the DG Environment Newsletter "Science for Environmental Policy" (Special Issue 11, February 2009).
"What is the best way to manage urban waste? Towns and cities generate huge volumes of waste that are often disposed of as landfill. In a new study, researchers explain that sorting urban waste into organic and inorganic streams, which can be turned into energy and fertiliser, offers a much more efficient and environmentally friendly solution.
Each year, 1.3 billion tonnes of waste is thrown away in the EU1. In several European countries, the main way of disposing of this waste is in landfill sites. In Greece, Portugal, the UK, Ireland, Finland, Italy and Spain more than half of all waste ends up as landfill. Aside from the negative environmental impacts of landfill, including heavy metal leaching and slow release of greenhouse gases, landfill sites are in short supply. Alternative waste management strategies are therefore urgently required.
Using the city of Rome as a case study, landfill was compared with four alternative waste management options:
landfill without biogas treatment
landfill with collection of biogas to burn for electricity production
direct incineration of waste with electricity recovery
a scheme where waste is sorted into organic and inorganic streams at landfill sites, and ferrous metals are recycled
In each case, the researchers calculated how much new waste was generated by the waste disposal process itself, how much energy the process required and how much it generated, and the estimated global and local emissions. The results suggest landfill represents the worst waste management strategy both in terms of environmental impacts and energy performance. The data reveal that even incinerating waste is a better option than landfill.
Separating organic and inorganic waste, proved most effective in terms of reducing environmental impacts and energy performance. In this case, organic waste is turned into biogas and fertiliser, and inorganic waste is converted to Refuse Derived Fuel (RDF) which is burned to generate electricity. This scenario could lead to an 80 per cent reduction in the amount of waste sent to landfill. In terms of global warming potential, this scenario has a positive effect on net greenhouse gas emissions (because the electricity and biogas produced can replace fossil fuels).
For comparison, under the landfill alone scenario, one year's worth of waste from Rome produces an estimated global warming potential equivalent to 1910 kt CO2 (mainly in the form of greenhouse gases emitted from the landfill site). If the waste is separated into streams, there is a net reduction in global warming potential equivalent to 345 kt CO2 from one year's worth of waste.
Although none of the options evaluated provide a full solution to the waste disposal problem, the researchers suggest that the fourth scenario is currently the most viable. This scheme produces twice as much energy as the direct incineration scheme and is the most energy efficient. From an environmental perspective, the same scheme offers the best solution, as the only remaining waste to enter landfill is burnt inorganic waste, which will not decompose further after disposal. In contrast, organic waste directly disposed of in landfill will continue to decompose for thousands of years, releasing greenhouse gases.
1. See: http://ec.europa.eu/environment/waste/index.htm
Source: Cherubini, F., Bargigli, S. and Ulgiati, S. (2008). Life Cycle Assessment of Urban Waste Management: Energy Performances and Environmental Impacts. The Case of Rome, Italy. Waste Management. 28: 2552-2564.
Theme(s): Climate change and energy, Urban Environments, WasteAdditional information: LIFE has funded a number of innovative projects designed to improve the sustainability of waste management. For project details, please download: http://ec.europa.eu/environment/life/themes/urban/documents/urban_waste.pdf