- Waste management
- The waste hierarchy
- Landfill regulations
- Recovering energy from waste
The UK government says better management of waste can offer the following benefits:
- Reduced greenhouse gases – most notably methane from landfill sites, but also carbon dioxide emissions through re-use and recycling
- Improved resource efficiency – saving energy and reducing material use through waste prevention, re-use, recycling and renewable energy recovery
- Protection of public health – through safe management of potentially hazardous substances
- Protection of ecosystems – such as soils, groundwater and air quality
- Safeguarding of local environments – by ensuring household waste is collected, fly-tipping by households and businesses is reduced, and nuisance levels from waste facilities are limited
The diagram below shows the 'waste hierarchy’. This represents the concept that reduction (via prevention or minimisation) is better than re-use, which in turn is better than recycling, which in turn is better than recovering energy by incineration, which, finally, is better than disposal to landfill.
The Waste Hierarchy
The European Union's Landfill Directive (99/31/EC) was introduced in 1999 in response to the fact that some EU member states were still sending more than 80% of their national waste to landfill. The directive is designed to prevent or reduce the adverse effects of landfill of waste on the environment, in particular on surface water, groundwater, soil, air and human health.
The directive obliges member states to reduce, progressively, the amount of organic waste going to landfill to 35% of 1995 levels by 2020.
The Waste Strategy for England 2007 said: "Reliance on landfill is already reducing and this should become the home of last resort for waste." However, the government also recognised that landfill would continue to have a role in the disposal of certain hazardous wastes.
The landfill tax and its associated tax escalator have proved to be important incentives to encourage companies to reduce, re-use or recycle more. The landfill tax is levied on every tonne of waste tipped into landfill sites, with the revenues spent by the government on waste reduction programmes. The escalator provides an acceleration of the tax to provide an even greater incentive for businesses to find alternatives to landfill disposal.
Recovering energy from waste
There are several ways to recover energy from waste, as follows:
- Anaerobic digestion – A naturally occurring process of decomposition and decay, where organic matter is broken down into a simpler chemical component under anaerobic conditions (ie without oxygen). See our Anaerobic digestion factsheet
- Incineration (direct combustion) – The controlled burning of municipal solid waste to reduce waste volumes and produce energy
- Secondary recovered fuel – The recovery of energy from waste that cannot realistically be reused or recycled from mechanical and biological treatment processes
- Pyrolysis – The heating of waste to high temperatures to break down any carbon content, through an absence of air, into a mixture of gaseous and liquid fuels and solid residue
- Gasification – The conversion of the carbonaceous content of a material through high temperature partial oxidation into a gas stream comprising carbon monoxide, hydrogen and methane
- Plasma arc heating – The heating of municipal solid waste to very high temperatures (3,000-10,000°C) using a plasma arc. Energy is released by an electrical discharge in an inert atmosphere, which converts organic waste into a hydrogen-rich gas and non-organic waste into an inert glassy residue
Each technology requires different feedstocks and generates different levels of carbon emissions, outputs and efficiency ratings.
Using waste as fuel can offer important environmental benefits as follows:
- It can provide a safe and cost-effective option for wastes that would otherwise present significant disposal problems
- It can help reduce CO2 emissions through the displacement of fossil fuels, while also improving energy security
- Methane emissions from landfill can be avoided
In terms of what can be incinerated, different waste types offer different calorific values. As can be seen in the graphic, mixed plastics waste offers a calorific value similar to coal.
Potential energy of different household waste compared with solid fuels
(SOURCE: Assure – Energy from Waste fact sheet)
The Association of Plastics Manufacturers in Europe estimates that if all the EU's non-recyclable plastics waste was turned into energy, it would offer the output of at least 17 million tonnes of coal. This is equivalent to 15% of total EU coal imports and would meet approximately 5% of the EU's energy needs for power generation.
Meanwhile, just 10% of pre-sorted EU municipal waste could meet 5% of the EU's energy needs, saving up to 14 million tonnes of oil per year. (Source: Assure – Energy from waste fact sheet 1)
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