Report: 應用生命週期觀點於技術評估平台之開發 –以臺灣氫能源技術為例
1 Introduction
There are many technologies being developed aiming at reducing environmental loads generated from the human activities to realize a shift towards a more sustainable society. Some of those technologies (such as crystalline silicon based solar cells) have already started to penetrate in the market of some of the countries, while other technologies are facing obstacles, and waiting for several more breakthroughs to happen.
Development stages and Environmental Technology Assessment
Conventionally, technologies that are developed earlier and have reached low cost compared to existing technologies have been penetrated into the market. Environmental assessment of such technologies is treated as something that will be addressed after the technology is technically and economically ready. If such kind of “stand-by” products do not meet some environmental requirements, additional arrangements would be
considered, but such assessment tends to be done only at the final stage of technology development. For example, Toyota Prius, the first hybrid vehicle to be introduced into the market, has been developed and marketed before they have some solution for recycling of such vehicles, believing that they could develop some way to deal with the end-of-life of such vehicles by the time there is a lot of Prius retiring from the market. Environmental considerations has been put less priorities in the various objectives, even for some technologies whose primary objective seems to be the “environmentally friendliness”.
Some researchers claimed on this situation, and have been pointed out that there could be clear advantage if environmental technology assessment can be carried out in earlier stages of technology development. For example, in chemical process design, Heizle and Hungerbuehler1 emphasize the need of incorporating life cycle analysis in the earlier stage of chemical process design, using Figure 1. Sharing the idea with them, Cano Ruiz2 have completed a methodology to incorporate LCA in the chemical process design aggressively introducing Monte-Carlo simulation and applying polynomial caos expansion and collocation of probability distribution to deal with the uncertainty. Hoffmann3 has extended this approach into multi-objective decision making problem.
Table 1 summarizes the characteristics of environmental technology assessment in different stages of technology development. As can be seen, questions that are addressed will be quite different in different stages. In the earlier stages, questions could be directed to each of the technology that builds up to a final product and its lifecycle stages. The amount of information available for environmental technology
assessment is less in the earlier stages, thus, studies in this part of matrix is few. However, as emphasized by the red colored figure, by overcoming the uncertainties and lack of information, there could be greater chance of improvement (environmental performance) if such environmental technology assessment could provide a feed-back to the development of the emerging technologies.
Because the information available at each of the stage increases as the technology becomes more developed, planning could incorporate more information. Especially, by extending the boundaries in the planning activities, chances to obtain a more favorable plan increases. For example, when a production
process of a certain material is investigated, choices in processes will be less when the raw materials are fixed. However, when research and development in such material is already matured, there will be a selection of
promising raw materials, therefore, combinations of processes and raw materials can be explored, and the optimal combination of raw material and process could be chosen.
However, such chances become less, if number of promising alternatives is already limited in the
development process of raw materials. Screening of alternatives are currently based on instinct of researchers, and in the modern society, it is getting more and more difficult to incubate promising alternatives to allow a long-sighted planning of technology development, because the width of technology has been exploding in the last century and continues on exploding in this century as well. If screening is performed based on benefits on the short term, future competitiveness could be traded off. To summarize, it is crucial and urgent 1) to provide researchers of environmentally friendly technologies at the earlier stages, with the information on chances of environmental impact, possible barriers, and bottom-lines of the technologies, and 2) to allocate R&D resource in a strategic manner being aware of importance of such technologies.
Hydrogen technologies
Hydrogen is considered as an ideal media for storing, transporting, and generating power. A rich amount of research efforts are invested into the technologies to realize “Hydrogen Society”. Such technologies form a “cluster” as discussed in the previous sections.
The benefits of realizing Hydrogen Society could be raised as follows:
1. Breakaway from dependency on the fossil fuels4: This is necessary from two reasons. First,
reproduction rate of fossil fuels is very slow, and if we use it as the main energy source, it will deplete. Second, Fossil fuel is unevenly distributed, and it has been a cause of political issues. Assuming we could produce hydrogen by sustainable means using evenly distributed resource, it will eliminate those problems.
2. Decentralized energy systems: The advantage of such an energy system is that it is less vulnerable to a disaster, and it could earn from the transmission loss. This advantage relies on the assumption that the distribution and storage of hydrogen is done in a safe and sustainable way.
3. Centralization of emissions of pollutants: Production of hydrogen would not be fully covered with renewable energy such as wind, solar, and hydro power. Therefore, there will be emission of pollutants and CO2 at production of hydrogen. However, by using hydrogen based technologies as power sources,
we can avoid emission at the distributed demand sites. In other words, the emissions could be centralized at the hydrogen production sites, and it could be dealt with emission mitigation technologies that we already have in our hand5.
4. High energy conversion efficiency: Hydrogen could use fuel cells for production of power, as well as engines and turbines. Because fuel cell has very high energy conversion efficiency, the efficiency of resource utilization rises, assuming hydrogen could be produced in an efficient method.
Although studies on hydrogen society are actively carried out worldwide, a comprehensive and localized picture of hydrogen society has not been drawn in Taiwan. Therefore, the benefits and pitfalls of Hydrogen society have not yet been examined in the local context of Taiwanese society.
2 Objective
In this project, a strategic technology development platform for hydrogen related technologies will be developed. The platform introduces life cycle perspectives on hydrogen and relevant goods and services, and considers interaction among the hydrogen production technologies.
Using the developed platform, possible hydrogen society in Taiwan will be illustrated. The example of questions addressed would be:
To what amount should we introduce hydrogen? For which applications should hydrogen be used?
How does a technology breakthrough affect environmental impacts?
How does such breakthrough affect the size of the future hydrogen society?
By making it possible to answer those questions, the platform could provide technology researchers with a clear understanding of roles of their technology in the entire hydrogen society as well as the relationships with the competing technologies, bottom-line and favorable target efficiencies, etc.
In the second year of this 3 year project, we have refined the methodology, and developed a
proto-type web-based evaluation tool.
4 Method
A new methodology termed “Composite Life Cycle Assessment” is developed in this project. The assessment method allows decision-makers analyze environmental aspects of technology scenarios for
hydrogen society in a strategic manner. Various collections of hydrogen technologies can be assessed with the LCA methodology for composite technologies developed in this study, termed composite LCA. A case study on assessment of Taiwanese hydrogen-based transportation system based on indigenous renewable energy is presented to demonstrate the methodology we propose.
Each hydrogen related technology falls into one of the four following categories: production, utilization, storage, and distribution. Among those technologies, in the proposed method, production and utilization are primarily focused, because storage and distribution needs depend on the extent of utilization of hydrogen in the society, which is analyzed by production and utilization. The results from our methodology will make it possible to further assess storage and distribution in the successive steps, as introduced in the case study later. The composite LCA methodology designed for assessment of hydrogen society is summarized in Figure 2. Figure 2 on the left presents the major building blocks of the methodology, which are related with the sections in case study. Figure 2 on the right elaborates on the concepts of production and utilization curves, as well as the scheme of synthesis of impact curve in the methodology.
First, an initial collection of hydrogen production and utilization technologies is set based on specific criteria and constraints. Each technology is classified into either production or utilization technology. Next, for the technologies classified in the production category, production curve (P curve) is developed. A cradle-to-gate LCA is conducted for hydrogen produced via each production technology to derive
environmental impact associated with production of unit amount of hydrogen. At the same time, resources available for hydrogen production are evaluated. By combining those two results, a segment can be drawn in a
coordinate with hydrogen production and environmental impact of primary interest in horizontal and vertical axes, respectively. The segments are linked to form a curve that start from the origin of the coordinate. For example, P in Figure 2 depicts how a P curve would reveal. Each segment (P1, P2, P3, and P4) represents different hydrogen production pathway.
For the technologies classified in the utilization category, utilization curve (U curve) is developed. A gate to grave LCA is conducted for hydrogen utilized via various hydrogen using technologies. Such analyses derive environmental impact reduction induced by utilization of unit amount of hydrogen in the respective technologies. At the same time, demands for functions delivered via respective utilization technologies are evaluated. By combining those two results, a segment can be drawn in a coordinate with hydrogen production and reduction in an environmental impact of primary interest in horizontal and vertical axes, respectively. The segments are linked to form a curve that start from the origin of the coordinate. For example, U in Figure 2 depicts how a U curve would reveal. Each segment (U1, U2, U3, and U4) represents different hydrogen utilization pathways.
If the segments are put in order by their gradients (P14, U14) the constructed curves are convex downward. Such P and U curves show the minimum environmental impact and maximum environmental impact reduction over hydrogen production respectively. Conversely, if the segments were put in the reverse order (P41, U41), the P and U curves will be convex upward and show the maximum environmental impact and minimum environmental impact reduction over hydrogen production using the same collection of production and utilization technologies. The P and U curves in reality would lie somewhere in between those two extremes, which intersects at the origin and at another end of the curves.
Combining the P and U curves, impact curve (I curve) can be synthesized to show the net changes in environmental impact over the extent of hydrogen use assuming a collection of technologies. For example, the lowest point on I curve shows the optimum extent of hydrogen utilization.
This framework is capable of evaluating consequences of technology breakthrough: for example, the extension capacity of P1 (dotted line in P’), efficiency improvement of P3 (P3’ of P’) and technical innovation (UN of U’). So the change of hydrogen society can be seen here. (dual-arrow in Figure 2) Furthermore, this methodology can assess different impact categories together with a main impact category of interest, as demonstrated in the case study on renewable resources-based hydrogen for transportation in Taiwan.
5 Results and Discussions
In the second year, an internet-based database system with a graphical user interface for the composite life cycle assessment methodology was prototyped, as shown in Figure 3. Users can either utilize data input by others, or by themselves. They can save data, and share the data with others. The maximum and minimum impact curves are formed for the reference and evaluated cases.
Reference
1. Heinzle, E. and Hungerbuehler, K., “Integrated Process Development: The key to Future Production of Chemicals. Chimia, 1997. 51:p.176-183
2. Alejandro Cano Ruiz, “Environmentally Conscious Chemical Process Design”, Massachusetts Institute of Technology, Ph.D. Dissertation (2000)
3. Volker H. Hoffmann, “Multi-objective decision making under uncertainty in chemical process design”, Swiss Federal Institute of Technology Zürich, Ph.D. Dissertation (2001)
4. J. POTHSTEIN, Hydrogen and fossil fuels, International Association for Hydrogen Energy, Int. J. Hydrogen Energy, Vol. 20, No. 4, pp. 283-286, 1995
5. Greg Brinkman, Economics and Environmental Effects of Hydrogen Production Methods, independent study, Fall 2003
