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incentives provided by the government (see Table 16). These measures may be targeted towards production forests, agroforestry and conservation forests. Conservation forests include those managed for soil erosion and watershed management. Those managed primarily for carbon sequestration would have to be located on lands with low opportunity costs, or else they would be likely to be encroached upon for other uses. Government subsidies may take the form of taxation arrangements that do not discriminate against forestry, tax relief for projects that meet specific objectives, and easy access to bank financing at lower-than-market interest rates.

Government subsidies have been important for initiating and sustaining private plantations. Since World War II, 3.15 Mha have been afforested in France, and the 1995 French National Programme for the mitigation of climate change calls for an afforestation rate of 30 000 ha/yr from 1998 onward, which will sequester 79-89 Mt C over 50 years at a cost of $70/t C. An interesting development in India in the last few years has been the planting of teak (Tectona grandis) by private entrepreneurs, with capital raised in private capital markets (SAR II, 15.3.3). This programme, while occupying only a few thousand

ha at present, has the potential to expand to 4-6 Mha of India's 66 Mha of degraded lands. The teak may be used in buildings and furniture.

In addition to national programmes, other programmes are being initiated and supported in some countries by foreign governments, non-governmental organizations and private companies. One example is RUSAFOR, which is a US IJIapproved afforestation project in the Saratov region of Russia (SAR II, Box 24-2). The project proposes to plant seedlings on 500 ha of marginal agricultural land or burned forest stands. Initial seedling survival rate is 65%. The project will serve as an example for managing a Russian forest plantation as a carbon sink. Another example is the Reduced-Impact Logging Project, for which funds were provided by New England Power Company (SAR II, Box 24-2). This project aims to reduce by half the damage to residual trees and soil during timber harvesting, thus producing less woody debris, decomposition and release of carbon.

For government forestation and agroforestry policies to succeed, the formulation of a coordinated land-use strategy,

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agreed-upon land tenure rights that are unambiguous and not open to legal challenges, and markets developed enough to ensure a sustained demand for forest products will be essential.

7.3.3 Substitution Management

Substitution management has the greatest mitigation potential in the long term. It views forests as renewable resources, and focuses on the transfer of biomass carbon into products that substitute for or reduce the use of fossil fuels, rather than on increasing the carbon pool itself. Growing trees explicitly for energy purposes has been attempted with mixed success in Brazil, the Philippines, Ethiopia, Sweden and other countries. but the potential for bioenergy is very large (see Section 5.2.5 for estimates of bioenergy supply potential; see also Box 5).

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Over time, the displacement of fossil fuels for low energyintensive wood products is likely to be more effective in reducing carbon emissions than sequestering carbon in plantations on deforested and otherwise degraded lands in developing countries, and on excess cropland in OECD Annex I countries. For example, substituting plantation wood for coal in the generation of electricity can avoid carbon emissions by an amount up to four times the carbon sequestered in the plantation (see Table 17) (SAR II, 24.3.3). The generation of biofuels and bioelectricity is far more complex, since commercialization is not easy and energy pricing and marketing barriers are yet to be overcome. Town and village biomass energy systems have the advantage of providing employment, reclaiming degraded land and providing associated benefits to rural areas. Central heating systems could be converted to biomass-based ones to supply heat and electricity in colder climates.

Box 5. Potential for Bioenergy for Rural Electrification

In non-Annex I countries, the majority of rural areas (where over 70% of the population lives) is not electrified, but the demand for electricity in these areas is likely to grow. The electricity loads are low and dispersed, in the range of 10-200 kW. Field demonstrations in southern India have shown the technical and operational feasibility of meeting rural electricity needs through decentralized woody biomass-based electricity systems using producer gas generators and cattle dung-based biogas systems. Bioenergy systems could also lead to reclamation of degraded lands, promotion of biodiversity with appropriate forestry practices and creation of rural employment. Thus, given the low loads, dispersed demand for electricity and local benefits, bioenergy systems could be considered as "no regrets" options for meeting the growing rural electricity needs.

Technologies, Policies and Measures for Mitigating Climate Change

In non-Annex I countries, the use of electricity in rural areas is low. In many countries, such as in sub-Saharan Africa, less than 5% of villages are electrified; in countries such as India, even though over 80% of rural settlements are electrified, less than a third of rural households have electricity. Appropriate government policies are needed that will: (i) permit smallscale independent power producers to generate and distribute biomass electricity; (ii) transfer technologies within the country or from outside; (iii) set a remunerative price for electricity; and (iv) remove restrictions on the growing, harvesting. transportation and processing of wood (except possibly restrictions on conversion of good agricultural land to an energy forest) (SAR II, 24.3.3).

8.1 Introduction

Methane is emitted during the anaerobic decomposition of the organic content of solid waste and wastewater. There are large uncertainties in emissions estimates, due to the lack of information about the waste management practices employed in different countries, the portion of organic wastes that decompose anaerobically and the extent to which these wastes will ultimately decompose.

About 20-40 Mt CH, (110–230 Mt C), or about 10% of global CH, emissions from human-related sources, are emitted from landfills and open dumps annually. Ten Annex I countries represent about two-thirds of global CH, emissions from solidwaste disposal, with the United States representing about 33%, or around 10 Mt (SAR II, 22.4.4.1).

CH, emissions from domestic and industrial wastewater disposal are estimated to be 30-40 Mt (170–230 Mt C) annually. again about 10% of total global emissions from human sources. Industrial wastewater, principally from the food processing and pulp and paper industries, is the major contributor, with domestic and commercial wastewater making up 2 Mt CH, annually. Unlike solid-waste emissions, the majority of wastewater emissions is believed to originate in non-Annex I countries, where domestic sewage and industrial waste streams often are unmanaged or maintained under anaerobic conditions without CH, control (SAR II, 22.4.4.1).

The most important technical option for source reduction is decreasing the use of materials that eventually turn up in the waste stream. This section, however, focuses on solid waste after it has been generated (consistent with SAR II, 22.4.4.2). The amount of organic solid waste may be reduced by recycling paper products, composting, and incineration. Paper products make up a significant part of solid waste in Annex I countries (e.g., 40% in the United States) and in urban centers of upper-income non-Annex I countries (typically 5-20%). A variety of recycling processes, differing in technical complexity, can often turn this waste into material indistinguishable from virgin products. Composting an aerobic process for treating moist organic wastes that generates little or no CHis most applicable to non-Annex I countries, where this type of waste is a larger fraction of the total, although there is also potential in Annex I countries (SAR II, 22.4.4.2). As a secondary benefit, the residue can be used as fertilizer. Reduced

land availability and the potential for energy recovery are increasing use of waste incineration in many countries: 70% of Japan's solid waste is incinerated. Stack air pollutant emissions and ash disposal are still issues, however, and characteristics such as moisture content and composition may make incineration more difficult and costly in non-Annex I countries.

The technical complexity of these source reduction options can vary significantly, although this does not greatly influence their effectiveness. In non-Annex I countries, where labour is cheap compared to equipment costs, labour-intensive recycling and composting are common. Annex I countries typically use more complicated, labour-saving machinery requiring higher operating skills.

Costs will depend on the type of system, the size of the facility, and local factors. Capital costs for solid-waste composting facilities can range from $1.5 million for a 300 ton per day (TPD) plant to $45 million for a more complex 550 TPD plant that also composts sewage sludge; associated operating costs can range from $10-90/t, but generally average $20-40. Yard waste facilities are typically smaller and less complex; capital costs range from $75 000-2 000 000 in the United States for plants handling 2 000-60 000 t/yr of waste; operating costs are roughly $20/t. Capital costs for incineration can be quite high. ranging from $60-300 million for 10-80 MW facilities, or approximately $125 000 per TPD capacity (SAR II, 22.4.4.2).

Source reduction is applicable to future solid-waste generation. CH, may be recovered from existing as well as future landfills, since organic materials in dumps and landfills continue to emit CH, (often called landfill gas) for 10-30 years or more. Frequently, more than half of the CH, can be recovered and used for heat or electricity generation, a practice already common in many countries (SAR II, 22.4.4.2). Landfill gas also can be purified and injected into a natural gas pipeline or distribution system; there are several such projects in the United States. In Minas Gerais, Brazil, purified landfill gas has been used to provide power for a fleet of garbage trucks and taxicabs.

Costs of recovering CH, from solid-waste disposal facilities are highly dependent on technology and site characteristics. For a landfill with 1 million tons of waste (serving a population

21This section is based on SAR II, Chapter 22, Mitigation Options for
Human Settlements (Lead Authors: M. Levine, H. Akbari, J. Busch,
G. Dutt, K. Hogan, P. Komor, S. Meyers, H. Tsuchiya, G. Henderson,
L. Price, K. Smith and Lang Siwei) and Chapter 23, Agricultural
Options for Mitigation of Greenhouse Gas Emissions (Lead Authors:
V. Cole, C. Cerri, K. Minami, A. Mosier, N. Rosenberg, D.
Sauerbeck, J. Dumanski, J. Duxbury, J. Freney, R. Gupta, O.
Heinemeyer, T. Kolchugina, J. Lee, K. Paustian, D. Powlson, N.
Sampson, H. Tiessen, M. van Noordwijk and Q. Zhao).

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of about 50 000-100 000), collection and flare capital costs will be approximately $630 000, increasing to $3.6 million for a 10 million-ton landfill. Annual operating costs could range from less than $100 000 to more than $200 000. Energy recovery capital costs (including gas treatment) can range from $1 000-1 300 per net kW. Direct use is typically less expensive, with pipeline construction representing the principal cost. Overall, typical electric generation costs for a complete system (gas collection and energy recovery) range from 4-7g/kWh. These costs are based on equipment and labor costs in the United States, and may vary over a wider range in other countries. Also, in many countries, some landfills and other solidwaste disposal sites already collect their CH, and either vent or flare it (often for safety reasons). For these sites, the cost of electric generation would be lower than stated above (SAR II, 22.4.4.2; SAR III, 9.4.1).

8.2.3

Methane Recovery and/or Reduction from Wastewater CH, emissions can be virtually eliminated if wastewater and sludge are stored and treated under aerobic conditions. Options for preventing CH, production during wastewater treatment and sludge disposal include aerobic primary and secondary treatment and land treatment. Alternatively, wastewater can be treated under anaerobic conditions and the generated CH, can be captured and used as an energy source to beat the wastewater or sludge digestion tank. If additional CH, is available, it can be used as fuel or to generate electricity. As a last resort, the gas may be flared, which converts the CH, to CO2, with a much lower global warming potential.

Wastewater treatment costs are highly dependent on the technological approach employed and site-specific conditions. Capital costs of aerobic primary treatment can range from $0.15-3 million for construction, assuming a range of 0.5-10 million gallons (2 000-40 000 m3) of wastewater flow per day; annual operation and maintenance costs are estimated to range from $20 000-500 000 for these volumes. Costs of aerobic secondary treatment can be moderately high because of the energy and equipment requirements, and depend to a great extent on the daily volume of wastewater flow into the facility. Costs can range up to $10 million depending upon the technology selected and volume requirements, with the high-end handling approximately 100 million gallons (0.4 x 106 m3) per day. Finally, costs for anaerobic digestors of wastewater and flaring or utilization can range from $0.1-3 million for construction and $10 000-100 000 for operation and maintenance, assuming wastewater flows of 0.1-100 million gallons (400 to 0.4 x 10 m3) per day (SAR II, 22.4.4.2).

High-rate anaerobic processes for the treatment of liquid effluents with high organic content (e.g., sewage, food processing wastes) can help reduce uncontrolled CH, emissions and are particularly suited to the warmer climates of most developing countries. Both Brazil and India, for example, have developed extensive and successful infrastructure for these technologies, which have lower hydraulic retention times than aerobic

processes and therefore are much smaller and cheaper to build. More importantly, unlike aerobic processes, no aeration is involved and there is little electricity consumption.

For upflow anaerobic sludge blanket reactors of 4 000-10000 m3 capacity (capable of handling a chemical oxygen demand of 20-30 kg/m3/day), capital costs have been estimated to be in the range of $1-3.5 million, with annual operating costs in the range of $1-2.7 million. At these costs, the total CH, production cost would fall in the range of $0.45–1.05/GJ, with values at the upper end for Europe and at the lower end for Brazil. Using these estimates, all of the costs would be recovered, as CH, would be produced at a price lower than that of natural gas almost anywhere in the world (SAR II, 22.4.4.2).

8.3 Measures for Methane Reduction and Recovery

In many countries, future actions that reduce CH, emissions from solid-waste disposal sites and wastewater treatment facilities are likely to be undertaken for environmental and public health reasons; CH, reductions will be seen as a secondary benefit of these actions. In spite of the benefits, however, a number of barriers prevents CH, recovery and source reduction efforts described above from tapping more than a small portion of the potential, especially in non-Annex I countries. These barriers include the following (SAR II, 22.5.3):

• There is a lack of awareness of relative costs and effectiveness of alternative technical options.

• While recently developed anaerobic processes are less expensive than traditional aerobic wastewater treatment, there is less experience available.

• It is less economical to recover CH, from smaller dumps and landfills.

• Many countries and regions where natural gas is not used extensively and equipment may not be readily available [e.g., Mexico City, New Delhi, Port-au-Prince (Haiti), and much of sub-Saharan Africa] have limited infrastructure and experience for CH, use.

• The existing waste disposal "system" may be an open dump or an effluent stream with no treatment, therefore no capital or operating expenses. The barriers previously noted, combined with the unhygienic conditions of the proposed site, may make it difficult to attract investment capital for CH, recovery and use.

• Different groups are generally responsible for energy generation, fertilizer supply and waste management, and CH, recovery and use can introduce new actors into the waste disposal process, potentially disturbing the current balance of economic and political power in the community (e.g.. failure to reach an agreement has delayed the start-up of a landfill gas recovery demonstration project funded by the Global Environment Facility in Lahore, Pakistan). This problem applies to both Annex I and non-Annex I countries.

For the successful implementation of CH, control projects, these barriers need to be addressed through appropriate measures. In