Perhitungan Emisi CO2

Aku pernah bertanya pada teman, bagaimana mendapatkan emisi CO2 dalam ton CO2 ? Seperti kita ketahui untuk mendapatkan emisi CO2 dengan menggunakan rumus konsumsi bahan bakar dikali factor emisi CO2. Konsumsi bahan bakar dalam Kilo Liter sedangkan factor emisi memiliki satuan Kg CO2/TJ. Pada akhirnya didapat emisi CO2 dalam satuan  ton atau Gigaton. Setelah beberapa lama akhirnya temanku  memberikan jawabannya. Berikut adalah perhitungan lengkapnya :
1. Konsumsi dalam Kilo Liter (KL) dikonversi menjadi BOE
Dari 2016 Handbook of Energy & Economic Statistic of Indonesia diketahui faktor pengali KL ke BOE sebagai berikut :
Faktor Konversi.jpg
2. Konversi BOE ke Joule
Dimana 1 BOE ~ 6,118 x 109 Joule
1 Joule = 10-12 TJ
Sebagai tambahan, BOE dalam bahasa Indonesia adalah SBM (Setara Barrel Minyak)
3. Emisi CO2
Konsumsi sudah dalam satuan TJ maka dengan mengalikan dengan factor emisi CO2 akan didapatkan satuan akhir emisi CO2 dalam kg CO2 . Tinggal dikonversi dari kg CO2 ke ton CO2 atau Gigaton CO2.

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CO2 emissions from fossil –fueled power plant and industrial processes

CO2 emissions from fossil –fueled power plant: large point sources (IPCC data)

Power plant fuel Emissions from identified sources (Mt-CO2 per year Number of large point sources Average annual emissions per sources (Mt-CO2)
Coal 7984 2025 3.9
Natural gas 1511 1728 0.9
Oil 980 1108 0.9

CO2 emissions from industrial processes: large point sources (IPCC data)

Process Emissions from identified sources (Mt-CO2 per year Number of large point sources Average annual emissions per sources (Mt-CO2)
Cement production

930

1175

0.8

Integrated steel mills

630

180

3.5

Oil refineries

800

638

1.3

Reference

Stephen A. Rackley. Carbon Capture and Storage. 2010. Elsevier Inc.

“Nasib” CO2 setelah ditangkap

Pernah ada pertanyaan di forum penelitian, setelah CO2 ditangkap terus diapakah gas tersebut ? Itu untuk penelitian penangkapan CO2 dengan adsorption. Apakah adsorbent yang sudah jenuh disimpan aza ? Itu namanya memindahkan masalah ke masalah lain. Lagi baca-baca jurnal tentang penangkapan CO2 keluar jawaban untuk hal di atas. Meskipun ini untuk absorption, bisa juga untuk metode penangkap CO2 yang lain :-).

The process for post combustion capture consists of four stages as sketched in Fig. 1. First, CO2 is removed from the flue gas by absorption in a packed absorber column. Then ‘rich’ solvent containing CO2 is led to a desorber column and heated in a reboiler to release the CO2. Next, CO2 is compressed and transported to a geological storage site or injected into an oil and gas reservoir. Finally the regenerated ‘lean’ solvent is recycled to the absorber.

a CO2 capture plant

Daftar Pustaka

Tim L. Sønderby et all. A new pilot absorber for CO2 capture from flue gases: Measuring and modelling capture with MEA solution. International Journal of Greenhouse Gas Control 12 (2013) 181–192

Penentuan CO2 dengan Ba(OH)2

Temanku ketika penelitiannya menggunakan metode ini untuk analisa CO2 di udara ambien. Prinsipnya adalah penyerapan CO2 ke dalam larutan berisi Ba(OH)(Barium Hidroksida)  yang menghasilkan endapan BaCO3 (Barium Carbonat), kemudian kelebihan Ba(OH) ini dititrasi kembali dengan larutan HCl dengan indikator phenolphtalein.

Ba(OH)+ CO2 –> BaCO3 + H2O

Ba(OH)+ 2HCl –> BaCl2 + 2H2O

Rumus perhitungan konsentrasi CO2-nya sebagai berikut

CO2

Dengan

CO2     = Kadar CO2 dalam udara ambien, (µg/m3)

Va       = Volume  Ba(OH), (liter)

Ma      = Konsentrasi Ba(OH), (mol/liter)

Vb       = Volume HCl untuk titrasi, (liter)

Mb      = Konsentrasi HCl, (mol/liter)

BM      = Bobot Molekul CO2

Vr        = Volume udara terkoreksi pada 25 oC dan 760 mmHg, (m3)

10^6     = Faktor Konversi g menjadi µg

Kalau menggunakan metode ini pastikan konsentrasi Ba(OH)lebih besar dari  konsentrasi CO2 karena ini metode ini menggunakan prinsip back titration. Selain itu jangan lupa analisa blank juga.

Daftar Pustaka

Ditanyakan dulu ke teman 🙂

The Separation Technologies for Post-combustion Capture

Dapat dari salah satu jurnal yang sedang dibaca untuk menambah pengetahuan tentang absorpsi kimia 🙂

Adsorption

Adsorption is a physical process that involves the attachment of a gas or liquid to a solid surface. The adsorbent is regenerated by the application of heat (temperature swing adsorption, TSA) or the reduction of pressure (pressure swing adsorption, PSA). Adsorbents which could be applied to CO2 capture include activated carbon, alumina, metallic oxides and zeolites. Current adsorption systems may not be suitable for application in large-scale power plant flue gas treatment. At such scale, the low adsorption capacity of most available adsorbents may pose significant challenges. In addition, the flue gas streams to be treated must have high CO2 concentrations because of the generally low selectivity of most available adsorbents. For instance, zeolites have a stronger affinity for water vapour.

Physical absorption

This involves the physical absorption of CO2 into a solvent based on Henry’s law. Regeneration can be achieved using heat, pressure reduction or both. Absorption takes place at high CO2 partial pressures. As such, the main energy requirements originate from the flue gas pressurization. Physical absorption is therefore not economical for flue gas streams with CO2 partial pressures lower than 15 vol%. Typical solvents are Selexol (dimethyl ethers of polyethylene glycol) and Rectisol (methanol).

Cryogenics separation

Cryogenics separation separates CO2 from the flue gas stream by condensation. At atmospheric pressure, CO2 condenses at −56.6 ◦C. This physical process is suitable for treating flue gas streams with high CO2 concentrations considering the costs of refrigeration. This is typically used for CO2 capture for oxyfuel process.

Membrane absorption

When membranes are used in gas absorption, membranes act  as contacting devices between the gas stream and the liquid solvent. The membrane may or may not provide additional selectivity. These offer some advantages over the conventional contacting devices such as packed columns as they are more compact and are not susceptible to flooding, entrainment,  channelling or foaming. They, however, require that the pressures on the liquid and gas sides are equal to enable CO2 transport across the membrane. Their separation efficiency such as flue gas streams from oxyfuel and IGCC processes.

Membrane-based separation

In membrane-based separation, selectivity is provided by the membranes themselves. These usually consist of thin polymeric films and separate mixtures based on the relative rates at which constituent species permeate. Permeation rates would differ based on the relative sizes of the molecules or diffusion coefficients in the membrane material. The driving  force for the permeation is the difference in partial pressure of the components at either side of the membrane. However, the selectivity of this separation process is low and thus a fraction of the CO2 is captured. In addition, the purity of the captured CO2 is low for the same reason. Multistage separation is employed to capture a higher proportion  of CO2 incurring extra capital and operating cost.

Chemical absorption

Chemical absorption involves the reaction of CO2 with a chemical solvent to form a weakly bonded intermediate compound which may be regenerated with the application of heat producing the original solvent and a CO2 stream. The selectivity of this form of separation is relatively high. In addition, a relatively pure CO2 stream could be produced. These factors make chemical absorption well suited for CO2 capture for industrial flue gases.

Daftar Pustaka

M. Wang, A. Lawal, P. Stephenson, J. Sidders, C. Ramshaw. Post-combustion CO2 capture with chemical absorption: A state-of-the-art review. Chemical engineering research and design 89 ( 2011) 1609–1624