Wednesday, January 23, 2013

Emergy Evaluation of the IBK-recirculation aquaculture system

Emergy Evaluation of the IBK-recirculation aquaculture system for fisheries production in Korea

Puji Rahmadi, Suk Mo Lee*
Department of Ecological Engineering, Pukyong National University

       A continuous decrease in fisheries capture production led Korea to pay greater attention on aquaculture. The Intensive Bio-culture Korean (IBK)-system has believed as a solution method for fisheries production.  This study was trying to analyze the energy and emergy flow inside the IBK-system. Further analysis was done with emergy indices calculation to predict the future application of IBK-system. The result of study shows the energy required in fish harvested from IBK-system (fish transformity) was 2.26E+09 J/g fish. This number represents it is needed more energy to produce per gram fish in IBK system compared to conventional fisheries in Ecuador and in Sri Lanka, but less energy needed than intensive aquaculture in China.  The EYR in this study was 1.02, even though the number is relatively low, this system has accepted to be consumer products or transformation steps than actual energy sources since the value is higher than 1. The value of ELR and EIR was pointed in the same number (68.74) because the system doesn’t have non-renewable sources, which is purchased input compared to renewable environmental loading (F/R). System more likely depend on purchased input which was indicated by very high EIR but in contrary relatively low EYR. Even though the EYR is low, EIR and ELR are high, and ESI has shown high risk condition, it doesn’t mean the system is not feasible to operate. In the real condition, higher price per kilogram fish could bring higher benefit in term of economic, therefore this system only suitable to apply in developed countries with limited area, limited of natural sources and fish consumptions relatively high.
Keyword: Emergy, Intensive Bio-culture Korean System, emergy indices

1.      Introduction
Korea is a peninsula with long coastline and covering huge number of islands within the territory. Endowed with an abundance of fisheries resources, Koreans have developed a distinct fish food culture-based on marine products (FAO, 2003). Aquaculture production has increased from 667,883 tons in 2000 to 839,845 tons in 2003 and 935,650 tons in 2009 (FAO, 2003; KOSTAT, 2010). Aquaculture has become a very important sector in the Republic of Korea. It provides food security, revenue and employment to the country. With the development of new technologies, aquaculture production has increased more than 40% of total fisheries production in 2010. In Korea fisheries production generally drives to the degradation of water quality in coastal, causing seawater intrusion and some places event reducing the quality of drinking water, and degradation of natural stock. Therefore, fisheries production should be practiced with waste water treatment for the reduction of pollution in the environment. The best solution believed by the ecologist and fisheries realm to produce sustainable fisheries production in the future is feeding aquaculture in inland water and in the protected coastal seas with the certain aquaculture method. Therefore we need to develop the technology of environmentally friendly aquaculture systems as completely as possible not only to preserve our natural environment but also to sustain aquaculture production.

Korea has a small land area and highly limited for water resources. The pollution of water and air has been a serious problem for the survival of the nation. Therefore several fisheries production method applied in some country like China, Sri Lanka, Ecuador or Philippine were not applicable in small developed country such as Korea and the other country with similar characteristic. In Philippine, Sri Lanka and even Ecuador (Bergquist, 2008; Odum&Arding, 1991), the conventional method and traditional way were still dominant, but in China they had practicing intensive aquaculture but still using huge area to produce fish in the aquaculture (Li, L., et al, 2010). In l998 the central government of Korea declared that all cage farms in the inland waters be discontinued after the terms originally permitted, almost all of which fall in before l999. Majority of the cage fans has already been dismantled. The bulk of freshwater fish has so far been produced from the net cage farms. The only substitution for outgoing fish production from the cage farms is expected by the development of the closed recirculating fish culture system which should be environmentally friendly as well as economically feasible especially in the era of the global open market. Recently recirculation aquaculture system (RAS) is well developed regarding as the best solution to substitute in fisheries production method. Considering the limit of water supply for fish growing experiments, many of researchers have been using closed recirculating aquaculture systems (RAS) for various fish growing experiments in the laboratory. This recirculating aquaculture system has been developed and redesigned as an Intensive Bio-production Korean System (IBK System). The IBK system, which was originated from the system by Professor In-Bae Kim (Korea-US Aquaculture, 2008) has continued improvement though modification up to now. Main principles for the system development of the RAS have been based on the basic principles for the high-density fish culture. The system design is very simple and does not employ highly sophisticated parts. The system structurally consists of rearing tanks, small sedimentation tanks, a pumping station, and multiple sections of the biological filter.
In order to increase fisheries production, fish farmer should consider the risk and negative effect of production activity to the environment. Therefore, before IBK-system could be well applied, it is better to explore the benefit and feasibility from the system. In this research, an aquaculture system of IBK-system was analyzed and emergy analyses were done to determine the efficiency and potential of sustainability. In the economic realm, typically we will easily calculate the amount of capital and yielded production to predict or analyze the benefit, yet when we try to compare the economic and the impact of production activity into our environment, we must be facing the constraints in terms of units, proportion and so on, here therefore the EMERGY method could be apply. Odum (1983, 1988, 1996) using the principles of Energy Systems Theory developed a comprehensive ecological economic evaluation method (i.e., emergy synthesis) to evaluate different energy, material and monetary flows in terms of their emergy. Emergy is defined as the amount of available energy of one type previously used up directly and indirectly to make a product or service (Odum, 1996), usually expressed as solar emjoules (sej). Emergy per unit values, i.e., transformity (sej/J), specific emergy (sej/g) and emergy/money ratio (sej/money unit), can be used to convert energy, material and monetary flows of all kinds to solar emjoules allowing direct comparison, addition and subtraction among them (Lan et. al., 2002). Thereby, emergy analysis can evaluate properly environmental contributions formerly missing from economic evaluations (Odum, 1988, 1996, 2007; Lanet. al., 2002).
  Since the IBK-system has considered as ones of solution methods on fisheries production, analysis of system efficiency are needed. The analyses were purposed on viability, benefit, and sustainability potentials from the system. In order to analyze economic and ecological factor, emergy analysis were then try to apply. Emergy analysis had completed with some emergy indices calculation, to describe and to predict the present condition also thereafter. Based on emergy analysis and those indices, some recommendations are expected for the application of IBK-system.

2.                     Material and Method
Generally there are three main approaches to do emergy analyses (input, process and output), but various intermediate forms exist. Therefore emergy analysis can be done simply through some steps, which are; determining the boundary, defining the important source, listing the process, diagraming energy flows, composing emergy table, and indices calculation.
In emergy analysis, each form of energy supporting the system will be translated into the same energy quality (mostly solar energy). The translations of energy could be done through conversion ratio, this ration called “transformity”. Base on the transformity, various kind of energy could be converted into the same kind of energy and can easily analyze each contribution to the system. In this study we also try to collect the raw data from each energy supporting the IBK system, and converted those data into solar energy equivalency. Furthermore, emergy indices are used for better evaluation of the concerned system. These indices indicate various performance of the system in term of efficiency and sustainability (Campbell, 1997). Associated with an aquaculture, some basic indices of ecological interest (Odum and Odum, 1983; Ulgiati et al., 1995; Odum, 1996; Brown and Ulgiati, 1997; Ulgiati and Brown, 1998) are calculated, those were Emergy Yield Ratio (EYR), Emergy Investment Ratio (EIR), Environmental Loading Ratio (ELR), and Environmental Sustainability Index (ESI).

2.1.      Application of IBK- system
The IBK system has been successfully tested to grow a number of freshwater fish species including tilapia, Israel strain of common carp, channel catfish and eels both Anguilla japonica and A. anguilla, but in this research, tilapia farming is the major species cultured in the experiment system; therefore tilapia culture using IBK-system has been evaluated by emergy analysis. IBK-system subjected for this experiment was located at Sangju, Gyeongsang Bukdo, South Korea. The system was built 30 years ago and will last long for 10 years more before the renovation. This system was made and designed for growing of fish at high densities with the minimum natural sources. Author was visiting, survey and interviewing the system in charge person. System was built on the area of 750 m2, inside the greenhouse with phenyl as a cover. There were 24 culture tank with some sediment chamber and bio-filter tank. The system could hold 400 m3 of fresh water as a media culture. This system was using daily exchange water about 1% of total volume, and whole water body was changed annually. 

Fig. 1. Sketch of IBK-system

Normal density of tilapia in this system has been at least 5% of the water volume in the rearing tank and could keep on normal growth until higher than 10% to 20% of water volume though the growth rate was decreased. Fingerling was used as a starter in a culture with the number of 500 individual per tank, along with the culture time (1 year) it will have survival rate about 80% and could achieve the harvesting size ±850gr/indv. Instead of fingerling, fish farmer should prepare the suitable feed for fish. In this experiment, farmer divide feeding regimes into 4 different group, those were <100 gr, <250 gr, <500gr, and >500 gr of body weight (BW), with the feeding ration of 2%, 1%, 0.7%, and 0.5% of BW respectively. Using those different feeding regimes, farmer counted to spend 7941 kg of feed/yr.
Korea is a country with the winter season; it is always being the problem for aquaculture in temperate country. To solve this problem, farmer in this experiment using boiler to keep the water temperature. Boiler consumes 300 L of fuel in average for a year.  The other cost which should be loaded by farmer were electricity as much 3650 kWh/year, labor cost, system maintenance cost 1.5 million/year, water quality and diseases controlling cost for 1.5 million/year. Detail of cost and energy spends by farmer will then converted into emergy unit which is listed in the Table 1.

2.2.     Energy Diagram
For better understanding, evaluating, and simplify, procedure of emergy analysis always start with diagraming the system of concern and followed by emergy table. The diagram of energy flow in the IBK-system were then has composed to figuring the energy circulation in the system.

2.3.     Emergy Table
Data which was collected in this experiment were listed into emergy table, priority has been made, and all energy was converted into solar energy equivalency using some transformity which has been published in some references.

2.4.     Emergy Indices
2.4.1.      Emergy Yield Ratio (EYR)
EYR is the ratio between total emergy feedbacks with the total emergy yield. In EYR, to avoid losing out from the point of view of energy, the output of a system should be at least equal to the investment that is when the emergy yield ratio is equal to one. The higher the value of this index, the greater the return obtained per unit of emergy invested.

2.4.2.      Emergy Investment Ratio (EIR):
EIR is the ratio of purchased resources to renewable and nonrenewable local inputs. It will tend to be economical if its ratio is less or equal to the one prevailing in the region (Odum, 1996). The less the ratio, the less the economic cost, so the process with lower ratio tends to compete, prosper in the market (Li, L., et al., 2010).
EIR = F/(R+N)

2.4.3.      Environmental Loading Ratio (ELR):
ELR is given by the ratio from purchased and nonrenewable local inputs, to the emergy from renewable resources. It is an indicator of the pressure of a transformation process on the environment and can be considered a measure of ecosystem stress due to a production. ELR = < 2 indicate of relatively low environmental impacts, when the number of ELRs = 3 – 10 indicate of moderate environmental impacts, otherwise ELRs = > 10 indicate of extremely high impacts to the environmental due to largeflows of concentrated nonrenewable emergy (Brown and Ulgiati, 2004).
ELR = (F+N)/R

2.4.4.      Environmental Sustainability Index (ESI)
This index is used to analyze the environmental and ecological sustainability in order to support the viability (continuity) of process. The larger the ESI, the higher the sustainability of a system.

3.                     Results and Discussions

  3.1.Energy Diagram

Fig.2. Diagram of energy flow in the IBK-system.

  3.2.Energy Table
Table 1. EMERGY evaluation of IBK-system in Korea, annual flow per m2
Data / Units
Solar Emergy
Em value
(J, g, ) / yr
Environmental Input

Pumped Water

Purchased Input

Good and Service

Maintenance Cost
Water quality control Cost
Disease control cost
Farm Installation

    a. Stone
    b. Sand
    c. Concrete
    d. Iron + Steel
    e. Phenyl

Annual yield (Y)

a). Brown & Bardi, 2001; b). Naam kook, 2001; c). Brown, 2011; d). Odum, 1996; e). Jin A, 2010; f). Campbell and Brandt-Williams, 2005; g). Brown and Buranakan, 2003; h). Odum & Odum, 1983; i). This study. All the Transformity for solar emergy equivalence was converted to 15.83E+24 sej/yr baseline.

Table 2. EMERY indices of fisheries production in Korea and other systems

This Study
This Study
Li, et al., 2010
Li, et al., 2010
Li, et al., 2010
fisheries in Philippines
Bergquist, 2008
fisheries in Sri Lanka
Bergquist, 2008
Fisheries in Ecuador
Odum & Arding, 1991

The results of study were listed in the Table 1 and Table 2 following. The data shows transformity for fish produced by IBK-system is 2.26E+09 J/g fish. This number was far higher compare to pelagic fish and ponded shrimp from Ecuador also semi intensive shrimp production in Sri Lanka, which only 2.20E+05 J/g, 3.17E+07 (Odum & Arding, 1991) and 8.11E+06 J/g respectively (Bergquist, 2008). Those mentioned aquaculture were using conventional method, out door and wide area of production, therefore the system more likely to dependent on natural resources and need less energy from purchased input. However fish transformity in this study was not really high compared to the same high-technology aquaculture applied in china, which were 5.79E+09 J/g fish for weever, 7.77E+09 J/g fish for ophicephalus, and 7.79E+09 J/g fish for eel culture. Those mentioned result shows while aquaculture method involving technology; the higher technology used the higher emergy needed to produce fish. However, when we look back the emergy table, there shows extra energy was swelled up from purchased input than from environmental loading, since the technology needs extra energy to maintain. Study were continued to analyze the factor supporting the processes on IBK-system, therefore emergy indices were calculated.

  3.4.Emergy Indices
3.4.1.      Emergy Yield Ratio (EYR)
Analyses of EYR and other emergy indices from Table 1 were shown in Table 2. The EYR in this study was 1.02 and was the lowest compared to EYR in other several fisheries productions. In term of emergy, this EYR number describing there was almost no energy benefit from system (benefit only 2%), the system only altering many kind of energy type with various portion into energy in the form of fish meat. Yet, fisheries in Philippines and Ecuador has a greater benefit because those were conventional fisheries activity, which need less emergy input either from purchased or from environmental. However, this not means the IBK system is not applicable, because EYR only consider about energy term, and fish is not energy sources as Brown and Ulgiati (2002) had reported for EYR higher than 1 has accepted to be consumer products or transformation steps than actual energy sources. In the other consent like economic benefit, it is need deeply study about IBK system economic proses for viability since renewable sources such as water were received freely from the environment. The underline result here was, as long as there is no loosing of energy invested (EYR<1), the system is permitted to apply if other consideration could support to the system operation.

3.4.2.      Emergy Investment Ratio (EIR):
The EIR has pointed at 68.74, which mean the system has very high economic cost. These also explain the system need more economic investment compare to other system in the table.2 (The less the ratio, the less the economic cost) because the system more depend on purchased energy than energy loaded from environmental. The value of ELR and EIR in this experiment was pointed in the same number because the system not involving non-renewable sources, practice ELR and EIR has similar factor which is purchased input compared to renewable environmental loading (F/R). System more likely depend on purchased input was indicated by very high EIR but in contrary relatively small/low EYR (Vassallo, et al. 2006). Hence effect from the system to the environment indicated by ELR value.

3.4.3.      Environmental Loading Ratio (ELR):
The result of ELR calculated in this experiment is 68.74, this number is very high even compare to other system with different realm. Based on the data, the system has extremely high ELR’s might resulted from the investment in a relatively small local environment, very concentrated inputs derived from purchased energies. A simultaneous increase of both EYR and EIR, indicates that a larger stress is being placed on the environment (Brown and Ulgiati, 2002), but this system was shows the opposite condition, while EYR recorded in low number followed by very high number of ELR, this means stress is not placed on the environment but rather to purchased factor (Bergquist 2008). Identic to interpretation for EIR, high ELR here can be assumed to produce 1 unit of fish meat, it was needed 1 part of environmental loading factor and more than 68 portion of purchased factor.

3.4.4.      Emergy Sustainability Index (ESI)
Subjected system in this study has calculated for ESI value of 0.02. The higher ESI indicating more economic relies on renewable and environmental loading. Since the non-renewable sources were not involved here, the ESI formula also distributed into ratio of yield emergy and environmental loading compared to quadratic power of purchased input, formula were listed below:
à EYR = Y/F
à ELR = (F+N)/R à N~0 than ELR = F/R
= (Y/F) / (F/R)
ESI = (Y*R)/F2
Based on above formula, it shows how ESI has effected by F as F factor were squared and independent to make division on Y and R factor. This mean, since R and F factor are predictable and Y as total harvested product is unpredicted, system is risky to have unsustainable in term of energy. Because a few decrement on harvested product, it could promote the degradation of ESI into 0 or even worse to minus, which mean energy contained in fish is lower than energy to produce it.
Even though the EYR is low, EIR and ELR are high, and ESI has shown high risk condition, those not mean that the system is not feasible to operate. Those conditions was happed as explained before, it was caused by high number of purchased factor needed, not caused by high consuming of non-renewable sources. In the real condition, price for each kilogram of fish also much higher than in the calculation as interaction with factor excluded in the boundary for this study (i.e. import and export, stock availability, price competition, etc.). Higher price per kilogram fish could bring high benefit in term of economic; therefor this system is acceptable to apply in Korea and other developed country with similar environment characteristic, especially which were natural sources are limited and fish consumptions are relatively high. Consider on area needed, environmental sources used, and degradation of fish population in natural stock, aquaculture especially IBK system has suitability to applied in Korea.

4.                     Conclusions
Energy needed to produce fish in IBK system is higher compare to natural and conventional fish production. The relatively low number of EYR is indicating the system only altering many kind of energy type with various portion into energy in the form of fish meat. The IBK system has high investment needed to produce fish since the system more depend on purchased energy than the environmental loading, indicate by high number of EIR and ELR. The system is risky to have unsustainable in term of energy if yield production less than expectations. Higher price per kilogram fish could bring high benefit in term of economic, therefore this system only suitable to apply in developed countries with limited area, limited of natural sources and fish consumptions are relatively high. The system not applicable in the developing countries with huge area since the IBK system needs very high investment. In the future, we need to develop the aquaculture method which has high benefit, low investment and low risk in ecologically as well as economically.

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