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The explosive increase in the state-of-the-art knowledge and case examples on life cycle assessment has made their comprehensive understandings much difficult. While the attainable system options on society, economic, and technology are complexly intertwined with each other, the viewpoints of their assessment have also been diversified. In this study, the requirements on technology assessments based on life cycle thinking are discussed through a bibliometric analysis of existing academic papers. Academic landscape system was applied for the bibliometric analysis of 19,327 papers including article, review, and letter published on Web of Science containing the terms, i.e., “life cycle assessment”, “life cycle analysis”, or “life cycle thinking” in their title, keyword, or abstract. The citation networks among the papers were visualized as clusters by text mining and network analysis for four groups based on the publication periods, i.e., – 2005, 2006 – 2010, 2011 – 2015, and 2016 – 2019. Since the target products, i.e., food, renewable energy, and biomass, and viewpoints, i.e., land use, water use and consumption, and the nexus among indicators, have become more and more complicated and diversified, it is definitely vital to address the adequate settings of methods, system boundary, functional unit, and data collection.

In evaluating technologies and systems, techno-economic analysis as well as life cycle assessment is of importance. In this paper, manufacturing cost, profit and business profitability evaluation are briefly introduced as an example of techno-economic analysis, and recent trends in techno-economic analysis in academic papers are showed by a bibliometric analysis of energy related technologies. In addition, a techno-economic analysis when introducing to overseas a novel system for sugar, ethanol and electricity production from high-yielding sugarcane was taken up as a case study, and various issues based on examples are introduced.

Lots of projects on technology development are actively conducted around the world. In such projects, the magnitude of contribution in realizing a transformation of the society into a sustainable condition is important as well as their economic feasibility. Therefore, it is often required to describe the advantage of the technology in achieving the envisioned transformation. Here, I describe the basic of an approach to formulate technology choice problem as an extension of conventional life cycle assessment, using a numerical approach. The potentials of assessment taking advantage of the constructed model is discussed.

This paper concisely reviews a variety of methods for technology assessment in a wide range of fields and points out that technology assessment is a multi-tiered concept. The word “technology assessment” was born in the United States of America in the 1960’s and then many methods for assessing technologies have been developed and implemented. The concept of technology assessment is composed of three elements: assessment of engineering characteristics of technology, assessment of social characteristics of technology and assessment of social values of technology. A better understanding of the concept of technology assessment provides a chance to discuss what type of technology assessment is required and what role it should play towards creating a sustainable society.

Japan faces serious energy issues such as high dependency on fossil resources from abroad and slow introduction of renewable energy. Although technological progress is urgently needed to solve these issues, consumers need to select energy in an appropriate way in terms of environmental and economic aspects. These actions require energy literacy which is the foundation for achieving acceptable and novel energy systems. Therefore, we need to discuss how all citizens can be energy literate. This study focuses on future decision-makers in energy choices, being high school students in Tanegashima High School located in Kagoshima Prefecture, Japan. In particular, it aims to examine how effectively energy education （‘workshop’） affects energy literacy including knowledge, affective and behavioural domains as well as their preferences and its willingness-to-pay in terms of selecting electricity plans by choice experiment questions. It is concluded that the active learning method used in the workshops had positive impacts on the students’ knowledge about energy; however, these students did not exhibit significant affective, behavioural, and preference changes after the workshops.

Taking an approach with Input-Output （IO） models to analyze local socio-economic effects induced by implementation of technologies and policies requires localized IO Tables （IOTs） that better reflect regionally-specific economic structures. Because a complete localization is costly, it is necessary to prepare them with various assumptions on localization. Here, we examine discrepancies caused by variants of IOTs, with a case study of an envisioned transformation to decentralized energy system on Tanegashima. Three variants of IOTs were prepared; local scope （Case I, benchmark）, prefectural scope （Case II） and a hybrid scope that is localized for a limited number of sectors while others taking the prefectural scope （Case III）. The increase in the total output induced by the transformation of energy system was 27.2% underestimated in Case II compared with Case I. This was caused by incorrect input structure in small number of sectors that supply resources to decentralized energy sectors. Therefore Case III which improved the input structure successfully reduced the discrepancies （+7.4% to Case I）. For analyses on implementation of decentralized energy system, a hybrid approach that elaborates on resource-supplying sectors can provide a reasonably good forecast to local decision makers with a significantly less cost than preparing completely localized IOT.

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