Oil Spill Removal Using Sorbent Carrying USWVpsrcentre.org/images/extraimages/35....

Oil Spill Removal Using Sorbent Carrying USWV

Navneet Krishna.Madhavann, Prasanna.Desikan

Abstract—Oil spill can be very hazardous to the environment as it affects the marine ecosystem and causes loss of aquatic life. In the present scenario, a lot of thought is being put in detecting the spill as soon as the accident has occurred. The amount of resources allocated to remove the spill is meager in comparison with the former. In this paper, we provide an insight on how to remove the oil spilled on the water bodies thus enabling us to save the coastal ecosystem. This paper summarizes the current trend in removing the slick, our innovative method and its effectiveness in doing the same. We propose to isolate the entire region of interest into segments leading to efficient cleansing of the polluted area. The USWV effectively utilizes the natural sorbent materials to adsorb the oil. This is an automated system which requires minimum human assistance to remove the lubricant. Keywords— Oil Spill, Sorbent material, USWV, Unmanned Surface Water Vehicle.

I. INTRODUCTION

N today’s oil hungry world, export and import of this non-renewable resource has become very vital in the development of every nation. During such exports, several

inevitable mishaps may tend to occur. This leads to spill of the oil over the water surface causing loss of aquatic life thereby creating an imbalance in the natural ecosystem. Such incidents may be either deliberate or accidental. With the increase in the movement of ships across borders there is a rise in the probability for such incidents. The current technology utilized to monitor these inter border shipping of oil is very expensive and not easy to implement. Apart from ship leaks, malfunction in oil wells can also pollute the water body. Proper maintenance and careful surveillance is very essential to prevent such unfortunate incidents. Standard and reliable devices for suction and transport of the oil from the seabed to the off shore location should be done with care and concern. Other sources of oil leaks are the mayhems that occur in pipelines that run under the water for several hundred miles. Prasanna Desikan is with Sri Sairam Engineering College, Sai Leo Nagar, West Tambaram, Chennai – 44 ( Phone: +91-9941436119; E-mail: [email protected]) Navneet Krishna Madhavann is with Sri Sairam Engineering College, Sai Leo Nagar, West Tambaram, Chennai – 44 (Email: [email protected])

Since they are at very low depths, optimum pressure and temperature should be maintained in and around the pipes so as to facilitate the proper transport of the lubricants. Absence of any of such parameters may lead to damage of pipes thereby releasing the oil into the water body. The release of this toxic pollutant will eventually cause heavy damage to the life under water. The major cause for such accidents is the lack of proper vigilance and ignorance of the authorities involved. However, these incidents cannot be completely avoided in several circumstances. Under such situations, it is very much necessary to detect the leak of oil. There are several methods to detect the oil leak. Some of the present scenario techniques used is the use of vessels, aerial surveillance and satellite. Vessels are utilized in places where oil sampling is required to detect the type of the oil but it covers only a limited area. Hence we use satellites for identifying the area affected. This is done by using Synthetic Aperture Radar [1] sensors.

But just the detection of leakage is not good enough as the repercussion has already begun. So the present trend concentrates on removing the spill as well. Dispersants, skimming and vacuuming of the lube are some of the recent techniques used in the process. The most effective amongst these methods is the use of dispersants. Dispersants are chemicals which act as catalysts which disintegrate the entire oil slick into several small oil droplets. These droplets are then naturally decomposed. However, the dispersants are chemicals and organic dispersants cease to exist. The chemicals used in its manufacture affect the marine habitat thus challenging their primitive use in saving the aquatic biome. Here we use USWV to remove the slick on the surface of the water. This is done by the use of sorbent materials which are tagged along with the USWV. This is a very eco-friendly and cheap methodology unlike the aforementioned techniques.

II. USWV – A PROTOTYPE

The use of an unmanned vehicle to remove the oil slick has not yet been introduced. Here, in this paper, we emphasize on the deployment of a completely autonomous vehicle to absorb the lubricant from the affected region. Our methodology consists of 2 phases: Phase 1 involving the deployment of the USWV and Phase 2 is use of the sorbent material to remove the slick. This material is then recovered by the USWV and returned to the mother ship. It can be deployed several times to cover the entire polluted area.

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3rd International Conference on Chemical, Ecology and Environmental Sciences (ICCEES'2013) January 4-5, 2013 Bali (Indonesia)

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mailto:[email protected]

mailto:[email protected]

A.USWV – Description In the current situation, ships are being utilized to remove

the oil leak. However, this method is very inefficient as the number of sorbent bags used to adsorb the oil is very small in number. Besides, once the bags are saturated the ship has to return to the seashore in order to replace materials. This is a very time consuming and expensive technique for removal. The USWV system scores in this situation.

B. USWV –Working The system is deployed from the mother ship which

carries the required sorbent bags. These bags are then attached to the rear of the USWV. The water vehicle is mounted with an appropriate engine in order to traverse through the surface water. However, the speed at which the USWV moves is set at a very slow pace so as to facilitate the absorption of the leak by the sorbent material. This is because very high speeds of travel on the surface of the oil slick will only aggravate the spread of oil. This additionally helps in keeping the sorbent bags afloat both before and after the absorption.

Fig. 1. Side view of USWV

Fig. 2. Top view of USWV

Fig. 3. Front view of USWV

The fig 1 gives the image of the side view of the USWV.

The body is dome shaped in order to make it easier to traverse through water. The body is attached with a wing shaped protrusion on which the hull is mounted. The propeller is attached to the rear of the hull. The load, in this case, sorbent material is attached to the rear of the body. Fig 2 provides the top view of the image and fig 3 gives the front view.

1) Phase 1: Deployment The images of detected oil are obtained from the SAR

sensors. This image is now analyzed and the area spilled with oil is extracted. The extracted image is then utilized for the removal process. The affected area is divided into several sub parts and GPS points are set within individual sub divisions.


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Fig. 4. SAR image locating oil spill[2]

The fig 4 gives the location of the oil spill by demarcating

the lubricant from its surrounding. This image is now segmented into several parts based on the sorbent material being used. Every absorbent has its saturation point and sorbent materials are not an exception to it. Based on the absorbing capability of the material used, the area is computed and the segments are divided based on the results obtained from this calculation. After segmentation of the images, each segment is analyzed and the GPS points are set a few feet away from the exterior outline of the dark region within each segment as in fig 5. The few extra feet are given in order to sweep through till the end of the border since the absorbing material is attached to the rear of the USWV. This ensures the proper and complete coverage of the region of interest.

Fig. 5. Image segmentation and set GPS points[2]

But the problem arises when the vehicle moves only along the designated GPS points. In order to cover the entire region of interest we propose the following algorithm. This algorithm helps in covering the area without any unnecessary movements of the vehicle thereby making it fuel efficient.

Fig. 6. USWV traversing algorithm from central point 1


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Fig. 7. USWV traversing algorithm from central point 2

The algorithm is used for preventing the USWV from visiting the cleansed area more than once as shown in fig 6 and 7. For this purpose, we set each of the GPS points as a central point. By taking one central location at a time, the USWV is made to visit the rest of the GPS points and return to the set central point. After one complete cycle of visiting is over, the next immediate GPS point is made as the next central location. The same procedure of making the USWV visit the other GPS points is done. However, it does not move along the direction of the first set central point as the slick along that path has already been removed. Thus, the cycle continues with change in the central points until all the GPS points have had their share of being the central location. In the above figures, the red dot represents the central location and the black dots represent the secondary GPS points. By this methodology, we hope to cover almost the entire region. The following image gives a flowchart for the proposed algorithm.

Fig. 8. Flow Chart of the proposed algorithm

2) Phase 2: Removal of Slick The mother ship from which the USWV is deployed contains the required sorbent bags as well. Both the new and utilized bags are placed within the ship. Once the USWV is floating, a boom from the ship is used to attach the sorbent bag on to the rear of the vehicle. Based on the segmented area and size of the sorbent bag, the number of USWVs used to carry the absorbent can be increased. It is then deployed along the set GPS points to adsorb the toxic. After covering a particular segmented region, the USWV returns back to the central point and then to the mother ship so as to replace the utilized sorbent bag with a new one. The entire process continues and the slick is removed slowly and steadily.

III. SORBENT MATERIALS

A sorbent is a material which is used to absorb or adsorb liquids. Based on their composition they can be made to remove the required material. For sorbents to work effectively in removing the oil, they should basically repel water and be attracted towards oil i.e. oleophilic by nature .Most of the sorbents adsorb oil rather than absorb. This is because adsorbing materials have more affinity towards oil than absorbing mediums.

weight of sorbent used-weight of unused sorbentSorbencyweight of unused sorbent

=

Though synthetic and inorganic form of these adsorbents is available, we prefer to use organic sorbent materials. This is because the former materials can pollute the environment if proper care and vigilant disposal methods are not followed. There are several sorbent forms like bulk, rolls, sweep, sheets, booms and many more. We intend to use sorbent booms as they have larger capacity and structural strength in comparison with the rest of the forms.

Fig. 9.Sorbent booms (adapted from IB times)

Start

P(i,j)=P(j,i)

Already Traversed

Not yet Traversed

Search for new route

Follow the GPS points

End

Return to central point


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Fig. 10. Sorbent booms[3]

Sorbent materials are mostly used in the seashores. They are also currently in use in various ships. However, large number of booms cannot be easily carried in the current methodology as shown in the fig 7 below. After the entire sorbent bag is saturated, the ship has to return to the seashore in order to dump the oil soaked sorbent and replace it with a new material.

Fig. 7.Ship with Sorbet booms (Adapted from Washington Post)

In USWV we attach these sorbent booms to the rear. According to the GPS points which have been already set, the USWV moves according to the algorithm and thus the leak is adsorbed. The USWV returns to the mother ship after completing the patrolling along the GPS points. Again a boom from the mother ship is used to detach the utilized sorbent from the rear and a new material is attached to the same. The following table gives the various forms of sorbent materials that are available.

TABLE I DIFFERENT SORBENT

FORMS[3]

Material Benefits Disadvantages • Organic-

including bark, peat, sawdust, paper-pulp, cork, chicken feathers, straw, wool and human hair.

• Often naturally abundant or widely available as waste by-product of industrial processes

• Can be low cost

• Difficult to control, can be spread by the wind

• Difficult to retrieve • Oil and sorbent

mixture can be difficult to pump

• Inorganic-vermiculite and pumice

• Can serve to protect wild life at haul-out sites

• Disposal of oil sorbent mixture more limited than oil alone

• Synthetic-primarily polypropylene

• All the above bulk materials can be enclosed in nets or mesh

• More straight forward to deploy and retrieve than loose sorbent.

• Enclosed boom has a greater surface area than continuous boom

• Structural strength limited to that of the mesh or net

• Organic booms can rapidly become saturated and sink Oil retention is limited

• Synthetic-

primarily polypropylene

• Long-term storage • Relatively straight

forward to deploy and retrieve

• High oil recovery ratio possible if used to full capacity

• Limited efficiency for weathered or more serious moils

• Do not readily decompose limiting disposal options

• Synthetic-primary polypropylene

• Effective on weathered and more viscous oils

• Less effective on fresh light and medium oils

IV. CONCLUSION

The USWV is much more fuel effective and eco friendly in comparison with other forms of oil removal techniques. This system is a very simple yet effective method to extract the oil spilled throughout. It retains the natural habitat as such without affecting the marine ecosystem. Thus the USWV system with the aid of sorbent keeps the aquatic life safe by removing the toxic slick.

REFERENCES

[1] Dark Formation Detection, Feature Extraction and Classification Algorithms Konstantinos N. Topouzelis Joint Research Centre (JRC), European Commission, Via Fermi 2749, 21027, Ispra (VA), Italy.

[2] Example of oil spill detection during the Prestige Oil Crises (ASAR ENVISAT Wide Swath product, Nov. 17 2002).

[3] Technical Information Paper by The International Tanker Owners Pollution Federation Limited.


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Abstract— Environmental economics postulates the

assumption of homo economicus and presumes that externality occurs as a result of the rational economic activities of economic agents. This paper examines this assumption using an experimental economic approach in the context of regime shift, which has been receiving increasing attention. We observe that when externality does not exist, economic agents (subjects of experimemt) act economically rationally, but when externality exists, economic agents avoid the risk of a regime shift that would have negative consequences for others. Our results suggest that environmental economics may have to reconsider the assumption of homo economicus.

Keywords—homo economicus, unboundedly rational economic agents, regime shift, experimental economics.

I. INTRODUCTION AINSTREAM economics asserts that economic agents are selfish and that households and firms maximize their

utilities and profits, respectively. As is well known, the assumption of homo economicus is underlying behind such explanations, where unboundedly rational economic agents are supposed. It is general knowledge that social welfare will be maximized as a result of selfish economic activities by unboundedly rational economic agents.

In some situations, however, market failures will occur under the abovementioned situations; an example would be externalities in the form of environmental issues. Mainstream economics has treated externalities as exceptional cases whereas environmental economics has regarded externalities as frequent events and has built the subject to treat issues attributed to externalities.

Until now, environmental economics has expressed disagreement with the fact that mainstream economics treats externalities as exceptions, but has connived at the assumption of homo economicus. Further, it examines solutions for externalities using tax, permit and other environmental policies. However, recently, doubts have been raised whether sustainable development can be achieved under the assumption of homo economicus (Becker [2]). In addition, many have argued that in the context of environmental economics, homo economicus and related agencies be replaced with other agencies such as homo

Yukichika Kawata is from the Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan (phone: +81-(0)155-49-5424 ; e-mail: [email protected]).

biologicus, homo corporativus, homo ecologicus, homo politicus, and homo sustinens (Becker [2], Bastien and Cardoso [1]). Kahneman [5] suggests that economic agents are boundedly rational and a series of results of ultimatum games seems to support his suggestion.

In this paper, we apply experimental economic methods to empirically examine the difference between a real human and homo economicus. We study regime shift, which has recently been receiving increasing attention and examine the behaviours of economic agents in the context of environmental issues using experimental economic approaches. Regime shift is a phenomenon where the environment changes catastrophically. The catastrophe theory was advocated by the French mathematician René F. Thom in the 1960s and covered in Thom [9]. Recently, many related studies—Scheffer et al. [8] and Scheffer and Carpenter [7]—have been done in the context of ecology or environmental management. To the best of the author’s knowledge, there is no existing research which treats regime shift in environmental issues as a topic of experimental economics.

II. MATERIALS AND METHODS The subjects were the attendants of the Agriculture and

Economics class, which is one of the author’s relay-type lectures at his university. In fiscal 2009, there are 201 freshmen in the university. The number of students who take this class is 163 (92% of the attendants are freshmen), of which 148 students attended the author’s lecture. The lecture and the experiment were performed on 3rd June 2009, when the freshmen were almost 2 months old. Almost all of the attendants will select an area of specialization other than economics in the future and we can regard that most of the students do not have any special knowledge of economics or any considerable concern related to economics. The 3rd June class lasted 90 minutes: an 80-minute lecture followed by a 10-minute questionnaire.

It is pointed out that those who have studied economics tend to be selfish (Marwell and Ames [6], Frank, Gilovich and Regan [3]-[4]). In the class, the author briefly explained that mainstream economics supposes selfish and unboundedly rational economic agents using simple examples. Before starting the experiment, the author clearly stated that subjects (students) can select whether or not they suppose selfish economic agents when they answer the questions. By doing so, it could be expected that some subjects reply based on rational economic decision making and others reply based on some other

Decision Making under Ecological Regime Shift: An Experimental Economic Approach

Yukichika KAWATA

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