Results of Energy Conservation Technology Development
Toward the Prevention of Global Warming
(August 24, 2006)
NEDO promotes the development of energy conservation technology through such activities as its Strategic Development of Energy Conservation Technology Project, which is funded under the Publicly Solicited R&D Subsidy System. Research on the three technology development themes introduced below was undertaken as part of this project, and successful results have been achieved for each theme. Ongoing progress is being made with respect to practical application and commercial use, and public recognition has been received through various awards conferred by the mass media and academia.
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1. Background of the Strategic Development of Energy Conservation Technology Project
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Under the Kyoto Protocol, which came into force in February 2005, Japan is obliged to reduce its CO2 and other greenhouse gas emissions by 6% below the level for 1990 during the first commitment period from 2008 to 2012. However, according to preliminary data for 2004 announced by the Ministry of the Environment, the nation’s greenhouse gas emissions have increased to 7.4% above the 1990 level.
In the Kyoto Protocol Target Achievement Plan approved by the Cabinet in April 2005, it is stated that Japan must address the development of energy conservation technology to achieve national emissions reduction goals while also pursuing a balance between the environment and economy. Thus, the development of energy conservation technology has become increasingly important now and for the future.
Japan’s final energy consumption has been relatively flat in recent years along with sluggish long-term economic growth. However, it is not possible to anticipate future crude oil price trends due to growing energy demand in developing countries. At the same time, final energy consumption in the commercial/residential and transport sectors has been increasing as people continue to pursue a more affluent lifestyle. In the commercial/residential sector in particular, energy demand has increased 34% in the commercial area and 26% in the residential area compared with 1990 levels. So, further efforts related to energy saving in this sector are inevitable.
In the Strategic Development of Energy Conservation Technology Project, basic research, commercial development and demonstrative research are being strategically carried out in the industrial, commercial/residential and transport sectors focusing on immediate tasks that will be effective in 2010 and mid- to long-term tasks that will be effective in subsequent years. Although the industrial sector has achieved remarkable results, this report focuses on the commercial/residential sector. The following outlines the achievements of three adopted themes in which the energy saving effect that will be realized in 2010 will amount to 3 million kl/year oil equivalent, which is equal to approximately 2.4 times the volume of the largest baseball stadium in Japan.
NEDO Contact:
Energy Conservation Technology Development Department
S. Furukawa, A. Sumi, S. Sato, S. Okazaki
Tel: +81-44-520-5281 Fax: +81-44-520-5283
Note:
This information is based on a project introduction announcement presented at a press conference held on May 22, 2006 in Tokyo.
This announcement can be viewed on NEDO’s Japanese-language Web site at:
http://www.nedo.go.jp/informations/press/kaiken/180523/news.pdf
For additional details (in Japanese) regarding the project, please visit NEDO’s Japanese-language Web site at:
http://www.nedo.go.jp/informations/press/kaiken/180523/shiryou.pdf |
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2. Outlines and Achievements of Representative Adopted Themes |
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| R&D of a Hydrate Slurry Air Conditioning System |
Following the Kyoto Protocol’s entry into force in February 2005, a target achievement plan was formulated. This plan positions research and development activities related to energy conservation as an important task. In particular, expectations are high regarding the adoption of effective measures to conserve energy in the commercial/residential sector due to the fact that energy demand in the this sector has been increasing and efforts to save energy have been further strengthened since the revision of the Law concerning Rationalization of Energy Use in April 2006.
In this theme, NEDO undertook research and development of a hydrate slurry air conditioning system in cooperation with JFE Engineering Co., Ltd. Technology development started in 1997 as basic research in the Broad Area Energy Utilization Network Systems program promoted by the Agency for Industrial Science and Technology (AIST) of the Ministry of International Trade and Industry (now the Ministry of Economy, Trade and Industry, or METI) through its New Sunshine Program. The technology was then put to practical use in NEDO’s Strategic Development of Energy Use Rationalizing Technology project that started in FY2001. This development effort has resulted in an original technology for reducing the growing energy consumption of commercial/residential sector buildings such as office buildings, factories, etc.
A hydrate slurry air conditioning system utilizes hydrate slurry as the thermal storage medium. Hydrate slurry is a durable and reusable fluid mixture composed of fine hydrate and aqueous solution, generated by cooling aqueous solution of a common chemical (catalyst), tetra-butyl-ammonium bromide (TBAB).
Chilled water has conventionally been used in air conditioning systems. However, hydrate slurry has a two to three times higher thermal storage capacity than that of water while having superior fluidity that enables this material to pass through pipelines and heat exchangers. Because of these characteristics, hydrate slurry is utilized as a heat transportation and thermal storage medium in NEDO’s newly developed latent heat air conditioning system. In other words, hydrate slurry has two to three times the thermal storage capacity of the same amount of water (larger thermal storage and lower heat source power can be obtained by replacing heat storage tanks). More heat can be obtained by effectively utilizing existing cold water pipelines and efficient use of discounted nighttime electricity is also possible. Hydrate slurry can achieve the same level of cooling as cold water does with less than half the amount, and the transfer power can also be reduced.
When installed in office buildings, factories, etc, this novel air conditioning system helps to reduce energy consumption for cooling. In seasons when cooling is needed, a freezer system and a hydrate slurry manufacturing system are operated at night utilizing nighttime electricity, and the produced hydrate slurry is stored in a thermal storage tank. The stored hydrate slurry is then pumped into the air conditioning system and used for cooling during the day. The air conditioning system outputs an aqueous solution that is returned to the thermal storage tank and circulated.
In office buildings, energy consumption for air conditioning, which accounts for approximately half of total energy consumption, can be reduced significantly. Combined with other energy saving systems, up to a 42% reduction in energy consumption (in terms of primary energy) per month has been achieved. The implementation sites for this research include the following:
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JFE Engineering Corporation, Tsurumi Engineering and Manufacturing Center (Yokohama City, Total site area: approx. 17,000m2)
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JFE Urban Development Corporation, Keihin Building (core building of THINK) (Kawasaki City, Total site area: approx. 20,000m2)
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Kawasaki Azalea (Kawasaki City, Total site area: approx. 57,000 m2)
This technology has been highly acclaimed and it was awarded the Prime Minister Prize at the 35th Japan Industrial Technology Grand Prix this year.
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| Estimated energy-saving effect in 2010: 350,000 kl/year oil equivalent (910,000 tons CO2 equivalent) |
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| Existing Technology |
Project Achievements |
- Water is used as a heat transportation medium
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- Latent heat storage material is used as a heat transportation medium
- Energy consumption for cooling is reduced by 25% for a full year and 30% in summer
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Demonstration at several sites, e.g. Kawasaki Azalea
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| Keihin Building (Kawasaki City) |
Kawasaki Azalea (Kawasaki City) |
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| Diagram of the facility |
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| Development of a High Efficiency Water Heater |
NEDO started the development of a CO2 heat pump water heater in cooperation with seven companies and the development of a latent heat recovery type gas water heater with two companies.
The Kyoto Protocol Target Achievement Plan approved by the Cabinet in April 2005 stipulates that 5.2 million CO2 heat pump water heaters and 2.8 million latent heat recovery type gas water heaters should be distributed by 2010 (as of 2005, a total of 200,000 CO2 heat pump water heater were in use). Based on this plan, NEDO started the development of a CO2 heat pump water heater last year in cooperation with seven companies (in an exceptional case, one company started its research two years ago) and the development of a latent heat recovery type gas water heater with two companies.
A CO2 heat pump water heater named “Eco-Cute” was put on the market in FY2001. This water heater is approximately twice as efficient as conventional water heaters with a coefficient of performance (COP) of 2.0 versus 0.9. However, since a heat pump unit larger than an outdoor air conditioner unit and a hot water storage tank of 450 liters are also needed, the number of installation sites is limited.
NEDO is undertaking joint activities with major domestic manufacturers of CO2 heat pump water heaters such as Denso Corporation and Matsushita Electric Industrial Co., Ltd. to develop a high efficiency, small size, all- in-one water heater with a COP of 5 (primary energy equivalent 2.0) and few installation restrictions. Specifically, the development of novel technologies such as a high power and high efficiency compressor, a high capacity heat exchanger, thermal storage, ejector cycle, etc. are being addressed.
One of the characteristics of a heat pump water heater is that its efficiency is more susceptible to outside air temperature than conventional water heaters. For this reason, the efficiency of this type of water heater in cold weather has not been satisfactory. To deal with this problem, NEDO is developing novel technologies such as a two-stage compression injection circuit and improved defrosting technology in cooperation with Mitsubishi Electric Corporation, Hitachi Appliances, Inc.* and others.
In addition, NEDO has located testing machines in Hokkaido, Iwate and Toyama. These machines were put into operation last winter in order to verify performance in cold weather conditions. This has helped to clarify technological problems in cold climates as well as providing feedback to the development process.
On the other hand, as for the latent heat recovery type gas water heater, more than a 10% increase in efficiency can be achieved compared to a conventional gas water heater with a COP of 0.8 since this type of water heater utilizes high-temperature exhaust gas in addition to a gas flame for heating water. So, future use of this heater is expected to increase in existing housing complexes where a CO2 heat pump water heater cannot easily be installed. The challenges for dissemination of the latent heat recovery type gas water heater are to make the size as small as conventional gas water heaters and to reduce the initial cost.
NEDO is undertaking technology development for adding a latent heat recovery function to a wall penetrating type bath water heater to replace balance flue type water heaters that have been widely used in existing housing complexes. In other word, this technology will not only achieve higher efficiency but will also allow use of a larger bathtub after the bath water heater is removed. For these reasons, this technology is widely expected to be rapidly commercialized.
The technology development described above will end between FY2006 and FY2007, and the developed technologies will be immediately incorporated into products. Through the commercialization of new products, NEDO aims to rapidly disseminate high efficiency water heaters while also establishing world-leading energy conservation technology in the field of water heaters. |
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| Estimated energy-saving effect in 2010: 2.6 million kl/year oil equivalent (6.76.million tons CO2 equivalent) |
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| * Formerly Hitachi Home & Life Solutions, Inc. (up to March 31, 2006) |
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| Existing Technologies |
Project Achievements |
- Heat pump unit and hot water tank
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Coefficient of performance (COP) of 4
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Low efficiency in a cold climate
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- Smaller size
- Higher efficiency (COP 5)
- Improved efficiency in a cold climate (minimum of -20 degrees centigrade)
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| Diagram of the facility |
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| Development of a Triple-effect High-performance Absorption Chiller-heater |
Air conditioners account for most of the ever-increasing energy consumption in the commercial sector, and it is important to reduce such consumption growth. If the efficiency of absorption-type water chiller-heaters, which are widely employed in large buildings, could be improved, this would contribute to a significant reduction in energy consumption. However, as efficiency improvement of double-effect absorption type water chiller-heaters has already reached the practical limit, it is now necessary to explore technologies to develop chiller-heaters with additional multiple effects in order to obtain higher efficiency. Against such a background, NEDO carried out the Development of a Triple-effect High-performance Absorption Chiller-heater project from FY2001 to FY2004 in cooperation with the Japan Gas Association and four absorption chiller-heater manufacturers (Hitachi Air-Conditioning System Co., Ltd.*, Yazaki Corporation, Daikin Industries, Ltd., and Kawasaki Thermal Engineering Co., Ltd.).
Triple-effect absorption chiller-heaters have three regenerators (high-temperature, intermediate-temperature, and low-temperature). The structure is similar to that of conventional double-effect systems except for the additional regenerator that is included. A cooling coefficient of performance (COP) higher than that of double-effect systems can be obtained by heating the regenerators with a high-temperature heat source such as city gas and then utilizing cascading heat in the absorption cycle process.
The high-temperature regenerator in a triple-effect system is exposed to a higher temperature and higher pressure than in a double-effect system. Therefore, the development of corrosion inhibition technology and safety improvement technologies, such as a novel once-through type high-temperature regenerator, emerged as key issues. At the same time, development of more compact and higher efficiency components, latent heat utilization, and control optimization were also technological challenges to be overcome. In this project, four manufacturers developed triple-effect systems utilizing their own proprietary methods based on solution flow methods adopted for existing double-effect systems. The Japan Gas Association, on the other hand, addressed common issues such as corrosion inhibition, measures concerning regulations, etc.
As for the development of corrosion inhibition technology, the results of various corrosion tests revealed that carbon steel, the material used in current double-effect systems, can be sufficiently effective under the high temperature conditions of triple-effect systems (220°C) when combined with a molybdenum inhibitor (corrosion inhibitor) as long as the appropriate inhibitor concentration is maintained.
A prototype system with a volume of 120% or less compared to current double-effect systems satisfied the development goals of a cooling COP of 1.6 or greater during rated operation and a 20% or greater gas reduction ratio when using waste heat. Furthermore, during partial load operation, excellent properties were also obtained.
Based on the results of this project, Kawasaki Thermal Engineering Co., Ltd. has introduced triple-effect absorption chiller-heaters to the market. In addition, this technology development received the JIE Progress Award (Technical Division) of the Japan Institute of Energy in 2005.
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| Estimated energy-saving effect in 2010: 40,000 kl/year oil equivalent (100,000 tons CO2 equivalent) |
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| * Now named Hitachi Appliances, Inc. |
| Existing Technologies |
Project Achievements |
- Single-effect systems with a
cooling COP of 0.7
- Double-effect systems with a
cooling COP of 1.2
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- Triple-effect system with a
cooling COP of 1.6
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| Diagram of the facility |
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| Diagram of the facility |
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