One interesting thing I learned when reading Tyler Volk's CO2 Rising deserves a blog post of its own: It's called the Suess effect, after the Austrian chemist Hans Suess, a fellow who I've quoted here before. The basic idea here is that by burning fossil fuels (oxidizing fossil carbon), we are diluting the amount of ¹⁴C in the atmosphere of our planet. As you may be aware, ¹⁴C is produced continuously in the upper reaches of our atmosphere as nitrogen atoms get bombarded by solar particles (specifically, thermal neutrons). Hydrogen is a byproduct of the reaction. It goes something like this:
This ¹⁴C isn't stable over the geologic long-term: it spontaneously breaks down, via radioactive decay, with a half-life of about 5730 years. This property means that ¹⁴C is really useful for dating organic matter of the relatively recent geologic past, a time of particular interest to us, since that's when our species developed its distinctive cultures. But the short half-life means that by the time 60,000 years or so have gone by, there's so little left that it's no longer useful for radiometric dating.

Of course, most of the fossil fuels we use are far older than 60,000 years [A lot of the coal we use formed during the Carboniferous, about 360-299 million years ago], so their store of ¹⁴C long ago reverted to ¹⁴N. When we burn this carbon, we combine it with oxygen and send it into the atmosphere. Isotopically, this fossil carbon looks different from the rest of the carbon in the biosphere.

So overtime, as we burn low-¹⁴C fossil fuels, we would expect to see the total atmospheric ratio of ¹⁴C to other isotopes of carbon decrease. The carbon in the atomsphere becomes more and more enriched in ¹³C and ¹²C as low-¹⁴C coal, oil, and natural gas get oxidized.

In other words, the abundance ratios of these different isotopes of carbon provide a fingerprint for where all that extra carbon dioxide is coming from: it has to be from ¹⁴C-depleted sources, like old carbonaceous sedimentary deposits. For a nice graph illustrating this, click here.

Last thing: The Suess effect holds up only until the early 1950s because after that extra ¹⁴C produced during nuclear bomb testing starts to build up again, skewing the overall trend.

See also this image. (A high-res slide explaining the phenomenon, and detailing different natural repositories of carbon isotope data.)

References:

P.P. Tans, A.F.M. de Jong, and W.G. Mook. "Natural atmospheric ¹⁴C variation and the Suess effect," Nature 280, 826 - 828 (30 August 1979); doi:10.1038/280826a0

Labels: books, CO2, coal, isotopes, oil

Today, I present a guest post from my student Hope W., who described her experiences visiting the Chalk Point Generating Station in Maryland on our Environmental Geology field trip the weekend before last. The essay is posted here with her permission. Enjoy! -CB

The Chalk Point Generating Station is a coal burning power plant owned by the Mirant Corporation. Our guide during our tour was Greg Staggers, the plant manager. There were three main subject areas that Mr. Staggers talked to us about: power generation, the economic supply and demand, and environmental regulations and precautions.

Power Generation:
Mr. Staggers explained how the station has two different types of units. They have steam units and combustion units. Mr. Staggers described how the two different types of units are designed. He said that the steam units are like giant boilers, and that the combustion units are like jet engines. The plant has four steam units and seven combustion units, both types use fossil fuels to produce energy. Mr. Staggers explained how when power is first generated it is at too high of a voltage to be safely used by the public in homes or offices; and how the current has to be run through various lines to transformers and substations in order to be brought down from 20,000 volts (the level generated) to 110-220 volts (the level used in homes and offices.) Mr. Staggers pointed out the transformer field we drove past on the way in on the aerial photograph of the plant explaining that that’s where the process of conversion begins.

In response to Sophia's question about why the plant was built next to the water, Mr. Staggers explained the complex system for using water from the river to cool the equipment in the plant. As he talked in depth about this system he described how ideas improved through time and experience, as well as environmental regulations which lead the plant to finding more efficient and ecological ways of utilizing the river water. Later on when we took our tour through the plant we had the opportunity to see the some pipelines that the river water runs through. The water runs through the pipe-lines to cool the steam that is emitted during the power generation process. When the river water is released back into the river from the plant it has picked up no chemicals, and has only increased in temperature by approximately 20°F.

Mr. Staggers told us about four of the units that get run; units 1 and 2 which are combustion units and units 3 and 4 which are steam units. When running at full capacity units 1 and 2 operate at 90% efficiency, burn 2.5 million pounds of coal per hour, and use 14 megaWatts of the energy produced to operate; and when units 3 and 4 are running at full capacity the burn 650 gallons of oil per minute. Mr. Staggers informed us that the enormous pile of coal we saw on our way in would last for 45 days if the plant were running at full capacity.

Economic Supply and Demand:
In the 1990's the system was deregulated, which basically means that the power generation, wholesaling of the utility, and the supply distribution were all split up. So when the Chalk Point station produces energy they sell it to PJM a 'middleman' who will then sell it to the suppliers like Dominion Power etc. who then sell and distribute the supply to the public. I mentioned the transformer field earlier in this paper in reference to the generation process, but the transformer field has economic implications as well. The transformer field is also where the producers pass of the ownership of the energy to the middleman.

Mr. Staggers explained the bidding system for establishing the market value for each day. In the bidding system if you are over producing you get paid the difference in price from your morning bid in real time. During the tour we got to see the control rooms where the market price rates were being adjusted in real time. In response to Dustin's question about how they know when to produce Mr. Staggers explained how the middle men suppliers make that call based on the morning bids and the actual demand by the public, when the suppliers make the decision about production levels they call the plant to inform them of how much they need to be producing.

In terms of the national economy coal is the cheapest in explicit costs, in equivalent quantities the price for coal is 1/3 that of oil and natural gas prices, which is why more than 50% of the U.S.'s power is generated by coal. In terms of the local economy the Chalk Point station produces a 500 thousand volt ring around D.C. It is estimated that in the next five years 1 million homes will be added to the market that the Chalk Point station caters to.

The demand for coal is influenced by seasonal changes which gives it a cyclical demand. Callan asked if the increased attention on alternative methods of energy has affected the demand for coal in terms of reduction. Mr. Staggers said that no such change has been apparent and that the cyclical trend has followed a predictable pattern.

Environmental Regulations and Precautions:
Mr. Staggers told us about the regulations the plant has been mandated to conform to, as well as what the plant has done of their own accord for the sake of the environment. Some of the changes that the plant made in the past include setting up new stack facilities in 1982 because of environmental regulations. When the clean air act was passed in 1992 brought down their level of pollutants they were releasing into the atmosphere from 1.4 to .7 Further regulations such as; the separated overfire air controls in 2000, selective auto-catalystic reduction in 2007, and selective catalystic reduction in 2008 brought the pollutant rate down to .06. All of the methods above have dropped total output capacity by some amount.

The plant has also put up two boundary nets to protect fish from the areas where hot water is released and two more boundary nets as well as a fine mesh screen to prevent the fish from getting sucked up into the pumps for the cooling system. The plant has many systems in place to reclaim energy where they can to avoid waste, such as how they use residual heat from the coal burning process to heat the incoming air from its current temperature to be closer to the temperature required for being used as an infuser in the combustion process. The plant is in the process of building a "scrubber" which will reduce the sulfur emissions by 98%. The method this "scrubber" will use will allow the plant produce and collect gypsum which the plant will sell for its use in drywall. The plant also has a system set up to collect ash by a precipitation method; the ash collected is also sold for its use in drywall.

The plant has continuous emissions monitors which monitor emission levels of CO2, SO2, and NOx. The data from the monitors is sent quarterly to the State and the E.P.A. In the control room Callan asked a question about the plant's ppm output of CO2. Mr. Staggers said that measure by percentage and he did not know the output in ppm . This discussion lead to a very clear statement by Mr. Staggers that he wasn't convinced that it really made a difference. Mr. Staggers informed us that the plant's output of CO2 is 12% of flue gas volume, which Callan calculated to be 120,000 ppm. From Mr. Staggers' point of view as a producer of a commodity it is hard to see much else besides bottom line explicit costs. This was not his position out of greed, but out of responsibility to keep the company running so he has a job to provide for his family, and his employees as well. On the other hand, scientists cannot escape the implicit costs of CO2 emissions.

There needs to be a level headed discussion in a neutral setting were the two groups can learn to understand each other and start to cooperate. We as individuals and a nation must step up and set the example. When we start working together we will create the safe harbor necessary for understanding and cooperation to grow and flourish.

Labels: coal, energy, environmental, maryland, nova, oil, teaching

Today's my final field trip of the spring semester. My environmental geology students and I are going to see some acid mine drainage, some coastal erosion, and a coal-burning power plant.

The coal bit reminded me to share with you this cobble I found the other day in a deposit of cobbles along the Potomac River:




It's a well-rounded prolate cobble of bituminous coal! Of course, it makes sense that there would be coal cobbles in the Potomac's bedload, since the Potomac drains those portions of the Valley & Ridge province where such layers outcrop. But it's also reasonably fragile stuff, and I've never noticed in out here before. Usually those cobble beds are full of quartzite, flint, and the like.

Labels: coal, sediment

Totally cool... from those crazy kids at U-Pittsburg Johnstown: The Colors of Coal...

Labels: blogs, coal, microscopy

Heh! This "clean coal" debunking campaign is directed by the Coen Brothers.

And another:

Behind the scenes:

Labels: climate change, CO2, coal, global warming, humor, politics

Very cool -- I think I want to design an Environmental Geology lab that uses Google Earth to access and evaluate this data. Kudos to the Vulcan Project for putting it together.

You can open these layers in Google Earth by clicking here.

Labels: climate change, CO2, coal, global warming

Sierra magazine has a cool feature this month: photos of people and their appliances, showing how much coal it takes to run those appliances for one month. A very clever visual technique, illustrated by the talented photographer Lauren Burke. Click through to read the accompanying article about mountaintop removal, and how most of us support it daily at home by doing things like blogging. Hat tip to Mike Tidwell, who showed us some of these pictures yesterday during his talk at NOVA.

Also, the New Yorker this month has its ~annual piece from John McPhee. This one is about the author's experience with fact-checking. It's an interesting read if you're a fan of McPhee like I am. Eldridge Moores is mentioned -- although if you watched the video I posted a while back, you've already heard that Aegean /Adriatic plate mix-up story.

Labels: art, coal, geologists, geology, news

This is pretty good... from the Coyote Crossing blog:

Labels: art, climate change, coal, environmental, global warming, politics

This map was in this morning's Washington Post. The red dots are currently-existing coal-fired power plants. The black dots with the central stars are proposed future coal-fired power plants.

Labels: CO2, coal, dc, energy, environmental, nova

A well-illustrated article by NASA's Earth Observatory discusses the issue of coal mining in Appalachia. Estimates are that we have 100 years or more coal reserves in the world -- far more than oil. The problem is, coal is dirty. Appalachian coal in particular is high in pyrite (FeS2), so that when it is burned, sulfuric acid is generated.

And then, of course, there is the issue of greenhouse emissions. When we heat or get electrical power from the burning of coal, we are reversing an ancient photosynthetic reaction. In the Carboniferous, great swampy deltas (much like the modern Mississippi Delta) stretched across what is today West Virginia. Great rivers draining the young Appalachians flowed west into a shallow epeiric sea. In these muddy deltas, plants grew in profusion. Those plants did what modern plants do: they sat in the sunlight and used its energy to fuse CO2 and H2O into sugars -- plant food. Before they got a chance to use that constructed food, and before any animals had a chance to eat the plants, they were smothered beneath additional layers of sediment, and the efforts of their photosynthesis were locked away underground. This went on for millions and millions of years. Now, humanity has discovered that coal burns well, releasing energy originally generated by the Sun 300 million years ago. Using coal for energy reverses the ancient photosynthetic reaction. When we burn coal, we are combining the coal's "carbohydrates" with oxygen, and re-producing the initial ingredients (CO2 and H2O) in the process. Of course, when water vapor in the air reaches a high concentration, it condenses and precipitates. Carbon dioxide is also removed from the atmosphere by geologic processes, but at a much slower rate. Hence the rise in atmospheric CO2 levels since the Industrial Revolution (when coal-burning picked up pace).

The Earth Observatory article deals with another issue, though: the question of how best to get at coal, given that it's underground in strata with other rock layers atop them. Every month, it seems like there is an item in the news about how there's been an accident in some underground coal mine somewhere in the world, always with a dozen or more miners killed or trapped. In West Virginia, strip mining is a favored tactic. It's safer to coal miners because it occurs at the surface, but there's the rub: The surface is also where everything else happens, too. When miners strip away the overlying rock layers, they also strip away the forest and everything that lives there. Often, unwanted rock is dumped into neighboring valleys, which causes a lot of stress on the freshwater ecosystems present in streams draining that valley.

Check out the article here. It is illustrated with great maps and satellite photos.

Labels: CO2, coal, global warming, mining, satellite imagery