314
3. Aggregate energy intensity
4. GHG intensity of energy
The first two terms of the Kaya Identity bring into focus issues central to human
development that were explored in Chap. 3.
The third term of the Kaya Identity, the aggregate energy intensity is a commonly
cited metric for energy efficiency. However, aggregate energy intensity encompasses all uses of energy regardless of their relationship to GDP. For example, residential energy use and personal driving do not measurably add to GDP but are
significant components of the energy intensity numerator. Further, certain types of
energy use are susceptible to “offshoring” where a product or service consumes
energy in another country before being imported and contributing to the economy.
Finally, economies change their structure over time in ways they affect energy use
but do not reflect changes in energy efficiency. Decomposing energy use reduces
some problems associated with the use of aggregate energy intensity into components that can be studied separately for insights into differences in the use of energy
in different parts of an economy before being re-aggregated.
The fourth term in the Kaya identity, the carbon intensity of energy, is again
a metric that aggregates all forms of energy. Decomposition of energy sources
provides a clearer understanding of the climate impacts of different energy
sources.
The utility of metrics like energy and carbon intensity, and broad formulations
like the Kaya Identity, are highest when applied narrowly with carefully chosen
boundaries, and with discrete (i.e., separate) understandings of each component
within an area of study. These issues with be explored further in Chap. 12.
The first three terms of the Kaya Identity also highlight the demand side of
energy use, while the final term highlights the supply side as it related to climate
change. Reductions in energy use through conservation and greater efficiency complement efforts to decarbonize energy supply. The energy-related demands of food
and water systems are significant and highlight the win-win solutions that can arise
from nexus thinking.
For example, during the California drought described above, water efficiency
policies enacted on utilities and end-users resulted in significant energy savings and
reductions in GHG emissions (Spang et al. 2018).
In a world of over seven billion people seeking to live materially prosperous
lives, reduced consumption alone will not reduce GHG emissions sufficiently to
avoid major adverse impacts from climate change. IPPC’s Fifth Assessment Report
(AR5) makes clear that
The stabilization of GHG concentrations at low levels requires a fundamental transformation of the energy supply system, including the long-term substitution of unabated fossil
fuel conversion technologies by low-GHG alternatives (robust evidence, high agreement).
Concentrations of CO 2 in the atmosphere can only be stabilized if global (net) CO 2
emissions peak and decline toward zero in the long term. Improving the energy efficiencies
of fossil power plants and/or the shift from coal to gas will not by itself be sufficient to
achieve this. Low-GHG energy supply technologies are found to be necessary if this goal is
to be achieved.
P. Saundry
3. Aggregate energy intensity
4. GHG intensity of energy
The first two terms of the Kaya Identity bring into focus issues central to human
development that were explored in Chap. 3.
The third term of the Kaya Identity, the aggregate energy intensity is a commonly
cited metric for energy efficiency. However, aggregate energy intensity encompasses all uses of energy regardless of their relationship to GDP. For example, residential energy use and personal driving do not measurably add to GDP but are
significant components of the energy intensity numerator. Further, certain types of
energy use are susceptible to “offshoring” where a product or service consumes
energy in another country before being imported and contributing to the economy.
Finally, economies change their structure over time in ways they affect energy use
but do not reflect changes in energy efficiency. Decomposing energy use reduces
some problems associated with the use of aggregate energy intensity into components that can be studied separately for insights into differences in the use of energy
in different parts of an economy before being re-aggregated.
The fourth term in the Kaya identity, the carbon intensity of energy, is again
a metric that aggregates all forms of energy. Decomposition of energy sources
provides a clearer understanding of the climate impacts of different energy
sources.
The utility of metrics like energy and carbon intensity, and broad formulations
like the Kaya Identity, are highest when applied narrowly with carefully chosen
boundaries, and with discrete (i.e., separate) understandings of each component
within an area of study. These issues with be explored further in Chap. 12.
The first three terms of the Kaya Identity also highlight the demand side of
energy use, while the final term highlights the supply side as it related to climate
change. Reductions in energy use through conservation and greater efficiency complement efforts to decarbonize energy supply. The energy-related demands of food
and water systems are significant and highlight the win-win solutions that can arise
from nexus thinking.
For example, during the California drought described above, water efficiency
policies enacted on utilities and end-users resulted in significant energy savings and
reductions in GHG emissions (Spang et al. 2018).
In a world of over seven billion people seeking to live materially prosperous
lives, reduced consumption alone will not reduce GHG emissions sufficiently to
avoid major adverse impacts from climate change. IPPC’s Fifth Assessment Report
(AR5) makes clear that
The stabilization of GHG concentrations at low levels requires a fundamental transformation of the energy supply system, including the long-term substitution of unabated fossil
fuel conversion technologies by low-GHG alternatives (robust evidence, high agreement).
Concentrations of CO 2 in the atmosphere can only be stabilized if global (net) CO 2
emissions peak and decline toward zero in the long term. Improving the energy efficiencies
of fossil power plants and/or the shift from coal to gas will not by itself be sufficient to
achieve this. Low-GHG energy supply technologies are found to be necessary if this goal is
to be achieved.
P. Saundry