Limiting the Magnitude of Future Climate Change (2010) / Chapter Skim
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3 Opportunities for Limiting Future Climate Change
3 Opportunities for Limiting Future Climate Change
Pages 51-90
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From page 51... ...
Liquid Transportation Fuels from Coal and Biomass, and (3) Real Prospects for Energy Efficiency in the United States, and an overarching report, America's Energy Future: Technology and Transformation (NRC, 2009a)
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From page 52... ...
An issue of key relevance is the practicality and acceptability of intervening to alter consumer behavior and preferences in ways that would reduce the demand for goods and services that result in energy consumption and GHG emissions. (We note this is different from the question explored in the following section: how to meet demand
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From page 53... ...
The United States has larger per capita energy use than many other countries with an equal or higher standard of living, such as Japan and most European countries. This differential is no doubt due to a variety of economic, demographic, geographic, and cultural factors, including differences in energy prices and energy efficiency.
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could lead to reductions in fuel use and CO2 emissions of about 1 percent by 2030, and 1.3 to 1.7 percent by 2050. Overall then "the committee believes that reductions in VMT, energy use, and CO2 emissions resulting from compact, mixed use development would be in the range of ~1 to 11 percent by 2050, although the committee members disagreed about whether the changes in development patterns and public policies necessary to achieve the high end of these findings are plausible." It is important to keep in mind, however, that these potential emissions reductions result ing from land-use changes would be occurring in the context of an overall increasing baseline of VMT; thus, even at the high end of the optimistic scenario, VMT in 2050 may be higher than it is today.
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Publicity campaigns and other actions to promote water conservation may thus be an area where public policy could contribute to reducing energy demand. The same is true for residential energy conservation, where some states and locales have long-standing commitments and significant expertise in interventions that combine technology and behavior change to reduce demand for electricity and natural gas -- although considerable work remains to be done in this area (Lutzenhiser et al., 2009)
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energy efficiency? Most analysts believe that the technical potential in the aggregate is large and much of it can be realized, especially if the price of energy increases.
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. Such market barriers have long been used to justify public policies devoted to boosting energy efficiency, prominent examples being the Corporate Average Fuel Economy (CAFE)
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households, the technical potential for emissions reduction is approximately 9 percent for phasing in more fuel-efficient vehicles, 6 percent for home weatherization and adoption of more efficient space conditioning equipment, 5 percent for more efficient household appliances, and 5 percent for universal adoption of compact fluorescent lighting. The study suggests that, with effective incentive programs, the great bulk of these efficiency improvements could realistically be achieved.
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Most energy use in the building sector is in the form of electricity, followed by natural gas. There are numerous options to reduce this energy use, ranging from simple insulation and caulking to highly sophisticated appliances (Granade, 2009)
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They recognized, however, that risk aversion and uncertainty over future prices for electricity and fuels can lead many firms to defer decisions on energyefficiency investments. The concern with such deferrals is that, once an asset is installed, it locks in a fixed level of energy efficiency for years or even decades (IEA, 2008)
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The AEF report concluded that these increases in vehicle fuel economy will be difficult but possible to meet, since many technologies are available that could be implemented at relatively modest cost. Some are already in use and could be expanded rapidly over the next decade (e.g., cylinder deactivation, direct injection, diesel engines, and hybrid electric vehicles)
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Of that decline, 57 percent was attributed to improvements in energy efficiency, 22 percent resulted from increases in aerodynamic efficiency, 17 percent was due to more efficient use of aircraft capacity through higher load factors, and 4 percent resulted from other changes, such as increased aircraft size. Reducing the Carbon Intensity of Energy Opportunities for reducing the carbon intensity of energy include switching from higher- to lower-carbon-content fossil fuels, advancing coal technologies such as gasification and combined-cycle plants, along with carbon capture and storage (CCS)
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. Natural Gas Natural gas is the cleanest of the fossil fuels, with the lowest GHG emissions per unit of energy, emitting about half of the CO2 of coal when burned for electricity generation.
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. We do not review the current technical status of individual technologies here, as this has been done in detail in other recent reports, including America's Energy Future: Real Prospects for Energy Efficiency in the United States (NRC, 2009a)
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and associated transmission lines can also present barriers (as is true, of course, for other energy technology options as well)
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These new technologies under development may allay some of the concerns and barriers described above, but it will be necessary to determine the functionality, safety, and economics of those technologies through demonstration and testing. Considering only technical potential (i.e., not accounting for the practical barriers discussed above)
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, it will be necessary to operate a number of large-scale capture and storage projects that encompass a range of different fuels (coal, natural gas, and biomass) , application types 5 Because the CO2 is captured before it is emitted to the atmosphere, it is classified here as an option for "reducing carbon intensity" rather than as "post-emission carbon management."
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Post-Emission Carbon Management Preventing or limiting GHG emissions from known sources is the classic abatement approach that dominates most current policy deliberations. However, fossil fuels will remain abundant and relatively inexpensive for many years to come; there is little evidence thus far that most nations of the world are willing to take maximum advantage of the GHG emissions-reduction opportunities discussed in the previous sections.
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. In terms of domestic action, the United States can augment its emissions-abatement efforts with a variety of practices to enhance carbon sequestration in its own forests and croplands.
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and in early years, carbon sequestration in agricultural soils and in forest management would be optimal as the dominant mitigation strategies; at middle to higher prices ($15 per ton CO2-eq or higher) in the early to middle years, afforestation becomes the leading strat 2500 Biofuel offsets Agricultural CH4 and N2O mitigation Fossil fuel mitigation from crop production 2000 Agricultural soil carbon sequestration Forest management Afforestation 1500 Mt CO 2-eq 1000 500 0 2015 2025 2055 Year FIGURE 3.2 Mitigation potential in the U.S.
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From page 71... ...
, the economic potential to sequester carbon in agricultural soils is less than two-thirds of the pure technical potential. Furthermore, at such high prices, soil sequestration has to compete with other strategies such as bioenergy and afforestation, which further reduce the competitive economic potential for soil carbon sequestration to less than one-third of the technical potential.
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(2009) identify a number of approaches that may alleviate the ecosystem satura tion effects that currently limit carbon sequestration potential, for instance: Biotechnology.
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Farm and forestry groups have reservations about making permanent commitments to carbon sequestration. Many such groups favor leasing rather than permanent sales, because they are worried about factors such as future carbon prices; requirements that land be managed in particular ways; potential increases in cost, particularly for weed and insect control; and critical reliance on the efficacy of chemical weed con trol compounds, in the face of possible development of resistance to control methods.
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suggested that more research is needed to effectively compare the economic viability of the different approaches, but at present, among these geochemical approaches, only alkalinity addition seems to provide a significant improvement beyond conventional CCS in broadening the economic scope of carbon storage options. Direct Air Capture of CO2 For large point sources such as power plants, on-site CO2 capture from an effluent stream is considered technically feasible and potentially cost-effective.
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. Major challenges remain in making such systems viable in terms of cost and energy requirements and improving overall capture energy efficiency.
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Coal mines Methane recovery and 39.2 combustion, flaring, ventilation air use Oil/gas systems Use of low-bleed equipment, 47.5 better management practices Livestock waste Methane collection from anaerobic 9 digestors and combustion (power, flaring) Ruminant livestock Improved production efficiency 12 through better nutrition and management Rice production Water management, organic 4 supplements N 2O Industrial sources Adipic acid (catalysts, thermal 25.9 destruction)
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already exist, but there is 6 If one uses the captured methane as a fuel, and this displaces the use of more carbon-intensive fuels, it is a net gain in terms of GHG emissions.
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non-CO2 GHG emissions. Combustion of fossil fuels by mobile (e.g., trucks, cars, buses, trains, and ships)
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Fluorinated GHG Emissions Although emissions of fluorinated GHGs are relatively small, contributing only about 2 percent to total CO2-eq emissions, their 100-year global warming potentials (GWPs) are significant, ranging from 124 to 22,800 times that of CO2.
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. Although less frequently mentioned in climate discourse, reducing atmospheric concentrations of short-lived atmospheric pollutants (namely, tropospheric ozone and black carbon particles)
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Here we assess whether the technical potential for domestic emissions reduction is sufficient to meet a domestic GHG budget in the suggested range (assuming, as discussed in Chapter 2, that international
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First, we find that the energy efficiency and energy production technologies available for near-term commercial use (i.e., by 2020) could attain the deployment levels required for meeting the emissions budget scenarios only under the most favorable circumstances.
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A wide variety of future energy mix scenarios is possible, but all cases project a greater role for energy efficiency, renewable energy, fossil fuels with CCS, and nuclear power. SOURCES: Adapted from Fawcett et al.
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. In Table 3.2, these AEF technical potential estimates are compared with estimates from EMF22 studies of the technological deployment levels required for meeting the domestic emissions budget goals discussed in Chapter 2.
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for Various Key Energy Technology Options, for the 167 and 203 Gt CO2-eq Budget Scenarios Energy Efficiency (% reduction from ref. case)
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The technical potential for expanding the use of biomass fuels in transportation appears to be near the low end of what is required. The AEF study shows that, even if we could meet the full technical potential for both vehicle efficiency gains and alternate fuels use, there would still be a need for roughly one-third of the 2035 demand for trans portation fuel to be met by oil.10 This suggests that further displacement of petroleum in the transportation sector will require additional strategies, such as significant deployment of pure or hybrid electric vehicles.
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contribution to global GHG emissions would risk further loss of opportunities to control GHG concentrations over the long term. THE LARGER CONTExT FOR TECHNOLOGY Although there are many possible opportunities for limiting GHG emissions, most strategies that the nation could adopt to make large, near-term contributions to reducing emissions center on the deployment of reasonably well-known technologies for energy efficiency and low-carbon energy production.
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From page 88... ...
As explained earlier, even if the existing "high-impact" technologies were to meet their full technical potential, they themselves are not likely to be adequate to meet the stringent demands of the emissions budgets discussed in Chapter 2. Our current energy system is largely based on R&D that was done two or more decades ago.
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From page 89... ...
In either case, realizing the full potential of known and developing technologies will require reducing many existing barriers to deployment; therefore, it is likely these technologies will fall short of their technical potential. This underscores the crucial need to strongly support R&D aimed at bringing new technological options into the mix (discussed further in Chapters 4 and 5)
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