Multi Region Carbon Capture and Storage Network in Indonesia Using Pinch Design Method

Abstract

Global warming, a rise in global temperatures average, is caused mainly by carbon dioxide (CO₂). Carbon capture and storage (CCS) technology is one of the best solution to mitigate CO₂. This technology is a series of activities starting from capturing CO₂ (source), transporting it, and storing it to the suitable geological sink (sink). In the CCS process, matching between source and sink may face some obstacles, such as time availability, capacity limit, and location. These problems can be solved by pinch design method. The development of multi region CCS process was conducted in this study, with of South Sumatra and East Java as boundary area with a total of five sources and six sinks. The development was done by calculating capturable CO₂ and cost needed using simultaneous and sequential method with time difference (Δt_min) 0, 5, and 10 years. The result of this research shows sequential method of CCS can capture the biggest amount of CO₂ with 93.86% in Δt_min 0 years, while simultaneous method can capture 83.94% of CO₂ in Δt_min 0 years. The least total annual cost is found in simultaneous method with Δt_min 4.6 years, which is US$ 159,259,000, compared to sequential method with Δt_min 4.5 years, which is US$ 166,667,000. Sequential method is best used if the CCS design prefers quantity of capturable CO₂ over the cost needed.

Introduction

Global warming is a phenomenon that is indicated by increasing of average temperature of earth surface. Global warming is mainly caused by high level of carbon dioxide (CO₂) in the atmosphere. In a period between January and September 2016, average temperature of earth surface is 0.88 °C higher than average temperature in a reference period between 1961 and 1990 (WMO 2016).

The 2014 global fossil-fuel carbon emission estimate, 9855 million metric tons of carbon have been released to the atmosphere. Globally, liquid and solid fuels accounted for 75.1% (7397 million metric tons of carbon) of the emissions from fossil-fuel combustion and cement production. Combustion of gas fuels (e.g., natural gas) accounted for 18.5% (1823 million metric tons of carbon) of the total emissions from fossil fuels in 2014 and reflects a gradually increasing global utilization of natural gas. The remaining emissions, at least 6.4% from cement production (568 million metric tons of carbon in 2014) and gas flaring, which accounted for less than 1% of global fossil-fuel releases (Boden et al. 2015; Global CCS Institute 2015).

ASEAN countries were considered as a rapid developing region where the energy demand projected to keep rising. Especially in the four countries such as Indonesia, The Philippines, Thailand, and Vietnam, they have been among the fastest growing economies in the world, and such growth projected to continue. Rapid economic growth, development, increased industrialization, and improved energy access have led to strong growth in the energy demand of these four countries.

The increase in energy use has been met through the consumption of fossil fuel. Commensurate with increased fossil fuel consumption, CO₂ emission have grown sharply across all four countries. Indonesia has the highest greenhouse gas (GHG) emission rate among the four countries. Its GHG levels grew 5.3% annually between 2000 and 2005 to reach 1760 Mt CO2e.

The International Energy Agency (IEA) projects for CCS in Southeast Asia reported that the initial estimates of CO₂ storage capacities of these four countries approximately 54 Gt. It is enough to store 200 Mt CO₂/year for over two centuries. Of the estimated storage capacity, 88% is located in saline aquifer. (ADB 2013).

Figure 1 shows CO₂ emission in Indonesia in 2009. Java and Sumatra are the biggest contributors of CO₂ emission, with 60 million and 25 million tonnes (Mt) per year respectively. Kalimantan and Sulawesi contribute as much as five million tonnes per year each of CO₂ emission.

Fig. 1

Carbon dioxide emission in Indonesia (LEMIGAS 2009)

Some solutions have been proposed to reduce CO₂ emission. There is a proposed solution to convert captured CO₂ to another chemical substance, such as methanol (Putra et al. 2017). Although converting carbon dioxide looks promising, it needs complex design and planning and can take a long time before a conversion plant can be started. The other solutions focus on how to replace fossil fuel with a more renewable fuel, which also needs a long time and an intensive research to be implemented.

One of the best solution to mitigate high level of CO₂ emission in short time and in huge scale is carbon capture and storage (CCS) technology. This technology is a series of activity, which includes reducing emission from industries (source), such as natural gas processing and power plant, by capturing CO₂ from its source. The captured CO₂ is then transported and stored to a suitable geological storage (sink), such as depleted oil or gas reservoir. According to the Ministry of Energy and Mineral Resources of the Republic of Indonesia, CCS is one of the technologies that has a potential to mitigate CO₂ emission.

Harkin et al. (2009) have investigated reducing the energy penalty of CO₂ capture and storage using pinch analysis. Integration of CO₂ capture and storage into coal-fired power stations is seen as a way of significantly reducing the carbon emissions from stationery sources.

Moh Nawi et al. (2016) had used pinch analysis targeting for CO₂ total site planning. They combined the CO₂ capture and storage with CO₂ capture and utilization. Therefore, the integration of CO₂ capture and storage and CO₂ capture and utilization was introduced.

Ladislav et al. (2016) had used pinch point analysis of heat exchanger for supercritical carbon dioxide with gaseous admixtures in CCS system. Chen (2016) had used pinch point analysis and design considerations of CO₂ gas cooler for heat pump water heaters. Olson et al. (2017) had used pinch analysis for industrial organic Rankine cycles.

However, the work of investigators had not given clear analogy with the basic integration for heat exchanger networks given by Robin Smith. A grid diagram for pairing between source and sink is not explained in detail. An overall process integration was chosen to pinpoint the maximum recovery that can be obtained instead. Therefore, a method to find out how the pairing can be made is introduced in this work. Hence, an analogy as given by heat exchanger networks can be built.

According to Fig. 2, it is estimated that in Indonesia, there are some sinks available; most of them are depleted oil and gas reservoir. Sumatra is estimated to have 373 million tonnes storage space, while Java has 105 million tonnes storage space. By looking to those numbers, it can be assumed that there are a lot of space to store CO₂ emission. Therefore, in practice, there is a possibility that the availability of source and sink is not matched, which means sink is not ready while source is already operated, or vice versa, so that it can be a problem in planning of CCS.

Fig. 2

Estimated location of sinks in Indonesia (Iskandar 2009)

Beside time availability problem, another problem that can arise is a location problem. There is a possibility that source and sink are not in the same region and the capacity of the sink is not enough to store all the CO₂ emission from the same region. Because of those problems, it is possible that CCS can be done in multi region, where the location of source and sink is far apart.

Pinch design method, which is a well-known method in heat exchanger network integration, can be applied to solve the problem. The pinch design method has already been done and proven to solve the problem that arises from planning of CCS (Ooi et al. 2012). A new graphical technique is proposed based on pinch analysis. However, the case study taken is only for single region and single time difference (Δt = 0 year) approach. In addition, graphical technique is cumbersome and therefore problem table algorithm for this work is more meaningful. Some parameters that are used in process integration using pinch design method are primarily capacity limit, location, flow rate, and time availability of both source and sink.

Sequential method of CCS can also be done other than simultaneous method, which is already a well-known method. With sequential method, it is predicted that percentage of captured CO₂ can be increased (Diamante et al. 2014). In his work, multi region and multi period of time are used to apply for the planning of CCS. They used problem table algorithm as opposed to graphical technique to calculate CO₂ capture. Pairing between specific source and sink was investigated. However, the grid diagram for multi periods of time and multi regions were not clearly illustrated and therefore this work will add to elucidate the problems on CCS planning. In the previous research, sequential method of CCS in multi region location has not been done, even though the method can overcome the problem on matching and integrating CCS network.

Because of that reason, this research focus on multi region CCS with sequential method and compare it with simultaneous method. This research also concerns about cost and several time differences (Δt_min) to get the best CCS network in terms of minimum total annual cost.

Carbon Capture and Storage Technology Description

Carbon capture and storage is a technology that prevents CO₂ to be released to the atmosphere. This technology includes capturing CO₂ that is produced by industries, compressing CO₂ for transportation, and injecting CO₂ to a geological sink carefully, where it will be stored permanently (Global CCS Institute 2011).

There are some technologies to capture CO₂ from industries; those are post-combustion, pre-combustion, and oxy-fuel combustion carbon capture. Those three technologies can capture up to 90% CO₂ emission.

• a. Post-combustion carbon capture

Post-combustion carbon capture technology captures CO₂ from flue gas that is released as a result of fuel combustion. This technology usually uses liquid solvent to capture CO₂ in flue gas. Ethanol amine and its derivative, such as mono ethanol amine (MEA) and diethanol amine (DEA), are used in most of the cases and can capture more than 90% of CO₂ in flue gas (Putra et al. 2016).

• b. Pre-combustion carbon capture

Pre-combustion carbon capture technology captures CO₂ before combustion of fuel happens. This technology processes main fuel in a reactor to produce carbon monoxide and hydrogen, or usually called as syngas, as its main component. Additional hydrogen, together with carbon monoxide, is formed in a shift reactor, where carbon monoxide reacts with water vapor. Mixture of CO₂ and hydrogen that is produced can be separated in two streams. CO₂ stream will be captured, while hydrogen stream is used as fuel to produce heat. This system is commonly used in power plant which used integrated gasification combined cycle (IGCC) technology (IEA 2013, IPCC 2005).

• c. Oxy-fuel combustion carbon capture

This system uses nearly pure oxygen, instead of ordinary air, to burn fuel. By using nearly pure oxygen, flue gas will contain mainly water vapor and CO₂, with CO₂ concentration, is higher than water vapor. Water vapor is then removed by cooling and compressing flue gas stream (IEA 2013, IPCC 2005). Theoretically, this system is very simple and cheaper than the other two technologies. However, producing nearly pure oxygen with 95–99% purity is quite expensive and needs a huge amount of energy.

Compressing and transporting captured CO₂ are important steps of the process. Generally, captured CO₂ will be transported to sink by using pipeline. CO₂ will be transported in liquid form, since it will need smaller pipe size than transporting in gas form. Even though transporting CO₂ using pipeline is the good choice, the use of ship to transport CO₂ is one of the alternative good choices, especially if the location of the sink is far apart (Leung et al. 2014).

Injecting CO₂ to sink is the last step of the process. Geological sink should be chosen carefully, since CO₂ will be stored permanently in there. Geological sink must be in stable condition and has a minimum risk of natural disaster, especially earthquake. Depleted oil or gas reservoir and deep saline are the best place to store CO₂ underground (Davison et al. 2001).

Problem Statement

Problem statements of this research are as follows:

• CCS network is determined to have five sources and six sinks. All sources are located in one region. Three sinks are located in the same region as the sources, while the other three are located in another region.

• Each CO₂ source is defined by a fixed CO₂ flowrate that can be captured from emission source. Time availability for each source, which is the time that the industry starts its first CO₂ capturing process, is defined with consideration that every source cannot start its capture process together.

• Each CO₂ sink is defined by maximum CO₂ injected to each sink. Time availability for each sink, which is the time while CO₂ is injected to sink for the first time, is defined. The time that CO₂ sink starts receiving the injection of CO₂ is different for each sink.

• The starting time and the end time for CO₂ source and CO₂ sink are the same for each pair and for 0 year of time difference. However, the starting time for CO₂ source always lags by the given time difference with respect to CO₂ sink.

• The aims of this work are to minimize the amount of unutilized and alternative storage and thus to maximize the CO₂ capture that is emitted from the source. It also tries to pair between source and sink available using sequential and simultaneous methods with 0, 5, and 10 years of time difference.

• Total annual cost which consists of annual capital cost and operating cost for each network will be calculated. By using annual capital and operating costs for each time difference, the minimum total annual cost is obtained.

Research Methodology

Data Collection

Data collection is one of the most important steps in this research. Accuracy of data collected will affect the actual result while implementing CCS in the real world. Some data that are needed for this research are source and sink of CO₂, time availability, operation lifetime, and capacity and flow rate for both source and sink.

Since this research will focus on multi region CCS, two regions are selected for this research, namely West Sumatra and East Java. Source will come from five industries in West Sumatra, namely PLN Bukit Asam, RU III Plaju, PT Merbau GGS, PT Semen Batu Raja, and Pusri Palembang, while sink comes from six places, three of them are coming from West Sumatra, namely Site I2, H2, 3, and the other three come from East Java, namely Banyu Urip, Sukowati, and Mudi (Usman et al. 2014, Satyana and Purwaningsih 2003).

Time availability for source is the time that the industry starts its first CO₂ capturing process from its emission, while time availability for sink is the time while CO₂ is injected to sink for the first time. Time availability for source is assumed based on consideration that every source cannot start its capture process together, because planning of capturing CO₂ is different in every source.

Operation lifetime is the duration of operation for source and sink. Operation lifetime for source is gathered from previous research, while operation lifetime for sink is based on assumption that duration of every CCS process cannot be done in exactly the same time, so that lifetime of the sink should be different for every sink.

Flow rate of CO₂ is the amount of CO₂, in mass, that can be captured from source emission or can be injected into sink on yearly basis. Flow rate of CO₂ has a strong relationship with total CO₂ load for every source and total CO₂ storage capacity for every sink.

Data that are already collected for this research is shown in Table 1 for source and Table 2 for sink.

Table 1 Sources data for carbon capture and storage in West Sumatra

Table 2 Sinks data for carbon capture and storage in West Sumatra and East Java

This research uses minimum time difference (Δt_min) as a parameter, because there is possibility that operation time of CCS is delayed. Delay of the process can happen because of some reasons, such as sink is not ready to be injected with CO₂. CO₂ sinks usually are provided after the CO₂ source starts to operate. The values of minimum time difference used are 0, 5, and 10 years. This variable will affect in optimum time that can be implemented in CCS, and the amount of alternative storage and unutilized storage needed.

Generating Cascade Table

Pinch design method, which was introduced by Linnhoff and Hindmarsh (1983), is used as a guideline to calculate CCS network pairing. Originally, pinch design method is dominated by heat exchanger network design to obtain minimum energy cost. In this research, that method will be used to obtain minimum alternative and unutilized storage. While heat exchanger network has hot and cold stream that can be exchanged, this research will use source and sink flow rate as exchanged stream. Pinch point will also be used in this research as a time where there is no mass transfer between source and sink.

Similar to heat exchanger network, generating cascade table is the first step to calculate CCS network. Cascade table is used to calculate the amount of minimum alternative storage needed and unutilized storage and pinch point that will be used for generating grid diagram. Generating cascade table is done in several steps (Diamante et al. 2014). A table with the following column name is written first: t (it means lifespan time), source, sink, Δt (it means time interval), flow rate CO₂, load CO₂, infeasible, and feasible cascade. Then, stream lines for source and sink in appropriate year are plotted in the same graph. Δt column is time difference between the CO₂ source and CO₂ sink. Flow rate CO₂ column is ƩSK − ƩSR. Load CO₂ column is flow rate CO₂ times Δt. Calculation on the amount CO₂ transferred in the CO₂ cascade column for different minimum time different Δt is done by adding the amount of CO₂ from the top to bottom for each interval. The source and sink pinch years are found from the column where there is no flow between the year interval.

Generating Grid Diagram

Grid diagram is the design of CCS network. Grid diagram will be made in two ways, simultaneous and sequential. In simultaneous method, there is no consideration about which region do source and sink belong; every source and sink can be paired without any region limitation. In sequential method, region limitation of source and sink is considered. As stated before, sources are assumed to be in one region, which is West Sumatra, while sinks are assumed to be separated in two regions, West Sumatra and East Java. In sequential method, source and sink which belong to the same region, which is West Sumatra, are paired first. The alternative storage that arises from single region pairing is then transferred to another region, so that some amount of CO₂ that needs alternative storage can be paired with sink from another region, in this case East Java.

Steps for generating grid diagram are described below (Smith 2005):

For simultaneous grid diagram:

• 1. A vertical line is drawn as pinch point line.

• 2. Horizontal lines are also drawn, in which each line represents each source and sink. Line direction is drawn from the left (starting operation year) to right (end operation year).

• 3. Calculation for shifted year is done by substracting pinch point time of sink by 0, 5, and 10 years for the source and sink pinch year.

• 4. Grid diagram consists of two zones, below pinch (left side of the pinch line) and above pinch (right side of the pinch line). There are some rules for designing integration process between source and sink regarding below and above pinch zone.

  • Mass transfer in below pinch zone, flow rate source ≥ flow rate sink, while in above pinch zone, flow rate source ≤ flow rate sink.

  • Mass transfer is started from pinch point.

  • Below pinch zone, there should be no unutilized storage and above pinch zone, there should be no alternative storage.

• 5. Pairing process between source and sink also concerns about the minimum time difference between paired source and sink. Find pairing that has the same or close to minimum time difference. To obtain suitable time difference, there is possibility that source and sink stream has to be split. Some rules for splitting stream are as follows.

  • Splitting process is only being done if pairing stream does not meet the requirement of pinch rules.

  • Splitting process is done by dividing one stream of source and sink to several streams with appropriate values.

  • Start and end year of the stream are not changed.

• 6. If pairing process has been done, but there is still unutilized storage below pinch zone and alternative storage above pinch zone, the additional pairing can be done without following the rule that has been stated before.

For sequential grid diagram:

• 1. Grid diagram is made using simultaneous method for single region only.

• 2. Alternative storage that is needed is then transferred to sinks that are located in the other region, in this case East Java.

• 3. Multi region pairing also considers about minimum time difference between paired source and sink, just like single region pairing process.

• 4. Multi region pairing does not follow the pinch rules.

Optimizing Based on Total Annualized Cost

In this research, calculation of total annual cost (TAC), which consists of annual operating cost (AOC) and annual capital cost (ACC), based on transferred load between source and sink is also calculated. Some of main costs that are calculated in determining TAC are transportation cost and penalty fee. Based on geographical location of each source and sink, transportation system is decided to use both piping and shipping. Shipping consists of three elements, ship cost, port storage cost, and loading cost, while penalty fee consists of alternative storage and unutilized storage penalty. Therefore, there are some calculations to calculate TAC, which are ACC (piping and shipping) and AOC (piping, shipping, and penalty).

For Piping ACC and AOC Calculation

• 1. Some variables to calculate ACC and AOC for piping system are as follows:

P_in = 152 bar, P_out = 103 bar, T = 25 °C, ρ = 884 kg/m³, μ = 0.0000606 Ns/m², surface roughness (ε) = 0.00015 m (galvanized iron), construction cost factor = US$ 826,338.58/m km, and O&M cost factor = US$ 3100/km (Heddle et al. 2003).

• 2. Piping ACC calculation

• Pipe diameter calculation

Calculation is done based on pressure drop and friction factor in turbulent flow (Geankoplis 2003). Pipe diameter calculation is done by using iteration, in which Reynold number is calculated first after assuming the value of D.

$$ \operatorname{Re}=\frac{4\dot{\mathrm{m}}}{\pi \mu D} $$

(1)

ṁ is CO₂ flow rate, which is obtained from grid diagram. After that, looking up fanning friction (f) based on correlation between Reynold number and friction factor in Moody’s graph (Perry and Green 2008).

$$ f=\frac{\varepsilon }{D} $$

(2)

Then, calculating new value of D by using equation below.

$$ {D}^5=\frac{32f{\dot{\mathrm{m}}}^2}{\pi^2\rho \left(\frac{\Delta P}{\Delta L}\right)} $$

(3)

The calculation above is repeated until constant value of D is obtained

• Pipe ACC calculation

After diameter of pipe is obtained, ACC of pipe is calculated using the equation below.

$$ \mathrm{Piping}\ \mathrm{ACC}=\mathrm{construction}\ \mathrm{cost}\ \mathrm{factor}\times D\times \mathrm{distance}\times \frac{i{\left(1+i\right)}^n}{{\left(1+i\right)}^n-1} $$

(4)

Total piping ACC is the summation of overall individual piping ACC.

• 3. Piping AOC calculation

Calculation of piping AOC is determined using the equation below.

$$ \mathrm{Piping}\ \mathrm{AOC}=\mathrm{O}\&\mathrm{M}\ \mathrm{cost}\ \mathrm{factor}\times \mathrm{distance} $$

(5)

Total piping AOC is the summation of overall individual piping AOC.

For Shipping ACC and AOC Calculation

• 1. Some variables that used to calculate ACC and AOC for shipping are as follows:

• Ship cost

Ship capacity = 10,000 ton; ship construction cost = US$ 35,000,000; crew, insurance, maintenance (CIM) cost = 5% construction cost; and fuel cost = $ 9150/day (Mitsubishi Heavy Industries 2004).

• Port storage cost

Storage capacity = 20,000 ton, storage construction cost = US$ 30,000,000, and O&M cost = 5% construction cost (Mitsubishi Heavy Industries 2004).

• Loading cost

Loading capacity = 20,000 ton, loading dock construction cost = US$ 8,000,000, O&M cost = 25% construction cost, and one cycle of loading CO₂ to ship = 2 days (Mitsubishi Heavy Industries 2004).

• 2. Shipping ACC calculation

Calculation for each ACC calculation is done by comparing existing system with desired system using the equation below.

$$ \mathrm{ACC}\ A=\mathrm{construction}\ \mathrm{cost}\ B\times {\left(\frac{\mathrm{capacity}\ A}{\mathrm{capacity}\ B}\right)}^{0.6}\times \frac{i{\left(1+i\right)}^n}{{\left(1+i\right)}^n-1} $$

(6)

A is the desired system, which is obtained from the total CO₂ flow rate transferred to sink in East Java each day, while B is the existing system. Total shipping ACC is the summation of ship cost, port storage cost, and loading cost.

• 3. Shipping AOC calculation

Calculation of shipping AOC is done by the following equations:

• Ship AOC

$$ \mathrm{Ship}\ \mathrm{AOC}=\mathrm{ship}\ \mathrm{CIM}\ \mathrm{cost}+\mathrm{fuel}\ \mathrm{cost} $$

(7)

• Port storage AOC

$$ P\mathrm{ort}\ \mathrm{storage}\ \mathrm{AOC}=\mathrm{O}\&\mathrm{M}\ \mathrm{port}\ \mathrm{storage}\ \mathrm{cost} $$

(8)

• Loading AOC

$$ \mathrm{Loading}\ \mathrm{AOC}=\mathrm{O}\&\mathrm{M}\ \mathrm{loading}\ \mathrm{cost} $$

(9)

Total shipping AOC is the summation of those three equations.

For Penalty AOC Calculation

• 1. Variable used to calculate AOC for penalty fee is as follows:

Carbon tax = US$ 20.74/ton CO₂ (Sofyan 2010).

• 2. Alternative storage penalty AOC

$$ \mathrm{Penalty}\ \mathrm{AOC}=\mathrm{carbon}\ \mathrm{tax}\times \mathrm{alternative}\ \mathrm{storage}\ \mathrm{flow}\ \mathrm{rate} $$

(10)

• 3. Unutilized storage penalty AOC

$$ \mathrm{Penalty}\ \mathrm{AOC}=\mathrm{carbon}\ \mathrm{tax}\times \mathrm{unutilized}\ \mathrm{storage}\ \mathrm{flow}\ \mathrm{rate} $$

(11)

Total penalty AOC is the summation of both alternative and unutilized storage penalty AOC.

For Total Calculation

• 1. Total annual capital cost (TACC) calculation

  $$ \mathrm{TACC}=\sum \mathrm{piping}\ \mathrm{ACC}+\sum \mathrm{shipping}\ \mathrm{ACC} $$

  (12)

• 2. Total annual operating cost (TAOC) calculation

  $$ \mathrm{TAOC}=\sum \mathrm{piping}\ \mathrm{AOC}+\sum \mathrm{shipping}\ \mathrm{AOC}+\sum \mathrm{penalty}\ \mathrm{AOC} $$

  (13)

• 3. Total annual cost (TAC) calculation

$$ \mathrm{TAC}=\mathrm{TACC}+\mathrm{TAOC} $$

(14)

Discussion

Carbon Capture and Storage Network Using Simultaneous Method

Cascade table, as described before, is made to determine the amount of alternative and unutilized storage needed of the system and to determine the pinch point of the system. Generating the correct cascade diagram is crucial, since the result of cascade table will be used for creating grid diagram later on. Cascade table for time difference 0 years is shown in Table 3.

Table 3 Cascade table for Δt_min equals 0 year using simultaneous method

From Table 3, we can see that the pinch point of the system is obtained in year 32. This is the source pinch year. The sink pinch year is also in year 32. It is shown also that in Δt_min equals 0 year, the alternative storage needed is 82.549 Mt while the unutilized storage of the system is 10.747 Mt. From data that are obtained from cascade table, grid diagram of the CCS network can be made and is shown in Fig. 3.

Fig. 3

Grid diagram for Δt_min equals 0 year using simultaneous method

As shown in Fig. 3, pinch point is divided in the grid diagram into two zones: below pinch point, where CO₂ needs storage, and above pinch point, where there is excess sink. Those phenomena are a common problem that will happen in real life, and therefore needs to be minimized.

It is shown in Fig. 3 that SK1 receive CO₂ from SR2 from year 7 until year 32 with the amount of CO₂ is 4.25 Mt, while CO₂ from SR1 is transported to SK2, which will end in year 29, with the amount of CO₂ transferred is 5.25 Mt. The other pairings are shown in Fig. 3. Grid diagram above gives exactly the same amount of alternative and unutilized storage as cascade table that has been made before. Alternative storage needed comes from SR1, SR3, and SR5 with 39.4, 2.261, and 40.798 Mt of CO₂ need alternative storage respectively, while all CO₂ comes from SR2 and SR4 is stored in available sink. Unutilized storage comes from SK3, SK4, SK5, and SK6 with 7.468, 1.222, 0.629, and 1.428 Mt of storage is unutilized respectively.

Cascade table for Δt_min equals 5 years is shown in Table 4. The amount of alternative storage needed for the system is 89.394 Mt, while unutilized storage is 17.682 Mt. Pinch point for the system remains the same from Δt_min equals 0 year, which is year 32. However, the sink pinch year is in year 27. From cascade table that has been generated, grid diagram for the system is made as shown in Fig. 4.

Table 4 Cascade table for Δt_min equals 5 years using simultaneous method

Fig. 4

Grid diagram for Δt_min equals 5 years using simultaneous method

It is shown in Fig. 4 that there are some differences between grid diagram for Δt equals 0 and 5 years, especially in grid line. In grid diagram for Δt_min equals 0 year, grid line for SK1 and SK2 is below pinch point, while in grid diagram Δt_min equals 5 years, line of SK1 and SK2 crosses pinch point, because of the time difference. Some notable pairings are all of CO₂ from SR1, which is 44.65 Mt, is not captured at all. SK1 receives 3.4 Mt of CO₂ from SR5, and SK2 receives 4.83 Mt of CO₂ from SR2. Because of the time difference, there are unutilized storage from SK1 and SK2. The other pairings are shown in Fig. 4. Alternative storage comes from SR1, SR2, SR3, and SR5, with 44.65, 0.42, 2.261, and 42.063 Mt of CO₂ needs alternative storage respectively. Unutilized storage comes from all of the sink, with 0.85 Mt of CO₂ from SK1, 0.42 Mt of CO₂ from SK2, 10.668 Mt of CO₂ from SK3, 1.6587 Mt of CO₂ from SK4, 0.9429 Mt of CO₂ from SK5, and 3.1427 Mt of CO₂ from SK6.

The last cascade table for simultaneous method, which is Δt equals 10 years, is shown in Table 5. As predicted before, the amount of alternative storage needed and unutilized storage is increasing. For Δt_min equals 10 years, the amount of alternative storage needed is 96.845 Mt of CO₂, while the amount of unutilized storage is 25.113 Mt of CO₂. Pinch point for Δt_min equals 10 years is year 32, similar with the other time differences. However, the sink pinch year is now in year 22. Grid diagram is made based on cascade table that has been generated before and is shown in Fig. 5.

Table 5 Cascade table for Δt_min equals 10 years using simultaneous method

Fig. 5

Grid diagram for Δt_min equals 10 years using simultaneous method

In Δt equals 10 years, every stream, either source or sink, needs either alternative storage or unutilized storage. SR1 and SR2 in Δt_min equals 10 years do not transfer any CO₂ to any sinks, which leads to requirement of alternative storage as big as 44.65 Mt of CO₂ for SR1 and 15.475 Mt of CO₂ for SR2. SK6 also does not receive any CO₂ from any sources, so there is 3.1427 Mt of CO₂ storage unutilized. The other requirements of alternative storage come from SR3, SR4, and SR5, with 2.261, 6.0687, and 28.39 Mt of CO₂ respectively. Unutilized storage comes from SK1, SK2, SK3, SK4, and SK5, with 0.636, 1.47, 14.792, 2.095, and 3.0173 Mt of CO₂ respectively.

Increasing uncaptured CO₂ and excess sink with increasing time difference, as mentioned before, is caused by the increasing possibility that sink has not been ready yet, while source of CO₂ has already started its capture process. Although Δt_min equals 0 year gives the best result in simultaneous method, it is very hard to be achieved in real world. Every aspect of CCS project needs to be perfect in order to achieve Δt_min equals 0 year. However, the presence of time difference generally acceptable, since there must be a little delay in planning of CCS project.

Carbon Capture and Storage Network Using Sequential Method

After CCS network is calculated using simultaneous method, next step is calculating mass transfer of CCS network using sequential method. This method is done by generating cascade table and grid diagram for single region, which is West Sumatra in this case, then the amount of alternative storage is transported to another region, in this case is East Java. Sequential method needs to be done in order to lower the amount of alternative and unutilized storage needed (Diamante et al. 2014).

Single region cascade table and multi region grid diagram for Δt_min equals 0 year are shown in Table 6 and Fig. 6.

Table 6 Single region cascade table for Δt_min equals 0 year

Fig. 6

Multi region grid diagram for Δt_min equals 0 year using sequential method

Table 6 shows the cascade table for single region CCS network with Δt_min equals 0 year. Pinch point is obtained in year 32, which is the same as simultaneous method. The amount of alternative storage needed is 85.248 Mt, while unutilized storage is 4.108 Mt. The CO₂ stream that needs alternative storage is then transported to another region. Results from cascade table are used to generate grid diagram, which is shown in Fig. 10.

Figure 6 shows that SR2, from year 7 to year 32 sends 11.226 Mt of CO₂ to SK3 and 4.25 Mt of CO₂ to SK1. SR4 sends 11.022 Mt of CO₂ to SK3 from year 10 until year 32 and continues sending 14.028 Mt of CO₂ to the same sink from year 32 until year 60. The other pairings are shown in Fig. 10. Alternative storage needed, based on grid diagram, is 75.819 Mt, which consists of 36.256, 2.261, and 37.301 Mt of CO₂ from SR1, SR3, and SR5 respectively. Unutilized storage needed is 4.108 Mt of CO₂, which comes from SK3.

Table 7 shows single region cascade table for Δt_min equals 5 years. Similar with simultaneous method, in sequential method, there is a tendency that alternative storage needed and unutilized storage is increasing with the increasing time difference. In Δt_min equals 5 years, the amount of alternative storage needed is 85.032 Mt of CO₂ and unutilized storage is 13.321 Mt of CO₂. Grid diagram is then generated and shown in Fig. 7.

Table 7 Single region cascade table for Δt_min equals 5 years

Fig. 7

Multi region grid diagram for Δt_min equals 5 years using sequential method

As shown in Fig. 7, SR1 does not transfer any CO₂ to sink, which leads to 44.65 Mt of CO₂ needs an alternative storage. SR3 and SR4 transfer all of its CO₂ to several sinks and do not need any alternative storage. SR3 and SR5 transfer some of its CO₂ to sink in another region. SR3 transfers 2.261 Mt of CO₂ to SK4, while SR5 transfers 0.982 Mt of CO₂ to SK4 and 3.143 Mt of CO₂ to SK5. Besides SR1, alternative storage comes from SR2 with 0.42 Mt of CO₂ and SR5 with 39.962 Mt of CO₂. Unutilized storage in the system comes from SK1, SK2, SK3, and SK6, with 0.85, 0.42, 8.908, and 3.143 Mt of CO₂ respectively.

Single region cascade table is shown in Table 8. As predicted before, the amount of alternative storage needed and unutilized storage is increasing. Now, for Δt_min 10 years, alternative storage needed is 91.732 Mt of CO₂ and unutilized storage is 20.021 Mt of CO₂. Pinch point for this system remains the same with the other systems. Grid diagram based on cascade table for Δt_min equals 10 years is shown in Fig. 8.

Table 8 Single region cascade table for Δt_min equals 10 years

Fig. 8

Multi region grid diagram for Δt_min equals 10 years using sequential method

In Δt_min equals 10 years, every source needs alternative storage, similar with simultaneous method for Δt equals 10 years. SR1, SR2, SR3, SR4, and SR5 need 44.65, 15.41, 1.995, 4.021, and 25.636 Mt of CO₂ alternative storage. The difference between simultaneous methods is SK4, and SK5 do not have unutilized storage. All of the storage capacity of those sinks is filled with CO₂ from SR3 and SR5. Unutilized storage from the system comes from SK1 with 0.636 Mt of CO₂, SK2 with 1.47 Mt of CO₂, SK3 with 14.772 Mt of CO₂, and SK6 with 3.143 Mt of CO₂.

Summary of results, either for simultaneous method and sequential method, are shown in Table 9.

Table 9 Summary of CCS network result

Based on table above, CCS using sequential method gives a better result in terms of capturable CO₂. For the same Δt_min, sequential method gives smaller amount of both alternative and unutilized storage. This is because in sequential method, sink in East Java region is utilized more, compared with simultaneous method. By utilizing more sink in East Java, alternative storage requirement will be lower and utilized storage will be higher, affecting amount of capturable CO₂.

Carbon Capture and Storage Network Optimization Based on Total Annual Cost

Based on CCS network design result, there are six schemes of mass transfer network that can be used. From each scheme, economic analysis based on minimum TAC is used to determine the best mass exchanger network. As mentioned before, calculated TAC will consist of TAOC and TACC of piping, shipping, and penalty, which will vary for each scheme. Based on formula that has been described before, calculation of TAC is shown in Table 10.

Table 10 TAC calculation

Based on Table 4, the graph between Δt and TAOC, TACC, and TAC can be generated to find the best and optimum time difference (Figs. 9 and 10).

Fig. 9

Optimum TAC calculation using simultaneous method

Fig. 10

Optimum TAC calculation using sequential method

From Figs. 9 to 10 above, the value of TAOC is increasing for each Δt_min either for simultaneous or sequential method. Increasing of TAOC is mainly caused by penalty fee. The bigger value of Δt_min, the amount of alternative and unutilized storage will also increase, which will affect in the amount of penalty fee that needs to be paid as TAOC.

For TACC in simultaneous method, the longer Δt_min of the system, the amount of TACC is decreasing, while for sequential method, there is a fluctuation regarding the amount of TACC. This fluctuation happens because in Δt_min equals 10 years, CCS network has a bigger number of multi region for mass transfer and shorter time operation compared with Δt_min equals 5 years. TACC is significantly affected by capital cost of piping, the further the distance, bigger flow rate, and shorter operation time of CO₂ transportation will give bigger TACC.

Based on TAC result, it is obtained that optimum time difference for simultaneous method is 4.6 years with TAC amount US$ 159,259,000. In sequential method, although there is fluctuation in TACC result as explained before, optimum time difference is obtained in 4.5 years with TAC amount US$ 166,667,000.

Conclusion

Our works have shown that pinch design method can be used exactly as the method used in the heat exchanger networks. The pairing between sources and sink was successfully done in this work. The pairing can use minimum time difference of 0, 5, and 10 years. With the pairing analogous to the heat exchanger networks, it will make it clear to all readers how to get maximum CO₂ capture in order to mitigate CO₂ emissions to the atmosphere. Two methods that are simultaneous and sequential methods were applied to problems in CCS. The results were the larger minimum time difference, the smaller the amount of captured CO₂ was, either for simultaneous or sequential method. Carbon capture and storage using sequential method is best applied if the only concern is the amount of CO₂ captured. In sequential method, maximum capturable CO₂ is 93.86%, while in simultaneous method, maximum capturable CO₂ is 83.94%. The least total annual cost is obtained in simultaneous method with time difference 4.6 years, which is US$ 159,259,000, compared to sequential method with time difference 4.5 years, which is US$ 166,667,000.

Appendix

Problem Table Algorithm for CCS Network Calculation

Algebraic technique developed to address CCS planning problem has been conducted by Ooi et al. (2013) and Diamante et al. (2014). This method is similar to problem table algorithm, a method of calculating energy targets directly without the necessity of graphical construction and analogous to material cascade analysis for resource conservation network. The problem table algorithm method is used to find the maximum energy recovery in the heat exchanger networks (Smith 2005). The general framework for this method is shown in Fig. 11.

Fig. 11

General framework for CCS cascade system design

Table 11 shows generic cascade table for CCS system. A table consists of eight columns with following name: lifespan time (t), source (S), sink (D), time interval (Δt), flow rate CO₂, load CO₂, and infeasible and feasible CO₂ cascade.

CO₂ cascade in column 7 yield the cumulative surplus/deficit CO₂ transfer. The largest deficit value represents the alternative CO₂ storage required for feasible cascade solution. Suppose Δm₁ + Δm₂ is the largest deficit value, then the pinch point of the system is obtained in lifespan time t equals 5 years. In lifespan time, t equals 1 year, alternative storage is Δm₁ + Δm₂. In lifespan time, t equals T + 1 years, the amount of unutilized storage is Δm₃ + … + Δm_T. Notice that at t equals 5 years there is no mass of CO₂ moving from the source to the sink. This is the rule for getting the maximum CO₂ capture.

Table 11 Generic cascade table for CCS system