Showing posts with label carbon dioxide. Show all posts
Showing posts with label carbon dioxide. Show all posts

Friday, April 5, 2013

Klaus Lackner works on carbon capture technology

Klaus Lackner,
Columbia University
Professor Klaus Lackner, director of the Lenfest Center for Sustainable Energy at the Earth Institute, at Columbia University, is working on technology to scrub carbon dioxide from the air. “Our goal is to take a process that takes 100,000 years and compress it into 30 minutes,” says Lackner.

Direct air capture of carbon dioxide is a method that takes carbon dioxide out of ambient air, as opposed to carbon dioxide that is captured from the point of emissions, say, from the smokestack of a coal-fired power plant.

Lackner and his team are developing a device they call an air extractor, modeled after what is most abundant in nature: the leaf of a tree. There is about 0.5 liter of carbon dioxide in a cubic meter of atmosphere. When the extractor is dry, it loads itself with carbon dioxide from the air; when it's wet it releases carbon dioxide it has captured.

“We can do this at a cost of about $30 a ton of carbon dioxide”, says Lackner, “we have designed a box that can extract about a ton of carbon dioxide a day; it fits into a shipping container”. “If we had 100 million of them", Lackner adds, “we could extract more carbon dioxide out of the air then is currently put in.”

The carbon can be stored in the form of mineral carbonate rock or it can be injected deep in the ground. Alternatively, the carbon dioxide can be used, e.g. by turning it into a fuel. Airplanes will likely need to be powered by fuel for a long time, so captured carbon dioxide could be used to more sustainably produce synthetic jetfuel.

In his lab at Columbia's Engineering School, Lackner has built a small greenhouse, demonstrating that  air extractors loaded with captured carbon dioxide can be placed inside a greenhouse; the humid atmosphere inside the greenhouse will make that the carbon dioxide is released. Adding carbon dioxide to the air inside greenhouses is beneficial for plant growth; the plants will take the carbon dioxide out of the air and use it to grow.



References

- Prof. Klaus Lackner Takes Step Toward Workable Carbon Capture Technology
http://news.columbia.edu/carbondioxide

- Klaus S. Lackner, Director of the Lenfest Center for Sustainable Energy, Columbia Universityhttp://www.earth.columbia.edu/articles/view/2523

- Prof. Klaus Lackner Takes Step Toward Workable Carbon Capture Technolog . .
http://www.youtube.com/watch?v=qGL21j10C8Q

- Direct Air Capture of Atmospheric Carbon Dioxide
http://large.stanford.edu/courses/2011/ph240/mccurdy1/

- The Great Debate: CLIMATE CHANGE - Surviving The Future (1:15 to 1:24)
http://www.youtube.com/watch?v=XPaTAC29W2I

- Funding of Carbon Air Capturehttp://geo-engineering.blogspot.com/2009/05/funding-of-carbon-air-capture.html

- Removing carbon from air - Discovery Channel
http://geo-engineering.blogspot.com/2008/10/removing-carbon-from-air-discovery.html

Friday, March 1, 2013

Using the Oceans to Remove CO2 from the Atmosphere

William H. Calvin, PhD, Professor at
University of Washington, 
author of: Global Fever: How to
Treat Climate Change
By William H. Calvin

1. Prospects for an Emergency Drawdown of CO2

Suppose we had to quickly put the CO2 genie back in the bottle. After a half-century of “thinking small” about climate action, we would be forced to think big—big enough to quickly pull back from the danger zone for tipping points and other abrupt climate shifts.

By addressing the prospects for an emergency drawdown of excess CO2 now, we can also judge how close we have already come to painting ourselves into a corner where all escape routes are closed off.7

Getting serious about emissions reduction will be the first course of action to come to mind in a climate crisis, as little else has been discussed. But it has become a largely ineffective course of action11 with poor prospects, as the following argument shows.

In half of the climate models14, global average overheating is more than 2°C by 2048. But in the US, we get there by 2028. It is a similar story for other large countries.

Because most of the growth in emissions now comes from the developing countries burning their own fossil fuels to modernize with electricity and personal vehicles, emissions growth is likely out of control, though capable of being countered by removals elsewhere.

But suppose the world somehow succeeds. In the slow growth IPCC scenario, similar to what global emissions reduction might buy us, 2°C arrives by 2079 globally–but in the US, it arrives by 2037.

 So drastic emissions reduction worldwide would only buy the US nine extra years.

However useful it would have been in the 20th century, emissions reduction has now become a failed strategy, though still useful as a booster for a more effective intervention.

We must now resort to a form of geoengineer­ing that will not cause more trouble than it cures, one that addresses ocean acidification as well as overheating and its knock-on effects.

Putting current and past CO2 emissions back into secure storage5 would reduce the global overheating, relieve deluge and drought, reverse ocean acidification, reverse the thermal expansion portion of sea level rise, and reduce the chance of more4 abrupt climate shifts.

Existing ideas for removing the excess CO2 from the air appear inadequate: too little, too late. They do not meet the test of being sufficiently big, quick, and secure. There is, however, an idealized approach to ocean fertilization5 that appears to pass this triple test.

It mimics natural up- and down-welling processes using push-pull ocean pumps powered by the wind. One pump pulls sunken nutrients back up to fertilize the ocean surface—but then another pump immediately pushes the new plankton production down to the slow-moving depths before it can revert to CO2.

How Big? How Fast?

The atmospheric CO2 is currently above 390 parts per million and the excess CO2 growth has been exponential. Excess CO2 is that above 280 ppm in the air, the pre-industrial (1750) value and also the old maximum concentration for the last several million years of ice age fluctuations between 200 and 280 ppm.

Is a 350 ppm reduction target12, allowing a 70 ppm anthropogenic excess, low enough? We hit 350 ppm in 1988, well after the sudden circulation shift18 in 1976, the decade-long failure of Greenland Sea flushing24 that began in 1978, and the sustained doubling (compared to the 1950-1981 average) of world drought acreage6 that suddenly began in 1982.

Clearly, 350 ppm is not low enough to avoid sudden climate jumps4, so for simplicity I have used 280 ppm as my target: essentially, cleaning up all excess CO2.

But how quickly must we do it? That depends not on 2°C overheating estimates but on an evaluation of the danger zone2 we are already in.

The Danger Zone

Global average temperature has not been observed to suddenly jump, even in the European heat waves of 2003 and 2010. However, other global aspects of climate have shifted suddenly and maintained the change for many years.

The traditional concern, failure of the northern-most loop of the Atlantic meridional overturning circulation (AMOC), has been sidelined by model results20-22 that show no sudden shutdowns (though they do show a 30% weakening by 2100).

While the standard cautions about negative results apply, there is a more important reason to discount this negative result: there have already been decade-long partial shutdowns not seen in the models.

Not only did the largest sinking site shut down in 1978 for a decade24, but so did the second-largest site23,28 in 1997. Were both the Greenland Sea and the Labrador Sea flushing to fail together2, we could be in for a major rearrange­ment of winds and moisture delivery as the surface of the Atlantic Ocean cooled above 55°N. From these sudden failures and the aforementioned leaps in drought, one must conclude that big trouble could arrive in the course of only 1-2 years, with no warning.

So the climate is already unstable. (“Stabilizing” emissions4 is not to be confused with climate stability; it still leaves us overheated and in the danger zone for climate jumps. Nor does “stabilized” imply safe.)

While quicker would be better, I will take twenty years as the target for completing the excess CO2 cleanup in order to estimate the drawdown rate needed.
The Size of the Cleanup

It is not enough to target the excess CO2 currently in the air, even though that is indeed the cause of ocean acidification, overheat­ing, and knock-on effects. We must also deal with the CO2 that will be released from the ocean surface as air concentration falls and the bicarbonate buffers reverse, slowing the drawdown.

Thus, I take as the goal to counter the anthropogenic emissions4,5 since 1750, currently totaling 350 gigatonnes of carbon. (GtC =1015g of Carbon=PgC.)

During a twenty year project period, another 250 GtC are likely be emitted, judging from the 3% annual growth in the use of fossil fuels5 despite some efforts at emissions reduction. Thus we need to take back 600 GtC within 20 yr at an average rate of 30 GtC/yr in order to clean up (for the lesser goal of countering continuing emissions, it would take 10 to 15 GtC/yr).

Chemically scrubbing the CO2 from the air is expensive and requires new electrical power from clean sources, not likely to arrive quickly enough. On this time scale, we cannot merely scale up what suffices on submarines.

Thus we must find ways of capturing 30 GtC/yr with traditional carbon-cycle8 biology, where CO2 is captured by photosynthesis and the carbon incorporated into an organic carbon molecule such as sugar. Then, to take this captured carbon out of circulation, it must be buried to keep decomposition methane and CO2 from reaching the atmosphere.

Sequestering CO2

One proposal26 is to bundle up crop residue (half of the annual harvest is inedible leaves, skins, cornstalks, etc.) and sink the weighted bales to the ocean floor. They will decompose there but it will take a thousand years before this CO2 can be carried back up to the ocean surface and vent into the air.

Such a project, even when done on a global scale, will yield only a few percent of 30 GtC/yr. Burying raw sewage3 is no better.

If crop residue represents half of the yearly agricultural biomass, this also tells you that additional land-based photo­synthesis, competing for space and water with human uses, cannot do the job in time.5 It would need to be far more efficient than traditional plant growth. At best, augmented crops on land would be an order of magnitude short of what we need for either countering or cleanup.

Big, Quick, and Secure

Because of the threat from abrupt climate leaps, the cleanup must be big, quick, and secure.

Doubling all forests might satisfy the first two requirements but it would be quite insecure—currently even rain forests4 are burning and rotting, releasing additional CO2.

 Strike One.  We are already past the point where enhanced land-based photosynthesis can implement  an emergency drawdown. They cannot even counter current emissions.

Basically, we must look to the oceans for the new photosynthesis and for the long-term storage of the CO2 thus captured.

Fertilization per se

Algal blooms are increases in biological productivity when the ocean surface is provided with fertilizer containing missing nutrients15 such as nitrogen, iron, and phosphorus.

A sustained bloom of algae can be fertilized by pumping up seawater5,16,19 from the depths, a more continuous version of what winter winds9 bring up.

Currently about 11 GtC/yr settles out of the wind-mixed surface layer into the slowly-moving depths13 as plankton die. To settle out another 30 GtC/yr, we would need about four times the current ocean primary productivity. Clearly, boosting ocean productivity worldwide is not, by itself, the quick way to put the CO2 genie back in the bottle.

 Strike Two. Our 41% CO2 excess is already too large to draw down in 20 yr via primary productivity  increases in the ocean per se.

However, our escape route is not yet closed off. There is at least one plausible prospect for an emergency draw down for 600 GtC in 20 yr. It seeks to mimic the natural ocean processes of upwelling and downwelling.

2. Push-pull ocean pipes

Upwelling and Downwelling

Upwelling from the depths is typically caused by winds which push aside surface waters, especially those strong westerly winds in the high southern latitudes that continuously circle Antarctica without bumping into land.

In addition to the heavier biomass (the larger fecal pellets and shells) that can settle into the depths before becoming CO2, there is downwelling, an express route to the depths using bulk flow. Surface waters are flushed via whirlpools into the depths of the Greenland Sea and the Labrador Sea23. This downwelling carries along the surface’s living biomass (from bacteria to fish) as well as the dissolved organic carbon (from feces and smaller cell debris).

Note that, in the surface ocean, there is a hundred times more dissolved organic carbon (DOC) than the organic carbon inside living organisms1. Bacterial respiration produces CO2 from this DOC that reaches the air within 40 days.

To augment normal downwelling, one could pump surface DOC and plankton into the ocean depths before they become CO2. Half of the decomposition CO2 produced in the depths rejoins the atmosphere when the deep water is first upwelled a millennium later. Thanks to ocean mixing in the depths and multiple upwelling sites at different path lengths, it will come back up spread out in time after that initial delay.

There is an even larger spread because the other half (called refractory DOC17) is somehow protected from becoming CO2 for a while, even when cycled through the surface layers multiple times.17 Average radiocarbon dates for DOC in the depths are about 4,000 years, not 40 days.

Thus, if we somehow sink 600 GtC into the ocean depths over 20 years,  the return of 600 GtC of decomposition CO2 to the air is spread out over, say, 6,000 years. That is an average of 0.1 GtC each year, about 1% of current emissions. Such a slow return of excess CO2 can be countered by slow reforestation or similar measures.

 From this analysis, we still have a plausible way out of the climate crisis, even on an emergency basis.

What follows is an idealized example of how we might implement it, using less than one percent of the ocean surface for the next twenty years to do the equivalent of plowing under a cover crop.5

Fig. 1. A plankton plantation design using windmill pumps (ref 5), including a fishing lane free of anchor cables. Shading shows the plume of nutrients from a single pump and the plume of organic matter dispersed in the depths. One advantage of windmills is that compressed air can be generated to be pumped into the depths, addressing anoxia problems. Spacing of windmills, however, is subject to the usual limitations of vortices downwind.

Plowing Under a Cover Crop

In addition to the up-pump of the fertilization-only example, add another wind-driven pump nearby that flushes the surface water back down into even deeper depths before its new biomass becomes CO2 again.

If we fertilize via pumping up and sink nearby via bulk flow (a push-pull pump), we are essentially burying a carbon-fixing crop, much as farmers plow under a nitrogen-fixing cover crop of legumes to fertilize the soil.

Algaculture yields25 allow a preliminary estimate to be made of the size of our undertaking. Suppose that a midrange 50 g (as dry weight) of algae can be grown each day under a square meter of sunlit surface, and that half is carbon. Thus it takes about 1 x 10-4 m2 to grow 1 gC each year. To produce our 30 x 1015 gC/yr drawdown rate would require 30 x 1011 m2 (0.8% of the ocean surface, about the size of the Caribbean).

But because we pump the surface waters down, not dried algae, we would also be sinking the entire organic carbon soup of the wind-mixed surface layer: the carbon in living cells plus the hundred-fold larger amounts in the surface DOC. Thus the plankton plantations might require only 30 x 10m2 (closer to the size of Lake Michigan).

Apropos location5, pumping down to 150 m near the edge of the continental shelf would deposit the organic carbon where it could be carried over the cliff and into the slower-moving deep ocean.

The ocean pipe spacing, and the volume pumped down, will depend on the outflow needed to optimize the organic carbon production (the chemostat calculation). Only field trials are likely to provide a better estimate for the needed size of sink-on-the-spot plankton plantations, pump numbers, and project costs. The obvious test beds are the North Sea and Gulf of Mexico where thousands of existing drilling platforms could be used to support appended pipes and pumps for field trials5. Without waiting for floating pumps, we could quickly test for impacts as well as efficient plantation layouts.

I have used windmills here for several reasons: they are familiar mechanisms and they enable a push-pull plantation layout to be readily illustrated. But there are a number of ways to achieve wind-wave-powered pumps, both up and down, such as atmocean.com’s buoyed pipes and Salter’s elevated ring23a to capture wave tops and create a hydrostatic pressure head for sinking less dense warm water into the more dense cool waters of the depths. Each implementation will have considerations peculiar to it; what follows are some of the more general advantages and disadvantages in the context.

Fig 2 A,B: A less expensive pump can be constructed that uses wave power and allows closer packing (ref 3). They would be more effective in the Antarctic Circumpolar Current because of the wave heights. Calvin (2012b), after P. Kithel’s design (atmocean.com).

Fig 3. Salter Sink23a uses a meter-high lip on a large floating ring to capture wavetops. This builds up enough hydrostatic pressure to push down warm surface water, kept enclosed by a skirt. It can also (not shown) achieve some upwelling.  Warm water exiting in the depths will rise outside the tube, entraining higher-density nutrient-rich cold water. The mix can rise above the thermocline into the surface layer, fertilizing plankton growth. Detail from figure in Intellectual Ventures white paper13a.

Pro and Con

Here we have an idealized candidate for removing 600 Gt of excess carbon from the air: the sink-on-the-spot plankton plantation that moves decomposition into the thousand-year depths. Push-pull pumping for fertilization and sequestration is relatively low-tech and merely augments natural up- and down­welling processes.

This idealized candidate has some unique advantages compared to current climate strategies: It is big, quick, and secure. It is impervious to drought and holdout governments. It does not compete for land, fresh water, fuel, or electricity. By bringing up cold water from the depths and sinking warm surface water into the thousand-year depths, it cools the ocean surface regionally. And there is a “cognitive carrot,” an immediate payoff every year (fish catch5, cooling hurricane paths9a) while growing the climate fix (the 600 GtC emergency draw down).

The idealized example intentionally uses technologies that are too old or simple to be patentable. The industries most likely to benefit would be fishing and the offshore services presently associated with oil and gas platforms.

It is against such advantages that we must judge the potential downsides5. Concerns voiced thus far include:
  1. Could we get international agreement fast enough? Continental shelves in the most productive latitudes belong to relatively wealthy countries. Their independent initiatives could quickly establish many plankton plantations just inside the shelf without new treaties.
  2. Won’t it pollute? Perhaps not as proposed here, using local algae and nutrients in a vertical loop, but the usual considerations would apply should we want to introduce exotic or modified algal species to achieve even higher rates of sinking potential CO2. Toxic blooms are possible during productivity transitions. With floating enclosures rather than plumes, this would change.
  3. Won’t anoxic “dead zones” form? Shallow continental shelf sites should be avoided because hypoxia will occur from the decomposition of the downwelled carbon soup in a restricted volume. Fish kills occur when anoxia develops more quickly than fish can find their way out of the increasingly hypoxic zone. However, a maintained hypoxic zone will mostly repel fish from entering.
  4. We don’t know what will happen. The novelty here is minimal, even less than for iron fertilization. Fertilizing and sinking surface waters merely mimics, albeit in new locations or new seasons, those frequently studied natural processes seen on a large scale in winter mixing and in ocean up- and downwelling. There is also prehistorical precedent. The 80 ppm drawdown of atmospheric CO2 in the last four ice ages is thought to have occurred via enhanced surface productivity, triggered by a major reduction in the Antarctic offshore downwelling27 that re-sinks nutrient-rich waters brought to the surface in high latitudes by the circumpolar winds.
  5. Won’t this just move the ocean acidification problem into the depths? Since the depths are 98% of ocean volume, there is a fifty-fold dilution of the acidity. Were countering out-of-control emissions to continue for a century, depth acidification might be more of a problem.
  6. Pumping up will just bring up water with higher CO2 than in the surface waters. A depth difference10 of 40 μmol/kg means that upwelling a cubic meter of seawater brings up an unwanted 0.48 g of inorganic carbon. The resulting fertilization will take that CO2 (and more) out of the surface ocean. Also, pumping down the same volume sinks 1 g of potential CO2 as DOC, even without fertilization.
  7. Aren't you going to run out of phosphate, what currently limits the global ocean productivity to a fraction of its capacity? Up-pump pipes could be sited to bring up bottom waters from the southern oceans that are currently rich in phosphate.
A Second Manhattan Project

Though these objections do not seem insurmountable  good reasons usually arise for not implementing most such projects as initially proposed.

This idealized push-pull ocean pumps proposal is meant to give a concrete example, easy to remember, that defines the response ballpark by being big, quick, secure, powered by clean sources, and inexpensive enough so that a country can implement it on its own continental shelf without endless international conferences. Other drawdown schemes—say, floating enclosures or wave-driven circulating cells — need to pass those same tests.

To do the planning job right is going to take a Second Manhattan Project of various experts to design cleanup candidates and evaluate their side effects. Lend them Los Alamos and let the Pentagon buy them what they need with wartime priorities. To field test their plantation designs, let them instrument the many abandoned oil platforms in the North Sea and the Gulf of Mexico. Then quickly deploy the best designs, using the abilities of the offshore services industry.

Aim to accomplish all this in the four year time frame of the original Manhattan Project. Ten years after that, the cleanup job should be half done, and without all of the economic pain of a quick (and ineffective) shutdown of fossil fuel use. At the beginning of World War II, Franklin D. Roosevelt used the metaphor of a “four alarm fire up the street” that had to be extinguished immediately, whatever the cost. Our need for fast action on climate deterioration requires devoting the resources necessary to radically shorten the developmental cycle for all carbon burial projects. We dare not wait until we are weakened before undertaking emergency climate repairs. Our ability to avoid a human population crash will be compromised if economies become fragile or if international cooperation is lost via conflicts. A serious jolt—say, a major rearrangement of the winds—could cause catastrophic crop failures and food riots within several years, creating global waves of climate refugees with the attendant famine, pestilence, war, and genocide.

Acquiescing in a slower approach to climate is, in effect, playing Russian roulette with the climate gun. The climate crisis needs wartime priorities now.

References

1. Amon RM, Budéus G, Meon B (2003) Dissolved organic carbon distribution and origin in the Nordic Seas: Exchanges with the Arctic Ocean and the North Atlantic. J Geophys Res 14: 1-17. www.agu.org/journals/jc/jc0307/2002JC001594/2002JC001594.pdf

2. Calvin WH (2008) Global Fever: How to Treat Climate Change. London and Chicago: University of Chicago Press. faculty.washington.edu/wcalvin/bk14

3. Calvin WH (2008) Estimates for sequestering organic carbon via sinking sewage in oceans. arXiv 0810.2275v1

4. Calvin WH (2012a) The Great Climate Leap. ClimateBooks.

5. Calvin WH (2012b) The Great CO2 Cleanup. ClimateBooks.

6. Dai A, Trenberth KE, Qian T (2004) A global data set of Palmer Drought Severity Index for 1870–2002: Relationship with soil moisture and effects of surface warming. J Hydrometeorology 5:1117-1130. www.cgd.ucar.edu/cas/adai/papers/Dai_pdsi_paper.pdf

7. Diamond J (2003) Collapse: How Societies Choose to Succeed or Fail. New York: Viking.

8. Falkowski PG, Laws EA, Barber RT, Murray JW (2003). Phytoplankton and their role in primary, new, and export production. In M. J. Fasham (Ed), Ocean Biogeochemistry (ch.4). New York: Springer. www.ocean.washington.edu/people/faculty/jmurray/chap-04.pdf

9. Feely RA, Sabine CL, Takahashi T, Wanninkhof R (2001) Uptake and storage of carbon dioxide in the ocean: The global CO2 survey. Oceanography 14:18-32. www.pmel.noaa.gov/pubs/outstand/feel2331/feel2331.shtml

10. Goyet C, Healy R, Ryan J, Kozyr A (2000) Global Distribution of Total Inorganic Carbon and Total Alkalinity below the Deepest Winter Mixed Layer Depths. ORNL Technical report NDP-076 at www.osti.gov/bridge/product.biblio.jsp?osti_id=760546

11. Greene CH, Baker DJ, Miller DH (2010) A very inconvenient truth. Oceanography 23:214-218. www.tos.org/oceanography/archive/23-1_greene.pdf

12. Hansen J, et al (2008) Target atmospheric CO2: Where should humanity aim? Open Atmos Sci J 2:217–231. doi:10.2174/1874282300802010217

13. Houghton RA (2007) Balancing the global carbon budget. Ann Rev Earth Planet Sci 35:313–347. doi:10.1146/annurev.earth.35.031306.140057

13a. Intellectual Ventures white paper (2009) Drains for hurricanes. http://intellectualventureslab.com/wp-content/uploads/2009/10/Salter-Sink-white-paper-300dpi1.pdf

14. Joshi M, Hawkins E, Sutton E, Lowe J, Frame D (2011) Projections of when temperature change will exceed 2°C above pre-industrial levels. Nature Climate Change 1:407-412, doi:10.1038/nclimate1261

15. Lampitt RS, et al (2008) Ocean fertilization: a potential means of geoengineering? Phil Trans Roy Soc A 366:3919–3945. doi: 10.1098/rsta.2008.0139

16. Lovelock JW, Rapley CG (2007) Ocean pipes could help the Earth to cure itself. Nature 449:403. doi:10.1038/449403a

17. McNichol AP, Aluwihar LI (2007) The power of radiocarbon in biogeochemical studies of the marine carbon cycle: insights from studies of dissolved and particulate organic carbon (DOC and POC). Chemical Reviews 107:443-466, doi:10.1002/chin.200724246.

18. Miller AJ, Cayan DR, Barnett TP, Oberhuber JM (1994) The 1976-77 climate shift of the Pacific Ocean. Oceanography 7: 21–26. meteora.ucsd.edu/~miller/papers/shift.html

19. Oschlies A, Pahlow M, Yool A, Matear RJ (2010), Climate engineering by artificial ocean upwelling: Channelling the sorcerer’s apprentice. Geophys Res Lett 37, L04701, doi:10.1029/ 2009GL041961

20. Pitman AJ, Stouffer RJ (2006) Abrupt change in climate and climate models. Hydrol. Earth Syst. Sci. Discuss., 3, 1745–1771. www.hydrol-earth-syst-sci-discuss.net/3/1745/2006/

21. Rahmstorf S (2006) Thermohaline Ocean Circulation. In: Encyclopedia of Quaternary Sciences, edited by S. A. Elias. Elsevier, Amsterdam. www.pik-potsdam.de/~stefan/Publications/Book_chapters/rahmstorf_eqs_2006.pdf

22. Rahmstorf S, Ganopolski A (1999) Long-term global warming scenarios computed with an efficient coupled climate model. Climatic Change 43: 353–367, doi:10.1023/A:1005474526406

23. Rhines PB (2006) Sub-Arctic oceans and global climate. Weather 61:109-118. doi: 10.1256/wea.223.05

23a. Salter S (2009) Wave-powered destratification for hurricane suppression, acidity reduction, carbon storage, and enhanced phytoplankton, dimethyl sulfide and fish production. Earth and Environmental Science. DOI:10.1088/1755-1307/6/5/452012

24. Schlosser P, Bönisch G, Rhein M, Bayer R (1991) Reduction of deepwater formation in the Greenland Sea during the 1980s: Evidence from tracer data. Science 251:1054–1056. www.sciencemag.org/cgi/reprint/251/4997/1054.pdf

25. Sheehan J, Dunahay T, Benemann J, Roessler P (1996) A Look Back at the U.S. Department of Energy’s Aquatic Species Program—Biodiesel from Algae, NREL/TP–580–24190. US DOE Technical Report. www1.eere.energy.gov/biomass/pdfs/biodiesel_from_algae.pdf

26. Strand S, Benford G (2009) Ocean sequestration of crop residue carbon: recycling fossil fuel carbon back to deep sediments. Environ Sci & Tech 43:1000-1007. doi:10.1021/es801555

27. Toggweiler JR, Murnane R, Carson S, Gnanadesikan A, Sarmiento JL (2003) Representation of the carbon cycle in box models and GCMs, 2, Organic pump. Global Biogeochem Cycles 17:1027, doi:10.1029/2001GB001841

28. VÃ¥ge K, et al (2009) Surprising return of deep convection to the subpolar North Atlantic Ocean in winter 2007–2008. Nature Geoscience 2:67–72.

Sunday, January 16, 2011

2011 starts with lowest Arctic sea ice extent on record

The year 2010 was the warmest year on record, as confirmed by the WMO and as illustrated by the NOAA graph below.
This is the more dramatic given that we’re in the middle of a strong La Niña, which pushes temperatures down, while we’ve been in “the deepest solar minimum in nearly a century.” NOAA has meanwhile published the data for 2010. A chart based on NOAA data is added below, with standard polynomial trendline added.
As the NASA map below shows, temperature anomalies are especially prominent at higher latitudes, close to the Arctic. Arctic sea ice cover in December 2010 was the lowest on record for the month, said the WMO, adding that sea ice around the northern polar region shrank to an average monthly extent of 12 million square kilometres, 1.35 million square kilometres below the 1979 to 2000 December average. Furthermore, 2011 has started with the lowest Arctic sea ice extent on record for this time of the year, as shown on the International Arctic Research Center graph below.
On the NSIDC graph below, monthly September ice extent for 1979 to 2010 shows a decline of 11.5% per decade.
The NSIDC image below shows that, at the end of the summer 2010, under 15% of the ice remaining in the Arctic was more than two years old, compared to 50 to 60% during the 1980s. There is virtually none of the oldest (at least five years old) ice remaining in the Arctic (less than 60,000 square kilometers [23,000 square miles] compared to 2 million square kilometers [722,000 square miles] during the 1980s).
Why is all this so important? The Arctic sea ice acts as a giant mirror, reflecting sunlight back into space and thus keeping Earth relatively cool, as discussed in this open letter. If this sunlight instead gets absorbed at higher latitudes, then feedback effects will take place that result in much higher temperatures, in a process sometimes referred to as Arctic amplification of global warming.
Above image is from a recent study, which found that 2010 set a record for surface melting over the Greenland ice sheet. The study warns that surface melt and albedo are intimately linked: as melting increases, so does snow grain size, leading to a decrease in surface albedo which then fosters further melt. A recent study concludes that the rate of Arctic sea ice decline appears to be accelerating due to positive feedbacks between the ice, the Arctic Ocean and the atmosphere. As Arctic temperatures rise, summer ice cover declines, more solar heat is absorbed by the ocean and additional ice melts. Warmer water may delay freezing in the fall, leading to thinner ice cover in winter and spring, making the sea ice more vulnerable to melting during the next summer.
Thin lines are raw data, bold lines are three-point running means…. (C) Summer temperatures at 50-m water depth (red)…. Gray bars mark averages until 1835 CE and 1890 to 2007 CE. Blue line is the normalized Atlantic Water core temperature (AWCT) record … from the Arctic Ocean (1895 to 2002; 6-year averages)…. (D) Summer temperatures (purple) [calculated with a different method]
The IPCC didn't take such feedbacks into account and didn't foresee a total September sea ice loss in the Arctic for this century. Many scientists have repeatedly warned about this, as mentioned in this early 2009 post and this early 2010 post.
Projections that start with more recent data will take some of this feedback into account. Projections that start with 1992 and 1995 data, as in the pink and purple lines on above image, predict a total loss of September Arctic sea ice by 2040 or 2030. A study that used 2007/2008 data as starting point predicts a nearly sea ice free Arctic in September by the year 2037. Albedo change is only one of a number of feedback processes. A rapid rise of Arctic temperatures could lead to wildfires and the release of huge amounts of carbon dioxide and methane that are now stored in peat, permafrost and clathrates, which constitutes further feedback that could cause a runaway greenhouse effect. Heat produced by decomposition of organic matter is yet another feedback that leads to even deeper melting.
The cumulative impact of multiple feedback processes and their interaction reinforces and accelerates Arctic warming, making downward curved projections more applicable than straight line extrapolation of earlier data. The pink dotted line on above chart shows a scenario that reflects the impact of a number of feedback processes. A study at the University of Calgary concludes that, even if we completely stopped using fossil fuels and put no more CO2 in the atmosphere, we've already added enough carbon in the oceans to cause the West Antarctic ice sheet to eventually collapse (by the year 3000), resulting in a global sea level rise of at least four meters. In other words, we have already passed the tipping point for the West Antarctic ice sheet, and additional emissions could cause its collapse to occur much earlier. According to a study published in the journal Nature Geoscience, ice and snow in the Northern Hemisphere are now reflecting on average 3.3 watts of solar energy per square meter back to space, a reduction of 0.45 watts per square meter between 1979 and 2008. "The rate of energy being absorbed by the Earth through cryosphere decline – instead of being reflected back to the atmosphere – is almost 30% of the rate of extra energy absorption due to CO2 increase between pre-industrial values and today," co-author Karen Shell said. A study by by National Center for Atmospheric Research (NCAR) scientist Jeffrey Kiehl found that carbon dioxide may have at least twice the effect on global temperatures than currently projected by computer models of global climate. Melting of ice sheets, for example, leads to additional heating because exposed dark surfaces of land or water absorb more heat than ice sheets. Without changes, this new study warns, Earth's average temperature appears set to rise this century by 29°F (16°C), to levels never before experienced in human history. Such a rise would make that many areas on Earth would become too hot to live in. Humans and other mammals cannot survive prolonged exposure to temperatures exceeding 95°F (35°C), says Steven Sherwood. Heat stress would make many parts of the globe uninhabitable with global-mean warming of about 7°C (12.6°F). Warming of about 21°F (11-12°C) would make places where most people now live uninhabitable. I have made recommendations to deal with global warming for years, most recently in this Global Warming Action Plan. What do you think should be done?

Tuesday, November 4, 2008

Adding lime to seawater

Shell Oil is funding a project that is studying the potential of adding lime to seawater to store carbon dioxide (CO2) in the sea.

Due to increased CO2 levels, the oceans have become more acid. Adding lime (calcium hydroxide) to seawater will increase the alkalinity of the water, making the water absorb more CO2 and reducing the release of CO2 from the water into the atmosphere.

Tim Kruger, a management consultant at London-based Corven, believes that this can be done most economically where there's plenty of limestone, and plenty of energy that is too remote to exploit for conventional commercial purposes.

"There are many such places — for example, Australia's Nullarbor Plain would be a prime location for this process, as it has 10,000km3 of limestone and soaks up roughly 20MJ/m2 of solar irradiation every day," said Kruger.

Although the process generates CO2 emissions, on paper it sequesters twice as much of the warming gas than it produces. Kruger says the process is therefore 'carbon negative'.

'This process has the potential to reverse the accumulation of CO2 in the atmosphere. It would be possible to reduce CO2 to pre-industrial levels,' he explained.

"We think it's a promising idea," says Shell's Gilles Bertherin, a coordinator on the project, which is being developed in an "open source" manner. "There are potentially huge environmental benefits from addressing climate change — and adding calcium hydroxide to seawater will also mitigate the effects of ocean acidification, so it should have a positive impact on the marine environment."

Sources and Links:

Shell Oil funds "open source" geoengineering project to fight global warming, at:
Mongabay.com

'Turning back the clock on climate change' - A technology to reverse climate change? To reduce ocean acidification? And that also promises to increase food production? Cath O’Driscoll investigates, at:
Chemistry & Industry Magazine

Adding lime to seawater feasibility study, funded by Shell, at: 

Thursday, October 23, 2008

Removing carbon from air - Discovery Channel

 David Keith works to remove CO2 directly from ambient air Professor David Keith of the University of Calgary is working on a device that removes carbon dioxide directly from ambient air.

Keith has built a tower, 4 feet wide and 20 feet tall, with a fan at the bottom that sucks air in. Keith expects the air coming out at the top to have approximately 50% less carbon dioxide than the air coming in.

The tower features in an episode of Discovery Channel’s new “Project Earth” series on TV. The series has the largest budget of any in Discovery Channel’s history, and it may eventually attract a global viewership of more than 100 million.

The episode on Keith’s research has already aired in the U.S. - if you're missed it, you can watch it on Discovery Channel’s website, at: http://dsc.discovery.com/tv/project-earth/project-earth.html - click on “Episodes.”

If the program hasn't aired in your country, you may not get access to the online episode, but you can read more at: http://dsc.discovery.com/tv/project-earth/lab-books/fixing-carbon/guide1.html - also click on the links under "MORE CARBON".

The picture below describes the Big Picture of recycling, in which I envisage aviation to fund CO2 air capture. When talking about recycling, most people think about recycling of industrial products only. They may also see composting of organic waste as a (second) way of recycling. Instead of composting, I actually envisage organic waste to be burned by means of pyrolysis, in order to produce agrichar and hydrogen. I also envisage a third way of recycling that includes removing CO2 from the air. This CO2 could also be used for the production of agrichar and for commercial purposes such as to enrich greenhouses and for the production of building material, carbon fiber, etc. Furthermore, this CO2 could be used as fuel for aviation.

To tackle emissions by aviation, we can switch to airplanes and helicopters that are powered by batteries and hydrogen, or switch to fuels other than fossil fuel. Growth of algae could be assisted by such captured CO2, which could also be turned directly into fuel.

By financially supporting air capture of CO2 and the use of such CO2 to produce fuel, aviation could close the circle of this third way of recycling. This could make aviation environmentally sustainable. Since government is such a large user of aviation (both the military and civil parts of government), it makes sense for the government to start funding such air capture as soon as possible. An international agreement, to be reached in Copenhagen in 2009, could further arrange for the proceeds of environmental fees on commercial flights to fund such air capture and its use for fuel.

 Recycling, the Big Picture - by Sam Carana

Further links:
http://dsc.discovery.com/tv/project-earth/explores/carbon.html - Discovery Channel

http://www.ucalgary.ca/news/september2008/keith-carboncapture - David Keith

http://www.ucalgary.ca/~keith/AirCapture.html - David Keith

http://www.ucalgary.ca/~keith/Misc/AC%20talk%20MIT%20Sept%202008.pdf - M.I.T.

views.blogspot.com - by Sam Carana



The post below is added for archival purposes. It was originally posted by Sam Carana at knol in 2009, which has meanwhile been discontinued by Google. The post received 4513 views at knol.


Funding of Carbon Air Capture


HOW CAN CO2 CAPTURE FROM AMBIENT AIR BEST BE FUNDED?

FEES ON JET FUEL CAN HELP FUND THE DEVELOPMENT OF CARBON CAPTURE FROM AMBIENT AIR.


AIR CAPTURE of CO2 (carbon dioxide) is an essential part of the blueprint to reduce carbon dioxide to acceptable levels. Fees on Air Capture Fundingconventional jet fuel seems the most appropriate way to raise funding to help with the development of air capture technology.

Why target jet fuel? In most other industries, there are ready alternatives to the use of fossil fuel. Electricity can be produced by wind turbines or by solar or geothermal facilities with little or no emissions of greenhouse gases. In the case of aviation, though, the best we can aim for, in the near future at least, is biofuel or synthetic fuel, produced from CO2 captured from ambient air. As discussed below, development of these two forms of renewable energy can go hand in hand. 
Carbon air capture and production of synthetic fuel and bio fuel can go hand in hand
Technically, there seems to be no problem in powering aircraft with bio fuel. Back in Jan 7, 2009, a Continental Airlines commercial aircraft (a Boeing 737-800) was powered in part by algae oil, supplied by Sapphire Energy. The main hurdle appears to be that algae oil is not perceived as price-competitive with fossil fuel-based jet fuel.

Additionally, the aviation industry can offset emissions, e.g. by funding air capture of carbon dioxide. The carbon dioxide thus captured could be partly used to produce fuel, which could in turn be used by the aviation industry, as pictured on the top right image. The carbon dioxide could also be used to assist growth of biofuel, e.g. in greenhouses and in algae bags, as described below.
Algae can grow 20 to 30 times faster than food crops. As the CNN video on the right mentions, Vertigro claims to be able to grow 100,000 gallons of algae oil per acre per year by growing algae in clear plastic bags suspended vertically in a greenhouse. Given the right temperature and sufficient supply of light, water and nutrients, algae seem able to supply an almost limitless amount of biofuel.
The potential of algae has been known for decades. As another CNN report describes, the U.S. Department of Energy (DoE) had a program for nearly two decades, to study the potential of algae as a renewable fuel. The program was run by the DoE's National Renewable Energy Laboratory (NREL) and was terminated by 1996. At that time, a NREL report concluded that an area around the size of the U.S. state of Maryland could cultivate algae to produce enough biofuel to satisfy the entire transportation needs of the U.S.
Apart from growing algae in greenhouses, we should also consider growing them in bags. NASA scientists are proposing algae bags as a way to produce renewable energy that does not compete with agriculture for land or fresh water. It uses algae to produce biofuel from sewage, using nutrients from waste water that would otherwise be dumped and contribute to pollution and dead zones in the sea.

algae yieldThe NASA article conservatively mentions that some types of algae can produce over 2,000 gallons of oil per acre per year. In fact, most of the oil we are now getting out of the ground comes from algae that lived millions of years ago. Algae still are the best source of oil we know.

In the NASA proposal, there's no need for land, water, fertilizers and other nutrients. As the NASA article describes, the bags are made of inexpensive plastic. The infrastructure to pump sewage to the sea is already in place. Economically, the proposal looks sound, even before taking into account environmental benefits.

Jonathan Trent, lead research scientist on the Spaceship Earth project at NASA Ames Research Center, Moffett Field, California, envisages large plastic bags floating on the ocean. The bags are filled with sewage on which the algae feed. The transparent bags collect sunlight that is used by the algae to produce oxygen by means of photosynthesis. The ocean water helps maintain the temperature inside the bags at acceptable levels, while the ocean's waves also keep the system mixed and active.

algaeThe bags will be made of “forward-osmosis membranes”, i.e. semi-permeable membranes that allow fresh water to flow out into the ocean, while preventing salt from entering and diluting the fresh water inside the bag. Making the water run one way will retain the algae and nutrients inside the bags. Through osmosis, the bags will also absorb carbon dioxide from the air, while releasing oxygen. NASA is testing these membranes for recycling dirty water on future long-duration space missions.

As the sewage is processed, the algae grow rich, fatty cells that are loaded with oil. The oil can be harvested and used, e.g., to power airplanes.
In case a bag breaks, it won’t contaminate the local environment, i.e. leakage won't cause any worse pollution than when sewage is directly dumped into the ocean, as happens now. Exposed to salt, the fresh water algae will quickly die in the ocean.
The bags are expected to last two years, and will be recycled afterwards. The plastic material may be used as plastic mulch, or possibly as a solid amendment in fields to retain moisture.
A 2007 Bloomberg report estimated that the Gulf of Mexico's Dead Zone would reach more than half the size of Maryland that year and stretch into waters off Texas. The Dead Zone endangers a $2.6 billion-a-year fishing industry. The number of shrimp fishermen licensed in Louisiana has declined 40% since 2001. Meanwhile, U.S. farmers in the 2007 spring planted the most acreage with corn since 1944, due to demand for ethanol. As the report further describes, the Dead Zone is fueled by nitrogen and other nutrients pouring into the Gulf of Mexico, and corn in particular contributes to this as it uses more nitrogen-based fertilizer than crops such as soybeans.
The Louisiana coast seems like a good place to start growing algae in bags floating in the sea, filled with sewage that would otherwise be dumped there. It does seem a much better way to produce biofuel than by subsidizing corn ethanol.
Not Millions, but Billions of Dollars!
Carbon air capture could produce a form of renewable synthetic fuel that could be used to power aviation. Carbon air capture could also help produce biofuel to power aviation. It would therefore make sense to encourage development in carbon air capture by imposing fees on conventional jet fuel and by using the proceeds of those fees to help fund air capture of carbon dioxide.
According to zFacts.com, corn ethanol subsidies totaled $7.0 billion in 2006 for 4.9 billion gallons of ethanol. That's $1.45 per gallon of ethanol (or $2.21 per gallon of gas replaced). As zFacts.com explains, besides failing to help with greenhouse gases and having serious environmental problems, corn ethanol subsidies are very expensive, and the political backlash in the next few years, as production and subsidies double, will damage the effort to curb global warming.
On 15 May, 2009, U.S. Secretary of Energy Steven Chu announced that $2.4 billion from the American Recovery and Reinvestment Act will be used to expand and accelerate the commercial deployment of carbon capture and storage (CCS) technology.
At UN climate talks in Bonn, the world's poorest nations proposed a levy of about $6 on every flight to help them adapt to climate change. Benito Müller, environment director of the Oxford Institute for Energy Studies and author of the proposal, said that air freight was deliberately not included. The levy could raise up to $10 billion per year and would increase the average price of an international long-haul fare by less than 1% for standard class passengers, but up to $62 for people traveling first class.
In the light of those amounts, it doesn't seem unreasonable to expect that fees imposed on conventional jet fuel could raise billions per year. Proceeds could then be used to fund rebates on air capture of carbon dioxide, which could be pumped into the bags on location to enhance algae growth. Air capture devices could be powered by surplus energy from offshore wind turbines. With the help of such funding, the entire infrastructure could be set up quickly, helping the environment, creating job opportunities, making the US less dependent on oil imports, while leaving us with more land and water to grow food, resulting in lower food prices.
Cost of Carbon Air Capture
As to the cost of carbon air capture, GRT puts the current cost to harvest one ton of CO2 at $200 andestimates that, 2-3 years from now, it will cost about $150, while the price will come down to $30 to $20 as the technology is fully mature. 
Currently, carbon air capture isn't more expensive than to capture CO2 from smokestacks. The coal industry wants politicians to subsidize "clean coal", but current cost of capture (i.e. excluding transport and storage) is estimated at $100-150/tCO2 initially, possibly reducing to one third of that as the technology matures. That would price coal out of the market, while it doesn't even cover the cost of transporting the CO2 away from the plant and the subsequent sequestration, policing and monitoring all this over many years, etc.
Carbon air capture can be done at off-peak hours when cost of electricity needed for capture is low. Carbon capture from ambient air can also be done anywhere, meaning that it can take place on location, i.e. where the carbon is to be sequestered, which would save on the cost of transport. Or, even better, carbon capture can take place where the carbon is to be used for industrial or agricultural purposes, such as in greenhouses, algae bags or as soil supplements. By mixing carbon with hydrogen, the carbon can also be used to produce carbohydrates, i.e. synthetic fuel that could be used to power shipping and aviation. Such usage can help pay for the cost of carbon air capture.
 David Keith and his team are working to capture CO2 from ambient air Professor David Keith (left) of the University of Calgary is working on a tower, 4 feet wide and 20 feet tall, with a fan at the bottom that sucks air in. The tower looks like it's made mainly of plastic, which could be made with carbon produced by such a tower. Inside the tower, limestone or a similar agent is used to bind the CO2 and to split CO2 off by heating it up. The limestone is recycled within the tower, although it does need to be resupplied at some stage. Anyway, the main cost appears to be the electricity to run it. Keith and his team showed they could capture CO2 directly from the air with less than 100 kilowatt-hours of electricity per ton of CO2. At $0.10/kWh, that would put the electricity cost at $10 per ton.
In the U.S., each person emits about 20 tons of CO2 annually. In other words, each person in the U.S. could remove as much CO2 from the air with such a device, with annual operational costs of $200 for 2 Megawatt-hours of electricity. By comparison, a refrigerator consumes about 1.2 Megawatt-hours annually [2001 figures]. Of course, the additional cost of carbon disposal will make it more attractive to use large facilities at places where there's demand for carbon and where the associated economies of scale would facilitate lower operational costs. 

Towards a Sustainable Economy

The following comments were posted by Sam Carana under this knol:

Jul 19, 2010

There are several efforts under development to produce a carbon-neutral fuel. Two of them were recently described in article in New Scientist, entitled: Green machine: Cars could run on sunlight and CO2.
http://www.newscientist.com/article/dn18993-green-machine-cars-could-run-on-sunlight-and-co2.html
See also Sandia
https://share.sandia.gov/news/resources/releases/2007/sunshine.html

Whereas many may think that this is a good way to power cars, I agree with you that it makes more sense to have electric cars. However, aviation is a bit more difficult to clean up, that's why aviation in particular can benefit from such technology, and that would justify that aviation made financial contributions to fund such developments.

As air capture technology matures with financial assistance funded by fees on aviation, it will be in a better position to develop into a more general technology used to reduce CO2 in the atmosphere to more acceptable levels.
Jul 19, 2010
In my above reply, I referred to the use of concentrating solar power (CSP) plants to produce temperatures high enough to split water vapor into hydrogen and oxygen, and ambient carbon dioxide into carbon monoxide and oxygen. A team led by Athanasios Konstandopoulos has successfully managed to also split carbon dioxide into carbon monoxide and oxygen in this way. The hydrogen and carbon monoxide can subsequently be combined into hydrocarbons, i.e. synthetic oil.
http://www.newscientist.com/article/dn19308-the-next-best-thing-to-oil.html

Aug 27, 2010
An article in Nature describes the use of a solar cavity-receiver reactor to heat up non-stoichiometric cerium oxide to a temperature at over 1,500 °C, forcing the release of oxygen. Then, to re-oxidize it with H2O and CO2 at below 900 °C to produce H2 and CO – known as syngas, the precursor of liquid hydrocarbon fuels.
http://www.sciencemag.org/content/330/6012/1797

Jan 28, 2011

Milking algae

Instead of harvesting algae for processing into biofuel, there is prospect for "milking" the algae, i.e. extracting oil from the algae without killing them.

This method is followed by Joule Unlimited.
http://www.theglobeandmail.com/news/opinions/opinion/a-brave-new-world-of-fossil-fuels-on-demand/article1871149/

And also by Algenol, Synthetic Genomics (Craig Venter’s venture) and BioCee
http://theenergycollective.com/tyhamilton/50300/joule-cool-not-alone-quest-sunlight-fuel-game-changer

Jul 5, 2011

British company set to make renewable jetfuel

British company Air Fuel Synthesis plans to capture carbon dioxide from the air, and mix it with hydrogen extracted from water through electrolysis, in order to make liquid hydrocarbon fuels for transport, including for aviation.
http://www.airfuelsynthesis.com/technology.html
http://www.airfuelsynthesis.com/technology/technical-review.html
http://www.airfuelsynthesis.com/faqs.html