noteworthy from the standpoint of energy efficiency improvement.

Here, there is a hope for the development of the so-called “cascade” technology. This technology would allow for thermal energy to be consumed gradually and thoroughly, at any stage regardless of the level of its energy, which would maximize energy efficiency. The cascade-like stage-by-stage utilization of thermal energy can be depicted as a linear flow from “engine” or “gas turbine” to “vapor turbine,” “hot water for water heater” and “warm water for air conditioner,” for instance.

Also, cryogenic heat draws attention. Cryogenic heat remained unused until its potential as an energy source came to be revealed thanks to an emerging potential technological application, and the value of cryogenic heat is now being recognized. For materializing practical utilization of cryogenic heat, it is hoped that the binary power-generation technology for geothermal power, etc. will be promoted.

## (3) Control technology for sophisticated integration

There is a technology that aims to improve energy efficiency by making integrated controls of an entire system in a comprehensive manner. Here, the system includes products, buildings and regional networks, and such technology is already being put to use in some areas. It is important to further promote such control technology from the standpoint of energy efficiency.

It is hoped that this technology will be integrated with information technologies to establish regional networks of local businesses for the purpose of energy trade, for example. Also, a system for effective utilization of dispersed energies, such as natural energies, could be materialized through the practical use of control technology.

## (4) Development of new materials or devices

Development of sophisticated high-performance materials or devices that have a new function or ability could possibly provide a breakthrough in our fight against global warming. Here, utilization of microtechnology or nanotechnology might be effective. For example, such new materials that support effective, efficient utilization of energy include carbon nanotubes, which are hoped to upgrade semiconductors, thermo-electric materials (which would allow for mutual conversion between thermal energy and electric energy) and organic electroluminescence, which is a promising material for lighting equipment. RD&D activities for those new materials are in progress.

There are other potential innovative technologies such as the CCS ( $ CO_{2} $ capture and storage) technology (See the Column in Section 2) and nuclear reactor technologies. It is hoped that the development and promotion of those technologies will effectively contribute to global warming countermeasures.

Figure 3-5-4: Cascade-style utilization of thermal energy, in the case of heat generated through the combustion of natural gas

Source: Hiroshi Morishima, “The new century for natural gases,” Gas Energy News (2003)

Figure 3-5-5: System for the control of dispersed energy (Micro-grid)

Source: New Energy and Industrial Technology Development Organization (NEDO)

Ceramic thermo-electric module composed of 140 pairs of thermo-electric junctions

Photo: courtesy of National Institute of Advanced Industrial Science and Technology (AIST)

Figure 3-5-6: Carbon nanohorn

Sources: NEC Corporation, Japan Science and Technology Agency (JST)