U.S. Energy-Related Carbon Dioxide Emissions, 2018 November 2019

Independent Statistics & Analysis

www.eia.gov

U.S. Department of Energy

Washington, DC 20585

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U.S. Energy Information Administration | U.S. Energy-Related Carbon Dioxide Emissions, 2018 i

This report was prepared by the U.S. Energy Information Administration (EIA), the statistical and analytical agency within the U.S. Department of Energy. By law, EIA’s data, analyses, and forecasts are independent of approval by any other officer or employee of the United States Government. The views in this report therefore should not be construed as representing those of the U.S. Department of Energy or other federal agencies.

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Table of Contents Introduction .................................................................................................................................................. 3

Overview of CO2 Emissions ......................................................................................................................... 4

U.S. energy-related CO2 emissions increased 2.7% (139 million metric tons) in 2018 ........................ 4

In 2018, U.S. energy‐related CO2 emissions were 222 MMmt higher when compared with the average 2007–2017 trend ....................................................................................................................... 5

Fuels .............................................................................................................................................................. 6

Weather conditions influenced the U.S. energy-related CO2 emissions increase in 2018 .................. 6

End-Use Sectors ............................................................................................................................................ 7

In 2018, CO2 emissions increased in all U.S. end-use sectors ................................................................ 7

U.S. buildings sector energy‐related CO2 emissions increased .............................................................. 8

Natural gas is becoming the dominant source of U.S. industrial CO2 emissions ................................. 9

U.S. transportation sector CO2 emissions continue to increase with the economy .......................... 10

Electricity Generation................................................................................................................................. 11

Non-carbon electricity generation became more prominent than coal or natural gas in 2015 ........ 11

Changing fuel mix has reduced the carbon intensity of U.S. electricity generation .......................... 12

Growth in U.S. wind and solar electricity generation has contributed to a decline in the carbon intensity of U.S. electricity generation ................................................................................................. 13

Future Implications of the 2018 Increase in U.S. CO2 Emissions ............................................................. 14

Further Analysis of Sector Contributions to the 2018 Energy-Related CO2 Emissions Growth in the United States .............................................................................................................................................. 14

Method for Including CO2 Emissions from Electricity Generated Outside the Electric Power Sector .... 15

Terms Used in this Analysis ........................................................................................................................ 16

Methodology Used in this Analysis ............................................................................................................ 17

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Introduction U.S. energy-related carbon dioxide (CO2) emissions increased in 2018. Weather was one driver of this increase: the winter months were colder and the summer months were warmer than in 2017. In addition, U.S. transportation-related emissions continue to rise with gross domestic product (GDP), which has been a trend since 2012.

This analysis examines economic trends and changes in fuel mix that influence energy-related CO2 emissions in the United States. As a result, most of the CO2 emissions being discussed are the result of fossil fuel combustion or their use in the petrochemical and related industries.

In the short term, energy-related CO2 emissions are influenced by factors such as weather, fuel prices, and disruptions in electricity generation.

In the long term, CO2 emissions are influenced by

• Policies to encourage renewable energy • Reduced costs and improved efficiency of new technologies • Demand-side efficiency gains such as vehicle miles per gallon or appliance efficiencies • Economic trends such as the changing profile of U.S. manufacturing industries

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Overview of CO2 Emissions

U.S. energy-related CO2 emissions increased 2.7% (139 million metric tons) in 2018

• Real U.S. gross domestic product (GDP)1 increased 2.9% in 2018, up 0.6% from growth in 2017.

• Energy-related CO2 emissions in the United States increased by 2.7% (139 million metric tons [MMmt]) from 5,130 MMmt in 2017 to 5,269 MMmt in 2018, but they were 730 MMmt (12%) lower than 2005 levels.

• The overall carbon intensity2 (CO2/GDP) of the U.S. economy declined 0.1% in 2018 compared with a 2.9% decline in 2017. This 0.1% decline resulted from a 0.6% increase in energy intensity3 (British thermal units [Btu]/GDP) offset by a 0.8% decline in the carbon intensity (CO2/Btu) of the energy consumed. Increases in weather-related and transportation energy demand were factors in the energy intensity increase.

1 U.S. Bureau of Economic Analysis, Current-Dollar and “real” Gross Domestic Product. U.S. Census Bureau. 2 Carbon intensity definition. 3 Energy intensity definition.

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In 2018, U.S. energy‐related CO2 emissions were 222 MMmt higher when compared with the average 2007–2017 trend

• One way to disaggregate the factors that combine into total U.S. energy-related CO2 emissions is an equation known as the Kaya identity. The Kaya identity relates percentage changes in energy-related CO2 emissions to changes in four factors: energy intensity, per capita GDP, carbon intensity, and population.

• U.S. CO2 emissions for 2018 appear to be 4.4%, or 222 MMmt higher than if components of the Kaya identity (shown in Figure 2) matched their previous decade (2007–2017) trend rates.

• Largely due to weather and transportation demand in 2018, U.S. energy intensity increased by 0.6% compared with a 1.6% average decline in the previous decade, which led to 2018 U.S. CO2 emissions that were 117 MMmt higher than if the trend of the previous decade had continued.

• As a result of relatively strong economic growth, U.S. GDP per capita grew by 2.2% from 2017 to 2018, compared with the previous decade’s average annual growth rate of 0.6%. Higher U.S. GDP per capita growth in 2018 put upward pressure on CO2 emissions, adding about 84 MMmt compared with what the previous decade’s average trend would have predicted.

• In 2018, the carbon intensity of U.S. energy consumption declined by 0.8%, a lower rate than the previous decade’s average annual decline of 1.4%. As a result, 2018 U.S. CO2 emissions were 33 MMmt greater than what they would have been if the previous decade’s trend had continued.

• Slower population growth of 0.6% in the United States, compared with the previous decade’s average of 0.8%, resulted in 12 MMmt lower 2018 CO2 emissions than would have been predicted with the previous decade’s trend.

Sources: U.S. Energy Information Administration, Monthly Energy Review, October 2019, Table 11.1, Carbon Dioxide Emissions from Energy Consumption by Source. U.S. Bureau of Economic Analysis, Current-Dollar and “real” Gross Domestic Product. U.S. Census Bureau, U.S. Population 2018. See details on the Kaya identity. See page 17 for the methodology of this analysis. Note: GDP refers to gross domestic product, and CO2 refers to carbon dioxide.

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Fuels

Weather conditions influenced the U.S. energy-related CO2 emissions increase in 2018

• Energy-related CO2 emissions in the United States increased by 2.7% (139 MMmt) from 5,130 MMmt in 2017 to 5,269 MMmt in 2018. From 2009 to 2018, total energy-related CO2 emissions declined by 2% (123 MMmt).

• U.S. natural gas CO2 emissions increased every year from 2009 to 2016, declined 1.3% (20MMmt) in 2017, and then increased 10.2% (151 MMmt) in 2018. Because natural gas is the primary heating fuel in much of the country, the colder winter temperatures drove greater use of natural gas and a corresponding increase in CO2 in 2018. In addition, the natural gas share of U.S. electricity generation has been growing. The total generation-related natural gas CO2 emissions increased an average of 5.6% per year from 2009 to 2016. Economy-wide, natural gas CO2 emissions surpassed total emissions from coal in 2015. Between 2009 and 2018, natural gas emissions increased 32% (391 MMmt).

• Figure 3 shows that U.S. CO2 emissions from coal declined by 33% (617 MMmt) in 2018 compared with 2009. The graph also shows CO2 emissions from petroleum and other liquids have increased by 5% (102 MMmt) in 2018 compared with 2009 levels.

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End-Use Sectors

In 2018, CO2 emissions increased in all U.S. end-use sectors • Emissions from the residential and commercial sectors in the United States, defined collectively

as the buildings sector, led the growth in emissions at 95 MMmt (5.2%). This growth was mostly the result of colder winter and warmer summer weather in 2018 compared with 2017. U.S. residential sector emissions are more influenced by weather, and they increased by 70 MMmt (7.4%) while commercial sector emissions rose 25 MMmt (2.8%).

• Transportation-related CO2 emissions have been increasing steadily in the United States since 2012 because of a recovering economy and moderate fuel prices. Energy-related CO2 from the U.S. transportation sector increased by 28 MMmt (1.5%) and is now 8% higher than 2012 levels.

• CO2 emissions from the U.S. industrial sector have been declining, but they increased by 16 MMmt (1.1%) in 2018 as a result of a growing economy.

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U.S. buildings sector energy‐related CO2 emissions increased • Buildings accounted for 68% of the increase in total energy-related U.S. CO2 emissions with 50%

coming from the residential sector.

• Building-related CO2 emissions are from the direct consumption of fuels for heating (e.g., natural gas or fuel oil heating equipment) and the indirect burn of fuels (e.g., electricity consumed by the end-use consumer). Although electricity-related CO2 emissions correspond most closely to cooling demand, parts of the country also heat with electricity.

• Figure 5 shows CO2 emissions related to direct use grew by 8.4% and 12.0% in the commercial and residential sectors, respectively, and emissions from the generation of electricity grew by 0.8% and 5.2% in the commercial sector and residential sectors, respectively.

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Natural gas is becoming the dominant source of U.S. industrial CO2 emissions • The U.S. industrial sector's CO2 emissions, which increased by 1.1% (16 MMmt) in 2018,

have remained relatively flat in recent years despite increasing industrial output. Continuing growth in less energy-intensive industrial output was a factor in stabilizing emissions in this sector.

• Industrial natural gas CO2 emissions in the United States have risen every year, except in 2015, since 2009. In 2016, industrial CO2 emissions from natural gas exceeded those from electricity generation. However, increasing use of natural gas has helped reduce overall U.S. CO2 emissions growth because it is the least carbon-intensive of the fossil fuels used in electricity generation.

• Petroleum CO2 emissions in the U.S. industrial sector have been relatively flat in recent years.

• Coal and coke-related industrial CO2 emissions declined by 59% in the United States from 1990 to 2018.

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U.S. transportation sector CO2 emissions continue to increase with the economy • During the period from 1990 to 2007, emissions generally increased in the U.S. transportation

sector, averaging 1.4% per year for a total increase of 430 MMmt. Dominated by increased use of motor gasoline and diesel fuel, this growth period corresponded with a growing U.S. economy and ended with the recession.

• From 2007 to 2012, U.S. transportation sector emissions generally declined because of lower consumption of transportation fuels, driven by rising world oil prices that followed a weak economy. The average annual rate of decline in the United States was 2.5% during the five-year span. All the major fuel types experienced similar rates of decline. By 2012, U.S. transportation sector emissions dropped by 244 MMmt from the 2007 levels.

• After 2012, U.S. transportation sector emissions began to increase slowly but consistently to 1.3%, almost returning to the 1990–2007 average growth rate. This period saw a stronger U.S. economy coupled with decreasing fuel prices.

• From 2017 to 2018, U.S. transportation sector emissions growth came predominantly from diesel fuel, and motor gasoline emissions remained unchanged. Diesel fuel consumption responds more to economic growth than motor gasoline.

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Electricity Generation

Non-carbon electricity generation became more prominent than coal or natural gas in 2015

• The non-carbon electricity generation share of U.S. power generation, including nuclear and renewables, exceeded that of coal and natural gas in 2015 and remained higher through 2018. The increases in natural gas and non-carbon electricity generation helped lower the carbon intensity of U.S. electricity supply in recent years.

• In 2005, 761 billion kilowatthours (BkWh) of natural gas generation produced 349 MMmt of CO2 emissions. Natural gas’s 35% share, or 1,468 BkWh, in 2018 produced 614 MMmt of CO2.

• In 2005, 2,013 BkWh of coal generation produced 2,001 MMmt of CO2 emissions. Coal's 50% share of total U.S. electricity generation in 2005 decreased to 27% in 2018, or 1,146 BkWh, producing 1,156 MMmt of CO2.

• In total, coal and natural gas generation produced 2,350 MMmt of CO2 emissions (0.847 metric tons[mt]/megawatthour[MWh]) in 2005 compared with 1,770 MMmt (0.667 mt/MWh) in 2018.

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Changing fuel mix has reduced the carbon intensity of U.S. electricity generation

• A major factor in recent reductions in the carbon intensity of electric generation in the United States is the reduced generation of electricity using coal at the same time that generation has increased using natural gas, which emits less CO2 for the same amount of electricity generated, and non-carbon generation (including renewables), which emit no CO2.

• Between 2005 and 2018, EIA has calculated that cumulative U.S. CO2 emissions reductions attributable specifically to shifts from coal to natural gas and to non-carbon generation totaled 4,621 MMmt (see methodology on page 18). Of this total, 2,823 MMmt resulted from decreased use of coal and increased use of natural gas. 1,799 MMmt resulted from decreased use of coal and increased use of non-carbon generation sources. Figure 9 shows how the emissions reductions as a result of these factors occurred in each year during the period.

• Between 2005 and 2017, total U.S. electricity generation increased by almost 4% while related CO2 emissions fell by 27%. During that period, fossil fuel electricity generation declined by about 9%, and non-carbon electricity generation rose by 35%.

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Growth in U.S. wind and solar electricity generation has contributed to a decline in the carbon intensity of U.S. electricity generation

• Wind and solar (combined) accounted for about 24% of U.S. non-carbon electricity generation in 2018 and exceeded hydropower for the past three years.

• Historically, hydropower had the largest share of renewable electricity generation in the United States. With the growth of other renewables, its share has declined from 34% in 1997 to 19% in 2018.

• Although nuclear power remains the dominant source of non-carbon electricity generation in the United States, growth in wind and solar generation has contributed to its share decline.

• Other renewables, such as biomass, have remained relatively flat at about a 5%–6% share of U.S. electricity generation since 2001.

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Future Implications of the 2018 Increase in U.S. CO2 Emissions

The 2018 weather conditions that put upward pressure on CO2 emissions in the United States relative to 2017 do not necessarily reflect future trends.

For EIA’s forecasts and projections on U.S. emissions and their key drivers, see the Short-Term Energy Outlook (STEO), with monthly forecasts through 2020, and the Annual Energy Outlook (AEO), with annual projections through 2050. EIA’s International Energy Outlook (IEO) contains projections of international energy consumption and emissions through 2050.

The analysis of energy-related CO2 emissions in the United States presented here is based on data published in the Monthly Energy Review (MER) reports. Monthly U.S. energy-related CO2 emissions are derived from EIA’s monthly energy data. For the full range of EIA's emissions products, see EIA’s Environment analysis.

Further Analysis of Sector Contributions to the 2018 Energy-Related CO2 Emissions Growth in the United States When analyzing year-to-year changes in energy-related CO2 emissions, it is helpful to understand the role different sectors have on the overall change in CO2. A particular sector’s share of the total change in CO2 can be calculated by dividing the change in CO2 emissions for a sector over the total change in CO2 emissions for all sectors. For example, as shown in Figures 4 and 5, the residential sector’s CO2 increase of 70 MMmt in 2018 accounted for about 50% of the total CO2 increase of 139 MMmt in that year.

However, additional analysis on emissions by sector shows how the annual change in CO2 is affected by changes in:

1. Electricity demand levels 2. The fuel mix of electricity generation that determines the carbon intensity of electricity

consumed 3. Primary energy demand levels 4. The fuel mix of primary energy that determines the carbon intensity of primary energy

consumed

Table 1 shows the contribution that each sector made to the total growth in energy-related CO2 for the U.S. economy in 2018. It incorporates the effect that sector changes in the four attributes outlined above have on total changes in CO2. The table includes

• The amount of CO2 resulting from the change in the generation of electricity for residential consumption (Btu) and the amount of CO2 resulting from the change in carbon intensity of that electricity demand (CO2/Btu)

• The amount of CO2 resulting from the change in primary energy consumption (Btu) and the amount of CO2 related to carbon intensities (CO2/Btu) by sector

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• The CO2 changes in each sector based on the sum of the changes for electricity and primary energy consumption

• These sector totals summed equal to the overall change in CO2 emissions from 2017 to 2018

For example, in the residential sector, the 34 MMmt increase in electricity consumed between 2017 and 2018 would have been an increase of 45 MMmt had it not been offset by a decline in carbon intensity of the electricity supply that reduced emissions by 11 MMmt. The actual change in residential primary energy-related CO2 emissions of 36 MMmt is 2 MMmt lower than it would have been if carbon intensity had not declined.

When the CO2 values from electricity and primary energy use are added, the total change for the residential sector equals 70 MMmt. Relatively equal increases in CO2 emissions from electricity and primary energy use in the residential sector indicates that both heating and cooling requirements increased relative to the previous year. Table 1. Sector contributions by electricity and primary energy changes to the total energy-related carbon dioxide emissions change from 2017 to 2018

Method for Including CO2 Emissions from Electricity Generated Outside the Electric Power Sector Not all electricity used in the United States is generated by the electric power sector. In particular, in the commercial and industrial sectors, coal, natural gas, and petroleum are also used onsite to generate power for use onsite. To estimate CO2 emissions from electricity generation for sectors outside of the electric power sector, EIA made additional calculations. Table 2 presents the results of calculations made for this analysis based on MER Table 7.3c, Consumption of Selected Combustible Fuels for Electricity Generation: Commercial and Industrial Sectors (Subset of Table 7.3a). To perform this calculation, EIA used carbon dioxide factors as follows:

• Coal, 95.35 million metric tons per quadrillion Btu for both sectors • Natural gas, 53.07 million metric tons per quadrillion Btu for both sectors

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• Petroleum, 78.8 million metric tons per quadrillion Btu for the commercial sector and 72.62 million metric tons per quadrillion Btu for the industrial sector

EIA made these calculations to account for the changes in the CO2 intensity of electricity generated from all sources during the timeframe presented in Figure 9 of this analysis.

Table 2. CO2 emissions from the generation of electricity in the U.S. commercial and industrial sectors million metric tons of carbon dioxide

CO2 emissions from generation within the

commercial sector CO2 emissions from generation within the

industrial sector

Commercial and industrial CO2 emissions

Coal Natural gas Petroleum Total Coal Natural gas Petroleum Total Total

2005 0.80 1.84 0.25 2.89 15.87 28.25 2.42 46.54 49.43

2006 0.73 1.89 0.14 2.76 15.57 29.23 1.90 46.70 49.46

2007 0.76 1.86 0.11 2.72 10.85 30.18 1.87 42.90 45.63

2008 0.81 1.82 0.07 2.70 10.79 28.35 1.35 40.49 43.19

2009 0.69 1.86 0.08 2.63 9.73 28.28 1.21 39.21 41.85

2010 0.68 2.14 0.07 2.89 16.92 30.15 0.88 47.95 50.84

2011 0.73 2.56 0.06 3.35 11.79 31.00 0.77 43.56 46.91

2012 0.62 3.43 0.11 4.17 9.54 34.46 1.70 45.69 49.86

2013 1.04 3.63 0.13 4.80 9.62 35.03 1.37 46.03 50.83

2014 0.41 3.94 0.18 4.54 9.50 34.18 0.92 44.59 49.13

2015 0.32 3.86 0.10 4.29 8.10 34.40 0.67 43.18 47.46

2016 0.21 2.55 0.05 2.81 6.06 29.42 0.60 36.08 38.90

2017 0.18 2.75 0.08 3.01 5.52 29.76 0.54 35.83 38.84

2018 0.17 2.86 0.11 3.14 5.38 30.38 0.50 36.27 39.41

Sources: U.S. Energy Information Administration, Monthly Energy Review, October 2019, Table 7.3c, Consumption of Selected Combustible Fuels for Electricity Generation: Commercial and Industrial Sectors (Subset of Table 7.3a). Carbon dioxide factors source.

Terms Used in this Analysis British thermal unit(s) (Btu): The quantity of heat required to raise the temperature of 1 pound of liquid water by 1 degree Fahrenheit at the temperature at which water has its greatest density (about 39 degrees Fahrenheit).

Carbon intensity (economy): The amount of carbon by weight emitted per unit of economic activity—most commonly gross domestic product (GDP) (CO2/GDP). The carbon intensity of the economy is the product of the energy intensity of the economy and the carbon intensity of the energy supply. Note: this value is currently expressed as the full weight of the carbon dioxide emitted.

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Carbon intensity (energy supply): The amount of carbon by weight emitted per unit of energy consumed (CO2/energy or CO2/Btu). A common measure of carbon intensity is weight of carbon per Btu of energy. When only one fossil fuel is under consideration, the carbon intensity and the emissions coefficient are identical. When several fuels are under consideration, carbon intensity is based on their combined emissions coefficients weighted by their energy consumption levels. Note: This value is currently measured as the full weight of the carbon dioxide emitted.

Cooling degree days (CDD): A measure of how warm a location is during a period of time relative to a base temperature specified as 65 degrees Fahrenheit. The measure is computed for each day by subtracting the base temperature (65 degrees) from the average of the day's high and low temperatures, and negative values are set equal to zero. Each day's CDD are added to create a CDD measure for a specified reference period. CDD are used in energy analysis as an indicator of air conditioning energy requirements or use.

Energy intensity: A measure relating the output of an activity to the energy input to that activity. Energy intensity is most commonly applied to the economy as a whole, where output is measured as GDP and energy is measured in Btu to allow for the addition of all energy forms (Btu/GDP). On an economy-wide level, energy intensity is reflective of both energy efficiency and the structure of the economy. Economies in the process of industrializing tend to have higher energy intensities than economies in their post-industrial phase. The term energy intensity can also be used on a smaller scale to relate, for example, the amount of energy consumed in buildings to the amount of residential or commercial floorspace.

Gross domestic product (GDP): The total value of goods and services produced by labor and property located in the United States. As long as the labor and property are located in the United States, the supplier (that is, the workers, or, for property, the owners) may be either U.S. residents or residents of foreign countries.

Heating degree days (HDD): A measure of how cold a location is during a period of time relative to a base temperature, most commonly specified as 65 degrees Fahrenheit. The measure is computed for each day by subtracting the average of the day's high and low temperatures from the base temperature (65 degrees), and negative values are set equal to zero. Each day's HDD are added to create an HDD measure for a specified reference period. HDD are used in energy analysis as an indicator of space heating energy requirements or use.

See EIA’s glossary for other definitions.

Methodology Used in this Analysis With the exceptions of Figures 2 and 9 (whose methodologies are described below), the data in this report are either published values in EIA’s Monthly Energy Review (MER) or are calculations based on published values, such as CO2/Btu.

Figure 2. Changes in CO2 emissions attributed to Kaya identity factors from 2017 to 2018 compared with the trend from the previous decade (2007–2017): This figure gives context to the most recent year-to-year change by comparing it with the average change for key parameters during the previous decade. The key parameters are

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• Population • Per capita GDP (GDP/population) • Energy intensity • Carbon intensity of the energy supply (also factors in the Kaya identity)

The changes in these key parameters determine changes in energy-related CO2. By comparing the rate of change for each parameter from 2017 to 2018 with the average rate of change for that parameter for the previous decade, the contribution of each parameter to the overall deviation from trend can be calculated. The table below summarizes the rates of change used in the calculations. The larger the positive value, the greater the increase in energy-related CO2 emissions measured in MMmt. The larger the negative value, the lesser the increase in MMmt of CO2 emissions.

Table 3. Rates of change for 2017–2018 compared with 2007–2017

Sources: Population, U.S. Census Bureau; Carbon intensity, EIA; Per capita GDP, U.S. Bureau of Economic Analysis and U.S. Census Bureau; Energy intensity, EIA.

Figure 9. Electricity generation CO2 savings from changes in the fuel mix since 2005: This figure shows the emissions savings from two factors that have resulted in decreased emissions intensity from 2005 to 2018. The first factor is the shift within fossil fuel generation from coal (and some petroleum) to natural gas. The second factor is the increase in non-carbon electricity generation.

To capture this CO2 savings from the shift to natural gas, the fossil fuel carbon factor (fossil fuel CO2/fossil fuel generation) remains constant at the 2005 level. This factor is then multiplied by the actual fossil fuel generation for subsequent years. The difference between that value and the actual value for fossil fuel-generated CO2 emissions is the savings in that year. For example, the carbon factor in 2005 for fossil fuel generation was 2,465 MMmt divided by 2,896,058 million kilowatthours (kWh) times 103 to yield 0.851 metric tons per megawatthour (mt/MWh). By 2018, the carbon intensity had declined to 0.683 mt/MWh. Multiplying the 2005 carbon factor (0.851) by the 2018 level of fossil generation (2,638,977) yields 2,246 million metric tons (MMmt) of CO2, versus the actual value of 1,802 MMmt. Therefore, the savings from the shift to natural gas from coal and petroleum are estimated to have been 2,246 MMmt minus 1,802 MMmt, or 444 MMmt of CO2, in 2018.

Because non-carbon generation (the second factor) has a zero-carbon factor for direct emissions, the overall reduction in total carbon intensity was applied to total generation, i.e., multiplying total generation in 2018 (4,207,353 million kWh) by the 2005 value of 0.608 mt/MWh for total generation. The savings in fossil fuel generation was subtracted from the total, and the difference was credited to

Parameter

Previous decade (2007–2017) annual percentage change

2017–2018 percentage change

Population +0.8 +0.6

Carbon intensity (CO2/Btu) -1.4 -0.8

Per capita GDP (GDP/population)

+0.6 +2.2

Energy intensity (Btu/GDP) -1.6 +0.6

Change in energy CO2 -1.5 +2.7

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non-carbon electricity generation. For example, the total savings in 2018 was 755 MMmt, so the amount allocated to non-carbon generation (755 MMmt minus 444 MMmt) equals 311 MMmt of CO2.

Table 4. Factors used to estimate CO2 savings from the shift to natural gas and the increase in non-carbon electricity generation since 2005

2005 2018

Data from the Monthly Energy Review

Carbon dioxide from electricity generation all sectors

(MMmt CO2)

2,465 1,802

Fossil fuel electricity generation from all sectors (million kWh) 2,896,058 2,638,977

Total electricity generation from all sectors (million kWh) 4,055,766 4,207,353

Calculations made for this analysis

Carbon dioxide intensity for fossil fuel generation for all sectors

(mt/MWh)

0.851 0.683

Carbon dioxide intensity for total generation for all sectors

(mt/MWh)

0.608 0.428

Counter-factual using 2005 carbon factors

Counter-factual 2018 fossil-fuel generation with 2005 carbon

factor (million kWh)

2,246

Counter-factual 2018 total generation with 2005 carbon factor

(million kWh)

2,557

Calculated savings comparing actual to counter-factual CO2 emissions

Savings with actual (MMmt CO2)

444

Savings with actual—total generation minus fossil generation equals non-carbon davings (MMmt CO2)

311

Savings with actual from total generation (MMmt CO2) 755