The environment and energy is an issue-driven science and technology field, in which various technologies should be combined in order to establish a sustainable society under the constraints of resources and the environment. The scope encom-passed is broad, and the mobilization of all sorts of scientific and technological knowledge is required. This report is compiled by the Center for Research and De-velopment Strategy of the Japan Science and Technology Agency (CRDS-JST), in which we have tried to overview the environmental and energy field including overseas research trends with the cooperation of frontline researchers and other experts.

Taking into consideration the recent domestic situation such as the Great East Japan Earthquake and the Fukushima nuclear power plant accident, we decide to focus the overview upon the energy fields. First, we survey Japan's energy flow and the relationship between the volume of imported resources and CO2 emissions, and broadly ascertain the supply and demand structure of energy in Japan. Based on this, with the basic stance of simultaneously attaining the "3Es" (Energy, Environment and Economy) that form the fundamental principles of energy policy, we split for our consideration the coverage into the four major overview categories, i.e., "fossil energy," "renewable energy," "nuclear energy," and "energy usage technologies and systems." It is noted that this report does not directly touch upon the nuclear energy category, but envisages it as something that will be used, while maintaining safety, to complement the other three categories according to their technological development; it is therefore left as a topic for the future. An overall scope of the overview is provided in the diagram below. In the three categorized fields, we identify 25 major research areas that should be promoted in the years ahead ac-cording to future social needs formulated from current issue knowledge; these were then classified into short and mid-to-long term target fields as shown in another table below.

Key Research and Development Areas
Looking back on the history of Japan's energy in recent years, we see that after the oil crisis of the 1970's an emphasis was placed upon energy security, and stable growth was achieved through curbing consumption under a policy of becoming less dependent on oil, i.e., developing and introducing alternatives to oil, and en-couraging energy saving. In the 1990s the needs to address the issue of global warming grew on an international scale, and environmental measures were bol-stered. Since the first decade of the 21st century we were faced with the challenging issues of simultaneously achieving the 3Es, but no valid solutions have been found. In the midst of economic stagnation, the nation's energy strategy is wavering. Although Japan is a world leader in efficient energy utilization and energy saving, the introduction of renewable energies to the market is making little progress, and while excellent results are obtained in technological developments little notable innovation has been made. Against this backdrop, the Great East Japan Earthquake and the Fukushima nuclear accident have presented an opportunity for fundamentally questioning the ideal formats for national energy supply and demand over the mid- to long-term.

On the other hand, the global environment surrounding Japan is changing greatly. In particular, the energy demand in the emerging economies continues to rise, and this is leading to an ongoing increase in greenhouse gas emissions. As ever, it is mainly fossil fuels that are satisfying the demand for energy, but the in-troduction of renewable energies has also made solid progress. There are high hopes for biomass fuels, although the questions of energy balance and sustainable land use remain unanswered. With regards to oil, geopolitical risks in the Middle East are increasing, while the U.S. is pursuing the fully-fledged production of new oil and gas, so the world's power balance and economic situation continues to shift.

In terms of the direction of future research and development, for the time being there is no choice but to depend upon fossil resources as the main energy source; a marked improvement in the efficiency of their usage should be a matter of the ut-most urgency, for which mid- to long-term research and development strategies are necessary. With regard to renewable energies, there is an urgent need to establish technologies to maximize their usage, as there is no longer a consensus among the Japanese public in favor of being heavily dependent on nuclear energy. It is essen-tial that, having comprehensively evaluated the environmental characteristics and economy of these energy resources, we promote research and development from a perspective of the best energy mix. Furthermore, from a viewpoint of energy utili-zation technologies and systems, there is a need to accelerate research and devel-opment on elemental as well as systems technologies covering social systems for improving the overall energy efficiency at the demand side including renewable energies and also for establishing smart energy supply and demand systems to se-cure energy in a time of emergency.
The following is an outline of the main features in each country based on the fields covered in the overview.

JAPAN
Although the fundamental technologies in Japan are on a level well beyond other nations, the fact that there are a declining number of researchers in some fields, such as in coal, is a problem. Moreover, cross-disciplinary cooperation is weak, and the creation of new technologies through joint work between different disciplines tends to lag behind that of the U.S. In the field of applied and development re-search, the industrial sector is making fervent development efforts with help from the government, but only a few of these efforts have widely materialized. With re-gard to renewable energies, a large number of basic and applied research projects on solar energy and biomass have been fruitfully conducted, but efforts to commer-cialize them fall behind those of other nations. Likewise, basic and applied research on geothermal power is widely carried out and technologies are used overseas, but domestically the field is foundering due to policy reasons. With regard to energy utilization, Japan's environmental and energy-saving technologies are globally competitive, but there is a need to conduct research and development pursuing innovative technologies that can be transferred overseas. It is essential that mid- to long-term research and development on usage systems be pursued with a global perspective.

U.S.A.
The basic technology level for fossil resources is high, but overall researchers are somewhat thin on the ground. However, the U.S. is a fruitful soil for nurturing in-novative technologies, and there is a base for optimism regarding future innova-tions. Application and commercialization is being pursued through the expansion of existing technologies overseas, while on the other hand the already vibrant basic and applied research on geothermal and solar energy is also moving healthily to-wards commercialization. A dexterous research and development system for bio-mass has led to high-level basic and applied research, and its commercialization is proceeding. In the field of energy usage technologies and systems, America's basic research is advancing, but its applied research and commercialization is just mid-dling. In the light of the deterioration of its infrastructure and from the perspective of fostering new industry, the Department of Energy (DOE) is at the center of some wide-ranging strategic initiatives covering both basic and applied research.

EUROPE
Large-scale projects under the Seventh Framework Programme (FP7) and so on are being pursued, and there is a good depth and balance in the region's basic and applied research and industrialization. Floating wind turbine research and devel-opment is very advanced, centering on the efforts of the United Kingdom, Norway and Holland, and industrialization is proceeding well. The industrialization of ge-othermal power in Iceland is advancing, but not much effort is being put into re-search and development. In the field of solar power, research and development re-lated to sub-Saharan Desertec initiatives is being pursued. Regional networks for electricity and gas are being constructed, including those in Eastern Europe and Russia. In the fields of individual usage technologies too, the transport engine technologies are the best in the world, and there is a positive attitude to the intro-duction of renewable energies, which is being accelerated as social systems.

CHINA
The level of basic research in fossil resource field is not particularly high, but there is an ongoing introduction of technologies from overseas politically guided by concentrated investment, and further progress is expected in the future. Although basic and applied research and industrialization regarding conventional solar power technologies are steadily growing, there is very little research into next-generation solar cells. Efforts ranging from basic research to industrialization are numerous in the field of solar thermal energy. As in South Korea, the technol-ogy transfer from overseas is rapid, the domestic research setup is starting to ex-pand, and it is quite feasible that the quality of environmental and energy tech-nologies in China will one day be on a par with those of the developed nations. In terms of energy usage, China faces many issues, not least of all its environmental problems, and it is about 20 to 30 years behind Japan.

SOUTH KOREA
With the exception of the field of steelmaking, efforts toward fossil fuels are sparse. Again, as is the case in China, while there is a steady growth in basic and applied research and industrialization regarding conventional solar power tech-nologies in South Korea, hardly any research into next-generation solar cells is visible. Their incorporation and industrialization capabilities of industrial ele-mental technologies of Japan, the U.S. and Europe are high, and these are being put to good use in expert industries. The creation of domestic systems is, as is the case in Japan, something for the future; but South Korea's consolidation of its industries and its excellence in implementing strategic policy are strong points worth continuing observation.