Ayami Hayashi

Risk of Hunger Under Climate Change, Social Disparity, and Agroproductivity Scenarios

Considering the projected population growth in the twenty-first century, some studies have indicated that global warming may have negative impacts on the risk of hunger. These conclusions were derived based on assumptions related to social and technological scenarios that involve substantial and influential uncertainties. In this paper, focusing on agrotechnology and food access disparity, we analyzed food availability and risk of hunger under the combined scenarios of food demands and agroproductivity with and without climate change by 2100 for the B2 scenario in the Special Report on Emissions Scenarios. The results of this study suggest that (1) future food demand can be satisfied globally under all assumed combined scenarios, and (2) a reduction of food access disparity and increased progress in productivity are just as important as climate change mitigation for reducing the risk of hunger.

A model-based analysis on energy systems transition for climate change mitigation and ambient particulate matter 2.5 concentration reduction

One of the most serious concerns facing developing countries is high concentrations of ambient particulate matter (PM2.5). Concurrently, climate change has also been a major challenge for countries around the world. Energy systems are dominant emission sources of both PM2.5 and carbon dioxide (CO2). This study investigates cost-efficient energy system transitions for individual or dual targets of climate change mitigation and PM2.5 concentration reduction by a global energy systems model. We set two levels of mitigation efforts for each of the CO2 and PM2.5 emissions, whose stringent one corresponds to the long-term target of the Paris agreement and current national air quality standards, respectively. For PM2.5 reduction, a combination of moderate improvement in energy efficiency and a transition from coal to gas and renewable energies and a significant deployment of end-of-pipe measures for scrubbing air pollutants is shown to be among the most cost-efficient strategy. For CO2 reduction, drastic improvement in energy efficiency and a rapid transition from coal to gas, renewable and nuclear energies is the most cost-efficient strategy, in contrast. There is a larger co-benefit on PM2.5 concentration reduction from CO2 reduction measures than the converse, and the co-benefit varies regionally. Developing countries such as India have a huge potential of co-benefits, and energy efficiency improvement and fuel switching are key measures to bring them. The simultaneous achievement costs of the dual targets are smaller than the sum of individual achievement costs, and the cost reduction varies significantly depending on the level of each mitigation target.

A global analysis of residential heating and cooling service demand and cost-effective energy consumption under different climate change scenarios up to 2050

Climate change and energy service demand exert influence on each other through temperature change and greenhouse gas emissions. We have consistently evaluated global residential thermal demand and energy consumption up to the year 2050 under different climate change scenarios. We first constructed energy service demand intensity (energy service demand per household) functions for each of three services (space heating, space cooling, and water heating). The space heating and cooling demand in 2050 in the world as a whole become 2.1–2.3 and 3.8–4.5 times higher than the figures for 2010, whose ranges are originated from different global warming scenarios. Cost-effective residential energy consumption to satisfy service demand until 2050 was analyzed keeping consistency among different socio-economic conditions, ambient temperature, and carbon dioxide (CO2) emission pathways using a global energy assessment model. Building shell improvement and fuel fuel-type transition reduce global final energy consumption for residential thermal heating by 30% in 2050 for a 2 °C target scenario. This study demonstrates that climate change affects residential space heating and cooling demand by regions, and their desirable strategies for cost-effective energy consumption depend on the global perspectives on CO2 emission reduction. Building shell improvement and energy efficiency improvement and fuel fuel-type transition of end-use technologies are considered to be robust measures for residential thermal demand under uncertain future CO2 emission pathways.

Evaluation of co2 Capture Technology Developments by Use of Graphical Evaluation and Review Technique

Publisher Summary This chapter describes analyses which were made, using Graphical evaluation and review technique (GERT), to evaluate R&D (research and development) processes of several CO2 capture technologies having different levels of energy efficiency. Five types of the technologies are studied for evaluation: chemical absorption, physical adsorption, membrane separation, O2/CO2 recirculation boiler, and integrated hydrogen separation gas turbine technologies. Various kinds of CO2 capture technologies applicable for thermal power plants have been investigated which are expected to be commercially operated within 20-30 years, when CO2 sequestration will be an acceptable option to mitigate CO2 emissions. Their development requires a wide range of elemental technologies and also require huge amounts of R&D (research and development) investment. Thus, evaluation of R&D processes is of great importance.