Since 1978, the city of Zurich, Switzerland has collected green waste through its recycling and waste management unit, ERZ Entsorgung+Recycling Zurich, and processed it into compost at its Werdholzli facility in western Zurich, adjacent to the city’s wastewater treatment plant along the Limmat River. The source-segregated organic municipal solid waste (MSW) is collected from the city’s 400,000 residents, businesses and from surrounding communities. It includes waste from households such as tree and lawn cuttings, and organic kitchen waste like fruits, vegetables and foodstuffs, as well as organic wastes from restaurants and food processors. Until 2013, up to 25,000 tons of organic waste was collected annually and open-air composted at the facility, which created ongoing concerns from local urban residents because of odors.
As early as 2002, the Zurich City Council began studying the odor problem, as well as a broader solution to address a better utilization of the organic wastes collected from in the city, in support of the 2,000-Watt Society. The 2000-Watt Society is an environmental vision, first introduced in 1998 by the Swiss Federal Institute of Technology in Zurich, which postulates that Swiss citizens reduce their overall primary energy usage to no more than 2,000 watts per year, per resident, by the year 2050, without lowering their standard of living.
The concept addresses the total energy consumed for the whole society, divided by the population. Two thousand watts is approximately the current world average rate of total primary energy use, whereas, Swiss usage is approximately 5,000 watts annually—still considerably lower than most industrialized nations. A component of the 2,000-Watt agenda is that carbon-based fossil fuels would be reduced to no more than 500 watts per person within 50 to 100 years. The vision was developed in response to concerns about climate change and the future availability of energy supplies.
