| 摘要 | 1. Background and Research Questions
In recent years, there have been emerging controversial views of the hydrogen economy among energy experts and energy policy makers. Some energy experts articulate a critical position against the advent of the hydrogen economy. Many energy experts, however, expect that the hydrogen economy is a key to the sustainable energy system and will eventually materialize. Hydrogen is an energy carrier, and can be produced from a wide variety of energy sources such as fossil fuels, nuclear power, biomass, wind, and solar energy.
One of the major concerns in transition to a hydrogen economy is the construction of a cost effective hydrogen infrastructure. Accordingly, a systemic approach is needed since hydrogen is used through multiple steps of production, storage, transportation, and conversion. In this regard, this study focuses on finding an efficient hydrogen delivery system based on long-term strategies and a road map of the national project report, A National Vision of Hydrogen Economy and Action Plan (Boo, 2005).
With this in mind, this study attempts to answer the following research questions:
First, what is the optimal strategy in transition to a hydrogen economy in terms of constructing a cost-effective infrastructure?
Second, what is the optimal delivery network between hydrogen plants and filling station?
In addition to these two major research questions, this study addresses scenario analysis to how to produce and supply hydrogen to meet the demand by sector and by energy sources for hydrogen production.
2. Methodology
This study adopts three approaches: First, production system is categorized into central off-site and distributed on-site. Second, scenario approach to calculating regional fuel cell deployment as well as hydrogen supply by energy sources. Third, transportation plan (LP) to optimize the transportation system of hydrogen.
Hydrogen production, if seen in terms of production location, can be categorized into a central off-site plant of large scale hydrogen production and a distributed on-site station. In addition, hydrogen transportation implies that hydrogen produced in a central off-site plant is delivered to an end-user, that is, a filling station. For a distributed on-site production of hydrogen, the object to be delivered is feedstock such as natural gas, naphtha, LPG, etc., but not hydrogen.
The optimization model for the hydrogen transportation system is formulated as a transportation model. Transportation model is a special type of linear programming which deals with shipping a commodity from sources (hydrogen plants) to destinations (hydrogen filling stations). The objective is to determine the transportation schedule that minimizes the total shipping costs while satisfying supply and demand limits. The optimal hydrogen transportation plan is obtained by applying the well-known LINGO optimization software.
3. Major Findings and Policy Implications
Major findings of this study are as follows:
First, an optimal mix of energy resources for hydrogen production should be sought by considering the climate change, the energy security, the energy cost, the economic pervasive effect, and the social acceptance. Nuclear power can be an influential energy source for the off-site hydrogen production because of its superiority on aspects of cost and environment. Also, electrolysis of water will be cost effective hydrogen production method for the on-site hydrogen production in our country if there is a significant technological break-through.
Second, basic approach in building a system of demand and supply for hydrogen in this study is two-tiers of clustering and concentration. Clustering and concentration interact with each other and grow in diverse ways. In other words, as clustering advances, concentration will develop around them. In turn, this concentration will promote a large supply of hydrogen which, in turn, will stimulate another clustering to be formed.
Third, this study adopts 4 major clustering at the early stage which will eventually expand into 7 major clustering for concentrated off-site hydrogen production and delivering. Other 4 areas will be distributed on-site hydrogen production which are excluded from the cases for transportation plan.
Fourth, it is expected that the off-site hydrogen production will be introduced in 2030, and most hydrogen produced from central hydrogen plants will be transported to destinations via pipelines. Therefore, it is desirable to jointly plan the off-site hydrogen production system and the hydrogen pipeline transportation system.
Lastly, most hydrogen produced from central hydrogen plants is transported to destinations via pipelines in 2040. In 2040, the average transportation distance from sources to destinations is estimated as 43.5km, and the average transportation cost is estimated as $0.218/kgH2. It is also estimated that the structure of hydrogen pipeline networks will resemble that of natural gas pipeline networks.
4. Suggestions for Further Studies
Major focus of this study is on finding the optimal hydrogen transportation system as an option of multiple pathways towards an cost-effective hydrogen economy. However, it is insufficient to analyze potential energy resources and locations for hydrogen production. It is assumed that energy sources, locations, and quantities of hydrogen productions are predetermined by a hydrogen supply scenario. Therefore, further research is needed to address the analysis of energy sources and availability of hydrogen supply.
In addition, it is required to analyze the hydrogen infrastructure. The details of hydrogen fueling stations and transportation systems should be determined for the analysis of the hydrogen infrastructure. Also, it grasps influences and potential changes on existing energy sources and infrastructures when the hydrogen infrastructure is introduced.
Needless to say, systemic approach is a critical method for an efficient transition to a hydrogen economy. The objectives of hydrogen economy can be achieved efficiently and effectively by a systemic approach. The DOE(department of energy) is developing a system analysis tool for analyzing and modelling of the hydrogen economy system, and Korea also needs to develop an analysis model which is suitable for analyzing the domestic hydrogen economy.
Lastly, the scope of this study is confined to the transportation sector. However, hydrogen can be used in other sectors such as the residential and commercial sector, the industry sector, and the electricity generation sector. Therefore, it is desirable that study scope should be extended to all sectors. |
