Memo 3: Annotated Bibliography: Virtual Trees

To: Professor MacBride

From: Richard Chan, Amanda Huang

Date: April 15, 2013

Re: Artificial Trees

Artificial Trees: The Annotated Bibliography

1. Keith, David W., Minh Ha-Duong, and Joshuah K. Stolaroff. “Climate Strategy with Co2 Capture from the Air.” Climatic Change 74, no. 1–3 (January 2006): 17–45.

This journal article goes into detail the thermodynamics, physics, mathematics, chemistry and other limits of carbon capture. This is a hypothetical set of calculations, with the intent to identify the outer limits of this particular carbon capture technology, and using it as a baseline for more realistic scenarios. It then extrapolates from those hypothetical limits a more reasonable cost-benefit analysis argument, identifying energy outputs and costs, both physical and economic, as well as a predictive risk analysis of atmospheric carbon levels with and without the carbon capture technology, as well as various scenarios, presumably to cover the range of best- and worst-case scenarios. The appendices of this article are ripe with data, and more critically, an almost step-by-step analysis of an example carbon capturing tower device. All of the information is made with the presumption and notion that such technology is well within reach by current standards, and has simply yet to be implemented on a large scale.

This source is incredibly rich in detailing many important variables regarding carbon capture technology. While the example is not exactly an artificial, carbon-capturing “tree”, it uses the same chemical process, and functions fairly similarly, if not identically, as that which is described by the artificial tree and carbon capture pioneer Klaus Lackner. The source details the energy required for carbon capture (that is, in Joules), the space in which such technology must be deployed in (the amount of carbon captured within a time frame), the costs that would entail the capture of carbon, and future projections depending on how this technology is implemented. Appendix B shows, in extreme detail, how such a device will work, down to the chemical reactions of sorbents and recycling sorbent materials, with an example device with hypothetical conditions, as well as an excellent diagram of the process. Such a description will be paramount in relating this technology into realistic terms, as it may provide a foundation in which further extrapolatory analyses may be considered, beyond the scope of the article and implemented on a New York City scale.

2. Lackner, Klaus S., Patrick Grimes, and Hans-J. Ziock. “Capturing Carbon Dioxide From Air,” 2001.

Capturing Carbon Dioxide from Air explores the feasibility of air extraction in terms of technology and cost. Though alternative sources to carbonaceous fuels have been proposed, Klaus, Grimes, and Ziock argue that this technology poses multiple obstacles. For starters, it is not economically beneficial. It would also take much longer to make the transition to alternatively-fueled vehicles and may render existing energy and transportation infrastructure obsolete. Carbon dioxide capture, on the other hand, could collect CO₂ emissions after the fact, from any source, does not require a network of pipelines to the disposal site, and can be implemented virtually immediately.. The burden of the cost lies more in sorbent recovery than the actual process of capturing. Essentially, the atmosphere would serve as a temporary storage and transport system.

Klaus, Grimes, and Ziock then do a dimensional analysis, concluding that extracting CO₂ is more efficient than collecting wind energy. Their analysis estimated that using alkaline solutions of Ca(OH)₂ as a sorbent will result in $10-$15 per ton of CO₂ and 3 cents worth of coal per gallon of gasoline. Though there is energy and CO₂ released during this process, it is significantly lower than what it removes. The cost could still be lowered by using other sorbents with lower binding energies and chemical kinetics. The researchers also explored the overall scale of capturing carbon. This source details preliminary research and exploration performed by Klaus and his team prior to development of artificial trees. These beginning studies lead to the feasibility of the extraction of CO₂ from the air, as well as further investigation of other potential solvents and process design.

3. Figueroa, José D., Timothy Fout, Sean Plasynski, Howard McIlvried, and Rameshwar D. Srivastava. “Advances in CO2 Capture technology—The U.S. Department of Energy’s Carbon Sequestration Program.” International Journal of Greenhouse Gas Control 2, no. 1 (January 2008): 9–20. doi:10.1016/S1750-5836(07)00094-1.

This journal article is about the governmental pursuit of reducing carbon dioxide from the air. It addresses the United States’ concern over the rate at which carbon dioxide concentration is increasing, and will increase in the coming decades. The article describes three potential solutions to solving the problem of exhaust output from productions facilities: post-combustion, pre-combustion, and oxy-combustion systems. Post-combustion methods involve the removal of carbon dioxide after the fuel is burned, via the flue gas. Pre-combustion methods involve the removal of carbon dioxide prior to burning, which may result in the production of (and subsequent use of) synthetic hydrogen gas. Oxy-combustion methods emphasize the concentration of carbon dioxide within the flue gas, which, when burned, leave primarily water and carbon dioxide, resulting is more ease in extracting the carbon dioxide for sequestration. Each technique has its own advantages, disadvantages, and limitations of application; thus, every option is explored to maximize usage in their respective niches.

This particular article does not explain how an artificial tree works. Rather, it explains a separate yet intriguingly similar technology: extracting and siphoning carbon dioxide from power plants. While artificial trees are intended to scrub relatively ambient air for carbon dioxide, these techniques are meant for generally more concentrated levels of carbon dioxide, given their proximities to heavy levels of exhaust. Thus, this article provides an effective backbone to our research on artificial trees. Its lengthy supplementation of various sorbent technologies, explained in fair detail and quite vital in understanding not only Klaus Lackner’s intended design, but alternatives as well. The governmental backing of this article lends much credibility in the success of such technology; as Lackner’s designs are essentially an offshoot from carbon capture filters for power plants, implementation of this technology within New York City seems more realistic and predictable, however improbable an actual implementation of artificial trees may or may not be (it’s a bit of arguing “if so, then why not”).

4. Anderson, Soren, and Richard Newell. “Prospects for Carbon Capture and Storage Technologies.” Annual Review of Environment and Resources 29, no. 1 (2004): 109–142. doi:10.1146/

This journal article describes broadly the feasibilities of carbon capture and storage technologies. It goes into some detail about various techniques of capturing carbon, from flue gas scrubbing to gasifying coal to oxy-combustion. It also compares the application and costs of carbon capture technology to several key industries, ranging from oil refining to cement mixing, that produce significant amounts of carbon dioxide exhaust. It then goes on to describe the costs and methods of moving and sequestering the carbon dioxide for more permanent storage. Finally, it lists alternative uses for carbon dioxide, aside from sequestering it into reservoirs, as well as address concerns regarding the storage and transport of carbon dioxide, especially the potential for leakage. Much of the article speaks in terms of costs and rates, as well as potential hazards. There is also some arguments for using carbon capture and storage technology for electricity generation, with accompanying models.

The major addressing point that we will derive from this article is the sequestration aspect. Most of the other sources focus primarily and extensively on the capture aspect, but few address the costs of what to do with that captured gas. The costs of piping carbon dioxide is laid out in a surprisingly simple equation (which, while being wary in its overly simplistic form, will nevertheless provide a bedrock for further calculations). Details into the effectiveness of certain reservoirs provide us with a way to analytically calculate the storage of locations nearest New York City (given that the Marcellus Shale Formation is obviously out of the question). Thus, two contingencies are covered: if nearby reservoirs are impractical, then pipeline costs is primary to reservoir costs, and vice versa. The idea of oceanic sequestering is incredibly intriguing, and should be considered an option (albeit a very hazardly one), given New York City’s geographic position.

5. Lackner, K. S. “Capture of Carbon Dioxide from Ambient Air.” The European Physical Journal Special Topics 176, no. 1 (September 1, 2009): 93–106. doi:10.1140/epjst/e2009-01150-3.

Unlike the journal article of a similar title, Lackner here goes into fine detail about his studies that culminated in a prototype carbon dioxide collection device. He uses a great deal of values and rates to describe the amount of energy needed to facilitate the scrubbing reaction, from mols to wattage. Several equations and scientific concepts set the backdrop for his concept of a passive, sorbent-based air collector. The concept is fraught with numerical details, considering variables such as wind speed and size of the collector. He also goes on to consider the type of sorbent material to be used in his concept device; rather than generic chemicals such as sodium hydroxide, his sorbent, amine-based resin seems more proprietary. His experiments and subsequent modifications then resulted in a prototype, one that could capture more carbon dioxide than it would produce via electricity. Finally, he leaves a word on future possibilities, including larger-scale and/or more efficient products.

This journal source is essentially the prime source about artificial trees, given Lackner’s involvement in this field more than anyone else (presumably, from data-gathering). Lackner puts forth all manner of scientific vernacular in describing his concept of an artificial tree to a tee. It also provides a level of redundancy with journal articles like that compiled by Keith, et. al. For the finest levels of detail, it would be paramount to use this source as the baseline for other articles to compare with, from construction technique to rate of scrubbing to sorbent material; it can also bind information from flue gas scrubbing of power plants and such, which use similar technology. With sufficient data concerning the conditions of New York City, it shouldn’t be too difficult to hypothetically, if not realistically, apply Lackner’s prototype to a cityscape or surburban scenario. The details to his sorbent resin material, which is never named, though is dealt with in depth, is vital in its own right in assessing his design, which may not be possible with generic sorbents.

6. Herzog, Howard J. “Peer Reviewed: What Future for Carbon Capture and Sequestration?” Environmental Science & Technology 35, no. 7 (April 1, 2001): 148A–153A. doi:10.1021/es012307j.

This article explores carbon sequestration that calls for enhancing uptake of CO₂ in natural sinks (soils, vegetation, and/or the ocean). The concept behind carbon capture and sequestration is derived from similar technologies used to lower SO₂, NOₓ, and particulates, and other pollutant emissions. This article is extremely useful in detailing the sources to capture and store anthropocentric CO₂. Prime sources to capture large quantities of carbon dioxide can come from industrial processes, power plants, or producing hydrogen fuels from carbon-rich feedstock. This carbon can be stored in geological sinks, such as deep saline formations, depleted reservoirs, and coal seams. Sequestering the carbon can be done by a combination of displacement, dissolution, and reaction of CO₂ with present minerals.

The article went on to discuss the Sleipner Project, which is the first commercial use of carbon capture and sequestration technology. Sleipner is being carefully monitored as it sets the precedent for future potential CO₂ injection projects. Other programs, such as the Research Institute of Innovative Technology for the Earth are also discussed and explored as foundations to further projects. It is essential to study these projects to ensure that sequestration is safe, practical, and environmentally sound. Since the ocean and atmosphere are ever changing, it is estimated that 15-20% will escape over a few centuries. In extremely high concentrations, CO₂ can cause suffocation. Though geological formations are thought of as insensitive, some are located near populated areas. The article argues that the best way to address these safety concerns is to conduct more simulated and closely supervised projects.

*Cited using Chicago Manual Style (full note).

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