The “Energy Security” concept has played the central role in Japan's energy policy. However, the definition of the concept is not clear. Though the concept was referred in policy documents as early as in the 1960s, it was established after the first oil crisis in 1973 as preparedness to cope with sudden reduction or disruption of energy imports. Energy security continued to be the primary goal for Japan's energy policy during the period of oil crises in the 1970s, although its meaning had already started to change to include long-term stable supply of energy. After the oil crises, energy security lost the utmost importance as a policy target. It was ranked with cost reduction in the mid-1980s, then with global environmental protection in the 1990s. Its meaning had changed further in the 1990s to imply the necessity of energy demand reduction. Recent years, however, energy security is regaining public attention.
The energy security concept has changed in accord with energy situation and policymakers' concern of the times. As a result, it is partly in confusion. The issues appeared in its historical changes should be addressed in order to conceptualize energy security and systematize related policy measures.

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We have carried out the examination of producing the hydrogen expected as the next energy source using high temperature and high pressure solid polymer water electrolysis system. Furthermore, developing the electrolysis cell which is durable for any power source by selecting the solar cell as the power source with the fluctuation, we obtained the satisfactory results in the examination.

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The saccharification of waste paper such as old handbill using hot compressed water (HCW) was carried out in a batch reactor of 6ml inner-volume and a semicontinuous reactor of 28ml inner-volume. Hindrance effects of added amount and particle size of calcium carbonate and promotive effect of several additives on saccharification of waste paper were examined. It was demonstrated that the sodium pyrophosphate and aluminum phosphate have a remarkable promotive effect in saccharification of a model system, mixture of cellulose and calcium carbonate powder with a few decades microns. However, sodium pyrophosphate and aluminum phosphate were slightly effective for waste paper compared to the model system, because of highly reactive nanosized calcium carbonate contained in the waste paper.
It was suggested that organic acids formed from cellulose at an initial stage of the saccharification reacted with nanosized calcium carbonate prior to hydrolysis of cellulose by HCW, and that as the result, pH of the reaction solution was raised up and thermal decomposition of saccharide was promoted.

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Progress of coal liquefaction was observed and analyzed for Tanito Harum coal heated in the preheater of 1t/d Process Supporting Unit (PSU) for the NEDOL Process. Direct measurement of the slurry temperature and sampling of the preheater effluents were conducted to obtain data necessary for the analysis. Interest has been focussed on preparation of basic design data on initial-stage coal liquefaction as well as product distributions at the preheater outlet which could be utilized as the inlet boundary conditions for the first-stage liquefaction reactor.
The results showed that decomposition of tetrahydrofuran insoluble component rapidly proceeds within the preheater. The actual residence time of coal slurry in the preheater was determined from the time required for complete replacement of the recycling solvent with the coal slurry, which was detected as variation of the pressure drop through the preheater along with the replacement. The residence time was utilized to estimate the slurry temperature distribution along the preheater and the progress of liquefaction. As a result, it was indicated that the rapid decrease in IOM (Insoluble Organic Matter: THFI) is reasonably explained by assuming coal to consist of reactive and less-reactive components.

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Progress of coal liquefaction was analyzed in the first reactor of 1t/d Process Supporting Unit (PSU) for development and optimization of the NEDOL Process. The reaction progress was evaluated by analyzing the composition of reactor content directly sampled as well as that of sample from the gas-slurry separator immediately after the reactor.
The yield of oil, i.e., the hexane-soluble fraction, in the reactor was found to reach nearly 55wt%daf, which amounted more than 95% of the final yield attained in the normal operation using the three reactors. Increase in the reaction temperature and/or the feed ratio of gas to slurry (G/L) resulted in a prolongation of the actual residence time of slurry in the reactor with appreciable decrease in the residue yield and increase in the oil yield. This was reasonably explained by a mechanism that the increased temperature and/or G/L would accelerate evaporation giving rise to a slight increase in the gas-phase holdup and a significant decrease in the slurry-phase flow rate in the reactor. Based on those results, progress of coal liquefaction in the reactor was kinetically analyzed, focussing on change in yield of IOM (Insoluble Organic Matter).

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