Waste is a resource. According to the European waste hierarchy waste should be prevented, reused, and recycled. Energy should be recovered from the residual waste that cannot be recycled because it is too dirty, mixed or degraded after several times of recycling, instead of going to landfill. In 2015 an average European generated 476 Kg of waste and 26% of this waste was landfilled which is the least desirable option. Landfills pose a number of environmental risks: they emit methane, a very potent greenhouse gas, microplastics from uncontrolled landfills are blown into water bodies, such as the ocean and rivers, and over time groundwater might get polluted through landfill leaching.
Under the current Renewable Energy Directive, energy recovery from the biodegradable fraction of municipal waste is considered renewable energy (biomass). While the obvious preferable option for biowaste is composting, this needs clean biowaste. If the biogenic waste is polluted or difficult to separate from the remaining residual waste (a good example of that is a used cardboard pizza box), this waste is not suitable for quality compositing or recycling. The best option for this waste is to be treated in Waste-to-Energy plants that produce clean, renewable and local energy from it.
With a population of over 46 million, Spain still landfills around 11 million tonnes of municipal waste every year which means that around 1/6 of all European waste that goes to landfills is Spanish waste. However, Districlima, a Heating and Cooling Network in the city of Barcelona is a clear example of how residual waste can contribute not only to sustainable waste management but also to the Energy Union targets of reducing greenhouse gas emissions and European energy dependence on fossil fuels.
Since the commissioning of the Districlima network back in 2004 TERSA, the Waste-to-Energy plant of Barcelona has been directly supplying the network with energy in the form of steam. The steam is used to produce heating or cooling, depending on the time of the year. Using district network for cooling also reduces the use of hydrofluorocarbons (HFCs) (normally used in stationary air conditioners), which are thousands of times more destructive to the climate than CO2.
TERSA Waste-to-Energy plant produces most of the heat and a good share of the cold for this 16.8 km long network, which helped Barcelona to reduce its fossil fuel consumption by 58% and save CO2 emissions of almost 19,000 tonnes yearly. Because of the reduced CO2 emissions in heating and cooling compared to fossil fuels, the energy performance of the buildings served by Districlima improved from 99.83 kgCO2/m² (E-label) to 55.14 kg CO2/m² (C-label). The network currently supplies 95 clients including hotels, hospitals, convention and education centres and the network continues to expand.
 See footnote 1
 All Districlima data from: “A consolidated DHC”, A smart solution for a sustainable environment, 2017