10.5.1 Reducing landfill CH4 emissions
There are two major strategies to reduce landfill CH4 emissions: implementation of standards that require or encourage landfill CH4 recovery and a reduction in the quantity of biodegradable waste that is landfilled. In the US, landfill CH4 emissions are regulated indirectly under the Clean Air Act (CAA) Amendments/New Source Performance Standards (NSPS) by applying a landfill-gas generation model, either measured or default mixing ratios for total non-methane organic compounds (NMOCs), and restricting the emissions of NMOCs. Larger quantities of landfill CH4 are also being annually recovered to both comply with air-quality regulations and provide energy, assisted by national tax credits and local renewable-energy/green-power initiatives. As discussed above, the EU landfill directive (1999/31/EC) requires a phased reduction in landfilled biodegradable waste to 50% of 1995 levels by 2009 and 35% by 2016, as well as the collection and flaring of landfill gas at existing sites (Commission of the European Community, 2001). However, increases in the availability of landfill alternatives (recycling, composting, incineration, anaerobic digestion and MBT) are required to achieve these regulatory goals (Price, 2001).
Landfill CH4 recovery has also been encouraged by economic and regulatory incentives. In the UK, for example, the Non Fossil Fuel Obligation, requiring a portion of electrical generation capacity from non-fossil sources, provided a major incentive for landfill gas-to-electricity projects during the 1980s and 1990s. It has now been replaced by the Renewables Obligation. In the US, as mentioned above, the implementation of CAA regulations in the early 1990s provided a regulatory driver for gas recovery at large landfills; in parallel, the US EPA Landfill Methane Outreach Program provides technical support, tools and resources to facilitate landfill gas utilization projects in the US and abroad. Also, periodic tax credits in the US have provided an economic incentive for landfill gas utilization – for example, almost 50 of the 400+ commercial projects in the US started up in 1998, just before the expiration of federal tax credits. A small US tax credit has again become available for landfill gas and other renewable energy sources; in addition, some states also provide economic incentives through tax structures or renewable energy credits and bonds. Other drivers include state requirements that a portion of electrical energy be derived from renewables, green-power programmes (which allow consumers to select renewable providers), regional programmes to reduce GHG emissions (the RGGI/ Regional GHG Initiative in the northeastern states; a state programme in California) and voluntary markets (such as the Chicago Climate Exchange with binding commitments by members to reduce GHG emissions).
In non-Annex I countries, it is anticipated that landfill CH4 recovery will increase significantly in the developing countries of Asia, South America and Africa during the next two decades as controlled landfilling is phased in as a major waste-disposal strategy. Where this occurs in parallel with deregulated electrical markets and more decentralized electrical generation, it can provide a strong driver for increased landfill CH4 recovery with energy use. Significantly, both JI in the EIT countries and the recent availability of the Clean Development Mechanism (CDM) in developing countries are providing strong economic incentives for improved landfilling practices (to permit gas extraction) and landfill CH4 recovery. Box 10.2 summarizes the important role of landfill CH4 recovery within CDM and gives an example of a successful project in Brazil.