Excellent point. We measured the concentration of Methane out the vent in a Southern Illinois Mine and converted to a daily rate of 4 MMscfpd. They spray the walls to keep it down.

FF

For sure, any idea how much that is typically, per tonne of coal mined? I don't know which is why I closed the system at the mine mouth/well head (and ignored greenhouse gas emissions associated with coal transportation, assuming them small).

In addition to the methane emissions from mining, I wonder what the warming contribution from the black soot would do to the value for coal-generated burning. Soot has a much lower half-life, but it is a strong contributor nonetheless.

http://en.wikipedia.org/wiki/Black_carbon#Black_carbon_contribution_to_g...

Estimates of black carbon’s climate forcing (combining both direct and indirect forcings) vary from the IPCC’s conservative estimate of + 0.3 watts per square meter (W/m2) + 0.25[6], to the most recent estimate of 1.0-1.2 W/m2 (see Table 1), which is “as much as 55% of the CO2 forcing and is larger than the forcing due to the other greenhouse gasses (GHGs) such as CH4, CFCs, N2O, or tropospheric ozone."

If this is indeed the case, I believe the argument would shift strongly back in favour of gas.

The amount of methane is coal seams depends on the rank of the coal (higher rank. more methane), its porosity and pore size distribution, the depth of the seam (higher pressure, more methane) etc. Of course, we can only measure the adsorption capacity of coals after they have been mined and exposed to air.

Here are some measurements of adsorption capacities of US coals (on a dry, ash-free basis):

- 150-600 scf per ton of bituminous coal (dry and ash free) as the pressure increases from 100-1,000 psi,

- similar values for bituminous coals for the same pressure range,

- up to 100 scf per ton of subbituminous coal (Powder Basin, WY) for the same pressure range,

- up to 800 scf per ton of anthracite.

Exactly the point I was going to make - coal mines leak methane like crazy.

And chris - would you care to comment on the residence time of methane in the atmosphere. How long before it oxidises to CO2?

Its easy to put the fear of God into an ignorant public by claiming methane is even more potent than CO2 and the concentration has risen from 1500 to 1800 parts per billion (?) - i.e. 1.5 to 1.8 parts per million, i.e. from 0.00015 to 0.00018% (hope I got my decimals and all that right).

The CDIAC link above says CH4 has a 12 year lifetime. However, the GWP calculation producing the factor 25x over CO2 is integrated over a common 100 year horizon. Over a shorter period, the GWP is even higher.

I recall a five years half life (that is diferent from a 5 years lifetime). Also, estimates vary between it being 80 to 100 times more powerfull than CO2 before degradation, and I guess the 25 times more powerfull comes from the integral of the greenhouse power through time, taking into account the degradation (that means, with a decreasing exponential power). It surely can't be added up over time.

As the degradation is random, the half life is well defined, not the lifetime. But people have trouble dealing with half lifes, so the press likes to talk about lifetime, and everybody puts their zero at a diferent amount of degradation, so everybody's figure differ and there is too much confusion around simple numbers.

Best Hopes for CHPs,

I strongly suspect that NG power is a better target for carbon capture and storage than coal. Since the number of joules per gram of methane is higher, the increase in overal system cost of capture and disposal ought to be more favorable than for coal.

From: "Preliminary Assessment of the Greenhouse Gas Emissions from Natural Gas obtained by Hydraulic Fracturing"
http://www.eeb.cornell.edu/howarth/GHG%20emissions%20from%20Marcellus%20...

"..If we assume a 1.5% leakage rate, this would have a greenhouse gas warming potential equal to 14.8 g C of CO2 per million joules of energy. This would be additive to the emissions during combustion (13.7 g C of CO2 per million joules of energy) and to the emissions associated with obtaining and transporting the natural gas (very roughly estimated above as 4.5 g C of CO2 per million joules of energy)..."

The transport of any fuel requires significant energy. From the source I cited, it looks like about 30% (4.7g out of 13.7) of the available energy in natural gas is consumed in its transport.

In the US there are pretty good numbers for the last 10 years or so. You can find them here at the EIA:

http://www.eia.gov/dnav/ng/ng_cons_sum_dcu_nus_a.htm

Looks like pipelines consume about 2% of the total US natural gas produced. Fractioning the gas to seperate out the propane and ethane etc takes far more, about 5.5% ( total 7.5% Just for comparison total commercial building consumption in the US is 13.7% or right about twice that amount. That is a lot of buildings heated.)

So, for the EROI interested, US natural gas is below 12 to 1 EROI at the end of the distribution network alone and that does not include compressing and decompressing for winter, or paying the energy cost of drilling, the costs of building the pipelines, local distribution, or end use facility (burners) etc.

-Jon

The methane that is being released by global warming is a serious concern because it can become part of a positive feedback that moves out of our control no matter how much we cut back of fossil fuels. Perhaps it is already in that mode and nothing we do will change the outcome, only the timing.

I read that the Deepwater Horizon is an unusually high percent (40%) for such a well, but that it is staying for now in the ocean

The oil emanating from the seafloor contains about 40 percent methane, compared with about 5 percent found in typical oil deposits, said John Kessler, a Texas A&M University oceanographer who is studying the impact of methane from the spill.

That means huge quantities of methane have entered the Gulf, scientists say, potentially suffocating marine life and creating "dead zones" where oxygen is so depleted that nothing lives.

"This is the most vigorous methane eruption in modern human history," Kessler said.

http://www.palmbeachpost.com/money/gulf-oil-full-of-methane-adding-new-c...

How much can continue to be absorbed by the ocean? What does that do to ocean life? If this spill is not stopped when does this methane start escaping into the atmosphere and how much will that move up the global warming timeline?

I suppose to some degree those are unknowns as we are preforming what well may be a once in a civilization (or species) experiment.

Phytoplankton not only are a food source for other ocean going species but also provide 1/2 the planet's O2. Will the methane kill phytoplankton or be good for them?

In the process of photosynthesis, phytoplankton release oxygen into the water. Half of the world's oxygen is produced via phytoplankton photosynthesis. The other half is produced via photosynthesis on land by trees, shrubs, grasses, and other plants.

http://news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html

What in BAU is worth the risks we are taking?

Where did you get 0.1%? If you have pulled that out of your hat, I can do that with equal validity - as higher temps are inimical to the continued storage of that arctic methane, lets make the assumption that a few percentage points escape, a run away feedback begins, and 0.1% ultimately is what remains in storage rather than what is released. What is the limit of global warming in that scenario?
We explore space to gain insight here on Earth. Apparently Mars had an ocean over up to 1/3 of its surface for a very long time, and was much warmer. Its stable climate system fundamentally changed for an unknown reason. There is no law that I am aware of that a system will remain stable only because it always has been, after all, every person that has experienced a fatal event has a perfect record of avoiding such events prior to that.

Natural gas still promotes global warming. Better to switch to nuclear. perhaps a Liquid fluoride thorium reactor which has potential to be cheaper then coal.

The 60%/39% gas/coal difference is similar in the UK and included in the 360 and 890 g CO2/kWh figure I used. Do you think things have improved significantly in the US since that EPA report and it's 1.4% figure? I guess my main concern is whether the leakage rate Europe is experiencing will increase significantly or not as we import a growing amount from Russia and beyond.

Moving this coal by rail (train runs empty on return) a distance of 2000 miles (3230km) involves an energy cost that reduces by 10% to 20% the net energy content.

Could you provide your calculations? This looks too high to me.

I haven't had an opportunity to see Gasland yet, but I have read a lot of local news articles on the state of hydrofracking in the Marcellus Shale formation. (NY/PA in the United States)

In PA they've had quite a few blowouts and quite a few spills of residual fracking fluid. There also seems to be evidence that wells are suffering underground blowouts into drinking water aquifers - the aquifer in Dimock, PA became undrinkable within a few years of the beginning of drilling operations.

Natural gas is looking less and less green as time goes by, due to the difficulty of extracting it without side effects.

Nice :)

Things are a bit more complicated.

The big difference in the GHG potential of CO2 and methane comes from the phenomenon of band saturation.

The more CO2 we have in the atmosphere, the smaller will be the effect of adding a certain extra amount of it. In other words, 10 ppm of additional CO2 will block a lot more of the outgoing IR energy flux if they were added to an atmosphere containing 100 ppm of CO2, than if they are added to an atmosphere containing 385 ppm CO2. In fact, the amount of outgoing IR radiation "blocked" by the extra CO2 goes down in some exponential fashion as the total CO2 concentration increases.

Currently, the methane adsorption band is far from the saturation point (too little methane in the atmosphere, about 1.8 ppm). This makes every molecule of methane added to the atmosphere at this point about 21 times more powerful in blocking outgoing IR radiation than a molecule of added CO2.

When methane breaks down in the atmosphere, does it release heat?

Can the heat from the reaction contribute to global warming?

(I don't have much technical know how, so forgive me if this is being discussed in this thread)

I have no idea what the cause of the bubbles might be but my first guess would be that some water saturated with methane (at some significant depth) has upwelled at the waterfront and the methane is bubbling out due to the lower pressure at the surface.

I have seen methane bubble up fast enough in a stagnant pond to ignite it with a match.

Maybe there is a new dead zone in the immediate nieghborhood as the result of a plume of oily water passing by.Somebody here should know if a dead zone could produce methane in large enough quantities over short period of time capable of producing such bubbles.

"That" is a really low-res video, so who can tell? I tried it in HD, it still looked all blocky. Ticks me off, I cannot tell if some guy is just now noticing something that is rare-but-natural, or if it is truly unprecedented.

I think the separation of CO2 plus methane is fairly straightforward. The better NG drilling outfits will seperate it out and reinject it. I have seen NG companies run adds that say they are capturing and sequestering CO2. True, but deceptive, as the general public probably gets the impression that all the carbon is sequestered, not just the associated CO2.

Significant energy is used to cool LNG and then regasify it at the point of delivery. Increases the carbon-intensity of LNG relative to "local" methane.

Welcome to TOD!

I'm not a geologist nor am I an engineer, but I do keep a list of "Top 100 Worries." The methane tsunami is not on that list, which I've made up largely by reading and studying links on TOD during the past four years.

You should have a geologist answer your question, however. We have some good petroleum geologists who make comments on TOD; I leave it to you to find out who they are.

I feel you: I live in New Orleans.

I understood that, under those pressures and temperatures, methane forms ice: hence the problem they had with the first big cap they tried to put over the well: the methane ice crystals that built up and clogged the thing, and why they're pumping warm methanol into the new cap. The only reason why natural gas is coming up from the reservoir is because of the high temperatures several miles below the sea-floor. I guess the bid question for me would be that if this were a likely scenario, and I'm not convinced it is, why hasn't it happened yet? The reservoir was compromised the minute they punched a hole in it.

But consider this: the pressure in the reservoir is slowly being reduced by the "production" associated with the leak and we know from prior experience that a reservoir's pressure will often need to be supplemented within a few years of production just to keep its rate of extraction constant. In Norwegian deep water rigs they often use carbon dioxide to artificially pressurize the reservoir and sustain production.

Basically, everyday the pressure in that reservoir is being reduced. At what rate it's impossible to say for certain, but we know that it is.

Tsunamis are created with a minority of undersea earthquakes, most undersea earthquakes do NOT produce tsunamis.

A LARGE amount of water is displaced by a sudden (within seconds) shift of seafloor.

The reservoir is 13,000' below the seafloor. The oil & gas solution is soaked in sand (think wet beach 60' thick, but wet with oil & gas). The oil & gas mixture has to travel through sand out of the formation and then, somehow, up 2.5 miles to the bottom of the seafloor.

The gas does come out from the oil @ 5,000' down, but it is compressed significantly (over 2,000 psi) and begins to freeze immediately (into methane ice). So the volume of gas is MUCH smaller than at sea level. And the volume of water displaced is to.

We humans provided a hole, perhaps close to a foot diameter, down those 13,000' and lined it with steel. For more oil to come out the hole has to be enlarged (bit by bit), the oil & gas has to come out of the sand it has spent the last xx million years in, etc.

WORST WORST WORST case, all of that oil and gas would come out in months, not in seconds. No tsunami.

Hope that helps :-)
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If a tsunami hits a sandy beach, it can roll up and wipe out fishing villages & bottom floors of resort hotels. If they hit a swamp, not too much bad happens. Water goes up, covers marsh grass and maybe cypress trees, and then goes down. Not good for nesting birds and their eggs, but otherwise I cannot see much impact.

Alan in Lower Garden