Natural gas is one of the most hotly
debated fuels of recent time. It's proponents laud its clean-burning
low carbon nature and its cheap extraction and transport cost, and
it's environmentalist detractors claim significant damage from
natural gas extraction, and often have a general (not necessarily
unfounded) dislike of fossil fuels. Both sides go back and forth with
exposing “The Truth” (with a capital T) of natural gas, as
displayed by the diametrically opposed documentaries GasLand and FrackNation. As a large part of Obama's plan to cut carbon emissions, however, natural gas is worth a second look.
Natural Gas: Controversial Growth
Plant McDonough-Atkinson, a coal power plant recently retrofitted to burn natural gas
It's allies call it a “bridge fuel”, able to reduce CO2 emissions before renewables take over to dominate the energy sector. And as coal has slowly declined, natural gas has been expanding rapidly in the energy sector to fill that gap.
Natural Gas Electrical Generation
Data From the EIA.
From 1990 to 2012, natural gas
electrical grid generation has increased over 325%. And much of this
expansion has been in just the last few years- wondering why?
There are two major factors to natural
gas expansion, and the first is the mounting distrust of coal power.
Coal generation is the most carbon dioxide heavy form of
electricity generation in the US, according to the Intergovernmental
Panel on Climate Change (IPCC), so, there's reason to distrust it. As
worry over climate change and the environment mounts, coal is the
primary target of emission reduction campaigns- often in the form of
direct protests. As coal meets resistance, power companies
are looking for alternatives- and natural gas clocks in significantly
cheaper than most renewable technologies. Further, coal power plants
can be retrofitted to burn natural gas, which is considerably cheaper
than building a brand-new power plant. In fact, the act of replacing
coal with natural gas is common enough to have its own term: “fuel
switching”. This resistance to coal has actually impacted it greatly in the last 5 years, as annual coal-fired electricity generation in the US declined 24.76%. That's incredibly substantial for our largest generator.
The second major reason is a new stability in the costs
of natural gas. As conventional gas wells began to slow in their
production in the 1990s, natural gas prices experienced extreme
volatility.
Wellhead Price of Natural Gas Produced in the US
Data from the EIA
First things first, lets look at the chemistry. When it comes to carbon dioxide emissions, fossil fuels are far from being created equal. Coal is composed mainly of elemental carbon- atomically the same as diamond, but in a different form (the cost of diamonds isn't the only thing keeping your utility company from burning them for electricity). But lets look at the combustion:
Costs in the 1980s were rising, but
smoothly- and as natural gas demand slowly increased and well
production became more irregular, gas prices began to pinwheel
drastically. Seriously- if this chart were a roller coaster, the
passengers would be dead. But, after peaking in 2008, technology helped to pull down gas prices. Horizontal drilling
techniques and hydraulic fracturing allowed new access to gas trapped in
dense shale deposits that were previously considered impossible to
extract economically. This has brought a little more stability to the
market, and inspired trust.
Ironically, this new drilling is what
has triggered much of the resistance to natural gas- there's
significant public fear over hydraulic fracturing and environmental
concerns. And as natural gas drilling has begun to slowly drift into
the Liberal North, the Liberal North has struck back. These fears
aren't totally unfounded- but when natural gas is discounted out of
hand by environmentalists, I tend to hesitate- I want to take a
second look.
The Bridge Fuel
First things first, lets look at the chemistry. When it comes to carbon dioxide emissions, fossil fuels are far from being created equal. Coal is composed mainly of elemental carbon- atomically the same as diamond, but in a different form (the cost of diamonds isn't the only thing keeping your utility company from burning them for electricity). But lets look at the combustion:
Combustion of Coal
It's a suprisingly simple reaction. The
conversion of carbon towards carbon dioxide generates heat, which is
converted to electrical power. The important thing to remember here
is that the generation of CO2 is the only factor producing energy.
It's the only exothermic- heat generating- reaction.
Natural gas is a little different- it's
commonly called methane, and consists of a carbon atom bonded to four
hydrogen atoms- CH4. And these hydrogens make the combustion a little
more complex.
Combustion of Natural Gas
You'll note that in addition to the
carbon being converted to CO2, the hydrogen is converted to water-
and that reaction also produces energy. This means that in the
combustion of natural gas, for the same amount of carbon dioxide,
you're generating even more electricity- with the balance only
producing water vapor.
How much more? In 2011, the Intergovernmental
Panel on Climate Change (IPCC) did a literature review of over 900
estimates of lifecycle CO2 equivalent emissions approximations for common
electric sources, and came up with this chart:
Carbon Emissions from Different Generation Sources
Data from the IPCC
In grams of carbon dioxide equivalent per kWh of generation
In grams of carbon dioxide equivalent per kWh of generation
Coal produces somewhere near twice the
carbon dioxide as natural gas for the same amount of energy. Now, you
probably noticed that even hydro and wind power seem to be producing
CO2- and that's because this is a lifecycle analysis, including the
carbon produced by extraction of fuels, transporting of goods, and
construction. You're still moving those wind turbine blades down the
highway with a diesel truck before the turbine is built- so there's carbon
there. In the case of these renewable technologies, the carbon
released in the set-up is generally averaged out over
the lifetime of the technology. Life-cycle analyses are great ways to
get an idea of the technology with no hidden costs.
So where are we- sure, natural gas is
better than coal, but, wind is still much better than natural gas, from a climate perspective. So
lets take these numbers a little further. Let's look at the 50th
percentile values- those will probably be closest to the most
accurate number.
Since 2007, coal power has declined. But not only has it declined, it's been replaced- other technologies are expanding to fill that gap. From 2007 to 2012, you can see the changes in generated power from some new technologies:
And from the above chart, we can see
that natural gas has displaced more coal generation than wind- 553,104 thousand MWh of coal generation to wind
power's 311,917 thousand MWh over the last five years. Now of course, if that natural gas development had simply been more wind power, than we would be even better off then we are now- but this is where economics get in the way. Our electrical grid is set up for steady, baseload power, and existing infrastructure makes gas cheap and wind more expensive. The cost of wind and the needed upgrades to the electrical grid to make wind effective limit it's growth. So, if that natural gas generation had never occurred, then it's likely that it would still be coal.
If we assume that all of these technologies are displacing emissions from coal, we can calculate their contribution to reducing greenhouse gas emissions. Firstly, we can determine from the differences in emissions, every thousand MWh of natural gas avoids 536 metric tons of CO2, and every thousand MWh of wind avoids 989 metric tons of CO2- showing, as we know, that each wind development has a larger impact than a gas development of a similar size. And this means, that for natural gas:
~327 million metric tons of CO2 were avoided, and for wind
~340 million metric tons of CO2 were avoided.
If you extrapolate this to all of the other technologies that grew from 2007 to 2012, you can determine which ones had a role in the US decline of coal and the decline of carbon emissions:
And we can see that natural gas has a much greater impact on reducing carbon emissions than wind or even hydropower. And there's another surprise: nuclear electric power prevents more carbon dioxide emissions than any other technology, and the US has not built new nuclear capacity since the early 1980s. It's not inconceivable to think that if nuclear had continued to be built at the same rate as in the late 1960s, coal would already be a thing of the past.
There's a new problem, however, with natural gas's place as a top carbon reducer- recent research seems to indicate that natural gas fracking, which is rapidly expanding, has a larger carbon footprint than conventional drilling, due to excessive gas leakage. Methane is a more potent short-term greenhouse gas than carbon dioxide. As the IPCC report that the carbon numbers are based on was published in 2011, it's unclear how much of this is reflected in the analysis here. While it's doubtful that this will make it dirtier than coal, it could seriously hamper the benefits of fuel switching.
Sources:
http://www.eia.gov/naturalgas/
http://www.forbes.com/sites/greatspeculations/2011/03/07/dont-be-swayed-by-faucets-on-fire-and-other-anti-fracking-propaganda/
http://www.sciencemag.org/content/341/6142/164.abstract
http://www.naturalgas.org/environment/technology.asp
http://www.eia.gov/dnav/ng/ng_pri_sum_dcu_nus_m.htm
http://www.eecworld.com/component/content/article/73-latest-news/258-a-brief-history-of-hydraulic-fracturing
http://www.energyfromshale.org/
http://hotair.com/archives/2013/06/20/my-my-epa-declines-to-confirm-a-connection-between-fracking-and-groundwater-pollution-in-wyoming/
http://america.aljazeera.com/content/ajam/articles/2013/8/19/ohio-earthquakestriggeredbyfracking.html
http://www.dailykos.com/story/2013/08/07/1229636/-NOAA-Investigation-Finds-Massive-Methane-Emissions-from-Utah-Fracking-6-to-12-Lost-to-Atmosphere#
If we assume that all of these technologies are displacing emissions from coal, we can calculate their contribution to reducing greenhouse gas emissions. Firstly, we can determine from the differences in emissions, every thousand MWh of natural gas avoids 536 metric tons of CO2, and every thousand MWh of wind avoids 989 metric tons of CO2- showing, as we know, that each wind development has a larger impact than a gas development of a similar size. And this means, that for natural gas:
~327 million metric tons of CO2 were avoided, and for wind
~340 million metric tons of CO2 were avoided.
If you extrapolate this to all of the other technologies that grew from 2007 to 2012, you can determine which ones had a role in the US decline of coal and the decline of carbon emissions:
Wind just barely edges out natural gas
in preventing coal emissions, but they are almost indistinguishable.
This is important- it means that natural gas is just as effective
as wind at reducing carbon dioxide emissions. Environmentalists shouldn't reject natural gas as a fuel if it has
prevented the same amount of new coal carbon emissions as wind. Of course, each little bit of wind generation is does reduce more carbon than the equivalent in natural gas- but we have too give gas credit for reducing a significant portion of US carbon emissions in the last five years.
If we want to
expand this argument, we can also say that all current non-coal electricity
generation is displacing emissions from coal, ignoring their changes in the last five years. The math is similar to what was above, but we'll
only use the data from 2012: multiply the 2012 net generation from each
technology by the amount of CO2 emissions avoided by not using coal to generate that electricity. This gives us a picture of which technologies are having the largest impacts in preventing CO2 emissions.
And we can see that natural gas has a much greater impact on reducing carbon emissions than wind or even hydropower. And there's another surprise: nuclear electric power prevents more carbon dioxide emissions than any other technology, and the US has not built new nuclear capacity since the early 1980s. It's not inconceivable to think that if nuclear had continued to be built at the same rate as in the late 1960s, coal would already be a thing of the past.
The Catch:
There's a new problem, however, with natural gas's place as a top carbon reducer- recent research seems to indicate that natural gas fracking, which is rapidly expanding, has a larger carbon footprint than conventional drilling, due to excessive gas leakage. Methane is a more potent short-term greenhouse gas than carbon dioxide. As the IPCC report that the carbon numbers are based on was published in 2011, it's unclear how much of this is reflected in the analysis here. While it's doubtful that this will make it dirtier than coal, it could seriously hamper the benefits of fuel switching.
Further, natural gas will never be a cleaner source of energy than renewables, with the possible exception a large scale adoption of carbon capture and sequestration- eventually, we'll be in a position where we need to reduce natural gas in favor of renewables. Additionally, there are many claims that hydraulic fracturing has an increased risk of environmental contamination, although confirmed cases of drilling related contamination are rare. Finally, there is evidence that in rare cases hydraulic fracturing can trigger mild earthquakes. And on the nuclear front, there's a very good reason why development stalled in the 1980s- in the wake of the Chernobyl Disaster, it's impossible to pretend that the dangers of nuclear power are unimportant.
But, these problems just indicate that more research should be done, and harsher regulations should seek to eliminate risk. Hydraulic fracturing is newly widespread, which means there should be opportunities to refine the process and eliminate accidents. Fugitive emissions can be captured and put to use if enough attention is paid. There is no reason to not support the growth of natural gas, alongside supporting new safety and environmental regulations, in the fight to reduce greenhouse gasses. With more regulation ensuring stronger well walls and better control of fugitive emissions, natural gas is a significant step from coal. Dismissing it as “just another fossil fuel” is neglecting one of the country's most powerful weapons against carbon dioxide emissions.
But, these problems just indicate that more research should be done, and harsher regulations should seek to eliminate risk. Hydraulic fracturing is newly widespread, which means there should be opportunities to refine the process and eliminate accidents. Fugitive emissions can be captured and put to use if enough attention is paid. There is no reason to not support the growth of natural gas, alongside supporting new safety and environmental regulations, in the fight to reduce greenhouse gasses. With more regulation ensuring stronger well walls and better control of fugitive emissions, natural gas is a significant step from coal. Dismissing it as “just another fossil fuel” is neglecting one of the country's most powerful weapons against carbon dioxide emissions.
Sources:
http://www.eia.gov/naturalgas/
http://www.forbes.com/sites/greatspeculations/2011/03/07/dont-be-swayed-by-faucets-on-fire-and-other-anti-fracking-propaganda/
http://www.sciencemag.org/content/341/6142/164.abstract
http://www.naturalgas.org/environment/technology.asp
http://www.eia.gov/dnav/ng/ng_pri_sum_dcu_nus_m.htm
http://www.eecworld.com/component/content/article/73-latest-news/258-a-brief-history-of-hydraulic-fracturing
http://www.energyfromshale.org/
http://hotair.com/archives/2013/06/20/my-my-epa-declines-to-confirm-a-connection-between-fracking-and-groundwater-pollution-in-wyoming/
http://america.aljazeera.com/content/ajam/articles/2013/8/19/ohio-earthquakestriggeredbyfracking.html
http://www.dailykos.com/story/2013/08/07/1229636/-NOAA-Investigation-Finds-Massive-Methane-Emissions-from-Utah-Fracking-6-to-12-Lost-to-Atmosphere#
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