Natural Gas

  • Natural gas is primarily methane. It is naturally colorless and odorless, and highly combustible FERC, 5
  • 21.3% of American electrical energy production is natural gas as of 2010, 20.8% expected in 2035; nearly 95% of new generation installed 2000-2010 was natural gas EEI, 38
  • Natural gas is used across sectors: Natural gas use by sector (graph)
  • Electricity generation is the primary use of natural gas (since 2007) FERC, 8
  • As of 2014, unconventional gas makes up 2/3 of American natural gas recovery FERC, 14

Controversy

Natural gas is typically harvested in environmentally destructive processes. Like other fossil fuels, burning it causes GHG emissions – less CO2/Watt than coal, but more methane/Watt.

The key argument in its favor is that it's so economically viable to extract & burn it for power that its rise is currently causing the shutdown of coal mines and coal plants– thus transitioning us from a highly CO2-emissive power source to a highly CH4-emissive power source.

Methane gas is a more powerful GHG than CO2, but its effects are much shorter-lived, precipitating out of the atmosphere in a decade rather than hundreds of years.

Detractors assert that we can't afford to increase our methane emissions, because even a decades-long timescale for the high warming effects is too long for our current climate. However, there isn't another option that's currently available on the economic timescales we need to transition off of coal. (Ideally, we'd have strong investment in solar/wind, but production capacity will take some time to ramp up– and it would have to be a huge investment. While solar/wind are economically positive, they're nowhere near as economically attractive as natural gas.)

I have an article that goes into more detail on what to expect for natural gas based on the EIA's 2016 report– read it on Medium.

Natural gas as a transition fuel

  • Natural gas is so cheap that it's causing coal plants to close/switching American power generation away from coal EIA, 112
  • Methane emissions are highly warming, but they persist in the atmosphere only about 12 years, compared to 20-200 years for CO2 Clark
  • Government publications including FERC (2015) frequently tout natural gas as environmentally friendly FERC, 8

Climate change problems caused by natural gas

  • Natural gas has been argued for as a "clean alternative" to oil, but fracked natural gas may emit enough methane to make it comparable in "dirtiness" to coal Klein, 192
  • Methane has a warming potential 86 times greater than carbon dioxide Klein, 130 // According to the EPA it's 28-36x greater, not 86x- but GWP calculations are not standard so perhaps Klein is using a shorter timescale (EPA's is 100 years)
  • Modern fracking takes 70-300x the amount of fluid (usually water + sand) used in traditional fracking. This fluid often becomes toxic, radioactive waste. 280 billions of this waste were created from fracking in 2012. Klein, 312 //How does it get to be radioactive? Is this true?

Mechanics of natural gas

  • Expected U.S. natural gas extraction methods: screen shot 2016-12-08 at 3 40 33 pm EIA, 119
  • Fracking (hydraulic fracturing): Water is shot into the shale layer through a drilled hole. When water pressure exceeds the weight of the rock above it, the rock cracks to let the water expand. This lets gases (adsorbed into rock) escape. When water pressure is released, it spurts from the ground along with the released gas. Muller, 93
  • Compressed natural gas (CNG) is compressible to 250 atm and can be carried in steel or fiber composite tanks. At this level, CNG is 1/3 the energy density of gasoline (11kwh/g), 10x the energy density of li-ion, 4x the energy density of hydrogen at the same pressure, and 2/5 cost of gasoline Muller, 261

Natural gas delivery

  • Much like electricity, natural gas is considered a necessity for homes and businesses, so supply has to be set up to exactly match demand in real time FERC, 2
  • Natural gas uses storage sites close to sites and linepack to ensure capacity to meet demand FERC, 2
  • Natural gas flows through a pipeline at an average of 25mph, making storage near use sites particularly valuable FERC, 2
  • United States natural gas storage is primarily underground, specifically in depleted basins– so it can use the same infrastructure as when the basin was producing FERC, 29
  • Key characteristics of natural gas storage: deliverability rate (rate at which inventory can be withdrawn), cycling capacity (ability of a facility to quickly allow injections and withdrawals– salt caverns are notably good for this) FERC, 28
  • Natural gas storage requires a quantity of base gas, above which working gas can be used for delivery FERC, 29
  • Natural gas is typically stockpiled April–Oct to support increased winter loads (not typical in electricity storage) FERC, 30

Natural gas market mechanics

  • A natural gas hub can occur at the intersection of natural gas pipelines where natural gas is bought and sold. In the United States, the Henry Hub in Louisiana is used as a benchmark FERC, 6
  • Natural gas is traded on a cash market (daily sales for immediate delivery) and on a forward market (contracts for delivery in a month or more) FERC, 6
  • Natural gas pricing is inelastic; consumers don't typically have alternatives, so they buy natural gas regardless of its price– which implies a potential for price spikes in periods of short supply FERC, 8
  • Typically, natural gas demand is relatively constant in the industrial sector and more variable in the residential sector. In part due to this (and the expense of building for peak capacity), residential prices for natural gas tend to be higher than industrial FERC, 8

Economic future of natural gas

  • Both demand (including export) and supply (improved technology and lots of deposits) are expected to increase in the United States over the 2015-2040 period. This should keep natural gas prices stable & low over that time period EIA, 21
  • The vast majority of new gas projects in North America rely on fracking Klein, 192
  • Rising natural gas production makes byproduct fuels like HGL and NGPL more economically viable EIA, 83
  • Natural gas production from tight and shale gas formations increased 23% from 2010 to 2015 in the United States. This is a shift from traditional dry natural gas (which still dominates) to wet EIA, 83
  • Wet natural gas is slower to profit than dry natural gas (it requires processing into dry before it can be put in pipelines, and the formations have low initial yields) but the NGPL output can make it more profitable in the long run EIA, 86
  • "Because NGPL is produced during the processing of natural gas, either from natural gas wells or from gas associated with crude oil production, NGPL production levels are largely driven by the development of these resources. The revenue associated from extracting NGPL streams, such as ethane, propane, butane, and natural gasoline, justify the cost of producing areas with NGPL-rich resources. When the price ratio between crude oil and natural gas is high, a producer is more likely to develop higher NGPL recovery formations because they can overcome the higher cost of processing these resources. When the spread is narrow, a producer is likely to avoid these costs and focus on developing natural gas production areas with low or no NGPL." Wilczewski
  • Assuming easy supply, a natural gas vehicle (NGV) costs $0.04/mile; gasoline costs $0.10; all electric (including battery replacement) costs $0.44-0.75 Muller, 263

Nonfuel uses of natural gas

  • // What are the emissions effects of using natural gas as feedstock rather than fuel?
  • Feedstock uses of natural gas are expected to increase domestically over the 2015-2040 period as petroleum producers build processing plants capitalizing on the low cost of natural gas/stabilizing supply/demand of NG. These plants will predominantly produce bulk chemicals for export. Other major uses will be refinement for fuel, food products, mining, iron, steel, paper, and metal-based durables EIA, 23

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