Natural Gas, Friend or Foe of the Environment? | 24/10/14
by John Brian Shannon
While Natural Gas has been touted as the ‘bridge fuel towards a clean energy future‘ three major drawbacks have caused concern in recent months. The first is, of course, the negatives surrounding natural gas fracking which has been well covered by the media and I’m not going to repeat all that has been said on that account.
Rather, I will concentrate of the largely unreported issues of massive methane leaks escaping natural gas well heads, called ‘fugitive emissions’ and the practice of ‘flaring’ at natural gas wells.
Over a 100-year timeframe, methane is about 35 times as potent as a climate change-driving greenhouse gas than carbon dioxide, and over 20 years, it’s 84 times more potent.
Natural gas drilling could emit up to 1,000 times the methane previously thought, possibly significantly increasing the greenhouse gas footprint of the production of natural gas, the study shows. — Climate Central
There’s no doubt that natural gas has the capacity to be a cleaner fuel than coal and the various fuels that can be obtained from crude oil such as gasoline and diesel. But it isn’t.
So, what’s the problem?
The problem is two-fold. Problem number one is methane leakage at natural gas wells, and problem number two is the ongoing practice of natural gas flaring at well heads, distribution centres and gas processing facilities.
Methane emissions from improperly sealed natural gas wellheads, combined with natural gas flaring near well heads, dramatically lowers the advantage of ‘clean’ natural gas as compared to ‘dirty’ coal and crude oil.
Natural gas as a means to produce electricity is being hailed by the Intergovernmental Panel on Climate Change as the fuel that can act as a “bridge” between carbon-heavy coal and zero-carbon renewables, helping to reduce humans’ impact on the climate.
The idea is that burning natural gas involves fewer greenhouse gas emissions than burning coal. The IPCC in its Working Group III report says natural gas as a bridge fuel will only be effective if few gases escape into the atmosphere during natural gas production and distribution. — Bobby Magill
Natural gas has the potential to be 1 million times cleaner than coal or crude oil based fuels if gas industry best practices are employed. But the present situation is so bad that (low carbon) natural gas airborne emissions are almost on par with (high carbon) coal and crude oil airborne emissions — once you factor everything into the equation.
Why not properly seal the well heads?
Cost. Many gas drilling and extraction companies would like to hermetically seal their well heads to lower the death and injury rates of their workers due to raw gas exposure, to enhance overall gas recovery, decrease the waste of an incredibly useful fuel — and to lower emission levels thereby enhancing the reputation of gas as a 21st-century clean energy solution.
The reason companies won’t spend the extra ($100,000 on average) per well head (to fully encase the pipe in concrete slurry) is that shareholders don’t want lowered dividends. Nor do companies want to become less competitive as compared to the ones that don’t seal their well heads. To put this in some kind of perspective within the gas industry, some gas drilling/extraction operators have hundreds of well heads, while others only have tens of well heads.
At the end of it all, it turns out that improperly sealed natural gas wells and natural gas flaring are negating almost all of the benefits of super clean, natural gas — as compared to coal and crude oil sourced fuels.
Feel free to facepalm now.
Why not stop flaring at natural gas well heads?
Every natural gas well head must deal with pressure variables and with the normally-occurring contaminants found in natural gas. This is done onsite in a process known as flaring which is an incredibly toxic way of dealing with the problem of temporary pressure spikes and natural gas contaminants.
Contaminants in raw natural gas
Raw natural gas typically consists primarily of methane (CH4), the shortest and lightest hydrocarbon molecule. It also contains varying amounts of:
- Heavier gaseous hydrocarbons: ethane (C2H6), propane (C3H8), normal butane (n-C4H10), isobutane (i-C4H10), pentanes and even higher molecular weight hydrocarbons. When processed and purified into finished by-products, all of these are collectively referred to as Natural Gas Liquids or NGL.
- Acid gases: carbon dioxide (CO2), hydrogen sulfide (H2S) and mercaptans such as methanethiol (CH3SH) and ethanethiol (C2H5SH).
- Other gases: nitrogen (N2) and helium (He).
- Water: water vapor and liquid water. Also dissolved salts and dissolved gases (acids).
- Liquid hydrocarbons: perhaps some natural-gas condensate (also referred to as casinghead gasoline or natural gasoline) and/or crude oil.
- Mercury: very small amounts of mercury primarily in elemental form, but chlorides and other natural gas contaminants can be present.
- Naturally occurring radioactive material (NORM): natural gas may contain radon, and the produced water may contain dissolved traces of radium, which can accumulate within piping and processing equipment. This can render piping and equipment radioactive over time.
The raw natural gas must be purified to meet the quality standards specified by the major pipeline transmission and distribution companies. Those quality standards vary from pipeline to pipeline and are usually a function of a pipeline system’s design and the markets that it serves. In general, the standards specify that the natural gas:
- Be within a specific range of heating value (caloric value). For example, in the United States, it should be about 1035 ± 5% BTU per cubic foot of gas at 1 atmosphere and 60°F (41 MJ ± 5% per cubic metre of gas at 1 atmosphere and 15.6°C).
- Be delivered at or above a specified hydrocarbon dew point temperature (below which some of the hydrocarbons in the gas might condense at pipeline pressure forming liquid slugs that could damage the pipeline).
- Dew-point adjustment serves the reduction of the concentration of water and heavy hydrocarbons in natural gas to such an extent that no condensation occurs during the ensuing transport in the pipelines
- Be free of particulate solids and liquid water to prevent erosion, corrosion or other damage to the pipeline.
- Be dehydrated of water vapor sufficiently to prevent the formation of methane hydrates within the gas processing plant or subsequently within the sales gas transmission pipeline. A typical water content specification in the U.S. is that gas must contain no more than seven pounds of water per million standard cubic feet (MMSCF) of gas.
- Contain no more than trace amounts of components such as hydrogen sulfide, carbon dioxide, mercaptans, and nitrogen. The most common specification for hydrogen sulfide content is 0.25 grain H2S per 100 cubic feet of gas, or approximately 4 ppm. Specifications for CO2 typically limit the content to no more than two or three percent.Maintain mercury at less than detectable limits (approximately 0.001 ppb by volume) primarily to avoid damaging equipment in the gas processing plant or the pipeline transmission system from mercury amalgamation and embrittlement of aluminum and other metals — (from Wikipedia)
All of these contaminants are burned off during flaring. The problem is that it is a very incomplete burning cycle, one that is millions of times dirtier than the exhaust that exits your car’s tailpipe. Indeed historically, there have been many cases where people — or even large numbers of cattle or other livestock — living downwind of flaring stacks have died from breathing the partially burned gas.
Legislation is the obvious solution, but how?
If one state legislates against fugitive emissions from well heads and against the practice of natural gas flaring — all of the gas wells in that state will simply be capped and all gas-related economic and energy activity will cease within that state. That’s how competitive the gas industry is.
In North America, if the United States legislates against fugitive emissions and natural gas flaring, the flight of capital and natural gas companies to Canada would result in a huge economic boom for Canada and a dramatic loss for the United States. The reverse is also true.
The Only Solution is a Continental Solution
Therefore, there can only be one solution to the problem — and that is a continental solution to fugitive emissions and to natural gas flaring — whether this is done under the auspices of an amendment to the North American Free Trade Agreement (NAFTA) or as a standalone convention, it is high-time for such legislation to be passed.
It doesn’t need to be a policy masterpiece nor does it need to be technically perfect. It needs to stipulate one uniform standard that applies to all natural gas drilling/extraction/refining and transportation systems in North America.
Above all else, it needs to be done. Now.