F6 .. Today’s paradox: coal is not worse for climate than natural gas Posted on September 15, 2011 by Rolf Schuttenhelm
It´s basic chemistry: coal is mainly carbon, if you burn it you get lots of CO2. Natural gas is mostly methane, and that’s a different story. With methane just ’20 percent of the burned atoms’ are carbon, the rest is hydrogen, which transforms to pure, drinkable water if you force it to bind with oxygen.Coal natural gas climate effects
Although the energetic value of hydrogen is not as high as that of carbon, this by catch still helps to make the burning of natural gas considerably cleaner and less carbon-intensive, with fewer grams of CO2 per Joule of energy – hence gas is ‘better’ for the climate than coal.
Or so we thought.
But climate is not just about CO2. It can be about other agents that influence parts of Earth’s energy balance, either by absorbing infrared or reflecting ultraviolet radiance.
Methane warms and sulfur cools
To be more precise: climate is very much about leaking methane and emitting sulfur too. Methane to air emissions are an accidental byproduct of natural gas production [as well as of oil production – sloppy business apparently, as any methane leaked to the atmosphere is missed revenue for the energy companies – these people should think of something clever].
Sulfur aerosols, like sulfur dioxide and sulfates, can be considered a byproduct of the coal industry. Coal may be mostly carbon, it is far from pure. Apart from hydrogen and sulfur coal also contains heavy metals like mercury .. http://www.bitsofscience.org/mercury-soil-coal-fired-power-plants-2245/ .. - and coal-fired power plants release more radioactive trace elements .. http://www.bitsofscience.org/nuclear-coal-1848/ .. to the environment than nuclear plants. But let’s stick to the sulfur here.
However damaging that byproduct may be for human health and the wider environment, sulfate and sulfur dioxide aerosols do help to raise the atmosphere’s albedo, thereby reflecting more sunlight and offsetting part of the warming that coal’s CO2 causes.
Coal’s climate benefit in practice
In July a publication in PNAS stated over the period between 1998 and 2008 a doubling of Chinese coal consumption has offset* .. http://www.bitsofscience.org/sulphur-global-warming-2043/ .. part of the climate forcing of the worldwide rise in greenhouse gases over that period [but over that same time both a cooling phase in ENSO and declining insolation were of a larger magnitude]. In this respect the Chinese coal industry could be different from the Western coal industry because many plants are old-fashioned, with poor filtering and high emissions of additional pollutants, like sulfate.
[*) In order not to confuse matters: we of course owe more climatic warming to the Chinese coal expansion – as it released more CO2 than the sulfur could compensate. Besides, the old-fashioned part of the coal industry is a major emitter of atmosphere-warming soot aerosols as well – and soot is currently the most-ignored climate forcer.] .. http://www.bitsofscience.org/soot-policy-climate-change-2909/ ..
Many small methane leaks can also change the picture
Of course it’s true that gas should be much cleaner than coal. But that is if we burned it all, neatly to water vapour and to CO2. Any leaked natural gas however, which is current practice in the gas industry, is equivalent to leaked methane. Depending on how you compare the two greenhouse gases, methane is a 20-25 times more potent climate forcer than CO2. That difference can be of crucial importance to our climate. With the tundra climate feedback for instance we don’t quite know how we’ll have all those gigatonnes of extra carbon served to the atmosphere. If it would be as CO2 it would be bad news .. http://www.bitsofscience.org/climate-carbon-arctic-tundra-co2-methane-2792/ .. – but as methane .. http://www.bitsofscience.org/mass-extinction-methane-clathrates-triassic-2300/ .. it would be disaster.
Quantifying the coal to gas energy transition
All right, even if we accept sulfur is good and methane is bad for the climate. Does saying coal is nothing worse than natural gas hurt your intuitive understanding of climate change? Then you’re absolutely right.
Because on a single day you may be able to compare the climatic effects of sulfur, methane and CO2 – it becomes a lot more complicated if you look at longer timescales. Sulfur aerosols are only airborne for days, perhaps weeks. Methane’s atmospheric half-life is supposed around 8.4 years. However the CO2 we emit today is there for – practically speaking – ever.
That’s why a new publication .. http://www.springerlink.com/content/b430681263425q64/ .. in Climatic Change by the National Center for Atmospheric Research (NCAR) is so interesting. It has further quantified the long-term effects of a transition from coal to natural gas – and concludes the climate benefits are still quite marginal then.
A 50 percent energy shift doesn’t cool in decades
In the NCAR study a computer model was used to simulate the effects of a 50 percent decrease in coal consumption and a simultaneous 50 percent increase in natural gas consumption.
Under the researched scenario a range of methane leaks were assessed, from 0-10 percent, in accordance with practice. For any leakage rate temperatures initially rose in the model study as sulfur aerosol concentrations dropped, with a transition from coal to gas.
According to the model it would take to 2050 before the hypothetical zero leaks runs went into relative cooling mode. For the other methane leakage rates there would be net warming resulting from the energy transition up to 0.06 degrees Celsius for that year.
The 5 percent methane leaks runs dropped to relative cooling shortly after 2060. And with 10 percent methane leaks coming from natural gas production, the energy transition from coal would simply be bad for the climate – for the rest of the century.
Won’t cut a multi-degree warming trend
What may be equally surprising are the small benefits if we did manage to clamp down on those sloppy leaks. The zero leaks runs go to 0.14 degrees of relative cooling by 2100. If we lost 5 percent methane on average the whole energy transition would only amount to some 0.03 degrees of relative cooling over the century.
Maybe the people at NCAR need to tune their model. Or maybe we need to realise replacing the one fossil fuel with the other is not going to do the trick.
Fracking and faulting: how a gas extraction method produced tremors in UK
By John Timmer | Published about 6 hours ago
Climate activists and local residents protest plans by Cuadrilla Resources to drill for shale gas in Lancashire, UK. ( September 18, 2011)
In several US states, fracking has become a standard method of extracting natural gas. The technique, which involves cracking open rock seams with pressurized fluids, is only just starting to be used in Europe. And, as it arrives, it's apparently shaking things up. Earlier this year, a fracking operation near England's northwest coast set off small tremors that were noticed by the citizens of nearby Blackpool. An analysis of the events has now been completed, and its authors conclude that, although fracking isn't likely to ever cause a significant earthquake, there are ways in which these could have been avoided.
Fracking is shorthand for hydraulic fracturing, a technique in which fluids are pumped under ground at high pressures. The fluids can expand existing fractures within the rock, creating passages for natural gas to escape. For the most part, concerns about the procedure have focused on its environmental impact, as the fluids involved are returned to the surface with a variety of contaminants that must be safely disposed of.
Prior to the events in the UK, only a single instance of fracking had been associated with tremors. These occurred in Oklahoma, and were quite minor events, with magnitudes of 2.8 and 1.9. Most events have a magnitude of less than zero, and can't even be detected with normal seismic equipment. But at the UK site, over 50 events have been detected, the largest reaching magnitudes 2.3 and 1.5. As a result, operations at the site have been shut down awaiting an expert evaluation of the problems. That report has now been released.
The UK is not noted for being seismically active, but it does have a number of faults, and many of them are currently under stress. (The report spends a lot of time describing the local geology in the area, which dates back to the "Late Devonian and Early Pennsylvanian times.") Although the amount of stress isn't sufficient to actually cause a fault to rupture, it lowers the amount of energy required to trigger one. This, according to the report, was the key factor in triggering the small tremors.
It appears the well used in the fracking wasn't actually in a fault, but it was near one. As a result, the tremors didn't occur during the point in the operation where the pressures were highest; instead, it happened significantly afterwards. The high-pressure fluids diffused from the drill site for hours afterward, which allowed them to spread to the fault site. The pressure was much lower by the time the fluid got there, but it was still sufficient to lubricate a fault under stress. Once they reached the fault, the pressurized fluids did exactly what they're meant to do: force open existing fractures.
All of the wave forms of the seismic events are similar in nature, so the report concludes that there's nothing especially complex or unusual going on. And, based on their geological models, the process is unlikely to produce anything much larger than the tremors the area has already experienced, which were caused by local slippage of a single slip plane.
That said, the quakes occurred near the surface, which is the reason that many people were aware of it. They also occurred close enough to the drill site to damage some of the equipment—the report refers to a casing in the site that was "ovalized" for several hundred feet during the incident. On the whole, its authors don't think that the problems represent any sort of safety issue.
Still, they think it's probably best that the events should be prevented where possible. The simplest way to do so would be to remove the pressure as quickly as possible once the fracking process is over. That would involve pulling the fluids back out of the site quickly, rather than allowing the pressure to dissipate.
More generally, they recommend that sites be equipped with seismic monitors, and be able to adjust activity if tremors are noted. The report refers to a traffic light system, where a green light for all activity is given when there is no sign of seismic activity. Any sign of tremors switches it to yellow, which involves heightened monitoring for two days after activity stops. Any event with a magnitude of greater than 1.7 would require that all fracking be stopped, and fluid immediately pumped back out of the well.
Given that the tremors occurred at the UK's first fracking site, there's a reasonable chance that these practices could be adopted nationwide there. In the US, however, fracking is already widespread. However, in the states where it's currently restricted or banned, this report may help motivate a consideration of seismic issues, at least on sites where the geology suggests similar problems could occur.
Gas-Fracking Chemicals Detected in Wyoming Aquifer, EPA Says
Snake river and the tetons Image Source
By Jim Efstathiou Jr. - Dec 8, 2011 2:50 PM CT
The U.S. Environmental Protection Agency said for the first time it found chemicals used in extracting natural gas through hydraulic fracturing in a drinking-water aquifer in west-central Wyoming.
Samples taken from two deep water-monitoring wells near a gas field in Pavillion, Wyoming, showed synthetic chemicals such as glycols and alcohols “consistent with gas production and hydraulic-fracturing fluids,” the agency said today in an e- mailed statement.
The U.S. gets about one-third of its gas from fracturing, or fracking, in which millions of gallons of chemically treated water and sand are forced underground to break rock and let trapped vapor flow. The findings give ammunition to environmental groups, such as the Natural Resources Defense Council, that have said the drilling risks tainting drinking water and needs stronger regulation.
“This is just evidence of why we need better rules,” Amy Mall, senior policy analyst for the group in Washington, said in an interview. “It’s a game-changer. EPA experts and scientists have recognized that there is real contamination, that there is a real scientific basis for linking it to fracking.”
After complaints from residents of Pavillion, about 230 miles (370 kilometers) northeast of Salt Lake City, the EPA began investigating private drinking-water wells about three years ago. Calgary-based Encana Corp. (ECA), Canada’s largest natural- gas producer, owns about 150 wells in Pavillion, according to spokesman Doug Hock.
‘Not Definitive’
“They’ve used terms like ‘likely,’” Hock said today in an interview. “What they’ve come up with here is a probability. It’s not a definitive conclusion.”
Synthetic chemicals discovered in the aquifer are just as likely “the result of contamination from their own sampling,” he said.
Industry representatives such as Aubrey McClendon, chairman and chief executive officer of Chesapeake Energy Corp. (CHK), the most active U.S. oil and natural-gas driller among well operators, have said there haven’t been proven cases of fracking fluids contaminating drinking water.
“Try not to be the 51st person to write a story about the alleged contamination of somebody’s water well from fracking,” McClendon said April 8 at the Society of American Business Editors and Writers conference at Southern Methodist University in Dallas. “There have been some issues with drilling wells. They don’t come from fracking.”
Deep Monitoring
In 2010, the U.S. Department of Health and Human Services recommended that Pavillion residents use alternate sources of water for drinking and cooking. While testing detected petroleum hydrocarbons in wells and in groundwater, the agency at the time said it couldn’t pinpoint the source of the contamination.
The EPA dug two deep monitoring wells into the aquifer and found “compounds likely associated with gas-production practices, including hydraulic fracturing,” according to today’s statement. Levels of the chemicals in the deep wells are “well above” acceptable standards under the Safe Drinking Water Act, the agency said.
Fracking chemicals may have entered the aquifer through faulty well construction, gaps in impermeable rock or fractures created during drilling, the EPA said.
“There are various things that can go wrong, but it all points to the fact that we need stronger rules,” Mall said.
‘Poor Aquifer’
Encana has been providing drinking water to about 21 families in Pavillion since August, 2010, Hock said. Some residents were already using outside water sources “because they realize it’s a very poor aquifer,” he said.
Hock said he wasn’t sure if Encana used the synthetic chemicals found in the aquifer when fracking wells in Pavillion.
“I don’t believe that we did,” Hock said. “I don’t know for certain.”
Today’s draft findings are specific to Pavillion, where fracking is occurring “in and below the drinking-water aquifer” and close to water wells, the agency said. The findings will be submitted to an independent scientific review panel.
“Given the area’s complex geology and the proximity of drinking water wells to ground water contamination, EPA is concerned about the movement of contaminants within the aquifer and the safety of drinking-water wells over time,” the agency said.
To contact the reporter on this story: Jim Efstathiou Jr. in New York at jefstathiou@bloomberg.net To contact the editor responsible for this story: Larry Liebert at lliebert@bloomberg.net
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