The U.S. Environmental Protection Agency (EPA) released its draft 2018 Greenhouse Gas Inventory (GHGI) this week, and this latest data show that oil and natural gas system methane emissions declined from 2015 to 2016, continuing a downward trend since 1990 that has come at the same time production has skyrocketed.
The new EPA data show methane emissions from natural gas systems declined 1.5 percent from 2015 levels in 2016, while petroleum system emissions were down 100,000 metric tons CO2 equivalent in 2016 from 2015 levels.
The EPA report also notes that oil and gas methane emissions have declined a total of 31.6 million metric tons CO2 equivalent since 1990. This 14.7 percent decline has come at the same time natural gas production has increased 50 percent and oil production has increased 21 percent.
The following excerpt from the report provides more details on the emission declines that have occurred over the past 26 years:
“Methane emissions from natural gas systems and petroleum systems (combined here) decreased from 236.0 MMT CO2 Eq. in 1990 to 201.4 MMT CO2 Eq. in 2016 (34.7 MMT CO2 Eq. or 14.7 percent decrease from 1990 to 2016). Natural gas systems CH4 emissions decreased by 31.6 MMT CO2 Eq. (16.3 percent) since 1990, largely due to a decrease in emissions from distribution, transmission and storage, processing, and exploration…
“Petroleum systems CH4 emissions decreased by 3.0 MMT CO2 Eq. (or 7.2 percent) since 1990. This decrease is due primarily to decreases in tank emissions and associated gas venting…”
The latter is particularly noteworthy considering the Bureau of Land Management’s controversial venting and flaring rule remains hotly debated. BLM recently suspended key components of the rule until 2019.
The new draft EPA GHGI notes that methane emissions from venting and flaring decreased by 40 percent from 2015 to 2016, further confirming that such emissions are plummeting. Prior to the release of this 2016 data, EPA reported last year that venting and flaring methane emissions declined 77 percent from 2011 to 2015. This year’s inventory shows that venting and flaring methane emissions fell 53 percent from 2012 to 2016, as the following chart from the report illustrates.
EPA has also revised its methodology for calculating venting and flaring emissions this year, resulting in drastically reduced emission revisions from 1990 to 2013. The EPA report explains,
“The CH4 emissions estimate decrease was primarily due to recalculations related to associated gas venting and flaring which were updated to use a basin-level approach, and has the largest impact on years prior to 2013.”
To illustrate what the EPA explains above, notice the highlighted area in the below chart taken from the 2017 EPA GHGI inventory. Last year, 2012 venting and flaring emissions were reported at 14.7 mmt CO2 eq. As the above chart taken from this year’s GHGI shows, 2012 venting and flaring emissions were revised down to 3.4 mmt, a 77 percent decrease.
Similar revisions were made dating all the way back to 1990, and EPA explains that the revisions resulted in an “Average decrease of 10.9 MMT CO2 Eq. relative to the previous Inventory, resulting primarily from recalculation of associated gas venting and flaring emissions using a basin-level approach.”
The draft GHGI also shows that overall U.S greenhouse emissions continued to fall in 2016 as well.
EPA data show that overall GHG emissions fell two percent from 2015 to 2016 and are at their lowest levels since 1993. Overall carbon dioxide emissions also decreased two percent from 2015 to 2016 and are now 13 percent below 2005 levels. EPA rightly gives increased natural gas use for electricity generation major credit for these reductions:
“The decrease in total greenhouse gas emissions between 2015 and 2016 was driven in large part by a decrease in CO2 emissions from fossil fuel combustion. The decrease in CO2 emissions from fossil fuel combustion was a result of multiple factors, including:
- substitution from coal to natural gas and other sources in the electric power sector; and
- warmer winter conditions in 2016 resulting in a decreased demand for heating fuel in the residential and commercial sectors.
“Recently, a decrease in the carbon intensity of the mix of fuels consumed to generate electricity has occurred due to a decrease in coal consumption, increased natural gas consumption, and increased reliance on non-fossil generation sources. Including all electricity generation modes, electric power sector generators used natural gas for approximately 34 percent of their total energy requirements in 2016.”
The chart below shows how natural gas’ share of the electricity generation mix has grown in concert with the observed CO2 reductions.
Echoing this EPA data, the Energy Information Administration has acknowledged natural gas has prevented over two billion metric tons of carbon dioxide from being emitted since 2005. EIA has also credited increased natural gas use for almost two-thirds of the energy-related carbon reductions the U.S. has achieved since 2005.
The EPA’s most recent draft GHGI is just the latest evidence of how increased natural gas use has allowed the U.S. to achieve significant greenhouse gas reductions while growing the economy — an unprecedented decoupling trend that can be traced directly to fracking.