Present Status of Hydrogen Tr ansport Systems Utilizing Existing Natural Gas Supply Infrastructures in Europe and the USA 1

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1 Present Status of Hydrogen Tr ansport Systems Utilizing Existing Natural Gas Supply Infrastructures in Europe and the USA 1 Takeo Suzuki *, Shin-ichiro Kawabata **, Tetsuji Tomita *** 1. Introduction Hydrogen has been widely used as a gaseous form industrial raw material and, in Europe and North America, utilized in industries such as refineries or petrochemicals with a large-scale production and supply infrastructure. Regarding transportation of hydrogen, along with conventional means such as high-pressure or cryogenic tankers as well as cylinders, transportation via pipelines has been employed to cater to a specific range of mass-consuming users. In recent years, hydrogen has attracted a significant amount of public attention as an alternative source of energy replacing the traditional hydrocarbon based energies, along with its application in technologies such as fuel cells and fuel cell vehicles that could lead to the realization of a society based on this new energy source. The main difference in the delivery and supply aspects for hydrogen as a source of energy and hydrogen as an industrial raw material lies in the fact that the former element has to deal with supplying an unspecified range of general consumers. For this reason, successful dissemination of the new technology necessarily behooves not only development of technologies for producing and supplying hydrogen as energy but also examination into methods of transportation for its supply. From these points of view, after the turn of the century, various projects have been launched in Europe and the USA for technical as well as economic examinations regarding a method of transporting hydrogen by mixing it into the existing natural gas pipeline system wherein hydrogen is separated at the end users. The purpose of this report is to present the results of our investigation on hydrogen transport systems with a special focus on those utilizing existing natural gas supply infrastructures and to discuss their present status. To that end, we will first deal with the existing facilities for hydrogen transport via pipelines, together with the characteristics observed in such systems. We will subsequently provide detailed descriptions of various development projects undertaken by organizations such as the International Energy Agency (IEA) and other investigative bodies in Europe and the USA concerning: (a) a system for transporting natural gas/hydrogen mixtures utilizing an existing natural gas supply infrastructure, (b) a system for pure hydrogen transport utilizing an existing natural gas supply infrastructure, and (c) a system for pure hydrogen transport via a new infrastructure, along with some of our analysis and observations regarding the present situation. 1 This report is a part of A Study on the Current Status of Introducing Hydrogen Systems Utilizing Existing Natural Gas Supply Infrastructure in Europe and the USA, which was commissioned to the Institute of Energy Economics, Japan (IEEJ) by JFE Engineering Corporation and completed in December, JFE Engineering has recently allowed us to publish the study. We thank the parties concerned for their understanding and cooperation. * Senior Coordinator (Natural Gas)/Group Manager, Industrial Research Unit Oil & Gas Group, IEEJ ** Senior Researcher, Industrial Research Unit Oil & Gas Group, IEEJ *** Senior Coordinator, Global Environment & Sustainable Development Unit New & Renewable Energy Group, IEEJ 1

2 2. Existing hydrogen pipelines Presently, the aggregated length of pipelines for hydrogen transport that are known to be either in service, under construction, or under planning reaches approximately 1,930 km. The following can be mentioned as the noteworthy points characterizing these existing hydrogen pipelines: The operating entities of these pipelines are mainly large industrial gas producers such as Air Liquide, Air Products & Chemicals, etc., or organizations such as Los Alamos National Laboratory or NASA who use large amounts of hydrogen for specific purposes. It is also notable that these entities are concentrated in Europe and the USA. The design pressure for the pipelines varies widely and ranges from less than 1 MPa to over 10 MPa. Carbon steel or stainless steel is used as the material for these pipelines. In the case of carbon steel, high-strength materials such as API 5L or ASTM-specified grades that are also widely used for high-pressure gas pipelines are employed. The general trend is that the pipelines which have been put into service in more recent years tend to handle hydrogen in higher purity. The majority of hydrogen being transported is of high purity, with virtually no identifiable case where a mixed gas with low hydrogen content is transported even for a limited industrial purpose. 3. An overview of hydrogen infrastructure-related projects 3.1 Activities at the IEA Hydrogen Implementing Agreements Activities at the International Energy Agency (IEA) concerning hydrogen and fuel cells are conducted under the framework of the Implementing Agreements concluded between the IEA and the member nations and include the following three main activities among others: 1) Hydrogen (hydrogen production using renewable energy) 2) Advanced Fuel Cells 3) Greenhouse Gas R&D Programme (CO 2 capture and storage) Concerning the subject of hydrogen transport via pipelines as the object of the present study, a study conducted by Gastec N.V. as part of the IEA Greenhouse Gas R&D Programme will serve as a useful reference. The paper 2 presents a cost-benefit analysis on the concept of transporting mixtures of natural gas and hydrogen as a means for reducing CO 2, as well as technical considerations related to the infrastructure for the mixed gas transportation and the end-user appliances. The gist of the paper is as summarized below: Presented in the paper are (i) cost-benefit analyses for assumed cases of adding up to 25% of hydrogen into the existing natural gas system and, (ii) technical considerations related to the gas transportation infrastructure as well as the end-user appliances. Assuming the existing natural gas systems are utilized, there is almost no need for 2 E. A. Polman, M. Wolters, Addition of Hydrogen to Natural Gas, International Gas Research Conference (Vancouver), November

3 additional investment to the infrastructure if the addition of hydrogen is below 3%. On the other hand, when 25% of hydrogen is to be introduced into the system, the additional investment required becomes $12 to $23 per ton of CO 2 abated, which is higher than other CO 2 reduction options. For the majority of domestic demand, the most effective way appears to be to inject centrally produced hydrogen into natural gas at the connection points to the high-pressure gas transmission grid which can be used to transport the mixed gas. Adding hydrogen to natural gas slightly decreases the net energy transmission capacity of the pipeline system. While this will not give rise to any significant problem for a low-pressure supply operation, partial capacity enhancement of high-pressure transmission systems may become necessary. While it is known that hydrogen embrittlement will occur in high-pressure transmission of hydrogen containing gas, further study and research will be required in this respect. Including the foregoing, there remain various technical issues that require additional research and development. When the rate of hydrogen addition is 3% or higher, end-user appliances such as boilers engines, or gas turbines will also be affected Hydrogen Coordination Group In addition to the foregoing, in April 2003, a group called the Hydrogen Coordination Group (HCG) was established within the IEA in order to deal with the need for information exchanges among various hydrogen energy projects that are being developed in countries and regions all over the world. The HCG is organized within the IEA s Office of Energy Technology & Efficiency. The main role of the HCG is to review, analyze, and coordinate various national or regional policy measures and strategies concerning the development of hydrogen and fuel cells. In the first IEA HCG meeting, a report was presented concerning a study conducted under the IEA Greenhouse Gas R&D Programme for utilizing hydrogen as a fuel for power generation and with an aim of reducing CO 2 emissions. The report presented a study on a method for transporting hydrogen by mixing it with natural gas, in which piping materials, production and supply capabilities, and economics were discussed as the main research topics. A view presented in a hearing with Mr. G. Simbolotti of the HCG was that, based on the results of the above study under the Greenhouse Gas R&D Programme, the system of transporting hydrogen by mixing it with natural gas did not appear to offer an attractive CO 2 reduction option in terms of cost advantage as compared with other CO 2 abatement options. 3.2 Activities at the European Union At the EU, the European Commission is providing funding and transnational support for various research and technological development projects within the EU under the principles established in the Framework Programme. Under the Sixth Framework Programme (FP6) which started in 2002, funding is provided to the NATURALHY Project as described in the following section. 3

4 3.3 Hydrogen infrastructure-related projects in Europe While several hydrogen-related projects are currently under way in Europe, as far as the hydrogen transport via pipeline is concerned, studies worthy of considerable interest are undertaken under a couple of projects called NATURALHY and VG NATURALHY Project a) Background, related developments, and the position of the project Since an enormous amount of investment and labor over an extended period of time will be required to develop a new transportation and distribution system dedicated to pure hydrogen, the NATURALHY Project focuses on the utilization of existing natural gas networks that have been built and maintained over the years. Under the project concept 3, the system for transporting hydrogen/natural gas mixtures is considered to be an effective solution for the transitional period moving towards a hydrogen economy, i.e. under an expected situation where the demand for hydrogen is still low and the hydrogen supply is carried out in parallel with the existing natural gas networks, where both natural gas and hydrogen are utilized b) Project period and budget The NATURALHY Project started in May 2004, and is scheduled to continue for duration of five years. The total project budget is 17.3 million of which 11 million comes from a European Commission grant under the FP6 policy. c) Participants and assignments The project partners comprise 40 organizations as listed in Table 1, in which Gasunie Research (N.V. Nederlandse Gasunie) is assigned with the role of the project coordinator. Table 1: NATURALHY Project Partners Name of Organizations NV Nederlandse Gasunie (GASUNIE) Hӧgskolan i Borås (UCB) BP Gas Marketilng Limited (BP) Commissariat à l énergie atomique (CEA) Compagnie d Etudes destechnologies de l Hydrogène (CETH) Computational Mechanics lnternational Ltd (CMI) The European Association for the Promotion of Cogeneration (COGEN) Centro Sviluppo Materiali S.p.A (CSM) DBI Gas und Umwelttechnik GmbH (DBIGUT) Public Gas Corporation SA (DEPA) Danish Gastechnology Centre (DGC) Country Netherlands Sweden France France Belgium Italy Germany Greece Denmark 3 4

5 Energy Research Center of the Netherlands (ECN) EXERGIA Energy and Environment Consultants S.A. (EXERGIA) Technische Universität Berlin (TU BERLIN) Gaz de France (GDF) General Electric PII Ltd (GE PII) EUROGAS-Groupe Européen de Recherches Gazières (GERG) The Health and Safety Executive (HSE; ) Istanbul Gaz Dagitim Sanayi ve Ticaret A.S. (IGDAS) lnstitut Français du Petrole (IFP) lnstituto de Soldadura e Qualidade (ISQ) University of Leeds (UNIV LEEDS) Loughborough University (LOUGH) Tubitak Marmara Research Center Energy Systems and Netherlands Greece Germany France France Turkey France Portugal Turkey Environmental Research (MRC) Naturgas Midt-Nord I/S (MIDT-NORD) Netherlands Standardization lnstitute (NEN) National Technical University of Athens (NTU) Norwegian University of Science and Technology (NTNU) Planet-Planungsgruppe Energie und Technik GbR (PLANET) Ecole Nationale d'lngénieurs de Metz (ENIM) SAVIKO Consultants ApS (SAVIKO) Sheffield Hallam University (SHU) Shell Hydrogen B.V. (SH) STATOIL ASA (STATOIL) SQS Portugal-Sistemas de Qualidade de Software, Lda (SQS) Total SA (TOTAL) Netherlands Organisation for Applied Scientific Research (TNO) X/Open Company Limited (TOG) Transco plc (part of National Grid Transco plc) (TRANSCO) University of Warwick (WPTG) Source: O. Florisson & R. Huizing (2003) 4 Denmark Netherlands Greece Norway Germany France Denmark Netherlands Norway Portugal France Netherlands The project is further subdivided into eight Work Packages (WP) based on the area of research and development. The titles and the leading organizations of the WPs are as listed in Table 2, whereas the activities of these WPs are dealt with in the next section. 4 The NATURALHY project, International Conference Hydrogen, our future, 26-27, Nov

6 Table 2: NATURALHY Project Work Packages Project Title Project Leader WP1 Socio-economic and Life Cycle Analysis Sheffield Hallam Univ. WP2 Safety Loughborough Univ. WP3 Durability Gaz de France WP4 Integrity TNO WP5 End Use Appliance Warwick Univ. WP6 Decision Support Tool ISQ WP7 Dissemination Exergia WP8 Project management Gasunie Research Source: O. Florisson & R. Huizing (2003) 5 d) Project scope (Research and development work objectives) The NATURALHY Project is presently designed to cover the method for transporting hydrogen by adding hydrogen to the existing natural gas infrastructure, which will be employed in an initial stage of transition to a full hydrogen economy, with an ultimate intent of conducting research on the transportation of 100% hydrogen. The following work objectives are set forth for the research and development activities under the NATURALHY Project 6 : Definition of technical conditions: An effort to establish technical conditions under which hydrogen can be accommodated in the existing natural gas system with a certain allowable degree of risks, while preventing leakage and significant system degradation for the end users. Analysis on the socio-economic aspects of the envisaged system: Analyzing natural gas/hydrogen mixture transport systems or pure hydrogen transport systems in terms of job creation, system maintenance and management, capital investment and other economic effects, and comparing these with the traditional natural gas transport systems (including related facilities). Life Cycle Assessment (LCA): Comparing the proposed natural gas/hydrogen systems with the current natural gas systems in terms of the total resource requirement as well as the environmental impact, including assessment of the hydrogen production methods. Development of hydrogen separation devices (membranes): Devices considered necessary to help accelerate the transition to a full hydrogen economy. Education and motivation of all stakeholders: 5 The NATURALHY project, International Conference Hydrogen, our future, 26-27, Nov

7 Education and motivation of stakeholders present in the entire chain from production up to the final consumption in order to promote transition to a hydrogen economy. The target audience will include parties such as public authorities, end users, operators of gas transmission grids, related equipment and component manufacturers, etc. Assessment of the current status of related standards and regulations: Development of a Decision Support Tool Developing a tool to aid in the evaluation of the suitability of introducing hydrogen into an existing natural gas system (transportation, storage, distribution, end user infrastructures and others), in conjunction with models to determine the benefits on economic and environmental aspects of the entire chain from hydrogen production up to the final consumption. Activities for the above objectives are carried out in the Work Packages (WP) as described earlier. Among these, WP2 through WP6 are for handling technical matters, each using the apparent differences between hydrogen and natural gas in physical properties and the resultant effect of hydrogen over the safety issues as the basis for the respective study. Furthermore, although they are well known phenomena, the differences between hydrogen and natural gas in combustion characteristics or the effect of hydrogen permeating into piping materials (hydrogen embrittlement) are also concerns for study by these WPs. Concerning the acceptable defects due to corrosion cracking and defects in an embrittled region, the approach of the project is for WP3 to review and revise the related defect assessment criteria, and WP4 to reassess subjects such as inspection tools for evaluating the integrity of pipelines during transportation of the gas mixture, techniques for maintenance and management, and methods of repairing or servicing the system. The piping materials to be covered include polymer in addition to steel. The activities of WP2 through WP5 will be intensively carried out and completed in the first half of the NATURALHY Project, results of which will be used as the basis for work under WP6 (Decision Support Tool) and also for field experiments based on small-scale supply grids. The Decision Support Tool resulting from WP6 is expected to incorporate inspection methods, evaluation criteria, life prediction models, and material data. Moreover, it is expected to serve as a tool for predicting and evaluating the effects of hydrogen mixing on the transportation and supply systems as well as the end-user appliances from the aspects of durability, safety, economy, and lifecycle. e) Technical and economic tasks The technical tasks to be covered by the NATURALHY Project are limited to subjects concerning gas transportation and supply via pipelines, where the project is expected to deal with the following subjects of study: Gas transmission systems based on trunk pipelines 7

8 Gas distribution systems based on distribution pipes End-user infrastructure/adaptability, and hydrogen separation membranes f) Current status The first meeting of the full consortium to kick off the project was held during May 6 to 7, 2004 in Leiden, the Netherlands. Subsequently on July 14, Gasunie Research issued a press release. According to the announcement 7, (i) effects of hydrogen on the properties of pipeline materials and, (ii) development of separation membranes to extract hydrogen from the gas mixtures are specifically mentioned as items being researched VG2 (Vergroening van Gas: The Greening of Gas) Project a) Background, related developments, and the position of the project In the Netherlands, there is a subsidy program called the Dutch Economy, Ecology, Technology (EET) Program, which is jointly run by three Dutch Ministries, i.e., the Ministry of Economic Affairs, the Ministry of Education, Culture and Science, and the Ministry of Housing, Spatial Planning and the Environment. One of the main objectives of this program is to manage middle to long term R&D projects for non-commercial technologies requiring a time-to-market period of five to ten years. The VG2 Project is being implemented under the EET Program and can be positioned as a Dutch domestic version of the NATURALHY Project described in the foregoing. The Netherlands has been using natural gas produced from the Groningen gas field as town gas for a long time. The domestically produced gas contains a little less than 20% of nitrogen, which is further diluted with nitrogen to adjust the heating value and is supplied as L-Gas mainly for household use. In addition to this, the Netherlands has another gas supply system called H-Gas, which is based on imported natural gas having a higher heating value than L-Gas and very small nitrogen content. Furthermore, operations to dilute the H-Gas to produce L-Gas are being conducted at nitrogen stations installed at several locations within the country (see Table 3). In that context, the dilution of the H-Gas with hydrogen to adjust its heating value is considered to be synonymous with the nitrogen dilution currently in practice. The above-mentioned town gas situation which is unique to the Netherlands makes the impact of introducing hydrogen into the existing natural gas transport system relatively insignificant and lowers the economical hurdles for implementation of the system

9 Table 3: Dutch Gas Types Composition Groningen-gas Typical H-gas (North Sea) (Source: Gas Strategies Consulting Ltd.) Typical L-gas (onshore Netherlands) N 2 14% 1.50% 38% C0 2 1% 0.20% 0.70% CH % 94.40% 58.80% C 2 H % 3% 2.10% C 3 H % 0.50% 0.30% C % 0.40% 0.10% Properties: NCV (MJ/m 3 ) GCV (MJ/m 3 ) Wobbe (MJ/m 3 ) This project is unique in that it does not necessarily aim to obtain and utilize pure hydrogen by separating it from the gas mixture. The hydrogen containing gas mixture is considered to be a green gas (low carbon fuel) in the same context as green electricity such as wind-generated power to be offered as a choice to general consumers. b) Project period and budget The VG2 Project began in October 2001 and is scheduled to continue until January c) Participants Nine organizations, all being domestic Dutch institutes and corporations, participate in the project, and the Delft University of Technology is coordinating the project. d) Project scope (Research and development work objectives) The main research and development work objectives under this project are as listed below, with demonstration experiments using existing facilities being planned for the final stage of the project: Formulate the scenario (design) for transition towards a hydrogen economy: - Prepare a system design for a national hydrogen infrastructure- Develop the above based on the existing natural gas infrastructure Research the safety, reliability and effectiveness (economics) of the mixed gas supply system: - Facilities and equipment required in the shift from natural gas to hydrogen - Studies on the fundamental properties in regard to combustion and materials e) Technical and economic tasks The VG2 Project will deal with technical requirements related to the mixed natural gas/hydrogen transport system in regard to the safety, reliability, effectiveness, combustion properties and material properties (hydrogen embrittlement). 9

10 Comparison of the economics of the mixed gas transportation using existing pipelines with other means of transport or with pure hydrogen transport is also planned in the project. f) Current status In regard to the technical requirements, an official in charge of the project has indicated that a case study concerning the effects of increasing hydrogen content in the existing natural gas pipelines on the end-user appliances is being conducted. Concurrent with the study of the technical requirements, matters such as contractual or pricing issues associated with changes in heating value or the scenario concerning building up a hydrogen economy are also being investigated. 3.4 Hydrogen energy programs at the US DOE a) Background, related developments, and the position of the project At the US Department of Energy (DOE), various hydrogen-related technical development projects of both long and short terms are systematically being promoted. Of these, large-scale hydrogen-related programs are collectively referred to as Hydrogen, Fuel Cells & Infrastructure Technologies (HFCIT) Programs. The principal organ in charge of the HFCIT is the DOE Office of Energy Efficiency and Renewable Energy (EERE). The hydrogen-related R&D budget authorized for the EERE was $ 39.9 million in FY2003 and was announced to be $ 88.0 million for FY2004. Although detailed breakdowns are unavailable for the budgeted items, funds will be appropriated to R&D activities concerning production, storage, and transportation infrastructure for hydrogen fuels, development of codes and standards, as well as related education. Additionally, it is reported that the US government is committing $ 1.2 billion or more for the hydrogen-related R&D budget over a five-year period through FY b) Roadmap As a key development concerning the hydrogen-related R&D, a long-term blueprint for the hydrogen energy development entitled National Hydrogen Energy Roadmap was released by Energy Secretary Abraham on November 12, Subsequently in February 2004, a document entitled Hydrogen Posture Plan was released to translate the Roadmap mentioned above into specific actions and reality. The Posture Plan outlines the R&D activities, milestones, and DOE s plans to support America's shift to a hydrogen-based energy system. More specifically, the Posture Plan integrates research, development, and demonstration activities undertaken by the DOE, and identifies milestones for technology development over the next decade. Four phases as illustrated in Fig. 1 are envisaged to take place in the transition to a hydrogen economy. First, in Phase I, the necessary technologies will be developed, followed by initial penetration to the marketplace in Phase II, investment into the infrastructure in Phase III, and finally the formation of a fully developed market and infrastructure for the 8 FY2004 Budget Request to Congress; Statistical Table by Appropriation, DOE 10

11 hydrogen economy in Phase IV. While there is no clear indication of the timelines for each Phase, a full-fledged hydrogen economy is not expected to happen until the latter half of the 2020 s. Fig. 1: Envisaged Transition to a Hydrogen Economy (Source: DOE, Hydrogen Posture Plan Feb. 2004) c) Planned program activities As a result of further developments following the Roadmap mentioned in the previous section, the HFCIT Multi-Year Research, Development and Demonstration Plan 9 was released in This publication gives a more detailed description of the planned research and development activities for hydrogen and fuel cells through Matters concerning the pipeline infrastructure are dealt with in the section entitled Hydrogen Delivery. As shown in Fig. 2, the related technical development programs are subdivided into six Technical Tasks, in which the plans concerning hydrogen gas pipelines fall under Task 4. Summarized below are descriptions related to the pipeline infrastructure appearing in the publication: For mass transportation of hydrogen, as with the case of natural gas, the pipeline based infrastructure appears to be the most economical in comparison with those based on trucks, trailers, or railcars. Hydrogen transport utilizing existing pipelines is feasible if the ratio of hydrogen addition into natural gas is 30% or less. Construction of a new pipeline system requires massive capital costs. Development of adequate materials and related technologies for items such as peripheral equipment, sensors, control systems, etc. is required to reduce the amount of investment. In addition, the possibility of utilizing the existing pipeline infrastructure without causing hydrogen embrittlement or leakage should be explored

12 Technical studies for the application of a pipeline system should be completed by The goals of the task will be to lower the cost of hydrogen transportation to less than $1.00/kg and to bring down the initial capital costs for building a hydrogen pipeline to 50% of current requirement. Fig 2: Planned Projects for Hydrogen Transport Infrastructure Source: DOE, Hydrogen, Fuel Cells & Infrastructure Technologies Program (Multi-Year Research, Development and Demonstration Plan - Draft), June 2003 d) Research on hydrogen transportation in the HFCIT Program The DOE has periodically provided an opportunity for concerned parties to report project activities and, especially since 2002, has organized yearly forums. Past presentations on the subject of hydrogen transportation via pipelines have included a report on a laboratory study result regarding the relationship between the gas temperature and the diffusion coefficient when hydrogen is passed through a high-tensile strength steel pipe. During May 24 to 27, 2004, the 2004 Annual Program Review Meeting was held by the Hydrogen, Fuel Cells & Infrastructure Technologies Program 10. In this meeting, progress and status of various programs were reported including topics on hydrogen transport systems. The following papers may be of some interest as reference regarding the pipeline based infrastructure: - Hydrogen Production and Delivery by EERE - Hydrogen Transition Modeling and Analysis by Oak Ridge National Laboratory

13 4. Summary 4.1 Present status of hydrogen transport systems utilizing existing natural gas supply infrastructure Current status in Europe The VG2 Project in the Netherlands reflects the actual conditions of natural gas utilization in that country having a system of town gas classified by heating value (H-Gas and L-Gas) 11. In the Netherlands, addition of nitrogen to natural gas, i.e. a heating value adjustment by dilution, is an on-going practice which makes it easier to accommodate the addition of hydrogen into the existing natural gas transport system, since such an operation is synonymous with reduction of heating value. In other words, the concept could be understood in such a way that the operation of injecting another diluent gas into bulk natural gas remains the same, whereas the only difference is to use hydrogen as the diluent rather than nitrogen. For this reason, as far as the situation within the Netherlands is concerned, the system for transporting hydrogen/natural mixtures is feasible without necessitating a new and massive investment in the transportation infrastructure Current status in the USA In the USA, although technical studies regarding the transportation of hydrogen or hydrogen/natural gas mixtures via pipelines are conducted individually by research centers affiliated with the DOE or business enterprises having past experiences in building hydrogen pipelines, presently there is no hydrogen transportation project utilizing an existing pipeline infrastructure Current trends of hydrogen projects One thing common in the NATURALHY and VG2 projects is the recognition that technologies such as separation membranes or PSA 12 to obtain high purity hydrogen by separating hydrogen from the gas mixture and refining it at the end users should present the largest obstacles. Despite the fact that development of a highly efficient and inexpensive separation technique is crucial to these on-going projects in Europe, we have to conclude that the possibility of acquiring such a technology in the near future is unpredictable at best. At the same time, it can also be understood that the projects mentioned above have an aspect of demonstration towards the realization of a future hydrogen economy. If that is the case, the separation and purification of hydrogen from the gas mixtures at the end users is not a prerequisite at the present stage, whereas the significance lies in acquiring a track record of hydrogen actually being transported via pipelines albeit mixed with natural gas. 4.2 Position of the hydrogen transport system in the future hydrogen economy When a hydrogen economy is achieved in the future, it is likely that hydrogen will be produced on-site, thereby dispensing with a system for transporting hydrogen. However, in 11 See Section Pressure Swing Adsorption; a method for separating and purifying hydrogen using a hydrogen adsorbing material which changes gas quantity being adsorbed depending on pressure. 13

14 the interim transitional period, it appears that a hydrogen transport system utilizing the existing natural gas supply infrastructure (hereafter referred to as the hydrogen transport system ) will have to be employed. Given below are some of the observations and analysis regarding the main elements or key segments of the envisaged supply chain encompassing from the hydrogen supply side to the end users, assuming such a hydrogen transport system is adopted Possibility of mass production of hydrogen According to an envisioned hydrogen economy in which the hydrogen transport system is in place and functioning, a substantial amount of hydrogen ought to be produced and injected into the existing natural gas supply infrastructure, i.e., typically at the dispatching end of the natural gas supply pipeline. Under such a circumstance, the common practice today for commercially producing a large quantity of hydrogen is to rely on an existing technology of steam reforming process which obtains the reaction heat from a fired furnace. However, since this method requires the reaction heat to be supplied through combustion of fuel and thus inevitably resulting in CO 2 emissions, it is not exactly compatible with the ideals of a hydrogen economy 13. Consequently, to centrally produce such a large quantity of hydrogen without generating CO 2 emissions, it could be conceivable to use methods such as: - Electrolysis using electric power obtained from a large-scale hydroelectricity plant installed in a mountain area; or - Steam reforming process using a heat exchanger type reformer using a cooling medium (such as high-temperature helium which be heat source for steam reforming reaction) in nuclear power generation or other facilities. However, the technology for these methods has yet to be established. In view of the foregoing, for the near future, it may not be absolutely necessary to look at the situation in which the hydrogen transport system is adopted from the angle of mass production of hydrogen as the starting point. Rather, the proposed system could be more realistically built around areas such as chemical industry districts where a large amount of by-product hydrogen is available as untapped hydrogen energy, or districts where a significant amount of hydrogen is potentially available, one such example being steel mills where hydrogen could be recovered from blast furnaces. In today s reality, renewable energies such as sun light or wind power with which electricity is obtainable without generating CO 2 emissions present concerns that they are not suitable for mass production of hydrogen since their energy intensity is too low. In summary, there seem to be a number of technical challenges to be solved concerning the technology for producing a large amount of hydrogen in a manner pertinent to the future 13 Furthermore, capture and sequestration of CO2 generated as a byproduct of steam reforming will become necessary. 14

15 hydrogen economy in which hydrogen is supposed to replace conventional hydrocarbon based energies Storage and transportation of hydrogen When a distributed form of energy consumption is presumed, a hydrogen transport system by definition may represent a departure from the original notion of being distributed. The fundamentality of a distributed system exists in that no intervening infrastructure or network is employed as hardware. In that context, the hydrogen transport system as discussed here may be taken as a transitional means of transportation to function in an introductory period towards a hydrogen economy. As a result, on-site hydrogen production above all should be considered as the primary element and, whereas the hydrogen storage may also be an important matter for consideration, hydrogen transport should probably be considered as a secondary matter. Obviously, if hydrogen is to be produced on-site in accordance with the local requirements, transportation should not be required although storage would be required Hydrogen requirement From an operational viewpoint, the hydrogen transport system in discussion may be positioned as a system for intensively transporting and supplying hydrogen to well-established districts with highly concentrated energy requirement. In other words, it could be understood that such a system should allow both natural gas and hydrogen to coexist side by side during a transitional period heading for a hydrogen economy. It is a situation in which hydrogen as a new form of energy is beginning to penetrate into the established system comprising natural gas as the conventional type energy. In such a situation, main applications at the end users of the existing natural gas supply system will be for small-lot civil use such as fuel cells for household or business use, hydrogen-based fuel cell vehicles, and so on. Consequently, individual hydrogen requirements will not be too large in scale but comprise numerous small consumers. When a hydrogen economy is envisaged to take place in districts not served with an existing natural gas supply system, i.e. in the current Japanese gas market for example, rural portions of the society mainly served by bottled supplies of LPG as opposed to urban districts with a fully developed town gas system, such districts that are only served with bottled LPG will have no choice but to rely on hydrogen produced on-site since no channels will be available for a continuous hydrogen supply from a central source. Under such circumstances, the conversion to hydrogen would be more likely to take place in a stepwise manner, in contrast with the previously described model of a gradual and continuous hydrogen penetration in which conventional types of energy such as LPG coexist with hydrogen. Additionally, developing a method for producing relatively small quantities of hydrogen to be applied in the above described situation will remain a technical challenge. 4.3 The future of hydrogen transport systems utilizing existing natural gas supply infrastructures 15

16 From the foregoing discussion, it may be concluded that there will be an opportunity to build a hydrogen transport system utilizing existing natural gas supply infrastructures, provided there are a substantial amount of unutilized hydrogen and a pipeline to connect the source to a location of demand. Moreover, since the period in which natural gas and hydrogen coexist and the systems based on the two are operated concurrently is likely to last for a certain length of time, adoption of the hydrogen transport system in discussion is considered practical in the interim period and the role it plays substantial. However, with regard to the technology for separating hydrogen from the natural gas/hydrogen mixture, which is a crucial element for building and realizing the system in discussion, we have to conclude from the current status that the present possibility of acquiring such technology and the timing of realization are unpredictable. Generally, for the unit operation of separation, common knowledge states that it is difficult to maintain a high recovery rate when the target element is a minority component and is also required in high purity. Particularly, when the mixing ratio of hydrogen to be transported via the pipeline is at the most 25%, as is the case with the NATURALHY or the VG2 projects, availability of an effective means for hydrogen separation and purification at the end users will have to be carefully watched. Further, for the present plans based on the maximum hydrogen ratio of 25%, it is also required to ensure that comprehensive knowledge is established for the actual transportation of a large quantity of a gas mixture comprising natural gas (methane) and hydrogen at a ratio of 3 to 1. Upon ensuring that the design specifications of the existing pipelines are equally applicable for the gas mixture transport system in discussion, other challenges for the realization of the system will include subjects such as establishing desired conditions for the examination of piping materials under high pressure, or hydrogen leakage sensors to be installed along the pipelines, as well as techniques for maintaining and managing the system in operation. In order to achieve a hydrogen economy in the future, it is indispensable to develop and establish various component technologies in the areas of hydrogen production, storage and delivery as well as final use. It should be kept in mind that the group of component technologies must be concurrently developed in a coordinated manner. Finally, for the introduction of hydrogen into the society, due attention should be paid to building a national consensus and acceptance by dispelling the potential resistance against hydrogen or by offering thorough explanations about safety considerations or other issues of concern. Contact: report@tky.ieej.or.jp 16