315
As already noted, nearly half of energy-related emissions and approximately
35% of total anthropogenic GHG emissions are related to the extraction, movement,
conversion, storage of energy to end-users—the supply side of energy systems.
Fortunately,
Multiple options exist to reduce energy supply sector GHG emissions (robust evidence,
high agreement). These include energy efficiency improvements and fugitive emission
reductions in fuel extraction as well as in energy conversion, transmission, and distribution
systems; fossil fuel switching; and low-GHG energy supply technologies such as renewable
energy (RE), nuclear power, and carbon dioxide capture and storage (CCS).
Challenges to reducing and decarbonizing energy use also exist in the transportation, industry, commercial, residential, and agricultural sectors. Each sector has distinct characteristics that shape possible pathways to decarbonization.
The commercial and residential sectors, for example, account for about one-third
of energy use and 19% of GHG emissions. Energy use in these sectors is primarily
related to buildings and the energy services delivered inside them. Electricity provides the largest share of energy used in buildings for heating and cooling space,
heating of water, refrigeration of food, lighting, and the powering of a host of
machines and devises. Thus, on the demand side, there are many pathways to
increase the efficiency of obtaining energy services. On the supply side, since electricity can be produced from many energy sources, there are also additional pathways with allowing for competition and trade-offs between technologies, especially
renewable (low- and non-carbon) energy sources.
Renewable energy sources include a wide array of technologies, including
hydropower, solid biomass, liquid biofuels, biogas (methane from renewable
sources), wind, solar, and geothermal technologies.
Infrastructure and integration challenges vary by RE technology and the characteristics of
the existing background energy system (medium evidence, medium agreement). Operating
experience and studies of medium to high penetrations of RE indicate that these issues can
be managed with various technical and institutional tools. As RE penetrations increase,
such issues are more challenging, must be carefully considered in energy supply planning
and operations to ensure reliable energy supply, and may result in higher costs.
In contrast, over 90% of energy use in the transportation sector is from petroleumbased fuels. Therefore, the pathways to the decarbonization of transportation are
significantly fewer than in buildings. Demand-side strategies include vehicle efficiency, alternatives to travel, alternative modes of transportation. Supply-side strategies include the use of biofuels and natural gas, and emerging electric vehicles.
Electric vehicles represent the most significant alternative transportation energy
option because it opens up the various pathways and options associated with the
electricity sector.
Various policies that advance low carbon energy sources have different attributes
that make them more or less effective in different contexts.
Greenhouse gas emission trading and GHG taxes have been enacted to address the market
externalities associated with GHG emissions (high evidence, high agreement). In the longer
term, GHG pricing can support the adoption of low-GHG energy technologies due to the
resulting fuel- and technology-dependent markup in marginal costs. Technology policies
(e.g., feed-in tariffs, quotas, and tendering/bidding) have proven successful in increasing
the share of RE technologies (medium evidence, medium agreement).
11 Climate Change
As already noted, nearly half of energy-related emissions and approximately
35% of total anthropogenic GHG emissions are related to the extraction, movement,
conversion, storage of energy to end-users—the supply side of energy systems.
Fortunately,
Multiple options exist to reduce energy supply sector GHG emissions (robust evidence,
high agreement). These include energy efficiency improvements and fugitive emission
reductions in fuel extraction as well as in energy conversion, transmission, and distribution
systems; fossil fuel switching; and low-GHG energy supply technologies such as renewable
energy (RE), nuclear power, and carbon dioxide capture and storage (CCS).
Challenges to reducing and decarbonizing energy use also exist in the transportation, industry, commercial, residential, and agricultural sectors. Each sector has distinct characteristics that shape possible pathways to decarbonization.
The commercial and residential sectors, for example, account for about one-third
of energy use and 19% of GHG emissions. Energy use in these sectors is primarily
related to buildings and the energy services delivered inside them. Electricity provides the largest share of energy used in buildings for heating and cooling space,
heating of water, refrigeration of food, lighting, and the powering of a host of
machines and devises. Thus, on the demand side, there are many pathways to
increase the efficiency of obtaining energy services. On the supply side, since electricity can be produced from many energy sources, there are also additional pathways with allowing for competition and trade-offs between technologies, especially
renewable (low- and non-carbon) energy sources.
Renewable energy sources include a wide array of technologies, including
hydropower, solid biomass, liquid biofuels, biogas (methane from renewable
sources), wind, solar, and geothermal technologies.
Infrastructure and integration challenges vary by RE technology and the characteristics of
the existing background energy system (medium evidence, medium agreement). Operating
experience and studies of medium to high penetrations of RE indicate that these issues can
be managed with various technical and institutional tools. As RE penetrations increase,
such issues are more challenging, must be carefully considered in energy supply planning
and operations to ensure reliable energy supply, and may result in higher costs.
In contrast, over 90% of energy use in the transportation sector is from petroleumbased fuels. Therefore, the pathways to the decarbonization of transportation are
significantly fewer than in buildings. Demand-side strategies include vehicle efficiency, alternatives to travel, alternative modes of transportation. Supply-side strategies include the use of biofuels and natural gas, and emerging electric vehicles.
Electric vehicles represent the most significant alternative transportation energy
option because it opens up the various pathways and options associated with the
electricity sector.
Various policies that advance low carbon energy sources have different attributes
that make them more or less effective in different contexts.
Greenhouse gas emission trading and GHG taxes have been enacted to address the market
externalities associated with GHG emissions (high evidence, high agreement). In the longer
term, GHG pricing can support the adoption of low-GHG energy technologies due to the
resulting fuel- and technology-dependent markup in marginal costs. Technology policies
(e.g., feed-in tariffs, quotas, and tendering/bidding) have proven successful in increasing
the share of RE technologies (medium evidence, medium agreement).
11 Climate Change