Various authors have made estimates of the costs of measures per tonne of CH4 emission reduction. With some technical measures, CH4 emissions can be significantly reduced and experience of these measures has been developed in actual CH4 reduction projects. A body of literature is available on measures to reduce CH4 (for example AEAT, 1998; IEA, 1999; Hendriks and de Jager, 2000; De la Chesnaye and Kruger, 2002; Graus et al, 2003; Gallaher et al, 2005; Delhotal et al, 2005; Harmelink et al, 2005). Measures are considered cheap if they are below $20 per tonne. Some measures even generate money and can be implemented for -$200 to $0 per tonne of reduced CH4. These are called 'no-regret' measures. Most measures, however, are more expensive and can only be implemented at $20-500 per tonne of CH4 reduced. Very expensive options are available at $500 per tonne or more. Van Amstel (2005) made a first global estimate of costs.
The IPCC (2007) showed that climate is already changing and that these changes are likely to accelerate in the next 50 years as a result of human activities. To limit these changes, greenhouse gas emissions should be reduced rapidly worldwide. The UNFCCC has a stated objective to stabilize atmospheric concentrations of greenhouse gases at a level that will avoid dangerous climate change. The science, technology and expertise are potentially available to meet this goal. Proposals to limit atmospheric CO2 concentrations to prevent the most damaging effects of climate change have often focused on stabilization targets of 550ppm - almost doubling the pre-industrial average concentration of 280ppm. The current CO2 concentration is 386ppm, with a growth rate of ~2ppm yr-1.
Greenhouse gas emissions are reported to the Climate Convention and the Kyoto Protocol. IPCC (2006) developed guidelines for national inventories of emissions. In general, greenhouse gas emissions from fossil fuels can be controlled by energy efficiency measures, energy conservation and decarbonization of the economy, which includes fuel switching to renewables. Short-term options are carbon capture and storage, fuel switching from coal to gas (i.e. from a high to a lower carbon-density fuel) or from fossil to biomass fuels (biomass is a carbon-dense fuel but emitted CO2 is taken up by the vegetation in a closed short-term cycle) (Leemans et al, 1998; Pacala and Socolow, 2004). Some even advocate a large increase in nuclear power generation around the world, but the problems of nuclear waste storage and security remain unresolved in many areas.
Pacala and Socolow (2004) have suggested that the policy gap between a business as usual (BAU) scenario and a stabilization scenario could be tackled stepwise through stabilization wedges, using current technologies. In a BAU scenario, carbon emissions are increasing by 1.5 to 2 per cent per year. In their view, every wedge contains a package of measures that reduces the emissions substantially. Wedges can be achieved from, for example, energy efficiency, the decarbonization of the supply of electricity and fuels by means of fuel shifting, carbon capture and storage, nuclear energy and renewable energy. With energy conservation and efficiency improvements, large reductions in carbon dioxide emissions have already been achieved in some sectors and regions. In industrialized countries, the autonomous energy efficiency improvement (AEEI) of the total economy was 2 per cent per year over the last four decades, with a levelling off during the last 20 years (Schipper, 1998).
Van Amstel (2009) developed scenarios for 2100, and estimated climate change with methane reduction measures. Every possible measure to reduce the other greenhouse gases, including CH4, should be added to the greenhouse gas technology portfolio. Methane emitted to the atmosphere is 21-25 times more powerful than CO2 and, as we have seen in previous chapters, it can often be captured and used for energy generation. For CH4, this means tracking down and removing all leaks in the exploration, mining and supply sectors of the fossil fuel industry. It means abandoning wasteful venting and flaring in the oil and gas industry and capturing coal mine ventilation air CH4.
Pre-mining degasification in 'gassy' coal mines must be promoted to increase safety and to capture and use the CH4 for energy generation. A market for ventilation air CH4 use and oxidation is emerging in many of the world's coal-producing countries with an equipment sales market of more than $8.4 billion (EPA, 2003; Gunning, 2005; Mattus, 2005). Harvesting biogenic CH4 from landfills, manure fermentation and wastewater treatment plants, for example (IEA, 2003; Maione et al, 2005; Ugalde et al, 2005), should also be promoted wherever possible.
Below, I discuss different options that are already being deployed at an industrial scale and that could be scaled-up further. Methane can also be seen as the perfect carrier for hydrogen in the hydrogen economy (it is much cheaper than metal hydrates). This chapter then continues with a conceptual section focused on the way to determine the costs of emission reductions and a technical section in which the reduction measures are described.
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