CO 2 Conversion to Methane Project

Transcription

1 CO 2 Conversion to Methane Project Author: Aujchara Weerawong Specialist, Technology Development, PTT Exploration and Production PCL 1. Introduction The effect of greenhouse gas (GHG) content in the atmosphere is currently well-accepted by the public as the reasons for extreme weathers the mankind are facing. Therefore, all authorities in the international and national levels focus on the effective plan to mitigate or manage these GHG emissions. For Thailand, natural gas in the gulf of Thailand is the key energy resource to power the country growth and support extensive industry initiatives. However, as this natural gas resource contains variable content of the key GHG i.e. carbon dioxide (CO 2 ) over the sales specification of 23% CO 2. It is, therefore, required that some field development plan includes bulk CO 2 removal prior to export into the pipeline. Producing CO 2 along with natural gas, PTTEP has a record of high CO 2 (GHG) emission as compared to operators with same production level as shown in Figure 1. Several GHG emission reduction projects are initiated, for example, hydrocarbon loss reduction in the CO 2 -separation membrane, energy efficiency and waste heat recovery. Figure 1 Forecast Green House Gas Emission in PTTEP Thailand Operations Source: Ref.1 Among the three key CO 2 management options which are a) Afforestation and reforestation, b) CO 2 capture and storage (CCS), and c) CO 2 capture and recycle (CCR), PTTEP explores and/or pursues all these CO 2 management options as follows: a) Afforestation and Reforestation: PTTEP has 10-year reforestation project with the 200,000 rais target. The expected CO 2 absorption is 620,000 CO 2 ton equivalent in At present, the project already achieved 100,000 rais plantation in

2 PTTEP 10-Year Reforestation Project ( ) 10 Year ( ) 200,000 rai (6 Year Plantation) , , , , , , Maintenance 200,000 Rai ,000 ton CO2 (absorption target) Figure 2 PTTEP 10-year Re-forestation Project b) CO 2 Capture and storage (CCS): The option to re-inject the separated CO 2 into depleted reservoir or aquifers were studied in coordination with Government Authority and the key technical issues being the highlyfaulted, small reservoir sizes and the high re-injection pressures leading to high energy consumption and unacceptably high product gas price. c) CO 2 Capture and Recycle (CCR): Table 1 gives the key advantages of CCR as compared to CCS which is the available product to be used especially fuel or energy storage. Table 1 Key Consideration for CO 2 Management CCS Carbon Capture and Storage CCR Carbon Capture and Recycle CO 2 Purification Required Yes Yes Product available for use No Yes Continuous liability for CO 2 Yes No Leakage : onshore / offshore Support Energy Demand No Yes Large Geological Structure Required Yes No CO 2 can be recycled or utilized with or without conversion reaction in various ways as shown in Figure 3. However, the progress of CO 2 conversion technology development towards the large/commercial scale is quite different as shown in Table 2. Figure 3 CO 2 Utilization Options Source : Ref. 2

3 Table 2 Current Major CO 2 Conversion Technology Development Methane Methanol Liquid Fuel Polymer Basic Reaction CO 2 + 4H 2 CH 4 CO 2 + 3H 2 CH 4 + CO 2 C5- Polypropylene + 2H 2 O CH 3 OH + H 2 O 10H n + H 2 O carbonate H 2 Source Water electrolysis Geothermal energy Methane - Product Familiarity + Toxicity Equal amount of Unfamiliarity consideration Infrastructure CH4 required Pilot Scale Yes Yes Yes Yes Industrial Scale No Yes ** No Yes * Note * [Ref. 3] ** [Ref. 4] As methane is widely accepted by the public as flexible and clean fuel e.g. compressed natural gas (CNG) for automobiles and fuel for power plant, PTTEP pursues the CO 2 conversion to Methane (CCM) technology development with Hitachi Zosen Corporation that has developed the CCM catalyst since early 1980 s. The inventor for this catalyst is Prof. Koji Hashimoto of Tohoku Institute of Technology. CO 2 conversion to methane (CCM) reaction follows the equation: CO 2 + 4H 2 CH 4 + 2H 2 O 300 C 1 atm The reaction was discovered by Sir Paul Sabatier in 1912 using Ni-based catalyst. The reaction is therefore called Sabatier reaction and Sir Paul Sabatier received Nobel Prize in chemistry after several years of experimental work.[ref. 5] With the green objective to reuse the CO 2, it is necessary to use green H 2 i.e. H 2 that is generated from green source or from water electrolysis using renewable energy. Renewable Energy Power H 2 Generation from Water Electrolysis CO 2 Methanation Reactor Figure 4 Key Technologies for CO 2 Conversion to Methane Project The known use of Sabatier reactor in the spacecraft converts CO 2 from astronaut s breath to generate water and this water can be electrolyzed to obtain O 2 (2 H 2 O 2 H 2 + O 2 ). The reaction and the catalyst had been studied further for the application on Mars Expedition. Since Mars atmosphere contains 95% CO 2 with no known source of H 2, the plan is to carry H 2 to Mars to begin the reaction with the produced CH 4 to be used for the exploration vehicle engine and the H 2 O for use or as the source of O 2 for breathing. [Ref. 6] 2. CCM Technology Application The benefit of CCM technology can be shown in its various application as follows: a) Renewable Energy (RE) Storage and Distribution As the H 2 used in the reaction comes from renewable energy (RE) which is uncertain/fluctuating in nature, the key CCM technology application is for the RE (electrical power) storage and distribution in the form of methane (chemical power). This adds the distribution benefit over the battery which allows only storage.

4 Also, as the higher heating value of methane product vs the much-lower heating value content of H 2, the storage is smaller. The Germany government concluded that CCM is the technology to be adopted to store and distribute the vast amount of RE generated from solar and wind power. CCM is now critical path towards Germany plan of 100 % RE use in the future.[ref. 7] Figure 5 shows the RE storage with CH 4 generated from the surplus RE and this methane is used when the RE is insufficient. Figure 5 Basic Concept of Renewable Energy Storage with CCM Technology Source: Ref. 7 Figure 6 shows the scheme in which the high RE potential Hokkaido (both solar and wind power) can serve the power demand in Tokyo metropolitan area using the RE to generate H 2 for CO 2 conversion to methane reaction and CH 4 can then be transported to Tokyo without the need for long and high-capital-investment transmission line. Figure 6 Wind Energy potential in Hokkaido and opportunity to serve Tokyo using CCM Technology. Source : Modified Ushiyama, I, Wind Power Development in Japan, Mar 2012.

5 b) Biogas Upgrading As the biogas is a mixture of CO 2 and CH 4, CCM technology offers more efficient single process towards higher content of CH 4 as compared to CO 2 separation by the chemical absorption or membrane which usually requires 2-steps or more and larger footprint. c) Coal Gasification Product Gas upgrading The Coal gasification technology is developed so that the large coal resource can be used with much less GHG emission. However, the produced syngas (Mixture of H 2, CO and CO 2 ) cannot be readily used by the public due to toxicity and other safety concerns. The conversion of this produced syngas to methane allows well-accepted product of methane or synthetic natural gas (SNG). Figure 7 Coal Gasification product upgrade to synthetic natural gas (SNG) readily usable by the public d) High CO2 Natural Gas field Development Several large natural gas resources contain high CO 2 content e.g. 14% CO 2 in Gorgon Field (Australia) shown in Figure 8 and 71% CO 2 in East Natuna Field (Indonesia). CCM technology allows the produced CO 2 to be utilized instead of being re-injected (CCS) which incurs continuous risks of leakage.

6 Figure 8 Gorgon Field Development with CO2 re-injection to 2,500 m. depth beneath the Barrow Island Source : Ref Joint R&D Project with Hitachi Zosen Corporation R&D Cooperation in the CCM technology development commences in early 2012 with the 3 key areas of work a) Catalyst binding agent study Several binding agents are tested for optimum physical properties and durability in the high temperature environment of CCM reactor. b) Feed and Product cases consideration and catalyst testing PTTEP and Hitachi Zosen Corp. jointly constructed the integral reactor (Figure 9) allowing the study of reaction behavior similar to that of the actual reactor design. Figure 9 Integral Methanation Reactor constructed in the CCM Project December 2012

7 c) Conceptual design of the Reactor and Heat recovery systems As the Sabatier reaction is exothermic reaction, waste heat recovery technology is also reviewed to optimally capture and utilize the released energy in the process. The reactor system conceptual design includes main equipment such as Feed gas pre-treatment Reactor Waste heat recovery system Product treatment The results from catalyst testing and reaction rate examination were used as input to the process simulation and conceptual design of 1,000 Nm 3 /h CH 4 production system. 4. The Next Step of Pilot Unit Development PTTEP and Hitachi Zosen will continue this critical technology development to next step of prototype or pilot plant to be designed and constructed in Thailand, Rayong province. The technology development in this phase will allow design optimization for operation reliability leading to larger / commercial unit size in 4-5 years. 5. Conclusions With the focus on the green technology that manages CO 2 from the reservoir, PTTEP believes in the great benefit of CO 2 conversion to methane which is using the GHG to become useful fuel or the renewable energy storage or additional energy resources adding to the country energy independence for the benefit of the country. The Cooperation between our partner, Hitachi Zosen Corporation, and PTTEP allows significant value towards the scientific and corporate collaboration to mitigate the GHG emissions effect and create renewable energy storage options for all.

8 References [1] Forecast of PTTEP Domestic Operations Green House Gas Emissions TSH, January, [2] Carbon Dioxide Utilization Electrochemical Conversion of CO 2 Opportunities and Challenges, DnV Research and Innovation, Position Paper [3] Recycling Carbon Dioxide to make Plastics, Gizmag magazine, May 20, [4] George Olah CO2 to Renewable Methanol Plant, Reykjanes, Iceland [5] Nobel Lecture by Sir Paul Sabatier in [6] In-situ Propellant Production on Mars : A Sabatier / Electrolysis Demonstration Plant, David L. Clark, Lockheed Martin Astronautics, Denver Colorado [7] Bioenergy and renewable power methane in integrated 100% renewable energy systems, Sterner, M., Renewable Energies and Energy Efficiency, Vol. 14, Fraunhofer, IWES, p [8] Wakeyama, T., and Ehara, S., Estimation of Renewable Energy Potential and Use A Case Study of Hokkaido, Northern-Tohoku Area and Tokyo Metropolitan, Japan, World Renewable Energy Congress 2011 Sweden, 8-13 May [9] Gorgon Fact Sheet : Carbon Dioxide Capture and Storage Project, January 2015.