The Feasibility Study on the Development of Ocean Thermal Energy Conversion Power Generation in Taiwan

Published at Sci-Tech Policy Review International Journal, December, 2007, Vol.1 No. 2

The Feasibility Study on the Development of Ocean Thermal Energy Conversion Power Generation in Taiwan

Cheng I Lai / Researcher

Science & Technology Policy Research and Information Center

National Applied Research Laboratories

1. Introduction

Since D’Arsonval, a French physicist, first came up with the concept of power generation using the thermal difference between the surface ocean and deep ocean in 1881, the feasibility of such a concept hadn’t been successfully proved until done by Cloudo, a French scientist, 1926. However, the follow-up studies had not been proceeded. In 1970s the oil crises caused the global attention on the development of Ocean Thermal Energy Conversion (OTEC) and some countries such as USA, Japan and India initiated the studies related to OTEC power generation and established several experimental power plants (Sinoteck Engineering Consultants, Ltd., 2002a). With the decrease of oil price and the impossibility of OTEC being a core power generation alternative in short-medium term, many relevant research activities were then terminated (Industrial Technology Research Institute [ITRI], 2006). Also, the oil crises in 1970s motivated OTEC studies in Taiwan. Since 1980s lots of research programs have been conducted by Taiwan Power Company (TPC) as well as the Bureau of Energy (BOE, formerly Energy Commission), Ministry of Economic Affairs (National Taiwan Ocean University, 2007). For example, the TPC’s programs include The Potential Study of OTEC Power Generation in the Offshore Area of Eastern Taiwan, The Offshore Seabed Investigation of Proposed Ho-Pin OTEC Power Plant Site, The On-land and Near-shore Topographic Survey of Jhang-Yuan OTEC Power Plant Site, The Study on the Application of Hybrid OTEC Power Generation, and so on. The BOE’s programs consist of The Preliminary Feasibility Study of Mixed OTEC Power Generation, Multiple Product OTEC Project, The Preliminary Feasibility Study on the OTEC Multiple Applications, Master OTEC Plan for the Republic of China, OTEC Utilization Study Project, and so on. Moreover, Taiwan advocated and finally organized the International OTEC Association (IOA) in 1989. IOA set up its Secretariat in Taiwan and issued the quarterly newsletters regularly.

Analyzing the OTEC research programs conducted in Taiwan in the past years, the main conclusions are: in view of the environment and technology at that time, the technology risk for constructing OTEC power plants is still high; the techniques need to be improved for fabricating, constructing and maintaining large cold water pipes; the problem of biofouling is severe; the available sites of on-land power plants encounter the potential risk of land sliding; the security problems of cold water pipes and power plant structures exerted by typhoon need to be solved; it is not cost-effective due to the power generation cost much higher than fossil fuels; it needs to enhance the exploitation benefits by combining the multi-utilization of deep ocean water application; nevertheless, OTEC power generation is one of the significant energy bases in the future and related researches should be moved on. Taking into account the increasing depletion of fossil fuels, the growing appreciation of their price, the urgent pressure of CO2 reduction resulting from the effectiveness of Kyoto Protocol, and the advance of ocean engineering technology along with the application of deep ocean water, this paper intends to analyze the feasibility in terms of the development of OTEC power generation in Taiwan in view of geographic environment, exploitation potential, power generation cost, power generation technique, and national policy. It is expected that the paper can be a viable reference for various fields, and more and more experts as well as scholars will contribute themselves in the field to advance the development of OTEC power generation in Taiwan.

2. Feasibility Study

2.1 Geographic Environment

Since the energy density of renewable energy is much lower than that of fossil energy, the power generation apparatus of renewable energy needs more land space. This is detrimental to the progress of renewable energy due to dense population and limited land in Taiwan. Though Taiwan possesses small land area, fortunately, it is surrounded by ocean which can provide much more spaces for installing power generation apparatus of renewable energy than land area. As a result, the development of offshore energy (including ocean energy) is superior in Taiwan. In addition, the large scale development of renewable energy on land often results in negative impacts on the human inhabitation environment, causing severe conflict with human life circle. Because the exploitation of ocean energy seldom occupies land space, it may eliminate the contact opportunity with human community and then reduce the objection from the general public. Therefore, ocean energy is suitable for Taiwan where lands are treasurable. On the other hand, the resource base for ocean energy is enormous and the distribution of ocean energy is wide, but the locality of ocean energy is significant. As to the OTEC power generation, the top feasible requirement is the temperature difference between surface ocean and deep ocean should be more than 20 ℃. Because the temperature at the depth of 1,000 meters below ocean surface is in the range of 0 to 5 ℃, the region with 20 to 25℃ of surface temperature is promising to proceed OTEC power generation. Taiwan is adjacent to “warm pool” where the highest ocean temperature exists globally. As compared to European countries and Japan which emphasize the application of renewable energy, the favorable geographic environment makes Taiwan be superior to develop OTEC. In general, the temperatures of surface ocean for the offshore areas of both southern and eastern Taiwan in summer are above 27℃ and above 20℃ in winter. They have good potential for developing OTEC power generation. Moreover, the water topography of eastern Taiwan is steep and the ocean depth away from coast 3 to 6 kilometers can be 1,000 meters. This may shorten the needed length of cold water pipe and then lower the development cost.

2.2 Exploitation potential

Apart from the advantage of geographic environment, some domestic researches indicate that Taiwan also has considerable potential for tapping OTEC energy. Ocean energy mainly consists of current, tide, wave, and thermal difference. According to Table 1 (Energy Program Office, 2006), it can be found that among the four kinds of above-mentioned ocean energy, OTEC power generation is the best based on both theoretical reserve and estimated exploitable amount. In 2006 the total installation capacity of power generation was 45,000 MW in Taiwan and 5,100 MW of them came from nuclear power generation (The Bureau of Energy, 2007a). These imply that OTEC could become an core type of power generation in Taiwan and to be a viable substitution of nuclear power. In his presentation of The prospects for developing ocean renewable energy, Liang (2006) pointed out that Taiwan was ineligible for exploiting tidal energy; the energy density of ocean current was low and the available sites of power plants were few; wave energy was unstable together with extremely destructive force; and OTEC was stable along with high energy density. He also indicated that the OTEC plants could be located in vast tropical ocean area as OTEC was used to produce hydrogen, ammonia and methanol. In case of sufficient exploitation, OTEC might solve energy problem and, therefore, should be the top option for exploiting ocean energy. Additionally, the research in terms of ocean energy reserve conducted by ITRI (2006) showed that the mean range of tide was more than 3 meters but its potential depended on the size of hinterland; ocean wave at offshore area was superior to that at coast area and most of them met the development requirements; the Kuroshio moved through Taiwan but its velocity was too low to be developed as considering the current power generator available in the world now; eastern Taiwan as well as a few areas located farther south of Pingtung county could meet the basic requirements of OTEC exploitation so that the development of OTEC was feasible.

 Table1. The Power Generation Potential of Ocean Energy in Taiwan

Type	Location	Theoretical Reserve (MW)	Estimated Exploitable Amount (MW)
wave	1,448 km coast island-wide	10,000	100
tide	coast of western Taiwan	1,000	---
OTEC	coast of eastern Taiwan	30,000	3,000
current	the Kuroshio area of eastern Taiwan	3,000	300

Source：Energy Program Office, 2006.

 

2.3 Power generation cost

Economic factor is one of the main considerations as many countries plan to develop renewable energy. The previous researches conclude that the cost of OTEC power generation is much higher than that of conventional energy, which leads to inferior economic competition. In accordance with the data of Business Communications Company, Inc., USA in 2004 quoted by ITRI (2006), however, the power generation cost respectively resulting from OTEC and coal will be the same in 2008, as shown in Table 2. Furthermore, the global oil price has been raised from 10.37 US$/barrel to 64.67 US$/barrel in the periods from January 1999 to June 2006. The increase percentage reaches 623.6 % during seven and half years. The price was beyond 80 US$/barrel in September 2007 and some experts predicted the price higher than 100 US$/barrel will come true in the near future. Especially, with the Kyoto Protocol taking effect in February 2005, it will increase the external cost of power generation using fossil fuel significantly due to the implementation of CO₂ reduction. It could further shorten the cost gap between the power generation by OTEC and by fossil fuel. On the other hand, the improvement and the innovation with respect to apparatus as well as technique of OTEC power generation could also cause cost down. After the commercial operation of large scale power plants in the future, it can drive the growth of relevant industry and then reduce the cost. Lots of researches highlight that multi-purpose application policy is beneficial for the OTEC development to enhance the gross economic benefits. In addition to power generation, for example, the spent deep ocean water in the process of OTEC power generation can be applied to air conditioning, agriculture, mariculture, recreation and tourism, health and care, water supply, and so on. The policy can advance the added value and create the relevant industry so as to reduce the total cost of OTEC power generation. According to the survey of United Nations Educational Scientific and Cultural Organization (Ho, 2003), the global reserve of ocean energy was 73.6 TW, in which around 40 TW was OTEC. International Energy Agency estimated the global power generation amount from OTEC could be 100,000TWk/y (IEA, 2006). It is obvious the global OTEC reserve is so enormous that OTEC can form a huge industrial market in the future. Currently, there is no commercialized OTEC power plant around the world, therefore, such an industrial market has not yet been monopolized by some developed countries. Provided that Taiwan can go into action in advance to grasp some key technologies, it will be easy for Taiwan to create niche industry and to occupy a leading and critical position in the global OTEC related industry in the future.

 Table 2. Cost Comparisons of Power Generation between Coal and Ocean Energy (US$)

 

Year  Type	2002	2003	2008
coal	0.048	0.049	0.051
wave	0.20	0.20	0.045
tide	0.115	0.115	0.075
OTEC	0.11	0.11	0.06
current	0.15	0.15	0.055

Source：ITRI, 2006.

 2.4 Power generation technology

In light of the research results conducted by TPC and BOE in the past years, the technique problems that have to be overcome in the development of OTEC power generation in Taiwan include the fabrication, construction as well as maintenance techniques of large cold water pipe, and the impact on the power plants security resulting from typhoon as well as earthquake. In 2001 Sinoteck Engineering Consultants, Ltd. executed the OTEC Utilization Study Project which was sponsored by BOE. A few key techniques data associated with OTEC power generation were collected, evaluated and identified. Then the site characteristics of prospective power plants located off eastern Taiwan were surveyed. After the optimal sites along with the specific key techniques being determined, the planning of pilot experimental plants and the design of conceptualization were made. Also, the economic feasibility, engineering feasibility, risk evaluation and environmental impact were studied. The project final reports are one of the state-of-the-art and more replete reports in Taiwan. The research conclusions were (Sinoteck Engineering Consultants, Ltd., 2002b): domestic industrial companies and academic institutes were able to implement the survey of ocean environment; domestic shipbuilding industry might import the design and fabrication technologies by cooperating with foreign countries; domestic companies had sufficient competence to individually perform the marine construction of power plants; domestic companies were able to provide the apparatus and system elements of what power generation needs; domestic companies could produce the undersea pipelines materials of in common use; and domestic excavation techniques for land-based power plants were fully mature. The conclusion of ITRI (2006) based on the analysis of preliminary feasibility study and development priority for exploiting various ocean energies in Taiwan was: among all of power generation techniques for ocean energies, OTEC is the most suitable one in Taiwan. One of the reason was that the relevant technologies were well-established in the world and Taiwan had technique competence to carry on such technologies. Moreover, the Energy Program Office of the Science & Technology Policy Research and Information Center (STPI), National Applied Research Laboratories performed the staff work of the Energy Policy and Technology Development Steering Group of Executive Yuan by contracting with National Science Council in 2006. The office organized several seminars to invite domestic experts from the industry, government and academia to discuss the feasibility for developing OTEC power generation in Taiwan, and the encountering problems together with their countermeasures. For example, the discussed problems are related to the fabrication, construction as well as maintenance of deep ocean intake pipe and so on. The main conclusions of these seminars were that Taiwan has already possessed the relevant R&D competence as well as industry infrastructure, and other immature technologies could be reinforced by the global technology collaboration as well as by in search of global funding support (Energy Program Office, 2007).

2.5 National policy

The evolvement of renewable energy depends greatly on government policies. In Taiwan, the competent authority of energy policies and relevant affairs is BOE, under the Ministry of Economic Affairs. In the White Paper on Energy Policy, BOE addresses “In order to cope with United Nations Framework Convention on Climate Change urging to reduce global emission of greenhouse gases, and in accordance with the agreed conclusions resulting from the “National Energy Conference”, “National Economic Development Conference” as well as “The Economic Development Advisory Conference”, the development of new and renewable energy is one of national focuses for developing energy in the future.” BOE has launched the 5-year demonstration and promotion program since 2000, mainly consisting of solar water heating system, photovoltaic and wind power, but excluding ocean energy. Due to the advocacy by several science and technology leaders in recent years, however, the development of ocean energy has gradually gained national attention. In order to manifest the importance of marine affairs, the Executive Yuan also plans to establish the Ministry of Marine Affairs and has setup Marine Affairs Facilitation Commission, Executive Yuan in advance. Moreover, a few important related conferences urge to develop ocean energy. Taking National Energy Conference held in 2005 as an example, one of its agreements was to strengthen the evaluation and study on the power generation by OTEC, ocean wave, ocean current and ocean tide (the Bureau of Energy, 2007b). In 2006, Presidential Human Rights Advisory Committee suggested: the application of OTEC should be studied; the technologies including OTEC power generation system, hydrogen manufacture, as well as air conditioning application should be conducted by domestic R&D, foreign import with duplication or domestic design; the test of pilot plant was further to be proceeded after having the technologies in hand. Since the domestic research resources were seldom invested in the field before, it should import technologies by international cooperation at the beginning. Once such technologies were established, it might be considered to construct power plants by transnational collaboration. In addition, the 2006 development strategy and planning report of government’s science and technology presented by earth environment sector insisted on to implement the R&D on the new energy including OTEC power generation, current power generation, and tide power generation. A future executive priorities suggested by the sector consisted of the survey as well as evaluation with respect to ocean energy distribution, the R&D as well as import on the technology of ocean energy power generation, and the technology establishment associated with construction, operation as well as maintenance of ocean energy power generation. Ocean energy topic will be also involved in the agenda of Strategic Review Board on science and technology organized by Science & Technology Advisory Group of Executive Yuan in November 2007.

3. Conclusions and Suggestions

Taiwan is a small country with dense population but limited natural resources. Currently, as much as 98% of energy is supplied by import and fossil fuels such as coal and petroleum serve as the main energy sources (the Bureau of Energy, 2007a). As a result, not only the security of energy supply is too weak, but also the amounts of greenhouse gas emissions are too much to decouple from economic development. Therefore, it is urgent for Taiwan to develop renewable energy. The global OTEC reserve is numerous and power generation by OTEC is much more stable than that by either solar or wind. Based on the above preliminary analysis in view of geographic environment, exploitation potential, power generation cost, power generation technology and national policy, Taiwan is one of the best countries to develop OTEC. This is consistent with other research conclusions drawn by domestic researches from academic and research fields. According to the previous experiences of domestic R&D, it should actively integrate the opinions from the domestic industry, government, academia and the research community and then make use of the R&D resources from all fields to form a long-term integrated program so as to advance gross effectiveness. In addition, it is necessary to search the international cooperation in order to offset the R&D weakness in Taiwan soon.

References

The Bureau of Energy. (2005). White paper on energy policy (in Chinese). Retrieved September, 2007, from http://www.moeaboe.gov.tw/

The Bureau of Energy. (2007a). The Energy situation in Taiwan, Republic of China (in Chinese). Retrieved September, 2007, from http://www.moeaboe.gov.tw/

 

The Bureau of Energy. (2007b). The research purpose (in Chinese). Retrieved September, 2007, from http://www.moeaboe.gov.tw/

Energy Program Office. (2006). 2006 National Energy Technology Development Project (in Chinese). Unpublished. Taipei: STPI.

 

Energy Program Office. (2007). The Report of Energy Program Office Expansion Project (in Chinese). Unpublished. Taipei: STPI.

Ho, C. L. (2003). The introduction of tide power generation (in Chinese). Energy Monthly. April.

International Energy Agency. (2006). Review and analysis of ocean energy systems development and supporting policies. Retrieved September, 2007, from http://www.iea-oceans.org/_fich/6/Review_Policies_on_OES_2.pdf

 

ITRI. (2006). Development of numerical techniques for estimating ocean energy distribution and assessment of exploitation (in Chinese). HsinChu: ITRI.

 

Liang, N. G. (2006). The prospects for developing ocean renewable energy (in Chinese). The Seminar on the Development Status and Future Orientation of OTEC Power Generation in Taiwan. Taipei: Energy Program Office.

National Science Council. (2006). The report on the strategy and planning of government science and technology development - Earth environment sector in 2006 (in Chinese). Retrieved September, 2007, from http://www.nsc.gov.tw/pla/public/Attachment/672417391771.pdf

National Taiwan Ocean University. (2007). OTEC history (in Chinese). Retrieved September, 2007, from http:// iss.met.ntou.edu.tw/~met/Energy/B/1/1c.htm

Sinoteck Engineering Consultants, Ltd.. (2002a). The evaluation report on the feasibility of key technology as well as conceptualization design and the suggestion of optimal adoption in Taiwan related to OTEC power generation (in Chinese). Taipei: Sinoteck Engineering Consultants, Ltd.

Sinoteck Engineering Consultants, Ltd.. (2002b). The evaluation report on the supply ability of industrial systematic elements in Taiwan related to OTEC Power generation in 2002 (in Chinese). Taipei: Sinoteck Engineering Consultants, Ltd.